Browsing by Author "Rathnayake, S.I."
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Item Characterisation and Implications for Potential Environmental Applications of Montmorillonite Extracted from Clay Deposits in Murunkan, Sri Lanka(Uva Wellassa University of Sri Lanka, 2019) Piyasena, K.L.R.I.; Rathnayake, S.I.; Pitawala, H.M.J.C.Montmorillonite (MMT) is one of the most commonly used smectite clay as a low‒cost adsorbent in water purification due to its ubiquitous nature, high cation exchange capacity, surface area and porosity. Although high purity MMT deposits are absent in Sri Lanka, MMT‒rich clay can be found in arid regions such as Murunkan, Mannar. Cadmium (Cd2+) is a known human carcinogenic heavy metal deemed as a high priority water pollutant by the USEPA. This study is focused on investigating the potential environmental applications of MMT as a low‒cost adsorbent for the removal of Cd2+. MMT was extracted using clay collected from Murunkan area by both wet and dry sieve methods. Wet sieve method resulted in higher percentage (14%) of fine clay fraction (<63 µm) compared to dry sieve method (3.8%). X‒ray Diffraction and Fourier Transform Infrared Spectroscopy revealed the beneficiation of montmorillonite in <63 µm fraction and main impurities were identified as quartz and feldspar. Upon sedimentation, impurity content was minimised and montmorillonite rich portion (MMT‒Ex) in <63 µm fraction was separated. The optimum adsorbent amount for effective Cd2+ removal was investigated by varying the amount of MMT-Ex (0.5‒4 g). The adsorbent was mixed with 25 ml of Cd2+ solution (5 mg L-1, pH 7.3) and agitated for 24 hrs at room temperature. The supernatant was separated by centrifugation and analysed using Atomic Absorption Spectroscopy. MMT‒Ex resulted 98% of Cd2+ adsorption with a low adsorbent dose (0.5 g). Overall, this study describes effective methods to extract MMT from MMT‒rich clay and shows its potential application as an economic and effective adsorbent for inorganic contaminants in wastewater treatment and environmental remediation.Item Extraction and Isolation of Anti-hyperglycemic Compounds from Cheilocostus speciosus to produce sustained release formulations(Uva Wellassa University of Sri Lanka, 2020) Induruwage, S.S.; Alakolanga, A.G.A.W.; Rathnayake, S.I.; Senarathna, K.G.C.; Wijesekara, K.B.Diabetes mellitus is one of the non-contagious diseases which has now become a major health problem all over the world. This study was conducted to identify a natural, safe, and reliable solution for “diabetes” with proper scientific validation. The objective of the study was to extract and isolate anti-hyperglycemic compounds from Cheilocostus speciosus leaves. For this, a successive extraction with diethyl ether, ethyl acetate, and ethanol using sonication at room temperature was performed to extract oven-dried (40 ℃, 48 h) leaves of C. speciosus. Percentage inhibition of the enzymes and the IC50 values were determined. But the extracts of diethyl ether and ethyl acetate did not exhibit proper percent inhibitions for both alpha-amylase and alpha-glucosidase activities. Porcine pancreatic alpha-amylase inhibitory activity was performed using the DNSA method and it was detected in ethanolic extract of C. speciosus leaves with an IC50 of 17.12 mg ml-1 and Saccharomyces cerevisiae alpha-glucosidase inhibitory activity was detected with an IC50 of 21.20 mg ml-1 . Both enzyme inhibitory activities were compared with that of commercial Acarbose (IC50 values for alpha-amylase and alpha-glucosidase enzymes are 65.44 µg ml-1 and 68.52 µg ml-1 , respectively). When comparing with acarbose, a crude extract of C. speciosus leaves show promising nature to isolate antihyperglycemic compounds. Results also indicate that the alpha-amylase and alpha-glucosidase inhibition by the ethanol extract of C. speciosus are dose dependent. Therefore, this study proves that the ethanolic leaf extract of C. speciosus has enzyme inhibitory activities toward alpha-glucosidase and alpha-amylase which may helpful for the development of an antihyperglycemic formulation to reduce the postprandial glucose level. This will be carried out by bioassay-guided fractionation and isolated active compounds