International Conference on Applied and Pure Sciences (ICAPS)
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Item The dance of contaminants: How silver nanoparticles and cadmium alter the quality of deionized water(Faculty of Science, University of Kelaniya Sri Lanka, 2024) Silva, G. S. T.; Gulawitage, G. T. P. S.; Gregory, M.; Silva, C. R.; Wickramarachchi, S. R.The rapid increase in the presence of both nanoparticles and heavy metals in aquatic ecosystems brought up concerns regarding their combined effect on the quality of water as they enter aquatic ecosystems at an alarming rate. This study underscores the combinatorial effect of silver nanoparticles (AgNPs) (0.05 ppm) and cadmium (0.03 ppm) upon the fundamental physicochemical properties of deionized (DI) water at their environmentally relevant concentrations. Purity and consistency of DI water provide a controlled environment, ideal for isolating and studying the specific interactions between AgNPs and Cd. Chitosan-stabilized silver nanoparticles (cs–AgNPs) were synthesized using chitosan as a stabilizing and reducing agent. The synthesis involved addition of 0.5 g chitosan into 0.5 L of 2 mM AgNO3 solution. Afterwards, NaOH was added in two portions: 1.0 mL of 1% solution after 5 minutes and 1.5 mL after 10 minutes. The formation of AgNPs was confirmed by the solution’s color change to reddish-brown and the appearance of a Surface Plasmon Resonance (SPR) band at 420 nm in the UV– visible spectrum. Transmission Electron Microscopy (TEM) revealed an average particle size of 5.94 ± 2.95 nm, with a 2-12 nm range. To test physicochemical parameters, samples containing AgNPs and Cd individually and in combination, were sonicated for one hour along with a control group. AgNPs exposure resulted significant increase in conductivity suggesting potential alterations in ionic mobility in water. pH was slightly lower in both individual treatments than the control, whereas the combined treatment exhibited a higher pH value indicating a shift towards alkalinity. Turbidity increased in the combined exposure whereas the dissolved oxygen (DO) level was slightly lower, implying a potential interference with oxygen availability in the water, which could adversely impact aquatic organisms. Notably, only the combined treatment significantly increased the Total Dissolved Solid (TDS) value. The findings highlight the fact that AgNPs and Cd act synergistically to alter water quality posing risks to aquatic ecosystems providing crucial insights for water treatment strategies and aiding in safeguarding ecosystems and public health.Item Encapsulating cinnamon bark oil in chitosan using ionotropic gelation and their characterization(Faculty of Science, University of Kelaniya Sri Lanka, 2024) Jayasinghe, J. M. H. M.; Shivanthini, K. D. C.; Wickramarachchi, S. R.Cinnamon bark oil (CBO) is well known for its antimicrobial properties. Hence, it has the potential to be used as a food preservative, an insecticide, etc. However, the direct application of CBO in their free native forms is limited due to some drawbacks like high volatility, changing texture and flavor etc. Therefore, encapsulation is a widely used technique to overcome the drawbacks of direct application of oil and to enhance the different potential functionalities of cinnamon bark oil. Encapsulation is a process to entrap active components within a thin coating. This study aims at encapsulating CBO using the ionotropic gelation technique. It is a technique that is used to synthesize micro- and nanoparticles based on electrostatic interactions between ions with different charges. In this technique, sodium tripolyphosphate (STPP) was used as the cross-linker, and chitosan was used as the polymer to formulate CBO-containing micro capsules. CBO was characterized using GC-MS. The micro encapsulation parameters were optimized by varying the amounts of polymer (1–3%), cinnamon bark oil (1–3 g), and STTP (0.5–1%). The effect of varying process parameters on the encapsulation efficiencies (EE%), oil loading capacity (LC%), and oil release profile were determined by weightbased calculation. The formulated capsules were characterized using scanning electron microscopy (SEM). The GC-MS analysis of CBO showed the presence of cinnamaldehyde (74.615%) as the major compound. The SEM images showed that the synthesized capsules are spherical in shape with a smooth surface. Their size varied between 100 and 1000 nm. Varying the process parameters has a direct impact on the EE% and LC%. The optimum formulation for cinnamon oil micro capsules is chitosan 3 g, CBO 3 g, STTP, 1% with an EE of 85.31% and a LC of 16.52%. The oil release rate increased with time, according to the oil release profile. These findings indicate that CBO can be successfully encapsulated within chitosan using the ionotropic gelation method.Item Evaluating the efficacy of cinnamon oil-chitosan microcapsules in inhibiting the growth of Aspergillus spp. in stored rice: A study on antifungal