International conference on Frontiers in Chemical Technology 2020 (FCT 2020)

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Antibacterial activities of peptaibols, trichocellin A-I and B-II, isolated from the endophytic fungus Trichoderma reesei
(Institute of Chemistry Ceylon Adamantane House, Rajagiriya, Sri Lanka., 2020) Madhushika, D. P. H.; Jayasundara, J. M. N. M.; Ratnaweera, P. B.; Williams, D. E.; de Silva, E. D.; Andersen, R. J.
Antibiotics are highly used in chemotherapy for bacterial infections worldwide. However, due to misuse and overuse of antibiotics pathogenic bacteria have developed and continue to develop resistance to the existing antibiotics rendering them ineffective. Thus there is an urgent need to develop new types of antibiotics to counter the spread of these lethal, drug resistant infections. Endophytic fungi of Cyperaceae plants are a relatively unexplored but a significant resource for the discovery of new biologically active natural products. Therefore, the main objective of this study was to isolate bioactive secondary metabolites of the endophytic Trichoderma reesei (GenBank accession number MT476871) fungus isolated from Cyperus iria in Sri Lanka. Initial screening of T. reesei showed antibacterial activity against the Gram positive Bacillus cereus and Staphylococcus aureus at 400 μg/mL. T. reesei was grown in large scale and extracted into ethyl acetate following an incubation period of 13 days. Solvent-solvent partitioning of the crude extract (1005 mg) led to an active chloroform fraction (580 mg), which was chromatographed on Sephadex LH20 size exclusion column chromatography. The active fraction B (143 mg) from the six fractions (A-F) obtained from size exclusion chromatography was further purified via C18 reversed-phase high performance liquid chromatography (HPLC) to yield two peptaibols. The structures of the peptaibols were determined as trichocellin A-I and B-II by nuclear magnetic resonance (NMR) and mass spectral data. Both peptaibols A-I and B-II were active against the two Gram positive bacteria tested with minimum inhibitory concentrations (MICs) of 64 and 8 μg/mL for B. cereus and 32 and 16 μg/mL for S. aureus respectively. The positive control Gentamycin gave a MIC of 2 μg/mL for both bacteria. To the best of our knowledge this is the first study to isolate trichocellins from an endophytic T. reesei fungus. The study revealed that the isolated trichocellins from T. reesei are potent antibacterial compounds.
Nitric oxide radical scavenging potential of selected widely used spices and in a mixture of spices
(Institute of Chemistry Ceylon Adamantane House, Rajagiriya, Sri Lanka., 2020) Wickramaratna, H. D. P.; Amarasiri, A. M. S. S.; Attanayake, A. P.
A remarkable research interest has been shown on phytochemicals in spices and their bioactivities during the last decade. Nitric oxide (NO) radical scavenging potential is one of the assays used in the determination of in vitro antioxidant activity. The study aims to determine NO radical scavenging potential of the aqueous extracts of ten selected Sri Lankan spices and a mixture of spices made from five selected spices with high NO scavenging potential. The spices were randomly collected within the areas of Sabaragamuwa and Southern provinces from their natural habitats. L-ascorbic acid was used as the reference compound in the assay. The NO radical scavenging potential were estimated following the standard protocol using a spectrophotometric assay. The half maximal inhibitory concentration (IC50) was calculated using regression analysis and the values were expressed as mean ± standard deviation (SD) of the three analytical triplicates. IC50 values of the selected spices were 269.33 ± 2.21 μg/mL (Piper nigrum), 270.24 ± 4.23 μg/mL (Curcuma domestica), 279.85 ± 1.62 μg/ mL (Elettaria repens), 288.88 ± 0.87 μg/mL (Myristica fragrans), 292.59 ± 11.83 μg/mL (Zingiber officinale), 322.05 ± 2.13 μg/mL (Eugenia caryophyllata), 341.11 ± 1.39 μg/mL (Cinnamomum verum), 355.94 ± 2.98 μg/mL (Cymbopogon citratus), 356.32 ± 1.31 μg/mL (Brassica integrifolia) and 394.19 ± 3.87 μg/mL (Capsicum frutescens). There was a statistically significant difference in between ten spices (p<0.05). The spices which showed the highest NO radical scavenging potential (lowest IC50) were selected for the mixture. Accordingly, P. nigrum, C. domestica, E. repens, M. fragrans and Z. officinale were selected. The mixture showed the highest NO radical scavenging potential with the lowest value of IC50 (256.42 ± 0.22 μg/mL) compared to the individual spices. Based on the results, all selected extracts of spices possess NO scavenging potential and the mixture showed the highest activity.
Comparison study of the oxalate content in commonly used green leafy vegetables
(Institute of Chemistry Ceylon Adamantane House, Rajagiriya, Sri Lanka., 2020) Liyanage, J. V.; Jayasundara, U. K.
