Diabetes mellitus is a metabolic disorder of glucose metabolism and management of blood glucose level is the hallmark in the treatment of this disease. The present study investigated chemical composition, in vitro antioxidant and antidiabetic activity of different fractions of 80% methanol Piper guineense leaves extract. The crude methanolic extract of P. guineense was obtained following 80% methanol cold extraction and was successively partitioned with dichloromethane (DCM), ethyl acetate (EtOAc), n-butanol (nBuOH) and aqueous solvents to give four fractions. The chemical composition of the fractions from P. guineense was determined using gas chromatography coupled with mass spectrometry (GC-MS) and their potentials as antioxidant and anti-diabetes were evaluated. The percentage yields were 3.16, 2.22, 0.68 and 0.66% (w/w) in n-butanol, DCM, aqueous and ethyl acetate fractions of P. guineense methanolic extract, respectively. The GC-MS analyses identified a total of 71 and 34 phytochemicals in n-butanol and ethyl acetate fractions respectively. Tributyl acetylcitrate (10.95%) and phytol (9.11%) were the major components in the n-butanol fraction while ethyl piperonyl cyanoacetate (27.35%) and phytol (15.17%) were the major constituents in the ethyl acetate fraction. Ethyl acetate fraction had the highest ferric reducing antioxidant power with a value of 53.96 ± 0.40 mgAAE/g while n-butanol fraction possessed highest total antioxidant power (9.98 ± 0.15) followed by aqueous fraction (9.72 ± 0.02). The ethyl acetate and n-butanol fractions with IC50 value of 0.24 ± 0.07 and 0.83 ± 0.15 μg/mL respectively elicited significant inhibitory activities against α-glucosidase while only n-butanol fraction (IC50 = 0.33 ± 0.09 μg/ml) exhibited appreciable inhibition against α-amylase activity. However, none of the four fractions showed significant inhibitory activity towards dipeptidyl-peptidase-IV. n-butanol and ethyl acetate fractions of 80% methanol P. guineense leaves extract can be a potential source of bioactive compounds of pharmacological importance in the management of diabetes.

中文翻译：

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非洲黑胡椒（Piper guineense）的体外抗糖尿病潜力，抗氧化活性和植物化学特征

糖尿病是葡萄糖代谢的代谢紊乱，控制血糖水平是该疾病治疗的标志。本研究调查了80％甲醇Piper guineense叶提取物不同馏分的化学组成，体外抗氧化剂和抗糖尿病活性。在80％甲醇冷提取后，获得了几内亚对虾的粗甲醇提取物，并将其依次用二氯甲烷（DCM），乙酸乙酯（EtOAc），正丁醇（nBuOH）和水性溶剂分配，得到四个馏分。使用气相色谱-质谱联用仪（GC-MS）测定了来自几内亚疟原虫的馏分的化学组成，并评估了其作为抗氧化剂和抗糖尿病药的潜力。在正丁醇，DCM中的收率分别为3.16、2.22、0.68和0.66％（w / w）几内亚疟原虫甲醇提取物的水和乙酸乙酯级分。GC-MS分析分别确定了正丁醇和乙酸乙酯馏分中的总共71种和34种植物化学物质。乙酰柠檬酸三丁酯（10.95％）和植醇（9.11％）是正丁醇馏分的主要成分，而胡椒基氰基乙酸乙酸乙酯（27.35％）和植醇（15.17％）是乙酸乙酯馏分的主要成分。乙酸乙酯级分具有最高的三价铁还原抗氧化能力，值为53.96±0.40 mgAAE / g，而正丁醇级分具有最高的总抗氧化能力（9.98±0.15），其次是含水级分（9.72±0.02）。乙酸乙酯和正丁醇馏分的IC50值为0.24±0.07和0.83±0。15μg/ mL分别引起对α-葡萄糖苷酶的显着抑制活性，而只有正丁醇级分（IC50 = 0.33±0.09μg/ ml）表现出对α-淀粉酶活性的明显抑制作用。然而，这四个部分均未显示出对二肽基-肽酶-IV的显着抑制活性。80％几内亚番石榴叶提取物的正丁醇和乙酸乙酯馏分可能是在糖尿病治疗中具有药理学重要性的生物活性化合物的潜在来源。