properties and storage stability(Faculty of Science, University of Kelaniya Sri Lanka, 2024) Dewduni, E. A. C.; Wickramarachchi, S. R.Understanding and controlling the growth of aflatoxigenic fungi is of paramount importance to ensure food safety. Aspergillus spp. are common storage fungi, which is responsible for producing aflatoxins in stored grains posing significant health risks. Cinnamon leaf oil (CNO) has gained attention as an antifungal agent due to its low toxicity to mammals, high effectiveness, and wide availability. However, the direct application of CNO presents challenges such as volatilization, degradation, of active compounds, and imparting unpleasant taste and odor to food products. Encapsulation is an effective technique to overcome these limitations and achieve controlled release thus increasing the bioavailability of the active compounds. In this study, a comprehensive investigation was conducted to assess the in vitro growth dynamics of colonies and spores of Aspergillus spp. (A. flavus, A. niger, and A. parasiticus) over a three- month period after treating with cinnamon leaf oil loaded chitosan microcapsules (CNO-CS-MCs). Microcapsules (MCs) containing cinnamon leaf oil were prepared by ionotropic gelation technique and crosslinking chitosan with sodium tripolyphosphate (STPP 1%). Previous studies have shown that the minimum lethal dose (MLD) of CNO-CS-MCs against Aspergillus spp. for spread method was 15 mg. Rice grains (BG-11-11) were packeted in polybags and treated (spread on rice) with the MLD of CNO-CS-MCs. The growth of Aspergillus spp. on treated rice was monitored monthly for 03 months by growing the fungal extracts of treated rice on potato dextrose agar (PDA) medium. Subsequent spore quantification was carried out using a hemocytometer. The results demonstrated a reduction of the fungal colony count and spore density throughout the three-month duration. Notably, the lowest mean colony count of 5.33 CFU mL-1(SD = 1.15 CFU mL-1) was observed in the third month, suggesting a significant reduction in fungal colonies after treating with CNO-CSMCs. Additionally, the lowest average spore density of 1.26 × 10-4 spores mL-1 was observed in the third month, suggesting a significant reduction in fungal spores after treatment. These findings emphasize the promising potential of CNO-CS-MCs as a natural fungicide to control the growth of aflatoxigenic fungi on stored rice, enhancing food safety and quality during their storage.Item Larvicidal activity of chemically synthesized and Trichoderma longibrachiatum mediated silver nanoparticles against Aedes aegypti(Faculty of Science, University of Kelaniya Sri Lanka, 2022) Gunawardana, W. G. T. N.; Perera, S. A. D. S.; Amarasighe, L. D.; Wickramarachchi, S. R.The mosquito Aedes aegypti is a critical vector of infectious diseases, including dengue, chikungunya and yellow fever. Prevention of these diseases is mainly achieved through mosquito population control due to the non-availability of a commercial vaccine except for yellow fever. The use of biogenic nanoparticles to control insect vectors has been studied in several research. Byproducts of the metabolism of organisms, including bacteria, fungus, and plants, which act as reducing and stabilizing agents, can be used in the green synthesis of nanoparticles. This study aims to determine the mosquito larvicidal potential of green synthesized silver nanoparticles using Trichoderma longibrachiatum biomass (Tl-AgNPs) and chemically synthesized silver nanoparticles (C-AgNPs). Synthesized AgNPs were characterized by ultraviolet-visible spectroscopy (UV-VIS), Transmission Electron Microscopy (TEM) and Scanning Electron Microscopy (SEM). The colour change from pale yellow to dark brown of the solution indicated the formation of AgNPs initially. The surface Plasmon Resonance (SPR) band in the range 415 - 400 nm in the UV-VIS confirmed the formation of Tl-AgNPs and C-AgNPs. TEM and SEM images confirmed that Tl-AgNPs and C-AgNPs were spherical in shape. Third instar larvae of dengue vector mosquito Ae. aegypti were subjected to larvicidal bioassay in a range of concentrations of Tl-AgNPs and C-AgNPs (10-50 mg/L). Both types of AgNPs were larvicidal against Ae. aegypti larvae. The percentage mortality of the Ae. aegypti was found to increase with the increase in tested concentrations of AgNPs. LC50 value of Tl-AgNPs was 16.82 ± 0.17 mg/L whereas C-AgNPs was 22.10 ± 0.71 mg/L for Ae. aegypti at 48 h exposure. Hence, Tl-AgNPs exhibit higher larvicidal activity than C-AgNPs. Tl-AgNPs have the potential to be developed as a green larvicidal treatment for Ae. aegypti.Item In-vivo growth control of Aspergillus flavus on stored rice using microencapsulated cinnamon leaf oil(Faculty of Science, University of Kelaniya Sri Lanka, 2022) Kumarathunga, P. G. J. D.; Wickramarachchi, S. R.Poor storage conditions of rice lead to fungal infestation associated with severe health problems in humans. Aspergillus flavus is one of the significant storage