Consumption of large amount of oxalate could be harmful because of the formation of calcium oxalate deposits in vital tissues or organs of the body. Patients with kidney stone problems are advised to limit dietary oxalate intake to 40-50 mg per day. In this study, commonly consumed green leafy vegetables (GLVs) such as spinach, Gotukola, cup leaves, Mukunuwanna, leeks, Kangkung, Hathawariya, Minchi, Kathurumurunga, Thebu, curry leaves, Bulath, manioc, cabbage and salad leaves were studied gravimetrically to determine the oxalate content. Edible portion of plant material was air dried, homogenized, refluxed for 12 hours, filtered, extracted with analytical grade diethyl ether, saturated with a calcium solution and then separated. The diluted and acidified solution with distilled water was titrated with standard KMnO4 assuming oxalate was the only oxidizable species. The experiments were carried out in triplicate for each species. Only a very few related studies are available in literature and the results were comparable. The results revealed that oxalate contents in GLVs ranged from (556.04 ± 1.60) mg to (3.20 ± 2.45) mg per 20 g of raw GLV portion. Also, the results confirmed that the GLVs can be divided into four categories based on the oxalate content as high (> 200 mg), medium (199 mg – 100 mg), low (99 – 10 mg) and undetectable (< 10 mg). Hathawariya, spinach, curry leaves and Kankung showed the highest amount of oxalate ranging from 556.04 ± 1.60 to 238.04 ± 1.84 mg per 20 g, while cabbage, salad leaves and leeks showed undetectable amount of oxalate ranging from 7.47 ± 1.84 to 3.20 ± 2.45 mg. It is interesting to note that commonly consumed GLVs by Sri Lankans have detectable amount of oxalate content which exceeds the minimum advisable level according to American Diabetes Association. Adding such GLVs to meal along with calcium supplements may worsen the health condition of kidney stone patients.
Bioaccumulation of nephrotoxic metals in rice grains (Oryza sativa) in a CKDu hotspot in Sri Lanka via soil analysis
(Institute of Chemistry Ceylon Adamantane House, Rajagiriya, Sri Lanka., 2020) Dayananda, M. D. N. R.; Liyanage, Janitha A.
Accumulation of nephrotoxic metals in edible crops and associated soil is a major international concerns today which results food safety issues and adverse health risks like CKDu. Soils are considered to be an excellent media to monitor and assess chemical pollution where the application, deposition and absorption of chemicals are taken place. Therefore, this study attempts to investigate the bioaccumulation of nephrotoxic metals in soil and rice grains (Oryza sativa) and to interpolate the spatial distribution of selected chemical elements using Inverse Distance Weighted (IDW) and Spatial Autocorrelation tools in ArcMap 10.2.2 software in a CKDu hotspot; Girandurukotte Grama Niladhari Division (GND), Badulla, Sri Lanka via soil analysis. Dambethalawa GND in Ampara district was selected as the reference site. 30 soil samples were collected according to random stratified design including 10 paddy cultivated sites and 10 composite rice grain samples were collected from those paddy fields separately. Microwave digested soil and rice samples were analyzed by inductively coupled plasma mass spectrophotometry. The average concentrations of Cd, Pb, As, Cr, Ca and Mg in soil were 0.45±0.02, 0.20±0.02, 0.65±0.25, 0.29±0.04, 4812.00±692.00, and 15157.00±1275 mg/kg respectively. According to the lower Moran’s indices given by the Spatial Autocorrelation, the selected metals were evenly distributed throughout the sampling area and Cd, Pb, Ca and Mg contents in CKDu prevailed area was significantly higher (p<0.05) than the reference. The higher bioaccumulation factors (from soil to rice grain) (BCF>1) indicated that rice grains tend to accumulate the nephrotoxic metals including Cd;2.35, Pb;7.48, As;2.60 and Cr;5.80. The calculated Enrichment factors (EF) which derives the degree of soil contamination by nephrotoxic metals were Cd;6.49, Pb;6.01, As;1.30 and Cr;1.48 and greater EFs (EF>1) indicates higher availability and distribution of metals in contaminated soil when compared to the reference. It can be concluded that the degree of soil contamination by nephrotoxic metals was higher in the selected CKDu hotspot than the reference. Hence, human renal dysfunctions can be related with consumption of contaminated rice with those metals.
Insight into the mechanism of the catalysis of urethane formation by organotin(IV) dicarboxylate using experimental and computational methods
(Institute of Chemistry Ceylon Adamantane House, Rajagiriya, Sri Lanka., 2020) Devendra, Ransi; Edmonds, Neil R.; Söhnel, Tilo
Polyurethane is made by reacting a polyisocyanate with a polyol. Organotin dicarboxylates are used as catalysts for this reaction. However, a deeper understanding of the mechanism in catalysis is essential in the polyurethane product manufacture. Although catalysis of aromatic and aliphatic isocyanates using organotin dicarboxylate in urethane formation was claimed to have the same mechanism for both, our work showed that they were different. In this work, we investigated urethane formation for both aliphatic and aromatic isocyanates in the presence of different organotin carboxylate compounds as catalysts using experimental and computational methods. In experimental methods, kinetic studies and FTIR analysis were used. As the computational method, the DFT/B3LYP-D3 functional with the LANL2DZ basis set for tin and the 6-31G* basis set for light elements was used. The results from the experimental and theoretical studies showed that an alkoxide complex was formed initially by the interaction between organotin di-carboxylate catalyst and alcohol. Then the interaction between alkoxide complex and isocyanate molecule was modelled using a computational method. This interaction resulted in the formation of organotin carbamate and carboxylic acid. Then the newly formed organotin carbamate was computationally modelled to interact with alcohol or carboxylic acid to form the urethane and to regenerate the active catalyst. By using thermochemical data from the computational investigation, it was possible to show that aliphatic isocyanates can be more sensitive to the carboxylic ligand content of the organotin carboxylate catalyst compared to aromatic isocyanates in urethane formation. Based on these findings, different mechanisms for aromatic and aliphatic isocyanates in urethane formation can be proposed when an organotin dicarboxylate is used as a catalyst. The new knowledge from our studies was essential to minimize the viscosity increase in storage of urethane pre-polymer when synthesised using organotin dicarboxylate as the catalyst.
