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Item Comparison of photoprotective properties and anti-diabetic properties of pink colour and yellow colour flowers of Mirabilis jalapa Linn(Faculty of Science, University of Kelaniya Sri Lanka, 2024) Chathuranga, S. M. N.; Rajapakse, C. S. K.Herbal medicines are considered as the core of traditional treatment methods worldwide. Plants rich in phytochemicals exhibit a wide range of medicinal applications. Mirabilis jalapa is one such plant that exhibits a wide range of therapeutically valuable properties such as antioxidant, anti-inflammatory, antimicrobial, and anti-diabetic properties. Due to limited research on the bioactivities of Mirabilis jalapa flowers, this study aims to examine the photoprotective and anti-diabetic properties of yellow and pink color flowers. The total tannin content (TTC) of the flowers was also assessed as tannins are frequently utilized in the pharmaceutical and cosmetic industries due to their astringent, antioxidant, and anticancer properties. First, the chemical constituents of air-dried yellow and pink-colored flowers were separately extracted into methanol by cold maceration. Then the photoprotective properties, antidiabetic activity, and TTC of yellow color flower extract (YCFE) and pink color flower extract (PCFE) were analyzed by determining the sun protection factor (SPF), alpha-amylase inhibitory assay, and acidified vanillin method respectively. The SPF values of PCFE, YCFE, and commercially available sunscreen were 18.92 ± 0.63, 19.45 ± 0.54, and 31.47 ± 1.15 respectively. However, no alphaamylase inhibitory activity was observed for either PCFE or YCFE. Kanakamani et al., 2018 have reported that there is an alpha-amylase inhibitory activity in the ethanolic extract of Mirabilis jalapa flowers (IC50 = 430.09 ± 2.09 µg/mL). TTC values of YCFE and PCFE were 14.61 ± 0.32 and 12.83 ± 0.30 mg of catechin equivalent/g of the dry weight of the extract. The results indicated that the yellow flowers of Mirabilis jalapa exhibit higher tannin content than the pink flowers. Since the two extracts exhibit SPF values ranging between 15–30, both extracts showed moderate protection against UV radiation, hence they have the potential to be used as additives in sun protection cosmeceuticals. Conducting further research to isolate and identify the tannins and other compounds responsible for photoprotective properties will be essential for the pharmaceutical and cosmetic industries.Item A comparative study of the nutritional, pharmaceutical and photoprotective properties of almond (Prunus dulcis) and tropical almond (Terminalia catappa) nuts(Faculty of Science, University of Kelaniya Sri Lanka, 2023) Panditharathna, G. M.; Rajapakse, C. S. K.This study focuses on the comparison of nutritional, pharmaceutical and photoprotective properties of methanolic extracts of Terminalia catappa (TC) commonly known as tropical almond or ‘kottamba’ and Prunus dulcis (PD) nuts (almond). TC is a popular folk medicine and has several proven biological properties. The objective of this research work was to evaluate in vitro antioxidant, α-amylase inhibitory, anti-lipase activities, and photoprotective properties of TC and PD nuts. First, the proximate composition of powdered nuts was determined by standard methods. Next, the phytochemicals in powdered nuts were extracted to methanol by cold extraction and phytochemical screening was conducted using standard biochemical tests. Further, 2,2-Diphenyl-1-picrylhydrazyl (DPPH), 2,2'-Azino-bis(3-ethylbenzthiazoline-6-sulfonic acid) diammonium salt (ABTS), and the ferric reducing power assays were used to determine the antioxidant activity of methanolic extracts of nuts. The α-amylase inhibitory activity and antilipase activity of extracts were determined by α-amylase inhibitory assay and anti-lipase assay respectively. Finally, the photoprotective property of the extracts was determined by a UV-Visible spectrophotometric method. Results showed that TC was significantly high in moisture (11.8%) with p value (0.00000097) less than 0.05 and low lipid content (32.16%) with p value (0.0000016) less than 0.05. There was