Chemistry
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Item Exploring the toxic metal contamination and unveiling the risks in staple grains grown in a CKDu hotspot in Sri Lanka(Faculty of Graduate Studies - University of Kelaniya, Sri Lanka, 2023) Perera, M. A. S. N.; Perera, W. P. R. T.; Perera, P. L. R. A.; Kadigamuwa, C.C.; Liyanage, J. A.; Premaratne, W. A. P. J.Toxic metals in dietary grains could pose health risks from direct ingestion. This investigation aims to analyze the concentrations of toxic metals in selected dietary grains and conduct a comparative risk assessment in a region endemic to Chronic Kidney Disease of Unknown etiology(CKDu) in a non-endemic region. Six household fields in the CKDu endemic region in Nikawewa Grama Niladhari Division(GND) and three in the reference region; Wewagedara GND were selected for sampling. Inductively Coupled Plasma-Mass Spectrometry(ICP-MS) was used to determine Arsenic (As), Cadmium (Cd), Lead (Pb), Chromium (Cr), Copper (Cu), and Zinc (Zn) in composite samples collected from both GND areas (pulses; [(Vigna radiata; n=20), (Vigna unguiculata; n=20), (Vigna unguiculata subsp.; n=20)] cereal; [(Oryza sativa; n=30)]. Descriptive statistics revealed average As concentrations in samples as follows; Oryza sativa (38.60±13.84 g/kg,) Vigna unguiculata (3.25±1.96 g/kg), As was undetectable in samples of Vigna radiate, and Vigna unguiculata subsp. in CKDu endemic area. The average As concentrations of Oryza sativa in the reference area was 5.56±1.87g/kg and As was not detected in other grain species. All values complied with FAO/WHO & Codex permissible limits (As-100-200 g/kg). The estimated Daily Intake (EDI) value of As (0.257 g/kg/day) in Oryza sativa in the endemic area did not exceed the Tolerable Daily Intake (TDI) (As-0.3 g/kg/day). The average concentrations of Cd and Pb were reported in the CKDu endemic area; Oryza sativa (Cd-1276.92±234.42 g/kg, Pb-419.31±98.78 g/kg), Vigna radiata(Cd-571.31±60.71 g/kg, Pb-344.15±93.75 g/kg), Vigna unguiculata (Cd-1354.33±265.34 g/kg, Pb-408.56±22.20 g/kg), and Vigna unguiculata subsp.(Cd-1546.23±355.23 g/kg, Pb-408.63±115.14 g/kg) and exceeded FAO/WHO permissible limit(Cd-400 g/kg, Pb-300 g/kg). But those values were within the limits in the reference areas. However, Cu, Cr, and Zn remained within FAO/WHO safe limits in both regions. A health risk can be generated owing to long-term consumption of staple grains grown in Nikawewa GND; CKDu endemic area.Item Toxic metal contamination in food chains via paddy plant; A study in CKDu endemic area in North Western Province, Sri Lanka(Faculty of Graduate Studies - University of Kelaniya, Sri Lanka, 2024) Gunathilaka, V. H. N. M.; Perera, W. P. R. T.; Perera, P. L. R. A.; Kadigamuwa, C.C.; Liyanage, J. A.; Premaratne, W. A. P. J.This study addresses the urgent need for a comprehensive risk assessment of toxic metal contamination in the food chain via paddy plants in CKDu-affected areas emphasizing the health hazards associated with the transfer of toxic metals from soil to paddy grains and evaluating the health risk of consuming rice through different risk indices. Twenty composite paddy soil samples and twenty paddy plant samples with rice grains in the exact locations were collected from paddy areas in Nikawewa Grama Niladhari division during the Maha growing cycle in 2023. The analysis of Cr, Pb, As, Cd, Ni, and Cu was conducted using inductively coupled plasma-mass spectrometry (ICP-MS). Descriptive statistics revealed the average metal concentrations in rice grains as: Cr(637.42±157.44 μg/Kg), Pb(262 ±62.35 μg/Kg), As(39.29±11.97 μg/Kg), Cd(1836±192 μg/Kg), and Cu(1567 ±466 μg/Kg). Cr, As, and Cu levels in rice grains remained within WHO/FAO and codex limits. However, average Pb and Cd levels surpassed permissible limits (Pb-200 μg/Kg, Cd- 50 μg/Kg; WHO). Nevertheless, the Target hazard quotient(THQ) values of Cr and Cd were greater than 1. The estimated Daily Intake(EDI) values of Cr(3.15 μg/Kg/Day) and Cd(9.15 μg/Kg/Day) are higher than Tolerable Daily Intake(TDI) values. The transfer factors(TF) for toxic metals in the soil-root system were determined as follows: Cr-0.069, Pb-0.30, As-0.67, Cd-0.49, Ni-0.10, Cu-0.23. Toxic metal transfer factors in the soil-root system were evaluated, indicating greater uptake by plant roots. When considering a metal transfer from roots to