Polyethylene degradation capability of Schizophyllum commune
(Institute of Chemistry Ceylon Adamantane House, Rajagiriya, Sri Lanka., 2020) Perera, T. W. N. K.; Attanayake, R. N.; Paranagama, P. A.
Tremendous increases in the manufacture and consumption of polyethylene, over recent decades have led to numerous environmental and economic concerns. This is the first comprehensive research on determination of Endolichenic Fungi (ELF), capable of degrading polyethylene substrates. The objective of this study was to identify the ability of various ELF, for the degradation of polyethylene in liquid media. Commercially available Low Density Polyethylene (LDPE) bags were used as the test material. ELF isolates cultured on Potato Dextrose Agar, were introduced into Mineral Salt Medium Broth containing LDPE strips. The isolate, Schizophyllum commune showed a positive growth response in the broth medium. The strips treated with this isolate, were tested for the reduction in dry weight, changes in peaks of Attenuated Total Reflection-Fourier Transform Infrared (ATR-FTIR) spectroscopy, reduction in tensile strain at break and changes in Scanning Electron Microscopic analyses. Results showed that isolate, reduced the weight of LDPE strip by 10.54%, after 21 days of incubation, while control showed 0% reduction. The control LDPE strip on ATR-FTIR analysis showed prominent peaks at 2916 cm-1, 2848 cm-1, 1463 cm-1 and 720 cm-1. Changes visible in sample infrared spectra after 21 days of incubation, were the fluctuations in the percentage transmittance of above peaks and formation of new peaks at 1740 cm-1, 1215 cm-1 and 1046 cm-1. The tensile strain at break, of treated strips, reduced by 27.41%, after 21 days of incubation while control showed 0% reduction. The presence of pits and cavities, in Scanning Electron Micrographic images, suggested the penetration of fungi, into the LDPE matrix, during degradation. The occurrence of several nonuniformly scattered whitened areas and erosion zones, indicated the surface erosion of LDPE strips, in degradation. These changes were not observed in the control LDPE strips. This study provides insight into the role of Schizophyllum commune towards solving the dilemma of polyethylene wastes, through biodegradation.
In vitro antiglycation and antioxidant activity of the aqueous extract of leaves of Solanum torvum
(Institute of Chemistry Ceylon Adamantane House, Rajagiriya, Sri Lanka., 2020) Irfan, F. A.; Deraniyagala, S. A.
Protein Glycation, is a non-enzymatic process which forms Advanced Glycation End Products (AGEs). Accumulation of AGEs in the body causes health complications, especially those related to diabetes. Oxidative stress is also considered to be a contributing factor for such health complications. The present study was undertaken to look into the inhibitory potential on the formation of AGEs as well as the anti-oxidant potential of the aqueous extract of the leaves of the Sri Lankan variety of Solanum torvum (thibbatu) [AELST].The extract was prepared according to the method of Kasaya preparation in Ayurveda medicine. Fructose mediated Protein Glycation was induced by using Bovine Serum Albumin and fructose in buffer of pH 7.4 to mimic AGE formation. The assay showed that AELST has a 7.7% - 85.1% inhibitory effect on AGE formation at a concentration range of 0.25 - 2.0 mg/mL. Amino guanidine which was the positive control, known to have much side effects showed AGE inhibition from 0%- 87.5% for the same concentration range. The plant extract showed the presence of phenols and flavonoids. AELST also showed a radical scavenging activity between 19.2% - 76.7% in the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay while the standard BHT showed a percentage inhibition of 13.2% - 83.5% for the concentration range of 25-200 μg/mL. In the hydroxyl radical scavenging assay AELST showed a percentage radical scavenging activity of 29.3% - 42.7% while the positive control ascorbic acid showed a percentage inhibition of 24.1% - 36.9% in a concentration range of 0.5 - 2.0 mg/mL. Hydroxyl radical is one of the potent reactive oxygen species in the biological system. The results show that AELST has the potential to be developed to suppress complications arising due to AGE formation in patients with chronic hyperglycemia and also as a remedy to prevent diseases in which radicals are implicated.
Isolation of cysteine-rich peptides from the deep-sea marine sponge Stryphnus fortis and determination of its antimicrobial effect
(Institute of Chemistry Ceylon Adamantane House, Rajagiriya, Sri Lanka., 2020) Kosgahakumbura, K. N. M. L. N; Hettiarachchi, C. M; Jayasinghe, R. P. P. K.; Cárdenas, P.; Gunasekera, S.
Cysteine-rich peptides are a promising resource for a wide range of pharmacological applications such as development of drug leads and as scaffolds for potential oral drug delivery due to their stable disulfide framework. A handful of these compounds have been isolated from marine sponges and it is speculated that plenty of them remain unexplored. In the present study, four peptides A, B, C and D containing three disulfides were isolated from the aqueous extract of the deep-sea marine sponge Stryphnus fortis (Demospongiae, Tetractinellida, Ancorinidae) from Norway, and were further purified using RP-HPLC (Reverse Phase High Performance Liquid Chromatography). The mass spectroscopic analysis using MALDI-TOF (Matrix-Assisted Laser Desorption/Ionization- Time Of Flight) revealed monoisotopic masses of 3331.809 Da [M+H]+, 3349.731 Da [M+H]+, 3517.973 Da [M+H]+, 3917.61 Da [M+H]+respectively for the four peptides A, B, C and D. The antimicrobial activity was screened using a peptide adapted Micro dilution assay against E. coli (ATCC 25922), S. aureus (ATCC 29213) and C. albicans (ATCC 90028) up to a concentration of 50 μM. The average concentration derived from triplicates that exhibited a growth inhibition on visual inspection was considered as the Minimum Inhibitory Concentration (MIC). Moderate antimicrobial activity for peptide C was observed against S. aureus (MIC = 36.14 μM) and C. albicans (MIC = 18.07 μM). However, no inhibition was observed against E. coli up to the highest concentration tested. The human antimicrobial peptide LL 37 was used as the control (MIC value around 1-2 μM). The sequence analysis of the four peptides, their structural characterization and investigation of their potential applications are currently underway.