no significant difference (p > 0.05) recorded in crude fiber (15.66% and 14.33%) (p value = 0.2000), protein (36.15% and 33.85) (p value = 0.2298), and carbohydrate (11.85% and 12.23%) (p value = 0.2690) for TC and PD, respectively. The present study revealed that both nuts are rich in phenols, alkaloids, flavonoids, steroids, terpenoids, glycerides, saponin, cardiac glycosides and triterpenes. PD extract showed significantly higher DPPH radical scavenging activity with an IC50 value of 78.55 ± 5.10 μg/mL while TC extract showed an IC50 of 89.22 ± 4.40 μg/mL. The ABTS radical scavenging activity of PD, with a value of IC50 57.19 ± 0.32 μg/mL is significantly higher than that of TC, (IC50 74.36±3.34 μg/mL). The ferric reducing power of TC (FRAP values of 41.6±0.23 mg potassium ferricyanide equivalents per gram (PFE/g) of dried extracts) is significantly lower than that of PD (39.15±0.21 mg PFE/g of dried extracts). The α-amylase inhibitory experiment demonstrated that the extracts of TC with an IC50 113.4±1.56 μg/mL and PD with IC50 128.3±1.12 μg/mL have inhibitory effects on the enzyme. In the anti-lipase assay, both samples showed anti-lipase activity (TC - 190.4 ± 5.22 μg/mL, and PD, 167.33 ± 6.35 μg/mL) indicating their potential to block the lipase enzyme, which aids in weight reduction. Compared to a commercially available sunscreen, both extracts exhibited moderate UV protection with SPF values of 14.52 ± 2.34 (TC) and 12.92 ± 1.78 (PD). These results suggested that not only PD, but also TC nuts are a great source of antioxidants, anti-diabetics, and antiobesity compounds despite not being commercially utilized. Therefore, Terminalia catappa can be used as an alternative to Prunus dulcis in food and pharmaceuticals.Item Evaluation of in vitro antioxidant, anti-inflammatory activities and photoprotective properties of methanolic extracts of fruits, leaves and bark of Flacourtia indica(Faculty of Science, University of Kelaniya Sri Lanka, 2023) Disanayake, D. M. S. T.; Rajapakse, C. S. K.Many plant-derived compounds are used medicinally as therapeutic measures against various disorders. Flacourtia indica commonly known as “Uguressa” or “Katulovi” is a medicinal plant used in ayurvedic medicine in Sri Lanka for treatment of various diseases. Therefore, this study focused on evaluating the antioxidant, anti-inflammatory activities and photoprotective properties of methanolic extracts of fruits, leaves and bark of Flacourtia indica. Phytochemicals in leaves, fruits and bark of Flacourtia indica were extracted into methanol by Soxhlet extraction. The presence of bioactive compounds was qualitatively identified by phytochemical screening of methanolic extracts. The total phenolic content (TPC) of each extract was determined by Folin- Ciocalteu (F-C) method. The antioxidant activity of each extract was determined by 2,2-diphenyl- 1-picrylhydrazyl (DPPH) free radical scavenging assay and the anti-inflammatory activity of each extract was assessed by protein denaturation assay. Photoprotective properties of the extracts of leaves, fruits and bark of Flacourtia indica were evaluated by determining the sun protection factor (SPF) of each extract using a UV-visible spectrophotometric method and applying the Mansur equation. The results of phytochemical screening revealed the presence of steroids, tannins, saponins, alkaloids, proteins and phenols in three tested plant parts. The DPPH free radical scavenging activity, anti-inflammatory activity and photoprotective properties of tested extracts were in the order of leaf>bark>fruit. The highest DPPH radical scavenging activity (IC50 = 27.02 ± 0.25 μg/mL), anti-inflammatory activity (IC50=186.08±0.80 μg/mL) and photoprotective property (SPF = 40.57 ± 0.11 at 2.0 mg/mL) were shown in the leaf extract. According to the results, extract of leaves of Flacourtia indica has high sunburn protection as sunscreens with SPF> 30 are considered as products with high sun protection and recommended by the most dermatologists. Among the three extracts, the methanolic leaf extract was rich in phenolics with TPC of 39.97±4.18 mg GAE/g of dry weight of plant material. According to the Pearson