will be intercalated to montmorillonite, an aluminosilicate clay with high cation exchange capacity, and large specific surface area to produce sustained release formulation. Keywords: Cheilocostus speciosus, Alpha-amylase, Alpha-glucosidase, Diabetes mellitusItem Extraction and Purification of Chitin and Chitosan from Portunus pelagicus Crab Shell Waste(Uva Wellassa University of Sri Lanka, 2021) Tissera, W.M.J.C.M.; Rathnayake, S.I.; Abeyrathne, E.D.N.S.Crab (Portunus pelagicus) shell waste is highly accumulated in Sri Lankan seafood processing factories, but not many efforts have been taken on utilizing it for commercial level chitin and chitosan extraction with a higher percentage purity. Therefore the objective of this study was to modify and develop a scale-up, simple, and high-yielding chemical method for extraction and purification of chitin and chitosan from locally underutilized Portunus pelagicus crab shell waste. A modified process including pre-demineralization (acetic acid), demineralization (citric acid), deproteinization (NaOH), decolourization (n-butanol) deacetylation (NaOH), and purification (EDTA and SDS) was optimized to obtain a new combination of treatments. Pre-demineralization was introduced as a new step when developing the process. Citric acid was found as the best alternative organic acid to replace HCl in demineralization. The final product was characterized by X-Ray Diffraction (XRD) Spectroscopy and Fourier Transform Infrared (FTIR) Spectroscopy and various physicochemical and functional properties were analyzed. Control chitin and chitosan samples were produced using a conventional method for comparison. The yields of crude chitin, crude chitosan, and purified chitosan were 32.52±0.68%, 26.28±0.47%, and 21.78±0.34% respectively whereas in the control chitin and chitosan the yields were 20.34±0.72% and 13.79±0.93% respectively (p<0.05). Percentage purity of the final product on a weight basis was 82.54±1.73% with a degree of deacetylation of 85.84±2.45%. The XRD data revealed that chitosan extracted from the developed methodology is a semi-crystalline compound with two characteristic crystalline peaks at 2θ =9.05° and 19.1° and Crystallinity Index of 67.22%. FTIR analysis revealed that developed chitosan was comparable with control chitosan. Chitosan produced from the developed method showed higher results in physicochemical parameters namely moisture (5.27±0.39%), ash (1.95±0.22%) whiteness index (72.37±0.66%), and functional properties namely water binding capacity (318.74±0.48%), fat binding capacity (351.663±0.69%) DPPH free radical scavenging activity (61.12±0.59%) and ferrous chelating activity (40.19±0.47%) compared with the control (p<0.05). Developed chitosan had no antimicrobial activity for Salmonella and Micrococcus but showed positive antimicrobial activity against locally isolated Escherichia coli at 2.5mg/ml. Thus the developed methodology can be used to obtain high purity and high-quality chitosan with better physicochemical and functional properties from crab shell waste Keywords: Portunus pelagicus; Shell waste; Chitosan; Pre-demineralization; XRD; Percentage purityItem Intercalation of Acarbose into Sodium Montmorillonite for Sustained Release Formulation(Uva Wellassa University of Sri Lanka, 2020) Mihiravi, H.K.S.P.; Lochana, E.A.L.; Rathnayake, S.I.; Alakolanga, A.G.A.W.; Senarathna, K.G.C.; Premarathne, E.P.N.; Wijesekara, K.B.Among the numerous antidiabetic drugs, acarbose is the most extensively used digestive enzyme inhibitor for the treatment of Type-II diabetes. A simple and rapid UV-Vis spectroscopy method reported in the literature was modified and successfully implemented for the determination of acarbose in aqueous media. The method is based on the formation of a green-colored complex of acarbose with alkaline potassium permanganate. Concentration (in the range of 10-50 ppm) is proportional to the visible light absorbance at 426 nm wavelength, therefore, the above parameters were selected for the quantitative determination of acarbose in aqueous solution. The Beer–Lambert law is obeyed in the above-mentioned range with a coefficient of determination (r2 ) value of 0.9826. The acarbose concentration in commercial