rice grains, Cd had a transfer factor greater than 1, indicating potential accumulation in grains, while Cr exhibited a notable increase in transfer factor compared to the soil-root system. The risk of toxic metal transfer from soil to paddy grains warrants concern due to potential human exposure and related health risks, including Chronic Kidney Disease, from the consumption of contaminated rice grains.Item In vivo and in silico Antifungal Activity of Cinnamon Leaf Oil and Lemongrass Oil containing Chitosan Microcapsules against Aspergillus flavus(2024-04) Kumarathunga, P.G.J.D.; Chathurangi, S.; Rajapaksha, R.P.S.P.; Sooriyawansha, A.M.S.C.; Jayawardena, P.A.S.N.P.; Dananjaya, P.D.H.; Alwis, M.D.N.; Kadigamuwa, C.C.; Dahanayake, J.N.; Wickramarachchi, SurangaThis study aimed to examine the potentiality of microencapsulated cinnamon leaf oil (CNO-CS-MCs) and lemongrass oil (LGO-CS-MCs) as natural fungicides against Aspergillus flavus. Oil encapsulated microcapsules were synthesized using ionotropic gelation method. Cinnamon leaf oil (CNO) and lemongrass oil (LGO) were characterized using GC-MS. A. flavus was isolated and identified using DNA sequencing. The minimum inhibitory and minimum lethal doses of oil-loaded microcapsules against A. flavus were evaluated under in vivo conditions and the results were further confirmed by in silico analysis. The major constituents of CNO and LGO were eugenol and citral, respectively. The minimum inhibitory doses of CNO-CS-MCs and LGO-CS-MCs were 5 mg and 7.5 mg, respectively. The minimum lethal dose of CNO-CS-MCs was 12.5 mg. As CNO showed considerably high antifungal activity than LGO, Computational investigations were carried out on the action of CNO against A. flavus. The highest protein-ligand interaction was observed for squalene epoxidase (SQ)-benzyl benzoate (BEN) complex with the binding energy of -7.70 kcal/mol. Molecular dynamics simulations were performed on SQ-BEN complex for 10 ns using CHARMM36 force field. The Rg, RMSD and RMSF results indicated the stabilization of the SQ-BEN complex throughout the simulation time.Item Computational studies of antiviral properties of curry powder water extract against Norovirus infection(Society for Conservation and Resource Development of Medicinal Plant, New Delhi, India., 2023) Weerarathne, H.K.; Sooriyawansha, A.M.S.C.; Jayawardena, P.A.S.N.P.; Kumarathunga, P.G.J.D.; Dananjaya, P.D.H.; Sandaruwan, W.A.M.; Dahanayake, J.N.; Kadigamuwa, C.C.Curry powder is a mixture of ground spices that are typically used to enhance flavor, aroma, color, and consistency in curries. The Sri Lankan roasted curry powder “bedapu thuna paha” consists of coriander seeds (Coriandrum sativum L.), cumin seeds (Cuminum cyminum), fennel seeds (Foeniculum vulgare Mill.), cinnamon sticks (Cinnamomum zeylanicum) and curry leaves (Murraya koenigii) as the main ingredients. Norovirus (NoV) is a single-stranded RNA virus belonging to the family Caliciviridae. The P domain capsid protein of this virus plays an important role in the host immune response and receptor recognition because when protruding domain 1 binds with receptor molecules, it is easy to penetrate the host cell. Therefore, twenty potential ligands contained in the curry powder decoction, which were identified through literature review, were docked to the active site in the P domain from norovirus strain saga4 in complex with HBGA, and Mahanimbine, Mahanine, and Fenchone ligands binding energies were greater than -6.00 kcal/mol. According to these interactions between ligands and the protein, which were given binding energies greater than -6.00 kcal/mol, only the Mahanine ligand interacted with the highest number of amino acids in the binding pocket compared to the other two ligands (Asp374, His347, Gly346) and this ligand was subjected to Molecular Dynamics (MD) simulations. MD simulations were performed on the proteinligand complex for 10 ns using the CHARMM36 force field. Rg, RMSD. The RMSF results indicated the stability of the protein-ligand complex throughout the simulation time and suggested that Mahanine phytochemical may be used as a potential anti-virus agent against Norovirus.Item Efficacy of methanolic extract of Zingiber officinale against seed-born fungi(Society for Conservation and Resource Development of Medicinal Plant, New Delhi, India., 