Chemistry
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Item Antioxidant and photoprotective properties of Flacourtia indica fruit extract:fractionation, and application in lipstick formulation(The Tri-Annual Publication of the Institute of Chemistry Ceylon, 2025) Dasanayaka, D. M. M. D.; Rajapakse, C. S. K.Flacourtia indica, known as Ugurassa in Sri Lanka, iswidely recognized for its ethnomedicinal applications.Despite its traditional use, scientific studies on itsantioxidant and photoprotective properties remainlimited. This study aimed to evaluate the antioxidantand photoprotective properties of F. indica fruitextract, perform sequential fractionation to identifybioactive fractions and incorporate a suitable bioactivefraction into a lipstick formulation to develop a herbalmultifunctional lipstick. Chemical constituents indried fruit powder were extracted by maceration usinghexane, acetone, ethanol:water (80%v/v), and methanol.The highest extraction efficiency (12.13%) was obtainedwith ethanol:water (80%v/v). The total phenoliccontent (TPC) and total flavonoid content (TFC) inethanol: water (80%v/v) extract were determinedusing Folin–Ciocalteu and aluminum chloride assays,respectively, yielding 21.10 ± 0.01 mg GAE/g and 34.70± 2.20 mg CE/g. Antioxidant potential was assessedusing 2,2-diphenyl-1-picrylhydrazyl (DPPH) radicalscavenging (IC₅₀ = 782.94 ± 12.61 μg/mL) and ferricreducing antioxidant power (FRAP) (0.348 ± 0.008mg BHT/g) assays. The photoprotective propertywas evaluated by determining the sun protectionfactor (SPF) spectrophotometrically with the Mansurequation, which indicated moderate UV protection(17.19 ± 1.63). Sequential fractionation of the extractwas performed using hexane, chloroform, ethyl acetate,and methanol. SPF evaluation showed notable valuesfor the hexane (30.85 ± 2.84), chloroform (17.19 ±1.63), and methanol (15.99 ± 0.65) fractions. Themethanol fraction exhibited the highest antioxidantactivity (DPPH, IC₅₀ = 296.50 ± 2.27 μg/mL). As themethanolic fraction was red and exhibited antioxidantand photoprotective properties, it was incorporatedinto a lipstick formulation. The developed lipstickformulation was evaluated for color (dark red), texture(smooth), pH (5.6), melting point (53 ºC), and skincompatibility (no skin irritation), confirming itssuitability according to the Bureau of Indian Standards9875:2018 guidelines for application, contingent uponthe completion of toxicity studies.Item Ethanolic Extract of Terminalia catappa Kernel: A Natural Remedy with Promising Pharmacological Potential.(Asian Journal of Chemistry, 2025) Jayawardhana, H.A.L.D.; DewageDona, D.H.D.; Rajapakse, C. S. K.A relationship between humans and nature began with our ancestral reliance on natural resources for survival and health. This relationship has profoundly influenced the field of pharmacology through the discovery and utilization of natural product drugs, demonstrating the enduring importance of nature in medicine and the ongoing exploration of its therapeutic potential. This study investigates the pharmacological potential of the ethanolic extract of Ceylon almond kernel (Terminalia catappa), highlighting its antioxidant (IC50 = 21.68 ± 1.97 µg/mL), anti-inflammatory (IC50 = 180.14 ± 3.99 µg/mL) and α-amylase inhibitory (IC50 = 147.77 ± 4.74 µg/mL) activities. It also showed antibacterial activity against various pathogens and minimal UV protection (SPF = 5.27 ± 0.63). These results suggest that the Ceylon almond kernel could be a promising natural source for pharmaceutical applications and drug development.Item Calamondin Peel Waste-Derived Activated Carbon as a Biosorbent for Heavy Metal Removal from Aqueous Solutions.(Asian Journal of Chemistry, 2025) Alwis, D. S.; Perera, R. A.; Rajapakse, C. S. K.This research focused on utilizing agricultural waste, calamondin (Citrus madurensis) peel, to produce low-cost calamondin peel-based activated carbon (CPAC), initially for Pb(II) ion removal from simulated water. CPAC, prepared by carbonizing chemically treated peel waste at 400 ºC for 120 min, achieved 99% Pb(II) removal under optimized conditions: 5 ppm initial Pb(II) concentration, 0.03 g adsorbent dosage, 20 min shaking time at pH 7. Isotherm studies confirmed chemisorption, with a maximum adsorption capacity of 10.63 mg/g. Furthermore, CPAC demonstrated a removal efficiency of 31.01% to 49.29% for Cd, Cr, Cu, Mn and Zn in water samples collected from the Kelani river, Sri Lanka. These findings emphasize the viability of CPAC as a cost-effective, environmentally sustainable adsorbent for the remediation of heavy metal-laden water, thereby advancing sustainable waste management and environmental remediation.Item Comparative analysis of the nutritional, medicinal, and sun protection properties of almond (Prunus dulcis) and tropical almond (Terminalia catappa) nuts.