correlation, a strong positive correlation was observed between the TPC and antioxidant activity (r=0.9730, p<0.05) indicating a strong contribution of phenolics for antioxidant activity of leaves, fruits and bark of the plant. The results of this study revealed that the leaves of Flacourtia indica could be used as natural source rich in plant-derived antioxidant, anti-inflammatory and photoprotective agents, which can be used in the pharmaceutical industry and as additives in sunscreen formulations.Item Guava (Psidium guajava L.) leaves as a source of phytochemicals with antioxidant, antimicrobial and photoprotective properties for sunscreen formulations(Faculty of Science, University of Kelaniya Sri Lanka, 2022) Dewage, D. D. D. H.; Karunaratne, S. H. S.; Rajapakse, C. S. K.The skin is the largest and most visible organ of the human body, which acts as the outer protective barrier. Exposure to solar radiation, including UV A and UV B can cause UV induced skin damage leading to sunburn and skin carcinogenesis. Sunscreens with natural ingredients for skin care have become a new trend in cosmetology as they protect skin against photo ageing and dermatologic disorders. Plant parts of guava are known to be rich in phytochemicals with antidiarrheal, anti-diabetic, antimicrobial, hepatoprotective, analgesic and antihyperglycemic activities, but less research has been conducted to explore their photoprotective properties and potential to be used in sun protection cosmeceuticals. Therefore, this study aimed to evaluate the antioxidant, antimicrobial and photoprotective properties of methanolic extract of guava (Psidium guajava L.) leaves to investigate its potential to be used in sunscreen formulations. Chemical constituents in guava leaves extracted into methanol by Soxhlet extraction were sequentially fractionated with hexane, dichloromethane (DCM), and aqueous methanol. Each fraction was tested for their bioactivities. The antioxidant activity of each fraction was determined by α, α-diphenyl-β-picrylhydrazyl (DPPH) free radical scavenging assay, hydrogen peroxide scavenging assay and ferric ion reducing antioxidant power assay (FRAP). Agar well diffusion method was used to determine the antimicrobial activity against the potential pathogens in cosmetics, bacterial strains of Escherichia coli (ATCC 25922), Pseudomonas aeruginosa (ATCC 9027), Staphylococcus aureus (ATCC 25923) and a fungal strain Candida albicans (ATCC 10231). Mansur equation was used to estimate the sun protection factor (SPF) of each fraction by in-vitro method using UV spectrophotometry. Among the fractions, aqueous methanol fraction exhibited the highest DPPH free radical scavenging activity with IC50 value of 90.07 ± 0.73 μg/mL and H2O2 scavenging activity with EC50 value of 12.65 ± 1.01 μg/mL. The ferric ion reducing ability of aqueous methanol fraction also was found to be the highest (247.0 ± 0.51 mg of Ascorbic acid equivalents/mL of extract) among the three fractions. Aqueous methanol fraction showed an antimicrobial activity against all the tested microorganisms and its activity was comparable (zone of inhibition of 20.0 ± 0.75 mm) to that of the positive control Amoxicillin (zone of inhibition of 22.0 ± 1.00 mm) against Pseudomonas aeruginosa. The aqueous methanol fraction had an impressive SPF value of 41.51 ± 0.64 which was higher than that of the reference sunscreen (SPF = 39.18 ± 0.56). As the results revealed among the tested fractions, the aqueous methanol fraction is the richest in phytochemicals with antioxidant, antimicrobial activities, and photoprotective properties with a high sun protection factor and guava leaves can be used as a natural source of these phytochemicals for the development of sun protection cosmetics.Item Pharmaceutical and cosmeceutical potential of methanolic extract of Kaffir lime (Citrus hystrix) leaves(Faculty of Science, University of Kelaniya Sri Lanka, 2022) Fernando, W. W. B. P.; Rajapakse, C. S. K.Kaffir lime (Citrus hystrix), commonly known as ‘gada dehi’ is a citrus fruit native to Southeast Asia. As less research has been conducted to investigate the potential pharmaceutical and cosmeceutical