fungus responsible for producing aflatoxins on stored grains. The use of cinnamon leaf oil (CNO) as an antifungal agent has gained great interest because of its low mammalian toxicity, high efficacy and availability. However, the direct application of CNO possesses many drawbacks, such as loss of bioactivity due to volatilization and degradation of active compounds and contribution to unpleasant taste and odour of foods. Microencapsulation is an efficient technique that can be used to overcome those drawbacks and obtain controlled release. This study aimed to determine the in-vivo growth control of A. flavus on rice by CNO-chitosan microcapsules (CNO-CS-MCs). CNO was encapsulated within biodegradable polymeric chitosan by ionotropic gelation method with sodium tripolyphosphate as the crosslinking agent. CNO was obtained from the local market and characterized using Gas Chromatography-Mass Spectrometry (GC-MS). Rice samples (Bg 11-11) were obtained from Rice Research Institute, Bathalagoda, Sri Lanka. Aspergillus flavus was isolated from stored rice and tentatively identified as A. flavus using morphological features and DNA sequencing. The minimum inhibitory dose and minimum lethal dose of free CNO and microencapsulated CNO against A. flavus were evaluated under in-vivo conditions. The GC-MS analysis of CNO showed the presence of eugenol (56.49 %), -caryophyllene (9.03 %), benzyl benzoate (8.43 %) and linalool (6.0 %) as the major constituents. Free CNO mixed with rice grains showed 100±0.00 % growth inhibition (visible) of A. flavus at 2 mg of oil (minimum inhibitory dose) and there was no revival of the growth of the fungus treated with ≥ 5 mg (minimum lethal dose) of oil, in PDA media. Both minimum inhibitory and minimum lethal doses of CNO-CS-MCs treated rice samples were higher than that of free CNO. The minimum inhibitory dose of CNO-CS-MCs mixed with rice grains was 5 mg and the minimum lethal dose was 12.5 mg, whereas those were 10 and 17.5 mg, respectively, in treatments with CNO-CS-MCs sachets. Both CNO and CNO-CS-MCs were fungistatic and fungicidal against A. flavus. This study indicated the potential of using microencapsulated CNO as a natural antifungal agent against the A. flavus.Item Mosquito larvicidal effect of Annona glabra fruit extract on dengue vector, Aedes aegypti(Faculty of Science, University of Kelaniya, Sri Lanka., 2021) Wijebandara, N. R. Y.; Ranasinghe, H. A. K.; Amarasinghe, L. D.; Wickramarachchi, S. R.Annona glabra is a plant of Family Annonaceae and many plant species belong to this family have been intensively studied since they were discovered to contain compounds with important biological properties. These properties include cytotoxic, antitumor, antiparasitic, antifungal, antispasmodic, repellent, and insecticidal activities. Insecticidal effects of plant extracts vary depending on the plant parts (leaf, seed, fruit, bark) used for the extraction. Larvicidal effect of A. glabra aqueous extract from leaves and seeds have been evaluated against Aedes aegypti mosquitoes in Sri Lanka, and larvicidal effect of fruit is not determined yet. Therefore, the present study was conducted to evaluate the effect of A. glabra fruit extract for its larvicidal efficacy on third instar larvae of Ae. aegypti. Fresh ripen fruits of A. glabra plant were collected from Hunupitiya, (N 06º 58.904/, E 079° 54.281/) in Gampaha district, Sri Lanka. The aqueous crude extract was prepared from powdered A. glabra fruits. Seven concentrations were prepared between the range of 3 g/L – 300 g/L. Batches of 25 third instar larvae of Ae. aegypti were used for larval bioassays. Ae. aegypti mosquito larvae were evaluated in accordance with guidelines of World Health Organization. The experimental setup was repeated four times per each concentration. Probit analysis was used to evaluate the relationship of mortality with the concentration of aqueous crude extract. The A. glabra fruit extract showed a dose-dependent effect against Ae. aegypti larvae after the 48-hour exposure period. The percentage mortality rates have shown a significant variance among different concentrations (P = 0.000). The recorded LC50 and LC90 values for aqueous crude extract were 87.71 ± 5.41 gL-1 and 510.79 ± 12.56 gL-1 respectively, after 48 hours of exposure period. Larvicidal activity of A. glabra plant is supported by previous literature, where the presence of phytochemicals such as saponins, flavonoids, steroids and tannins have shown combined effects in terms of larvicidal action against mosquitoes. Hence, there is a potential of A. glabra aqueous fruit extract as a potential source for the development of an environment-friendly plant-based larvicide against Aedes aegypti.Item Identification of marker compounds and antioxidant activity of Terminalia chebula Retz. fruit pericarps used in selected commercial herbal preparations in Sri Lanka(Faculty of Science, University of Kelaniya, Sri Lanka., 2021) Suraweera, K. P. C. D.; Amarasekara, H. M. R; Tennakoon, T. M. S. G.; Wickramarachchi, S. R.Medicinal