Determination of water quality and suitability in a chronic kidney disease of unknown etiology (CKDu) prevalence area, Sri Lanka
(Institute of Chemistry Ceylon Adamantane House, Rajagiriya, Sri Lanka., 2020) Botheju, W. S. M.; Liyanage, Janitha A.
Chronic Kidney Disease of unknown etiology (CKDu) is a global health obstacle that is presenting as kidney disease in patients who do not show common causative factors, such as diabetes or hypertension. Although the causative factors and major causes for CKDu prevalence are still in debate, most of the external factors which affect the disease are associated with drinking water. Therefore, this study investigated the water quality and suitability of drinking water in a CKDu prevalence area to assess its suitability for human consumption. The water samples were collected from 30 dug wells in Girandurukotte Grama Niladhari Division (GND), Badulla District which reported the highest number of CKDu patients and from Buddhangala GND in Ampara District (as reference sampling site) in dry season. Dissolved Oxygen (DO), Electrical Conductivity (EC) and Fluoride (F) were analyzed as on-site measurements. Calcium (Ca), Magnesium (Mg), Cadmium (Cd), Arsenic (As) were determined using Inductive Coupled Plasma Mass Spectrometry. Sulphate, Nitrate and Chlorides were analyzed using Ion Chromatography. Each analysis was performed in triplicates. The Water Quality Index (WQI) was calculated using standards of drinking water quality recommended by the World Health Organization (WHO). According to the results, pH, DO, EC, F, Ca, Mg, Cd, Cr, Pb, As, total hardness, sulphate, nitrate and chloride values in Girandurukotte GND were 7.03±0.08, 4.8±0.8 mg/L, 396.9±9.1 μS/cm, 1.64±0.04 mg/L, 1.05±0.90 mg/L, 202.85±5.60 mg/L, 0.124±0.074 μg/L, 54.75±0.54 μg/L, 0.20±0.05 μg/L, 30.64±8.60 μg/L, 83.60±4.02, 60.28±5.62 mg/L, 20.56±8.62 mg/L and 122.65±10.36 mg/L respectively. The results obtained for WQI in Girandurukotte and Buddhangala were 71.84 (51-75 poor) and 42.67 (26-50 good) respectively. Results indicate that water samples analyzed from Girandurukotte are not safe for human consumption and other domestic purposes while the water samples in reference site are safe for human consumption. Therefore, taking all necessary precautionary measures before the consumption can be recommended to avoid adverse health impacts.
Antioxidant, anti-inflammatory and antibacterial potentials of aqueous leaf extract of Pouteria campechiana (Kunth) Baehni (Ratalawulu)
(Institute of Chemistry Ceylon Adamantane House, Rajagiriya, Sri Lanka., 2020) Hettiarachchi, O. I.; Deraniyagala, S. A.; Hettiarachchi, C. M.
Antioxidants are of dietary importance in preventing oxidative stress due to the production of excess free radicals in our body leading to many diseases including cancer, atherosclerosis and diabetes as well in aging. Despite the advances in modern medicine, plant -based remedies play an important role in healthcare due to less side effects. Due to the side effects of NSAIDS and antibiotics, plant -based remedies would be beneficial. This study was conducted to assess the potential use of P. campechiana (Ratalawulu) as an antioxidant, anti-inflammatory and antibacterial agent. The aqueous leaf extract of Ratalawulu was prepared according to the method of decoction preparation in ayurvedic medicine. All assays were carried out according to previously published procedures. Aqueous leaf extract of P. Baehni showed a Total Phenolic Content of 230.71±7.62 mg (PGE)/g in the Folin-Ciocalteu method. Total flavonoid content was 140.98 ± 98.46 mg (QE)/g according to AlCl3 colorimetric assay [PGE- Pyrogallol equivalence, QE- Quercetin equivalence]. 2,2-Diphenyl-1-picrylhydrazyl radical scavenging activity of aqueous leaf extract of P. Baehni ranged between 1.4%-17.8% for concentration between 0.01-0.1 mg/ml whereas ascorbic acid showed 2.46%-43.93% for the same concentration range. Ferric ion reducing assay for aqueous leaf extract of P. Baehni showed gradual increase in reducing property relating to antioxidant action by donating a hydrogen atom to break free radical chains. Hydroxyl scavenging activity showed 5.73%-44.03% for concentration series of 20-100 mg/ ml whereas, Ascorbic acid ranged from 9.40%-47.06%. Hydroxyl radical is one of the potent reactive oxygen species in the biological system. Nitric oxide scavenging anti-inflammatory assay showed 58.06%-75.36% whereas ascorbic acid showed 80.73%-91.76% for concentration series of 0.4-6.4 mg/ ml. In the human red blood cell assay, percentage protection by aqueous leaf extract of P. Baehni was 15.0%-62.4% and that of ascorbic acid was 12.1%-72.8% for 6.0-300 μg/ml. Aqueous leaf extract of P. Baehni also showed antibacterial activity against Staphylococcus aureus. Taken together, these results suggest the potential use of aqueous leaf extract of P. Baehni as an antioxidant, anti-inflammatory and antibacterial agent, and merit further related investigation.
