Browsing by Author "Binuwangi, A.K.D.M."

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    Antioxidant activity and chemical constituents of methanolic extract of Durio zibethinus Murr. (durian) peels
    (MEDICINAL PLANTS - INTERNATIONAL JOURNAL OF PHYTOMEDICINES AND RELATED INDUSTRIES, 2021) Perera, P.J.; Binuwangi, A.K.D.M.; Silva, A.A.G.; Attanayake, R.N.; Wickramarachchi, S.R.; Rajapakse, C.S.K.
    This study aimed to determine the DPPH free radical scavenging activity, total phenolic content (TPC) and total flavonoid content (TFC) of methanolic extract of Durio zibethinus Murr. (durian) peels and its fractions. The chemical constituents of durian peels extracted into methanol by soxhlet extraction were sequentially extracted into hexane, dichloromethane and aqueous methanol. Among the fractions, the dichloromethane fraction showed the highest DPPH free radical scavenging activity (IC50 179.9 ± 6.6 μg/ml) with high TPC and TFC (85.82 ± 12.11 mg gallic acid equivalent/g of dried weight of extract and 12.66 ± 1.94 mg of quercetin equivalent/g of dried weight of extract, respectively). A very strong positive correlation (r = 0.9677) was observed between the DPPH free radical scavenging activity and the TPC of fractions and a strong positive correlation (r = 0.7858) was noticed between the DPPH free radical scavenging activity and TFC of the fractions indicating that phenolic compounds in durian peels may contribute to their strong antioxidant activity. As the dichloromethane fraction had constituents with the highest antioxidant activity, it was analyzed by Gas chromatography-Mass spectrophotometry to identify its volatile constituents. The results revealed that the dichloromethane fraction 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.
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    Antioxidant, a-Amylase Inhibitory Activities and Photoprotective Properties of Peels of Nephelium Lappaceum Linn. (Malwana Special)
    (Oriental Journal of Chemistry, 2021) Binuwangi, A.K.D.M.; Perera, M.P.J.; Silva, A.A.G.; Attanayake, R.N.; Rajapakse, C.S.K.
    This study focused on evaluation of antioxidant, α-amylase inhibitory activities and photo protective properties of peels of Nephelium lappaceum Linn. (rambutan); Malwana special. Methanolic extract of peels was sequentially partitioned in hexane, dichloromethane (DCM) and aqueous methanol. The methanol extract showed a significantly (p greater then 0.05) higher DPPH radical scavenging activity than that of butylated hydroxytoluene. Among the fractions, the highest total phenolic content (TPC) was found in the aqueous methanol fraction. DCM and aqueous methanol fractions were rich in flavonoids. In vitro α-amylase inhibitory activity of the aqueous methanol fraction was also significantly higher than the standard drug, acarbose. Partially purified aqueous methanol fraction of rambutan peels exhibited UV-B absorption with a moderate solar protection factor. The results revealed that the peels of Nephelium lappaceum Linn., Malwana special can be considered as a promising source for the development of natural antioxidant, cosmeceutical sunscreen and antidiabetic agents.