plants contain phyto-constituents which show pharmacological effects. This study is focused on identification and quantification of marker compounds and determination of the antioxidant activity of T. chebula Retz. fruit pericarps used in selected commercial herbal preparations in Sri Lanka. Commercial samples were obtained from Sri Lanka (SLC) and India (INC), separately from three different batches of T. chebula stocks from raw material quarantine section at Link Natural Products (Pvt) Ltd. As these commercial samples are a mixture of fruits from wider geographical locations, five samples (SLA) collected from known locations in Sri Lanka were included for comparison. Methanolic extracts (70 % v/v) were prepared from each sample. Chromatographic profiling was done using thin layer chromatography (TLC) and high- performance liquid chromatography (HPLC). Extracts were assayed for gallic acid content, total tannin content and antioxidant activity. Gallic acid and ellagic acid could be used as marker compounds in quality control of T. chebula commercial stocks. All samples had a low IC50 value than butylated hydroxytoluene (BHT) standard showing that T. chebula fruit pericarps have higher antioxidant activity than BHT. Variations in IC50 values were observed within and among SLA, SLC and INC suggesting that both intrinsic and extrinsic factors may lead to the change in antioxidant potential of the fruits. The mean IC50 value of SLC samples was (6.32 ± 2.09) µg/mL whereas that of INC samples was (7.42 ± 0.93) µg/mL suggesting that antioxidant activity was higher in SLC samples over INC samples. A variation in antioxidant activity in SLA samples was observed, depending on the sampling site.Item Bioactive compounds in Dioscorea alata L. (Raja ala) tuber cooking water collected under two common cooking methods(Faculty of Science, University of Kelaniya, Sri Lanka, 2021) Amarasekara, H. M. R.; Wickramarachchi, S. R.Nutritional compounds in yams may leach out to the cooking water under most traditional domestic cooking. Finding alternative uses of these waste waters without discarding, will maximize the health benefits of these yams. This study aimed to quantify the bioactive compounds in the cooking water collected during boiling of Dioscorea alata L. tubers under two domestic cooking methods. Raja ala yams were diced and boiled in water using conventional boiling (CB) in a closed stainless-steel pot for 45 minutes and using pressure cooking (PC) in a pressure cooker type autoclave for an overall period of 30 minutes. The cooking water of both methods was collected, filtered, and concentrated by evaporating at 70℃ to obtain the solid crude product. Aqueous solutions of the crude product (30 mg/mL) of CB (Crude-CB) and PC (Crude-PC) were prepared and subjected to qualitative phytochemical analysis. Further, they were assayed for total phenolic content (TPC), total flavonoid content (TFC), and total anthocyanin content (TAC). Antioxidant activity of each crude product was determined using 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay and total antioxidant activity (TAA) was determined using the phosphomolybdenum assay. A correlation between the antioxidant activity and TPC, TFC and TAC of the samples was developed using the Pearson’s correlation method. Phytochemical screening of crude-CB and crude-PC samples showed the presence of alkaloids, flavonoids, phenols, saponin, tannins and coumarins and an absence of proteins, thus indicating the presence of nutritional compounds in cooking water collected under both cooking methods. Crude-CB (14.713 ± 1.039 mg GAE/g FW) showed a significantly higher TPC than that of crude-PC (9.848 ± 0.548 mg GAE/g FW) whereas the TFC of crude-PC was higher than crude-CB suggesting that the leaching out of phenolic compounds including flavonoids are significantly affected by the cooking method. Both methods, however, showed no significant difference in TAC extraction implying that the loss of anthocyanins from the yam is similar when either of the two cooking methods are is employed. IC50 values of crude-CB (209.014 ± 10.428 µg/ml) and crude-PC (371.615 ± 8.982 µg/ml) samples showed moderate activity in the cooking water. TAA of crude CB and PC samples were 0.917 ± 0.016 and 0.707 ± 0.002 mg GAE/mg FW respectively. Antioxidant assays showed higher activity in CB samples over the PC, suggesting that a higher amount of compounds with antioxidant activity have been leached out under the CB method than PC method. The strong correlation observed between TPC versus DPPH activity (IC50 value) (r= -0.856) and TAA (r = 0.811) of the samples confirms that the phenolic compounds that have leached out into the cooking water possess antioxidant activity. Finally, it can be concluded from the overall results that although the leaching out of phenolics and antioxidants into cooking water is inevitable under both cooking methods, a greater loss takes place under CB than the PC method.