Acetylcholinesterase inhibition, antioxidant and identification of some chemical constituents of Phyllanthus atropurpureus cultivated in Egypt

Investigation of the lipid constituents of the aerial parts of Phyllanthus atropurpureus resulted in isolation and identification of the fatty acid mixture which consists of eight acids with linolenic acid as major and the unsaponifiable fraction that contain a series of hydrocabons, sterols, in addition to one triterpene (α-amyrin). The acetone insoluble fraction was found to contain two fatty alcohols and three n-hydrocabons in which the n-eicosane is the most abundant (44.16%). The flavonoidal constituents were isolated from ethyl acetate and butanol fractions which were identified as: luteolin-7-O-glucoside, kaempferol 3-O-(p-coumaroylglucoside), kaempferitrin, luteolin and kaempferol. Evaluation of different extracts as acetylcholinesterase inhibitors (AChI), established the chloroform fraction as a promising inhibitor of the enzyme. The antioxidant testing with DPPH radical revealed the potential of precipitate from MeOH extract as a radical scavenger.

对紫红叶下珠（Phyllanthus atropurpureus）地上部分的脂类成分开展研究，成功分离并鉴定出以亚麻酸为主要成分的八种脂肪酸混合物，同时获得不皂化物组分；该组分包含一系列烃类、甾醇类成分，此外还含有一种三萜类成分——α-香树素（α-amyrin）。丙酮不溶组分中含有两种脂肪醇与三种正构烃，其中正二十烷（n-eicosane）含量最高，占比达44.16%。从乙酸乙酯与正丁醇萃取组分中分离得到黄酮类成分，经鉴定分别为木犀草素-7-O-葡萄糖苷（luteolin-7-O-glucoside）、山奈酚-3-O-(对香豆酰葡萄糖苷)（kaempferol 3-O-(p-coumaroylglucoside)）、山奈苷（kaempferitrin）、木犀草素（luteolin）以及山奈酚（kaempferol）。对不同提取物开展乙酰胆碱酯酶抑制剂（acetylcholinesterase inhibitors，AChI）活性评价，结果证实三氯甲烷萃取组分对该酶具有良好的抑制潜力。采用DPPH自由基法进行抗氧化活性测试，结果表明甲醇提取物中的沉淀组分具备出色的自由基清除能力。