properties, the present study aimed to evaluate the antioxidant, antimicrobial and photo-protective properties of methanolic extract of Kaffir lime leaves. Dried and powdered Kaffir lime leaves were extracted into methanol by maceration. Constituents in the extract were then sequentially fractionated with hexane, dichloromethane (DCM), and methanol (50%). The antioxidant activity of each fraction was evaluated by α-diphenyl- β- picrylhydrazyl (DPPH) free radical scavenging assay. Total phenolic content (TPC) and total flavonoid content (TFC) of each fraction were determined by Folin-Ciocalteu and aluminium chloride colorimetric assays respectively. The antibacterial and antifungal activities of methanolic extract of leaves and its fractions were determined against selected strains of bacteria Klebsiella pneumonia, E.coli, Staphylococcus aureus, and fungi Aspergillus welwitschiae, Candida albicans by agar disc diffusion method. The photoprotective property of the methanolic extract and its fractions were assessed spectrophotometrically by determining the Sun Protection Factor (SPF) using the Mansur equation. Among the fractions, the DCM fraction showed the highest antioxidant activity (IC50 186.20 ± 4.95 μg/ml) with the highest TPC and TFC (0.64 ± 0.04 mg gallic acid equivalent/g of dried weight and 5.03 ± 0.21 mg of quercetin equivalent/g of dried weight, respectively). The methanolic extract showed inhibition against all the tested bacteria and fungi and among the fractions, the DCM fraction exhibited the highest inhibition against K. pneumonia, S. aureus, and C. albicans. All the fractions exhibited UV-B absorption, and among them, DCM showed the highest photo-protective property with an SPF of 34.03 ± 0.18 at 2 mg/ml while the SPF of the reference sunscreen was 33.48 ± 0.27 at 2 mg/ml. As the DCM fraction exhibited the highest antioxidant and photoprotective properties and significant antimicrobial activity, it was further separated by silica gel column chromatography into 6 subfractions. Further, the subfraction 3 (F3) was analysed by GC-MS as it contained the chemical constituents with the highest photoprotective property among the 6 subfractions and revealed that it is rich in volatile constituents including linalool oxide, α-terpinolene, 2,4-bis(1,1-dimethylethyl)-phenol, diethyl phthalate, hexadecanoic acid, methyl-3-(3,5-ditertbutyl-4-hydroxyphenyl) propionate and octadecanoic acid. These findings demonstrated that the extract of Kaffir lime leaves could be used as a natural source in the pharmaceutical and cosmeceutical industries as it is rich in phytochemicals with antioxidant, antimicrobial activities, and photoprotective properties with a high sun protection factor.Item Antioxidant activity and protein precipitating ability of peel extract of Nephelium lappaceum Linn. (Rambutan)(Faculty of Science, University of Kelaniya, Sri Lanka, 2021) Binuwangi, A. K. D. M.; Rajapakse, C. S. K.Nephelium lappaceum Linn. (Rambutan) peels, one of the tropical agricultural wastes, have been identified as a rich source of polyphenols with antioxidant properties. Plant phenolic compounds can interact with protein molecules and the polyphenol-protein complexes enhance the antioxidant capacity of polyphenols and therefore influences the bioaccessibility of phenolics. This study was aimed to determine the antioxidant activity and the bovine serum albumin (BSA) protein precipitating ability of peel extract of Rambutan (Nephelium lappaceum). Fresh Rambutan fruits of Malwana special variety were collected from a commercial cultivation in the Western province, Sri Lanka. Chemical constituents in dried, powdered Rambutan peels were extracted using cold extraction (extracting solvents = methanol, ethanol, and ethyl acetate) (6 days, 37° C) and methanolic soxhlet extraction (6 hrs, 60 °C) separately. Antioxidant activity and total phenolic content (TPC) of freeze-dried extracts were determined using 1,1-diphenyl-2-picryl-hydrazyl (DPPH) free radical scavenging assay and Folin-Ciocalteu assay, respectively. The correlation between antioxidant activity and TPC was analyzed using Pearson’s correlation. Since the methanolic crude