Development of a face and body cleanser using Cocos nucifera (coconut) oil, coconut shell charcoal and rice husk charcoal
(Institute of Chemistry Ceylon Adamantane House, Rajagiriya, Sri Lanka., 2020) Jayasooriya, J. A. C. T.; Udawatte, C. S.
Air pollutants and toxic elements can directly affect the skin as it is the outermost barrier protecting the body. In this study, a cleanser was formulated using charcoal, virgin coconut oil, and other local ingredients. An artificial sweat solution including NaCl, NH4Cl, acetic acid, lactic acid was treated with coconut shell charcoal (CSC) and rice husk charcoal (RHC) varying the particle size, dosage, and the contact time with the solution, in triplicates. The remaining organic acids, NH4 +, and Na+ were determined by formalin titrimetric method and flame photometry. CSC having the particle size of 0.25-0.50 mm exhibited higher adsorption towards the two main components in human perspiration; NaCl and NH4Cl than RHC, at an average contact time of 30 minutes. Therefore, CSC was used as the adsorbent. Virgin coconut oil was used as a moisturizer, an antioxidant, an emulsifying agent, sodium lauryl ether sulfate as the foaming agent and bee’s honey as the binding agent, a thickener, an antimicrobial and a humectant. Other ingredients used were kaolinite, sesame oil, and sweet orange essential oil. The pH of the product was 6; therefore, pH balanced. The product showed significant antibacterial activity against Staphylococcus aureus, Bacillus subtilis, and Pseudomonas aeruginosa when subjected to agar well diffusion method. The highest result was observed against Staphylococcus aureus, giving an inhibition zone of 2.5 cm for 100 mg of the product, while 5 μg of Ciprofloxacin showed an inhibition zone of 3.0 cm. The product was easily spreadable, washable, and had a thick consistency. Patch test was done by applying 400 mg of the product on the dorsal forearm of 10 volunteers with a diameter of 1 inch, for 30 minutes, then rinsed off with water. No adverse effects were exhibited. Therefore, this product can be considered safe, and it achieves the desired attribute as a cleanser.
Effect of fertilizer application to the agricultural soil and the determination of soil to plant transfer coefficients of selected elements
(Institute of Chemistry Ceylon Adamantane House, Rajagiriya, Sri Lanka., 2020) Perera, W. P. R. T.; Dayananda, M. D. N. R.; Botheju, W. S. M.; Liyanage, Janitha A.
Transfer of metals from soil to plant depends on the availability of particular elements in soil and the fertilizer which are applied to the agricultural fields. This study aims to determine the effect of fertilizer application to the agricultural soil and to determine the soil to plant transfer coefficients of selected elements in Eppawala Grama Niladhari Division (GND), Anuradhapura, Sri Lanka. Fifteen soil and rice root samples were randomly collected from paddy fields and composite fertilizer samples were prepared by adding Urea, Muriate of Potash and Rock Phosphate in the ratios which were used by farmers in sampled area. Metals were analyzed by Inductive Coupled Plasma Mass Spectrometry (ICP-MS-Agilent 7800). Mean concentrations of Cr, Fe, Cu, As, Cd, Pb and Zn in fertilizer composites were 445.00±171.00, 114638.00±46722.00, 92.90±38.40, 178.00±109.00, 5.56±3.41, 912.00±534.00 and 2553.00±1452.00 in mg/kg respectively. Mean concentrations of Cr, Fe, Cu, As, Cd, Pb and Zn in soil samples were 0.22±0.03, 135.10±38.90, 1.37±0.16, 0.25±0.30, 0.01±0.00, 0.32±0.07 and 40±10.3 in mg/kg respectively. The transfer coefficients (TC) of different metals were quantified to indicate the lability of metals in soils. Greater TC value indicates relatively poor retention of metal in soil or greater efficiency of plant roots to absorb metal, and low TC is attributed to strong sorption of metal to the soil colloid. TCs from soil to roots for Cr, Fe, Cu, As, Cd, Pb and Zn were 62.14, 260.04, 46.93, 6.94, 21.26, 14.14 and 3.37 respectively. It indicates that rice roots absorb higher amounts of metals in soil colloids which are resulting mostly from the fertilizer applications. It can be concluded that considerable amount of metals coming from the fertilizers are remaining in the soil and the efficiency of absorbing metals from plant roots is higher than the retention of metals in soil as having greater Transfer Coefficients.
Antibacterial activity of entomopathogenic fungi isolated from Vespa affinis and Apis dorsata in Sri Lanka
(Institute of Chemistry Ceylon Adamantane House, Rajagiriya, Sri Lanka., 2020) Sandeepani, H. P.; Ratnaweera, P. B.