2023) Hansini, Navoda; Sooriyawansha, A.M.S.C.; Jayawardena, P.A.S.N.P.; Kumarathunga, P.G.J.D.; Dananjaya, P.D.H.; Edirisinghe, E.A.C.P.; Alwis, M.D.N.; Daranagama, D.A.; Dahanayake, J.N.; Kadigamuwa, C.C.This study is focused on determining the efficacy of natural compounds present in Zingiber officinale methanolic plant extraction in controlling seed-born fungal pathogens Aspergillus flavus and Rhizopus oryzae. The maximum percentage inhibition of 94.01% and 90.43% was reported against. A. flavus and R. oryzae respectively for the crude extract in the poison food agar method. These results were further confirmed by computational investigation. [4]-gingerol, [6]-gingerol, [8]-gingerol, [10]-gingerol, and [6]-dehydroginger phytochemicals identified in the extract were docked to the active sites in chitin synthase from A. flavus and squalene epoxidase from A. flavus and R.oryzae, and to the RNA dependent RNA polymerase (RdRp) enzyme from R. oryzae. The highest binding energy (BE) (-8.12 kcal/mol) was noticed between the interactions of squalene epoxidase and [6]-dehydroginger, and this complex was subjected to Molecular Dynamic (MD) analysis. MD simulations were performed on protein-ligand complexes for 10 ns using CHARMM36 force field. The mean radius of gyration (Rg), root mean square deviation (RMSD), and root mean square fluctuation (RMSF) were calculated and hydrogen bond analysis (HBA) was also performed. Rg and RMSD results indicated the stability of the protein-ligand complex throughout the simulation time.Item Biodiesel and Its Importance as an Alternative Energy Source for the Fuel Crisis(Young Scientists Forum (YSF) National Science and Technology Commission Sri Lanka, 2023) Perera, B.S.S.; Kadigamuwa, C.C.Upsurging of the population throughout the world has given a negative effect on daily energy consumption. Fossil fuel reserves are decreasing gradually due to the energy demand and the need of finding alternatives is growing. Biodiesel is such an alternative that derived from crops and animals. It is also contributing to the green environment as it does not emit carbon dioxides, carbon monoxides, hydrocarbons and particulate matter comparative to petroleum diesel. There are several types of oils and fats that are used in deriving biodiesel such as edible oil and non-edible oils. Palm oil, jatropha oil, soybean oil, castor oil, algae and animal fats are some of the feedstocks used in producing biodiesel. Waste cooking oil is an economical alternative for the sources of biodiesel. The triglycerides of oils and fats are used to produce alcohols and esters which could be result from catalytic or non- catalytic reactions. Biodiesel is composed of mono-alkyl esters of long-chain fatty acids and is synthesized mainly by pyrolysis, microemulsion and transesterification. The transesterification is the most common and widely used method of manufacturing biodiesel. Acid catalyzed transesterification, alkali catalyzed transesterification, enzyme catalyzed transesterification and non-catalytic esterification are broadly used in the transesterification process. Properties, such as, cetane number, cloud and pour point, density and viscosity have an enormous impact on the quality of biodiesel. This chapter provides an overview of the manufacturing process and characteristics of biodiesel.Item Geochemical Release and Environmental Interfaces(John Wiley and Sons, Inc., 2023) Kadigamuwa, C.C.; Perera, N.T.; Perera, B.S.S.The geochemical release is the process of chemical weathering of minerals from their parent materials. These minerals originate from naturally occurring solids which interact with the environment through their surfaces. Depending on different environmental conditions that affect these surfaces, they could release minerals and gases to the environment. These released minerals and gases could transfer through environmental interfaces. Environmental interfaces are broadly de need as any surface in equilibrium with its surrounding environment. There are various types of environmental interfaces including geochemical, atmospheric aerosols, nanomaterials, and indoor surfaces. Thus, investigating the connection between geochemical release and these varied and complex environmental interfaces is necessary to understand both beneficial and adverse effects on living organisms.Item Antioxidant, anti-inflammatory, and antimicrobial actions of Paspanguwa: A