(Food Science and Applied Biotechnology, 2025) Panditharathna, G. M.; DewageDona, D. H. D.; Rajapakse, C. S. K.This study compares the nutritional, pharmaceutical, and photoprotective properties of methanolic extracts of Terminalia catappa (TC) and Prunus dulcis (PD) nuts. Phytochemical screening revealed both are rich in bioactive compounds. TC had higher moisture content (11.8%) than PD (3.40%), while other nutritional parameters showed minimal differences. PD exhibited stronger antioxidant activity (DPPH IC50: 78.55 ± 5.10 μg.ml-1; ABTS IC50: 57.19 ± 0.32 μg.ml-1) than TC (DPPH IC50: 89.22 ± 4.40 μg.ml-1; ABTS IC50: 74.36 ± 3.34 μg.ml-1), but TC had a higher FRAP value (41.6 ± 0.23 mg PFE.g-1) than PD (39.15 ± 0.21 mg PFE.g-1). PD showed greater phenolic (199.00 ± 14.65 mg GAE. g-1) and flavonoid (4.78 ± 0.077 mg QE. g-1) contents. TC demonstrated stronger α-amylase inhibition (IC50: 113.40 ± 1.56 μg.ml-1), while PD had better anti-lipase activity. Both exhibited moderate UV-B protection (SPF: 14.52 for TC, 12.92 for PD). These findings highlight TC as a promising alternative for functional foods, cosmeceuticals, and medicinal applications.Item Unveiling the Bioactive Potential of Kaffir Lime (Citrus hystrix) Leaves: Antioxidant, Antimicrobial, and Photoprotective Properties.(Chemistry & Chemical Technology, 2025) Fernando, B. P.; DewageDona, D. H. D.; Rajapakse, C. S. K.Kaffir lime (Citrus hystrix), a citrus species native to Southeast Asia, has limited research concerning its pharmaceutical and cosmeceutical potential. This study investigates the antioxidant, antimicrobial, and photoprotective properties of the methanolic extract of Kaffir lime leaves. The results demonstrate that Kaffir lime leaves are a promising herbal source for pharmacological applications, as they are rich in phytochemicals with antioxidant potential, strong photoprotective properties with a high SPF value, and antimicrobial activity against Staphylococcus aureus, Klebsiella pneumonia, Escherichia coli, Candida albicans and Aspergillus welwitschiae.Item Carotenoid pigments of Kocuria flava PUTS1_3 isolated from sediments of Puttalam lagoon mangrove ecosystem, Sri Lanka exhibit bioactive properties(Scientific Reports, 2025) Weerasinghe, K. E.; Kannangara, A. T.; Attanayake, R. N.; Rajapakse, K.; Halmillawewa, A. P.Microorganisms, inhabiting various ecological niches, exhibit a capacity to produce a diverse array of pigments with different shades. These colorful microbial pigments may also potentially possess beneficial bioactivities. This dual functionality together with the ease of mass production and downstream processing has shifted the global attention towards the use of microbially-derived pigments as bioactive colorants in different industries. Therefore, the present study was conducted with the aim of characterizing the pigments from Kocuria flava and identifying their potential biotechnological applications. The bacterium, PUTS1_3, was isolated using the surface sediment samples from the Puttalam mangrove ecosystem, Sri Lanka and it was identified as Kocuria flava using 16S rRNA gene sequencing. The yellow, intracellular pigment of PUTS1_3 was obtained by treating the cell pellet with methanol. Characterization of the pigment extract using UV-visible spectroscopy, TLC, and HPLC confirmed the presence of three carotenoid compounds, including β-carotene. The pigment extract also demonstrated antibacterial activity, against Gram positive bacteria tested. Antioxidant properties were observed with an IC50 value of 181.95 ± 4.57 µg/ml in the DPPH free radical scavenging assay. Although its sun protection factor was comparatively low (SPF 7.69 ± 0.01), the pigment showed promising results as a textile dye demonstrating good color performance and stability in washing and pH stability tests. Moreover, fabrics dyed with the pigment extract displayed antibacterial activity against Staphylococcus aureus (ATCC 25923). These findings suggest the potential use of the yellow pigments of K. flava PUTS1_3 for various biotechnological applications.Item Spatial variation of water quality in Nilwala river of the Southern Province of Sri Lanka(Ceylon Journal of Science, 2025) Diwyanjalee, G. R.; Premarathne, W. A. P. J.This study addresses the urgent need for comprehensive water quality assessments of the Nilwala River, a vital water source in Sri Lanka’s Matara district, to understand the impacts of anthropogenic activities on regional water resources. The research, conducted over an eight-month period encompassing both dry and wet seasons (March–October 2019), systematically analyzed water samples from eight strategic locations to assess spatial variations in key water quality parameters, including pH, electrical conductivity (EC), temperature, chemical oxygen demand (COD), biological oxygen demand (BOD), alkalinity, hardness, chloride, nitrate, and phosphate. Significant spatial differences were detected in parameters such as pH, EC, COD, BOD, hardness, alkalinity, and chloride (p < 0.001), with COD levels exceeding permissible limits at the Bandaththara power plant and urban Matara, highlighting the influence of industrial and urban discharges. The Weighted Arithmetic Water Quality Index (WAWQI) suggested that most sites require general treatment for drinking water, except Wellathota, which met acceptable standards. Principal Component Analysis (PCA) revealed that alkalinity, chloride, hardness, and COD were the primary