extract obtained from cold extraction was rich in phenolics, it was fractionated into hexane, dichloromethane (DCM), ethylacetate, and aqueous methanol, and their protein precipitation ability was determined using Bradford assay. Among the crude extracts, the highest percentage yield was obtained from soxhlet extraction (34.5 %). Methanolic cold extract had the highest TPC (332.56 ± 1.20 mg GAE / g of extract), and ethylacetate crude extract had the lowest TPC (210.13 ± 3.20 mg GAE / g of extract). Further, antioxidant activity of soxhlet extract (IC50 = 9.70 ± 0.50 µg/mL) and methanol (IC50 = 8.20 ± 0.35 µg/mL) and ethanol (IC50 = 8.31 ± 0.50 µg/mL) cold extract was significantly higher (p < 0.05) than that of synthetic antioxidant BHT (IC50=13.92 ± 1.19 µg/mL). Statistically significant (p < 0.01), a strong positive correlation was observed between DPPH radical scavenging activity and the TPC with Pearson’s correlation coefficient (r) of 0.99. Hence, the results suggested a potential for the utilization of peels N. lappaceum, as a nutraceutical enriched with natural antioxidants. According to results of protein precipitation potential of fractions, the highest percentage of BSA precipitate was observed (88.54 ± 0.92 %) in the ethyl acetate fraction. Thus, this study identified that Rambutan peel polyphenols have an affinity to bind with BSA at pH 4.5 in-vitro and the antioxidant activity of Rambutan peel extract would be masked by polyphenol–protein precipitation to some extent. Therefore, further studies should be necessary to isolate, purify, and identify polyphenols in Rambutan peels with their protein precipitation potentials to understand the mechanism of phenolic-protein interactions and their industrial applications.Item Correlation between sun protection factor and antioxidant activity, phenol and flavonoid contents of Ananas comosus (pineapple) peel(Faculty of Science, University of Kelaniya, Sri Lanka, 2021) Samarakoon, S. M. G. K.; Rajapakse, C. S. K.UV radiation can be categorized into three as UV-A (320 – 410 nm), UV – B (280 – 320 nm) and UV-C (200 – 280 nm) where UV-B radiation is considered as one of the main causes of skin damage leading to sunburn and skin cancers. Skin care products such as sunscreens are commonly used to reduce harmful effects of radiation as they absorb or reflect UV-B radiation and help prevent sunburn. Development of sunscreen formulations containing plant-based photoprotective agents is recently being explored as they also possess antioxidant properties and considered to be safer than the synthetic agents. Therefore, the aims of this study were to explore the possibility of using Ananas comosus (Pineapple) peel as source rich in phytochemicals with photoprotective properties and determine the correlation between Sun Protection Factor (SPF) and antioxidant activity, phenol and flavonoid contents of methanolic extract of pineapple peel. Firstly, the chemical constituents of the pineapple peel were extracted into methanol by Soxhlet extraction and it was sequentially partitioned into hexane, dichloromethane (DCM) and 50% methanol. SPF of all three fractions of methanolic extract of pineapple peel was determined by UV-Visible spectrophotometric method and Mansur equation. Antioxidant activity of the fractions were determined by α-diphenyl-β-picrylhydrazyl (DPPH) free radical assay. Total Phenolic Content (TPC) and Total Flavonoid Content (TFC) were assessed by Folin-Ciocalteu method and Aluminium Chloride colorimetric methods, respectively. Correlation between SPF and antioxidant activity, TPC and TFC was determined by the Pearson’s method. All the fractions of methanolic extract exhibited UV-B absorption properties and their SPFs were between 4.95 and 29.74. Among them, DCM fraction showed the highest SPF of 29.74 ± 0.03 at 1 mg/mL. The study also revealed that there is a strong positive correlation between SPF and TPC (r = 0.6366), a very strong positive correlation between SPF and TFC (r = 0.9497) and a very weak positive correlation between SPF and antioxidant activity (r = 0.095) suggesting that phenols including flavonoids in pineapple peel may contribute to its strong