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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 Defluoridation of drinking water using physically and chemically modified chitosan(Research Symposium on Pure and Applied Sciences, 2018 Faculty of Science, University of Kelaniya, Sri Lanka, 2018) Pathirannehe, P. N. S.; Fernando, T. D.; Rajapakse, C. S. K.Depending on the total intake, fluoride (F-) is known to have both beneficial and adverse effects on humans. As the occurrence of the Chronic Kidney Disease of unknown etiology (CKDu) is thought to be linked with excess levels of F- in drinking water, the search for efficient, readily available, more affordable and eco-friendly adsorbents that have defluoridation potential has intensified in recent years. Therefore, the current study focuses on use of chitosan-derived adsorbents, physically and chemically modified chitosan for the removal of F- from drinking water. Physically modified chitosan; chitosan beads (CB), and chemically modified chitosan; protonated glutaraldehyde cross-linked chitosan beads (GCLCB/H+) and protonated glycerol diglycidyl ether cross-linked chitosan beads (GDCLCB/H+) were prepared, and characterized by Fourier Transform Infrared Spectroscopy and Scanning Electron Microscope. Batch experiments were conducted to determine the effect of adsorbent dosage, initial F- concentration, pH and contact time on defluoridation capacity of GCLCB/H+ at 30 ± 20C and the defluoridation capacities of different chitosan derivatives were determined under the optimized conditions (adsorbent dosage = 0.6 g, initial F- content =15 mg/L, contact time = 30 min, pH = 7). Further, the adsorption isotherm studies were conducted to understand the F- sorption process. The results revealed that the defluoridation capacities of CB, GCLCB/H+ and GDCLCB/H+ under optimized conditions at 30 ± 20C were 76.04 mg/kg, 576.98 mg/kg and 655.37 mg/kg, respectively and these values were significantly greater than that of unmodified chitosan flakes (44.20 mg/kg). The results indicate that physical and chemical modification of chitosan have enhanced the F- adsorption capacity of chitosan-derived adsorbents. Further, the results of the isotherm experiments indicated that the adsorption process is well fitted to Langmuir and Freundlich isotherm models. Six water samples among the drinking water samples collected around Kirigollewa Grama Niladhari Division in Medawachchiya, have exceeded the permissible level of F- in drinking water as defined by WHO (1.5 mg/L), but were able to successfully reduce to the permissible range by treatment with GDCLCB/H+. The findings of this study demonstrate that chitosan derived adsorbents are efficient and cost-effective candidates to use in removing F- ions from drinking water.Item The effect of changing the oil concentration on oil content, encapsulation efficiency and release rate of cinnamon leaf oil encapsulated chitosan microcapsules.(International Research Symposium on Pure and Applied Sciences, 2017 Faculty of Science, University of Kelaniya, Sri Lanka., 2017) Muthumali, A.M.T.; Wickramarachchi, P.A.S.R.Antibiosis, insect repelling and stress reducing properties of essential oils have been widely studied and well established. However, the release speeds of these compounds are usually high. Encapsulation is one of the effective methods commonly used to control the release and to increase the bioavailability of these compounds. In this research, cinnamon leaf oil was incorporated into chitosan microcapsules (MCs) to achieve the above mentioned goals. Here, we investigated the effect of changing the oil concentration on oil load, oil content, encapsulation efficiency and release rate of MCs. MCs were prepared by decreasing the solubility of chitosan. Briefly, NaOH was dripped into pre-prepared oil-chitosan emulsion, with slow stirring. Glutaraldehyde (10 mmol/g of polymer) was used for further crosslinking of chitosan wall of MCs. The average particle size was determined using the stage micrometer. Oil release was studied by UV-visible spectrophotometry. Oil release, encapsulation efficiency, oil content and oil load in MCs were calculated. All the parameters were dependent on the amount of oil. The particle size, encapsulation efficiency, oil content and release rate of cinnamon oil increased with the increase in oil loading. Scanning electron microscopy study showed a change in surface characteristics of the microcapsules due to cinnamon oil loading.Item Growth promotion and preservation of bare rooted plants of Dracaena sanderiana for commercialization(2011) Gunathilake, C.; Abeywickrama, K.P.Bare rooted Dracaena sanderiana is a popular indoor plant with high commercial potential. D. sanderiana top cuttings were dipped in different growth promoting substances and preservatives to obtain disease free bare rooted plants within a short period of time. The six treatments tested included, three concentrations of chitosan, an organic root promoting extract, NaOCl and vinegar. Chitosan 0.002% w/v solution was found to be the most effective rooting substance. Plants grown in this solution had the highest root length (8.7 ± 0.8cm) and highest root number per plant (44.7 ± 2.2). Lowest number of Colony Forming Units (CFUs) of bacteria was recorded from the chitosan 0.002% w/v solution (18. 8 ± 3.3) compared to tap water (control) (233.2 ± 7.7). Considering both preservative and growth promoting effects, chitosan 0.002% w/v solution can be recommended for the production of disease free bare rooted plants within a short period of time.Item Synthesis of Chitosan Stabilized Silver Nanoparticles using Gamma Ray Irradiation and Characterization(University of Kelaniya, 2011) Hettiarachchi, M.A.; Wickramarachchi, P.A.S.R.Chitosan stabilized silver nanoparticles (AgNPs) were synthesized using gamma ray irradiation. Four different sample solutions were prepared [1 mM AgNO3 in 0.1% (w/v) chitosan, 1 mM AgNO3 in 0.5% (w/v) chitosan, 2 mM AgNO3 in 0.1% (w/v) chitosan 2 mM AgNO3 in 0.5% (w/v) chitosan] with controls maintaining dose of radiation at 20±2 kGy. The formation of AgNPs were determined by the appearance of the characteristic colour of the AgNPs, using the surface plasmon resonance band (SPR) at 400-432 nm range and the N-H band of the FT-IR spectrum. Stability of the maximum absorption wave lengths of the samples was monitored for three months by UV-visible spectroscopy. The particle size distribution of the stabilized sample, showed a wide distribution of 28-1106 nm. The sample, 2 mM AgNO3 in 0.5% (w/v) chitosan was stable for three months. FT-IR spectroscopic analysis revealed a shifting of N-H stretching vibration band from 3367-3228 cm-1 with the introduction of nanoparticles.