decoction of traditional five medicinal herbal mixture(Society for Conservation and Resource Development of Medicinal Plants, 2023) Madushani, H.M.R.; Jayawardena, P.A.S.N.P.; Kadigamuwa, C.C.The name ‘Paspanguwa’ term comes from a combination of five primary herbs Zingiber officinale, Hedyotis corymbosa, Solanum xanthocarpum, Coscinium fenestratum, and Coriandrum sativum. In the present study, water extracts of the individual ingredient and the Paspanguwa decoction were screened for their total soluble phenolic (TPC) & flavonoid (TFC) contents, DPPH radical scavenging activity, and their ability to inhibit protein denaturation. Furthermore, this study focuses on the evaluation of antibacterial and antifungal activities against selected bacterial, and fungal strains. The highest TPC and TFC were seen in C. sativum as 12.76 (± 1.00) μg gallic acid equivalent/g dry weight, and S. xanthocarpum as 778.19 ± 1.40 μg catechin equivalent/g of dry weight respectively. The highest IC 50 value for the DPPH assay and reducing power percentage were seen in S. xanthocarpum as 609.7 (± 5.6) μg/mL and C. sativum as 22.95 (± 0.96) respectively. The ability to inhibit protein denaturation varied in the order of Paspanguwa decoction > Z. officinale > C. sativum > C. fenestratum > S. xanthocarpum > H. corymbosa at all three concentrations (625, 1250, and 2500 μg/mL). According to the agar disk diffusion method, the aqueous extracts derived from coriander 0.7 (± 0.1) cm and Paspanguwa mixture 0.7(± 0.1) cm had shown antibacterial potentials only against Staphylococcus aureus bacterial strain. When it comes to antifungal effects, only favourable results were achieved against Candida albicans due to the antifungal activity of ginger 0.8 (± 0.1) cm and Paspanguwa mixture 0.7(±0.1) cm. These results suggest that Paspanguwa water extract is a good source of antioxidants with TFC and TPC with a higher ability to inhibit protein denaturation, but it is not effective in antimicrobial activities.Item Preliminary studies of antioxidant and anti-inflammatory activities in methanol extracts of mistletoe (Dendrophthoe falcata) in guava (Psidium guajava)(Society for Conservation and Resource Development of Medicinal Plants, 2023) Hashitha, Tharakee; Kadigamuwa, C.C.Mistletoe’s antioxidants and anti-inflammatory properties, attributed to bioactive compounds, make it a potential natural remedy for oxidative stress and inflammation-related ailments. This study is focused on evaluating the antioxidant and anti-inflammatory potential of mistletoe (Dendrophthoe falcata) grown on guava (Psidium guajava). Cold extraction with methanol was used to maximize the extraction of heat-sensitive bioactive compounds. Samples were collected from three guava trees hosting Dendrophthoe falcata mistletoe, including guava (S1 L, S2 L, S3 L) and mistletoe leaves (S 1 M, S 2 M, S 3 M). The mistletoe’s antioxidant activity was evaluated through total phenolic content (TPC), total flavonoid content (TFC), DPPH radical scavenging activity, and ferric-reducing power analysis. The mistletoe leaf sample (S 3 M) from tree 03 displayed the highest TPC (169.46 ± 2.06 GAE mg/g) and TFC (46.16 ± 1.15 CE mg/g). S 3 M also exhibited the lowest IC 50 value (0.091 ± 0.001 mg/mL) in the DPPH test, indicating strong radical scavenging activity. The FRAP assay yielded a value of 0.523 ± 0.010 mg/g BHT equivalent for S 3 M. Positive correlations were observed between TPC, TFC, and antioxidant activities. Additionally, the mistletoe leaf samples (S 3 M) demonstrated significant anti-inflammatory effects in the heat- induced hemolysis assay (IC 50 = 488.302 ± 23.407 μg/mL) and egg albumin denaturation assay (IC 50 = 311.582 ± 12.404 μg/mL), suggesting potential anti-inflammatory properties. The host leaf sample from host tree 03 displayed higher antioxidant activity (TPC: 239.06 ± 2.45 mg/g, TFC: 65.03 ± 1.65 mg/g, IC 50 for DPPH: 0.086 ± 0.004 mg/mL, FRAP: 0.565 ± 0.013 mg/g BHT equivalents) and anti-inflammatory activity (IC50 for heat-induced hemolysis: 466.889 ± 23.417 μg/mL, IC 50 for egg albumin denaturation: 120.758 ± 19.190 μg/mL). Despite sample variations, mistletoe’s antioxidant and anti-inflammatory properties were evaluated without hindrance. In conclusion, methanol extracts of mistletoe exhibit promising antioxidant and anti-inflammatory activity, require further research in this area.