photoprotective potential. As the DCM fraction showed the highest SPF, it was partially purified by column chromatography and analyzed by GC-MS and the results revealed that the pineapple peel was rich in chemical constituents with known bioactivities including antioxidant activity. Since there is a synergistic act of UV-B protection with radical scavenging activity of phytochemicals, the phenolics in peel of pineapple can be considered as a promising natural additive for enhancing photoprotective properties in sunscreen formulations.Item Phenolic and flavonoid contents and antioxidant activity of methanolic extract of Durio zibethinus Murr. Peels(Institute of Chemistry Ceylon Adamantane House, Rajagiriya, Sri Lanka., 2020) Perera, M. P. J.; Rajapakse, C. S. K.Durio zibethinus (durian), known as the King of fruits is one of the most important seasonal fruits in tropical Asia. Even though the edible parts of durian are known to be rich in bioactive compounds, less research has been conducted to investigate the potential bioactivity of durian peels and seeds which are of less commercial value and being disposed leading to environmental pollution. Therefore, this research was mainly focused on exploration of bioactive properties in methanolic extract of durian peels. Firstly, the dried durian peels were soxhlet extracted using methanol and then the crude extract was sequentially partitioned in hexane, dichloromethane and methanol (30%). The antioxidant activity, total phenolic content (TPC) and total flavonoid content (TFC) of each fraction were evaluated using DPPH (α, α-diphenyl- β- picrylhydrazyl) assay, Folin-Ciocalteu assay and aluminium chloride spectrophotometric assay respectively. Antioxidant activity (IC50) and its correlation to TPC and TFC were analyzed by the Pearson’s method. The dichloromethane fraction showed the highest antioxidant activity (IC50 179.9 ± 6.6 μg/ml) with high TPC and TFC (85.82 ± 12.11 mg gallic acid equivalent/g dried weight and 12.66 ± 1.94 mg of quercetin equivalent/g of dried weight, respectively). According to the Pearson’s correlation, a strong positive correlation was observed between the antioxidant activity and the TPC of fractions of methanol extracts of durian peels with a Pearson coefficient of 0.9904 and a moderate positive correlation was noticed between the antioxidant activity and TFC of the fractions with a Pearson coefficient of 0.6553 indicating that phenolic compounds in durian peels may contribute to their strong antioxidant activities with somewhat contribution from the flavonoid compounds. As the dichloromethane fraction had constituents with the highest antioxidant activity, it was further separated by column chromatography and analyzed by GC-MS to identify its volatile compounds. The results revealed that the dichloromethane fraction of durian peels was rich in [1,2-Benzenedicarboxylic acid, bis (2-ethylhexyl) ester], [2,3-Diphenylquinoxaline], [2-Coumaranone], [4-((1E)-3-Hydroxy-1- propenyl)-2-methoxyphenol], [7,9-Di-tert-butyl-1-oxaspiro (4,5) deca-6,9-diene-2,8-dione] and [Phenol, 2,4-bis(1,1-dimethylethyl)] which are known to exhibit antioxidant activity.Item Nephelium lappaceum L. peels as a source of phytochemicals with antioxidant and α-amylase inhibitory activities(Institute of Chemistry Ceylon Adamantane House, Rajagiriya, Sri Lanka., 2020) Binuwangi, A. K. D. M.; Rajapakse, C. S. K.Nephelium lappaceum L. (Rambutan) is a popular seasonal fruit native to Southeast Asia, enriched in varieties of phytochemicals including vitamins and secondary metabolites. This fruit is consumed fresh, canned, or as a processed food, but unfortunately its consumption results in production of vast amounts of waste from its seeds and peels which eventually create mosquito breeding grounds. Therefore, this study was conducted to investigate the potential of utilizing fruit waste (peels) of Sri Lankan variety of rambutan, Malwana special as a source of phytochemicals with antioxidant and α-amylase inhibitory activities. Phytochemicals of dried rambutan peels were first extracted into methanol by Soxhelt extraction. Then the crude extract was sequentially partitioned in