Nawrot-Hadzik Izabela, Granica Sebastian, Abel Renata, Czapor-Irzabek Hanna, Matkowski Adam
Nat Prod Commun. 2017 Feb;12(2):163-166.
Leaves of Eriobotryajaponica (loquat) have been used in Traditional Chinese Medicine with beneficial effects in numerous diseases. Extracts from loquat leaves are rich in antioxidants, containing among others: triterpenes, sesquiterpenes, flavonoids, tannins, and megastigmane glycosides. However, there is no conclusive study revealing which of these compounds are the main bioactive principles. The goal of this study was to pinpoint compounds responsible for strong antioxidant activity. Eriobotryaefolium was extracted and fractionated between solvents of increasing polarity. All extracts and fractions were screened for total polyphenols and tannins, and antioxidant activity was checked by DPPH, phosphomolybdenum and linoleic acid tests. The ethyl acetate fraction demonstrated the highest antioxidant activity and contained the largest amount of polyphenols. Applying HPLC-based activity profiling to localize antioxidants revealed that cinchonain IIb, as well as flavonoid glycosides such as hyperoside, isoquercitrin, kaempferol glycosides, quercetin-rhamnoside, as well as two tentatively identified protocatechuic acid derivatives are the main substances responsible for the strong antioxidant activity of the ethyl acetate fraction.
枇杷叶在传统中药中被用于治疗多种疾病且具有有益效果。枇杷叶提取物富含抗氧化剂，其中包括：三萜类、倍半萜类、黄酮类、单宁和巨大戟烷糖苷。然而，尚无确凿研究揭示这些化合物中哪些是主要的生物活性成分。本研究的目的是确定具有强抗氧化活性的化合物。对枇杷叶进行提取，并在极性递增的溶剂之间进行分离。对所有提取物和馏分进行总多酚和单宁的筛选，并通过DPPH、磷钼酸和亚油酸测试检查抗氧化活性。乙酸乙酯馏分表现出最高的抗氧化活性，且含有最多的多酚。应用基于HPLC的活性谱分析来定位抗氧化剂，结果表明，金鸡纳宁IIb以及黄酮糖苷，如金丝桃苷、异槲皮苷、山柰酚糖苷、槲皮素鼠李糖苷，以及两种初步鉴定的原儿茶酸衍生物是乙酸乙酯馏分具有强抗氧化活性的主要物质。