Antibiotic resistance of bacteria throughout the world has caused serious health issues. Thus, there is a crucial need for the discovery and development of new antibiotics. Entomopathogenic fungi infect and eventually kill their host insects. However, entomopathogenic fungi are known to be a rich source of bioactive secondary metabolites. The main aim of the current study was to isolate and investigate the antibacterial activities of entomopathogenic fungi of two insect species Apis dorsata and Vespa affinis collected from Uva Wellassa University library premises, Badulla, Sri Lanka (810 4’ E, 60 58’N). Freshly dead insect cadavers were collected, surface sterilized, crushed and spread on antibiotic (Amoxicillin, 10 mg/mL) enriched potato dextrose agar media plates. The emerging fungi were isolated, pure cultures were obtained and extracted into ethyl acetate. The fungal crude extracts were tested for antibacterial activity against Staphylococcus aureus (ATCC 25928), Bacillus cereus (ATCC 11718), Escherichia coli (ATCC 35218) and Pseudomonas aeruginosa (ATCC 9027) using agar disc diffusion method (400 μg/disc) and bioautography. The experiments were carried out in triplicate. For the identification of fungi, genomic DNA were isolated, the ITS region of the ribosomal RNA gene was amplified using ITS1 and ITS4 primers, the obtained PCR products were sequenced and BLAST analyzed. Nine morphologically different entomopathogenic fungal strains were isolated from A. dorsata while eight were isolated from V. affinis. Thirteen fungal extracts showed antibacterial activity against at least one bacterial species tested while four extracts were inactive to all bacteria. Ten, eight and nine fungal extracts showed some activity against S. aureus, B. cereus and E. coli respectively while none of the extracts showed any activity against P. aeruginosa. Talaromyces versatilis fungal extract from A. dorsata showed the best inhibition with a mean diameter of 13.00 ± 1.00 mm against E. coli with an activity similar to the positive control (Gentamycin, 1000 ppm). The bioautography assays revealed that T. versatilis and an Aspergillus extracts were active against S. aureus while A. nomius extract was active against B. cereus. The FTIR analysis and thin layer chromatography studies exhibited the presence of many secondary metabolites in all fungal crude extracts. This study shows that entomopathogenic fungi of V. affinis and A. dorsata are potential sources for the discovery of novel antibacterial drug leads.
Effect of a herbal capsule of Coccinia grandis (L.) Voigt (Cucurbitaceae) on lipid profile in patients with newly diagnosed type 2 diabetes mellitus
(Institute of Chemistry Ceylon Adamantane House, Rajagiriya, Sri Lanka., 2020) Wasana, K. G. P.; Attanayake, A. P.; Weerarathna, T. P.; Jayatilaka, K. A. P. W.
Herbal antidiabetic agents have been popular among general population due to their historical usage along with the exceptional therapeutic efficacy. The present study was aimed to determine the effect of a newly developed herbal capsule of C. grandis, which consists of freeze dried powder of the hot water extract of C. grandis leaves, on lipid profile in patients with newly diagnosed type 2 diabetes mellitus (T2DM). Three months long, placebo controlled, double blind, randomized clinical trial was conducted involving 147 individuals with newly diagnosed T2DM. Patients with known renal, liver, cardiac, respiratory, thyroid, psychiatric and any other chronic or acute diseases, and pregnant women were excluded. Individuals are using antilipidaemic drugs were also excluded. Selected individuals were randomly allocated into two groups of test and control. The test group received newly developed herbal capsule of C. grandis (500 mg) and the control group received placebo capsule (500 mg) once daily for three months. Serum lipid profile consisting of total cholesterol (TC), high density lipoprotein cholesterol (HDL-C), low density lipoprotein cholesterol (LDL-C), triglyceride (TG) and very low density lipoprotein cholesterol (VLDL-C) was estimated at the base line (week=0) and at the end of intervention (week=12). Independent sample t-test was used to compare the two groups. A percentage reductions of TC, LDL-C, TG and VLDL-C were 2.12%, 3.51%, 27.36% and 27.36% respectively and increment of HDL-C (1.92%) was observed in herbal capsule treated group. The results of the t- test revealed that TG (p=0.003) and VLDL-C (p=0.003) are significantly decreased in the herbal capsule treated group. There were no statistically significant changes (p>0.05) in TC, HDL-C and LDL-C between two groups. In conclusion, 500 mg of herbal capsule of C. grandis is beneficial in reducing elevated TG and VLDL-C in lipid profile of patients with newly diagnosed T2DM.
Antibacterial cytochalasin B from endophytic Curvularia lunata isolated from Cyperus iria of Sri Lanka
(Institute of Chemistry Ceylon Adamantane House, Rajagiriya, Sri Lanka., 2020) Kumarasinghe, K. H. T. P.; Pavalakantharasa, T.; Jayasundara, J. M. N. M.; Ratnaweera, P. B.
Antibiotic resistivity of bacteria has been increasing rapidly over the last few decades and currently it has become a severe human health crisis in the world. Therefore, isolating novel antibacterial drug leads from natural sources has become an essential requirement in today’s world. Thus, the main aim of the current study was to isolate the antibacterial compounds from the endophytic fungus Curvularia lunata isolated from an underutilized plant Cyperus iria of Sri Lanka. During a preliminary research C. lunata fungal extract showed antibacterial activity against Gram positive Staphylococcus aureus and Bacillus cereus. Hence the fungus was grown in large scale in 140 Petri dishes and was extracted to ethyl acetate after 21 days of incubation. The ethyl acetate crude extract (354 mg) obtained was purified using bioassay guided fractionations using a series of solvent/ solvent fractionations, Sephadex LH20 size exclusion chromatography using methanol as the eluent, normal phase silica gel chromatography using a gradient elusion and finally by reversed phase high performance liquid chromatography to isolate the major bioactive compound. The structure elucidation using 1H, 13C and 2D (COSY, HSQC, HMBC) nuclear magnetic resonance (NMR) and mass spectroscopic data revealed the identity of the major bioactive compound as cytochalasin B (1). Cytochalasin B showed prominent antibacterial activity with a minimum inhibitory concentration (MIC) of 64 μg/mL against S. aureus while the positive control Gentamycin showed a MIC of 4 μg/ mL. Further purification of other bioactive fractions with interesting 1H NMR spectra may to lead to novel antibacterial compounds. This study reveals that endophytic C. lunata of C. iria are potential producers of antibacterial compounds.