contributors to water quality variations, while BOD was negatively correlated with these factors. The analysis identified rural, agricultural, and urban-industrial sites as key areas where water quality is significantly impacted by land use practices, including sand mining, agriculture, and urbanization. The study underscores the necessity for targeted monitoring and management interventions to protect the Nilwala River, emphasizing the importance of implementing mitigation strategies to address pollution sources. The findings provide critical insights into the dynamics of river water quality and highlight the need for sustainable resource management through identifying the pollution hotspots and the factors driving water quality deterioration.Item Potential of Inhibiting the Receptor Binding Mechanism of SARS-COV-2 using Phytochemicals contained in Paspanguwa Water Extract: Molecular Docking and Dynamic Studies(Asian Journal of Chemistry, 2024-11-30) JAYAWARDENA, P.A.S.N.P.; SOORIYAWANSHA, A.M.S.C.; KUMARATHUNGA, P.G.J.D.; DANANJAYA, P.D.H.; KADIGAMUWA, C.C.; DAHANAYAKE, J.N.This study is focused on the SARS-CoV-2 virus by in silico screening of phytochemicals contained in ‘Paspanguwa’ water extract, targeting ACE2 receptors using molecular docking. Phytochemicals of the five herbal ingredients contained in ‘Paspanguwa’ were extracted into water and were identified based on the literature reviews. Ligands geometries were optimized using Avogadro software and transformed to PDBQT format files by detecting torsion root using AutoDock Tools 1.5.6. SWISS-MODEL server was used to model the structure of the ACE2 receptor based on the UniProt ID Q9BYF1. The stereochemical quality of the protein model was assessed using SAVES v 6.0 and ProSA servers. Finally, potential ligands were docked to the ACE2 receptor protein by considering all variants of this virus and their interactions with the ACE2 receptor. The highest binding energy (BE) (-10.42 kcal/mol) was given by carpesterol phytochemical with allosteric site-2 and allosteric site-3 in the ACE2 receptor and this complex was subjected to molecular dynamic (MD) analysis using a CHARMM36 force field. According to the radius of gyration (Rg), root mean square deviation (RMSD) and root mean square fluctuation (RMSF) results, the studied protein-ligand complex was stable throughout the simulation time.Item Influence of pumpkin seed powder on the characteristic properties of whole wheat cake(Elsevier eBooks, 2024) De, Suprakash; Bharti, D.; Pradhan, B. K.; Behera, H.; Kim, N. M.; Wickramarachchi, S.; Sarkar, P.; Pal, K.Pumpkin seeds are a good source of unsaturated fatty acids, dietary fibers, and minerals. It can be used as a food supplement as the nutritional value of the seeds is relatively high. This study incorporates PSP (pumpkin seed powder) in varying amounts (0%, 5%, 10%, 15%, and 20%) in cake samples. Afterward, their effects on physicochemical, thermal, mechanical, and electrical characteristics were observed. Adding PSP to the cake recipe significantly increased the porosity of the cake by only up to 10% PSP incorporation. The PSP improved the hardness and other textural properties of the cake samples. Also, we can deduce that the water retention capacity of the cake samples increased with the addition of PSP, which increased the moisture content of the cake samples. From the results, we can observe that the browning of the cake increased with the incorporation of PSP in the cake samples. From all the characteristics, we can conclude that the cake sample with 10% PSP had the best texture. This means that PSP can be incorporated into cake samples only up to 10% without compromising the texture and taste.Item Effect of pumpkin seed powder on the properties of cake batter prepared with whole wheat flour(Elsevier eBooks, 2024) De, Suprakash; Bharti, D.; Pradhan, B. K.; Behera, H.; Kim, N. M.; Wickramarachchi, S.; Pal, K.; Sarkar, P.Nutrition plays a crucial role in overall health. Recently, different fruit and vegetable seeds have been incorporated into various food products to increase their nutritional values. Due to its higher nutritional content, the research community has recently explored pumpkin seed powder (PSP) as an ingredient in different bakery products. In the current study the batter composition prepared by whole wheat flour at varying PSP concentrations (5%, 10%, 15%, and 20% w/w) has been studied. The obtained results from the current study suggested that incorporating PSP significantly alters the color, texture, and microstructure of the prepared batter samples. Also, the water retention and air incorporation capacity of the batter samples showed a significant increase after the PSP incorporation. From the 2,2-diphenyl-1-picryl-hydrazyl-hydrate scavenging assay, the antioxidant properties of the prepared batter samples were analyzed. The results suggested an increased antioxidant activity after PSP addition. Though PSP adds to the nutritional value, adding PSP greater than 10% adversely affects the texture of the batters. With 10% of PSP replacement the prepared batter showed a balanced textural property in our study.