hexane, dichloromethane (DCM) and methanol (30%). Total phenolic content (TPC) and total flavonoid content (TFC) of methanol extracts of rambutan peels and its fractions were determined using Folin- Ciocalteu and aluminium chloride method, respectively. Among the fractions, the highest TPC of 141.73 ± 18.66 mg gallic acid equivalents/g dried weight was found to be in aqueous methanol fraction and the DCM and aqueous methanol fractions were rich in flavonoids with TFC of 136.41 ± 32.25, and 110.67 ± 1.43 mg quercetin equivalents/g dried weight, respectively. Further, the radical scavenging properties of all the fractions were investigated using 1,1-diphenyl-2-picryl-hydrazyl (DPPH) free radical scavenging assay and their correlations with phenolics and flavonoids were analyzed using Pearson’s correlation. The methanol extract of peels (IC50 = 9.70 ± 0.50 μg/mL) and its aqueous methanol fraction (IC50 = 12.04 ± 0.80 μg/mL) showed higher DPPH radical scavenging activity than that of the control, butylated hydroxytoluene (IC50 = 13.92 ± 1.19 μg/mL). Strong positive correlations were observed between the antioxidant activity and the TPC and TFC with Pearson’s correlation coefficients of 0.9018 and 0.8493, respectively. Interestingly, it was also found out that the in vitro α-amylase inhibitory activity of the aqueous methanol fraction of the peels (IC50=75.17 ± 3.40 μg/mL) was significantly higher than the standard drug acarbose (IC50=171.5 ± 8.50 μg/mL). Results revealed that the peels of Sri Lankan variety of rambutan, Malwana special is a potential source of phytochemicals with antioxidants and α- amylase inhibitory properties.Item Preparation, characterization and properties of activated carbon derived from rice husk(4th International Research Symposium on Pure and Applied Sciences, Faculty of Science, University of Kelaniya, Sri Lanka, 2019) Perera, P. L. R. A.; Rajapakse, C. S. K.Rice, the staple food of the Sri Lankans is one of the important crops occupying 34% of the total cultivated area in the country. Thus, rice processing generates a large quantity of rice husk as waste material. The main objective of the present work was to investigate the potential of using this agricultural waste, rice husk as a precursor for the production of low-cost activated carbon (AC) as an adsorbent for the removal of heavy metals (Pb(II), Cd(II) etc.). Therefore, the present study was carried out to evaluate the effect of carbonization time and activating agent on AC production from rice husk and its Pb(II) removal capacity. Cleaned and dried rice husks samples (12.00 g) were separately carbonized at 400 °C under constant nitrogen flow for 60 minutes -150 minutes (60 min, 90 min, 120 min, 150 min) and chemically activated by HCl. The AC yield was calculated in each sample. In order to determine the lead removal percentages (Pb%) of AC derived from rice husk at different carbonized temperatures, first AC samples were added (1.00 g) separately to a Pb(II) standard solution (5.00 mg L-1), stirred for 1 hour at pH 7 at room temperature. The solutions were filtered and the residual Pb was determined by Atomic Absorption Spectrophotometry (AAS). All the experiments were performed in duplicate. Further, the AC with the highest Pb removal capacity was characterized by Scanning Electron Microscopy & Energy Dispersive Spectroscopy (SEM/EDAX), and Fourier Transform Infrared Spectroscopy (FT-IR). Proximate analysis, of the AC were also studied. The percent yield of AC prepared from rice husk with HCl activation, and its corresponding % Pb removal potential were fluctuated with increasing carbonization time. The highest AC yield (20.50%), the highest % Pb removal (93.31%) was observed for the AC prepared by carbonization of rice husk at 400 °C for 120 minutes with HCl activation. The results of the proximate analysis revealed that the ash content, moisture content volatile matter content and fixed carbon content of the AC were 32.47%, 34.94%, 24.20%, and 8.39% respectively. Based on the results, it can be concluded that AC derived from rice husk can be considered as an efficient and cost-effective adsorbent for the removal Pb(II) from wastewater