Synthesis of platinum complexes with N^N- sulphonamide ligands towards fluorescence imaging applications
(Institute of Chemistry Ceylon Adamantane House, Rajagiriya, Sri Lanka., 2020) Hettige, I. L.; Perera, N.T.
Ethylenediamine has been used as the backbone to synthesize the novel Pt-N^N complexes. The outstanding binding ability of ethylenediamine allows it to be used in the synthesis of hydrophilic ligand systems, by substituting the terminal amine group with bulky aromatic sulphonamide fragments which would also incorporate lipophilicity as well as enhanced fluorescence. Employing such amphipathic ligand systems would be an optimal approach of synthesizing platinum coordination complexes for biological applications with improved uptake by targeted cells. In this study, two ligands (L1=N(SO2biphenyl)ethylenediamine, L2=N(SO2azobenzene)ethylenediamine) (Figure 1) and their corresponding novel platinum complexes(C1=PtCl2(N(SO2biphenyl)ethylenediamine), C2=PtCl2(N(SO2azobenzene)ethylenediamine)) were synthesized. UV-Visible spectra of the ligands indicate clear changes from starting material along with the presence of intra-ligand π→π* and n→π* transitions, giving rise to absorption peaks around 200-400 nm. Shifts of these peaks can be observed in the UV-Visible spectra of the complexes related to MLCT transitions. The strong S-N band detected in the FTIR spectra of the ligands is found at 820 cm-1 in L1 and 842 cm-1 in L2 and shifts to lower wavenumbers in ethylenediamine complexes (801 in C1 and 836 cm-1 in C2) due to direct donation of nitrogen lone pair to platinum. Disappearance of the -NH and -NH2 stretching vibration frequency in the FTIR spectra of the complexes, found around 3300 cm-1 in the ligands, indicates the deprotonation of the amine groups on coordination in the complex. Methylene protons of the amine moiety of the ligands can be seen to be magnetically inequivalent in L1 and L2, appearing as triplets within the 2.00 - 3.00 ppm range in 1H NMR spectra. Complexes display slightly higher fluorescence intensity compared to the ligands, possibly due to rigidification of the ligand systems on developing the coordination complex. Structural data was obtained from single crystal X-ray diffraction of L2 and C1 which validated the formation of the ligand and complex.
Development of low-cost automated robot arm; its limitations and the validity of results through modified potentiometric experiments
(Institute of Chemistry Ceylon Adamantane House, Rajagiriya, Sri Lanka., 2020) Perera, K. A. N. K.; Rodrigo, S.; Liyanage, I.; Umayanga, I.; Perera, B.; Nawarathne, D.; Perera, D.; Jiffry, N.; Sirimuthu, N.; Ekanayake, E. M. M. S.
Robotics is used widely in design, construction and operation, further also in control, sensory, feedback and information processing. Robotics arm performs a crucial task in all the above. Automation in a chemical laboratory will be a major breakthrough in terms of productivity, quality and the reproducibility of the results, improved safety, reduce the time and cost of the whole running process. To catalyze this revolutionized system performances, as a combination of engineering and chemistry, we developed an automated robot arm and validated its results while overlooking the limitations via modified potentiometric experiments. The idea behind this concept is to use this robotics hand in places where it can be used to replicate the action of a human hand and thereby substituting its purpose in places where a human hand cannot be used. During this experiment robot arm involved in measuring cell voltage by using a standard calibrated potentiometer in a thermostat water bath at different temperatures; where it produced steady results compared to the manual procedure under same conditions while saving a considerable working time. The potentiometric reading equipment IEEE 488 fitted with an Interface Scanner 740 and a GPIB (General Purpose Interface Bus) program was used to obtain a continuous record of the potentials while test solutions were moving on a belt. For the validation, reading taken by using the automated arm and manual readings for the same sample were statistically analyzed (n=181) using t-test, linear regression and Spearman correlation coefficients which clearly indicate no significant difference between them. In summary, this work described an inexpensive and simple method for the automated potentiometric titration. The only limitation encountered during this process was the servo motors used, have only a maximum rotation of 180⁰ for 1m radius semicircle within 75s. Therefore, the area of movement is restricted to a certain region of space, but the arm can move an object from one-point coordinate to another in the x, y and z axes which could be adapted to many applications other than in a chemical lab.
Nephelium lappaceum L. peels as a source of phytochemicals with antioxidant and α-amylase inhibitory activities
(Institute of Chemistry Ceylon Adamantane House, Rajagiriya, Sri Lanka., 2020) Binuwangi, A. K. D. M.; Rajapakse, C. S. K.