tablets was determined using this method and the recovery was 99.65 % for 40 ppm solution. Short biological half-life and more side effects of acarbose have been recurring problems, owing to its low bioavailability and low patient tolerance, respectively. The controlled release of a therapeutic agent to patients is gaining prodigious importance during the recent time and clay minerals play a major role in modulating drug delivery. The present work is focused on the intercalation of acarbose into montmorillonite (MMT) as a controlled release drug carrier. MMT is an aluminosilicate clay composed of tetrahedral layers of silica stacked between octahedral layers of alumina with negatively charged surfaces. Due to its high cation exchange capacity and large specific surface area, MMT is extensively used in the formulation of various pharmaceutical products. In this study, acarbose was successfully incorporated into MMT by stirring MMT in a 100 ppm acarbose solution and showed 22.4% intercalation at pH 6. Acarbose intercalated MMT was characterized by X-ray diffraction and Fourier transformed infrared and the presence of N-H stretching peak at 1632 cm-1 and increase of d-spacing confirmed the successful intercalation of acarbose into the interlayers of MMT. The releasing properties of the synthesized acarbose-MMT composite would be investigated in the future. .Keywords: Acarbose, Montmorillonite, Intercalation, Drug delivery, CharacterizationItem A Study on Sustained Drug Releasing Properties of Acarbose Intercalated Na- montmorillonite for Potential Pharmaceutical Applications(Uva Wellassa University of Sri Lanka, 2021) Kawmudhi, P.A.S.; Lochana, E.A.L.; Premarathne, E.P.N.; Alakolanga, A.G.A.W.; Rathnayake, S.I.Acarbose is a well-known synthetic drug, which commonly treats type II diabetes. For diabetic patients, acarbose must be administered multiple doses a day to keep a stable glucose level in the body due to short biological half-life. Therefore, drug formulations with sustained releasing properties are developed using stable carriers like, Montmorillonite (MMT) due to its unique structure and properties. In this study, acarbose intercalated clay formulations were synthesized and their sustained releasing properties tested. Acarbose solution (100 ppm) was stirred with MMT (1 g) for 24 h at 4–8 pH. The highest intercalation of acarbose was observed at acidic pH due to electrostatic interactions between negatively charges clay layers and protonated acarbose molecules. The concentration of acarbose in aqueous solution was determined using the UV-Vis spectroscopy method. The calibration curve (2–40 ppm) of standard acarbose (r2 =0.9826) at 426 nm, was used for calculating the acarbose intercalation percentages. 2.18 mg g-1 (43.77%) and 5.1 mg g-1 (52.27%) of acarbose intercalated into MMT at pH 6 and the interlayer space of unmodified montmorillonite has been increased from 1.185 to 1.310 nm and 1.403 nm upon acarbose intercalation at 50 ppm and 100 ppm initial acarbose concentrations, respectively. This concludes that acarbose has been successfully intercalated into the interlayers of montmorillonite and the intercalated amount increased with increasing the initial acarbose concentration. Increased intensity and broadening of the peak corresponding to vibrations of OH groups (3687–3125 cm-1) was observed in FTIR spectra of acarbose intercalated montmorillonite, which may due to the presence of acarbose on or between the layers of montmorillonite. The in-vitro drug releasing properties of acarbose from acarbose intercalated montmorillonite was tested in artificial intestinal condition (pH 7.4 PBS solution) using dialysis tube method. Acarbose releasing from the montmorillonite matrix was gradually increased in the first 8 h and slow release was observed after that. Pseudo-second order kinetics model showed a good fit (r2= 0.9767) for the acarbose releasing data suggesting the release of acarbose from MMT matrix involves chemical desorption. Overall, this study demonstrates the potential applications of montmorillonite as matrix material for sustained release drug formulations for future pharmaceutical studies. Keywords: Acarbose; Montmorillonite; Sustained drug releasing; XRD; FTIR