Nephelium lappaceum L. (Rambutan) is a popular seasonal fruit native to Southeast Asia, enriched in varieties of phytochemicals including vitamins and secondary metabolites. This fruit is consumed fresh, canned, or as a processed food, but unfortunately its consumption results in production of vast amounts of waste from its seeds and peels which eventually create mosquito breeding grounds. Therefore, this study was conducted to investigate the potential of utilizing fruit waste (peels) of Sri Lankan variety of rambutan, Malwana special as a source of phytochemicals with antioxidant and α-amylase inhibitory activities. Phytochemicals of dried rambutan peels were first extracted into methanol by Soxhelt extraction. Then the crude extract was sequentially partitioned in hexane, dichloromethane (DCM) and methanol (30%). Total phenolic content (TPC) and total flavonoid content (TFC) of methanol extracts of rambutan peels and its fractions were determined using Folin- Ciocalteu and aluminium chloride method, respectively. Among the fractions, the highest TPC of 141.73 ± 18.66 mg gallic acid equivalents/g dried weight was found to be in aqueous methanol fraction and the DCM and aqueous methanol fractions were rich in flavonoids with TFC of 136.41 ± 32.25, and 110.67 ± 1.43 mg quercetin equivalents/g dried weight, respectively. Further, the radical scavenging properties of all the fractions were investigated using 1,1-diphenyl-2-picryl-hydrazyl (DPPH) free radical scavenging assay and their correlations with phenolics and flavonoids were analyzed using Pearson’s correlation. The methanol extract of peels (IC50 = 9.70 ± 0.50 μg/mL) and its aqueous methanol fraction (IC50 = 12.04 ± 0.80 μg/mL) showed higher DPPH radical scavenging activity than that of the control, butylated hydroxytoluene (IC50 = 13.92 ± 1.19 μg/mL). Strong positive correlations were observed between the antioxidant activity and the TPC and TFC with Pearson’s correlation coefficients of 0.9018 and 0.8493, respectively. Interestingly, it was also found out that the in vitro α-amylase inhibitory activity of the aqueous methanol fraction of the peels (IC50=75.17 ± 3.40 μg/mL) was significantly higher than the standard drug acarbose (IC50=171.5 ± 8.50 μg/mL). Results revealed that the peels of Sri Lankan variety of rambutan, Malwana special is a potential source of phytochemicals with antioxidants and α- amylase inhibitory properties.
Synthesis of DPA based NNN donor ligands having piperidinyl groups and their platinum complexes towards potent anti-cancer applications
(Institute of Chemistry Ceylon Adamantane House, Rajagiriya, Sri Lanka., 2020) Peiris, P. A. L.; Perera, N. T.
Dipicolylamine (dpa) moiety has received much attention due to its coordination versatility. Our objective is to incorporate piperidinyl groups into the dpa system due to possibility of the piperidinyl group to target sigma receptors as it shows high affinity to sigma receptors, which are expressed in high densities in breast cancer cells. In this study, two novel ligands; N((CH2)2piperidine)dpa (L1) and N((CH2)3piperidine)dpa (L2) (Figure 1) were synthesized by utilizing pendant piperidinyl groups having different chain lengths. The platinum complexes of novel ligands; [PtClN((CH2)2piperidine) dpa]Cl (C1) and [PtClN((CH2)3piperidine)dpa]Cl (C2) were also synthesized during the study. Structural data obtained from single crystal X ray diffraction for C1 confirms that L1 serves as a tridentate donor ligand. UV visible spectra of both ligands and complexes were recorded in methanol. Absorption peaks in 200-300 nm range in UV visible spectra of ligands are due to intra ligand π→π* transitions and peaks above 300 nm range are due to n→π* transitions in the ligands. As expected, no absorption peaks corresponding to n→π* transitions were observed in UV visible spectra of complexes due to lack of lone pairs in the coordination complexes. Methylene protons observed as a singlet (3.87 ppm) in 1H NMR spectrum of L1. The N-H bond of secondary amine group present in dpa gives an IR band in 3310-3350 cm-1 region. However, IR spectra of both ligands and complexes gave no transmittance peaks in region 3310-3350 cm-1 confirming the absence of the N-H group which also confirms the formation of ligands and complexes. Both ligands displayed intense fluorescence in methanol. However, fluorescence spectra of platinum complexes showed lower intensities than the respective ligands, possibly indicating static quenching of fluorescence upon coordination to metal. These ligands and complexes can be explored towards treatment of breast cancer due to incorporation of piperidinyl group.
The development of novel photodegradable linear low-density polyethylene (LLDPE) and investigation of the antibacterial properties
(Institute of Chemistry Ceylon Adamantane House, Rajagiriya, Sri Lanka., 2020) Kandambi, D. P. H.; Mudiyanselage, T. Kuruwita; Udawatte, C. S.
Plastic does not decompose easily under natural conditions and the need for degradable polyethylene has become an important area of research. In this study, the suitability of using cinnamaldehyde, in its natural and synthetic forms, and benzophenone, as photo oxidative sensitizers were evaluated. The results showed that oxidative degradation of linear low density polyethylene (LLDPE) increased significantly with the incorporation of these materials. Oxidative sensitization increased significantly with incorporation of natural cinnamaldehyde, Best results for oxidative sensitization were obtained by incorporation of 20% by mass natural cinnamaldehyde. The polymer composite films were prepared using a polymer solution in toluene and 2 cm x 2 cm films were caste between glass slides. 10 samples of each type were analyzed. The extent and nature of degradation was evaluated using FTIR spectroscopy, percentage weight loss and surface analysis techniques. The auto oxidative degradation of the composite films was carried out by accelerated UV initiated degradation, and also under natural rooftop conditions. Embrittlement and color development with aging in the photosensitizer incorporated polymer films were noticeably evident, when compared with the nonincorporated polymer films under similar conditions. Since polymer films are used for food and drug packing applications, antibacterial properties of the composite films were evaluated for four bacterial strains, Escherichia coli (ATCC 25922), Staphylococcus aureus (ATCC 25923), Pseudomonas aeruginosa (ATCC 27853) and Bacillus cereus (ATCC 11778) using agar disc-diffusion method. Cinnamaldehyde containing composite films displayed significant antibacterial properties against all four bacterial strains, whereas benzophenone containing films did not show antibacterial properties against these strains.