Chemistry Institute of Pharmaceutical Resources, College of Pharmaceutical Sciences, Southwest University, Chongqing 400716, PR China.
J Ethnopharmacol. 2012 May 7;141(1):228-33. doi: 10.1016/j.jep.2012.02.023. Epub 2012 Feb 17.
The root of Polygonatum odoratum (YuZhu), also a medicinal food has long been used for the treatment of diabetes. The objective of the study was to characterize the anti-diabetic active fractions or compounds in this herb.
Fractions with a different polarity were prepared by solvent extraction and macroporous absorptive resin (D101) column and their anti-diabetic potentials were evaluated by glucose uptake in HepG2 cells and STZ-induced diabetic rats. In addition, α-glycosidase inhibitory activities of active fractions were measured in vitro and chemical compositions including saponin, total flavonoids and total sugar in the fractions were determined.
The n-buthanol fraction, a saponin-rich fraction obtained by partitioning the ethanol extract with n-buthanol after petroleum ether and acetic ether showed the highest anti-diabetic potential in glucose uptake in HepG2 cells followed by acetic ether fraction which was rich in flavonoids. Further fractionation the saponin-rich fraction using macroporous resin column (D101), polysaccharide, flavonoid and saponin rich fractions were obtained by elution with water, 40% and 60% ethanol, respectively and their anti-diabetic potentials proved by glucose uptake test in HepG2 cells and STZ-induced diabetic rats were in the order of saponin rich fraction>flavonoid rich fraction>polysaccharide rich fraction. Long-term therapy test (60d) in severe diabetic rats indicated that saponin-rich fraction significantly ameliorated clinical symptoms of diabetes including the elevated blood glucose, body weight loss as well as the increased food and water intake while flavonoid-rich fraction was more potential than saponin-rich fraction to increase superoxide dismutase (SOD) activity and decrease malondialdehyde (MDA) level in rat plasma. Additionally, saponin-rich fraction and flavonoid-rich fraction showed α-glycosidase inhibitory activity with IC(50) value of 2.05±0.32 and 3.92±0.65mg/ml, respectively.
The results suggested that saponin in this herb was more important than flavonoid in exhibiting anti-diabetic activity and flavonoid contributed more to anti-oxidant activity in vivo.
玉竹（黄精）的根茎既是一种药材，也是一种药食同源的食品，长期以来一直被用于治疗糖尿病。本研究的目的是从该植物中鉴定具有抗糖尿病活性的化合物或化合物。
采用溶剂萃取法和大孔吸附树脂（D101）柱对不同极性的玉竹提取物进行分离，并通过 HepG2 细胞摄取葡萄糖和 STZ 诱导的糖尿病大鼠评估其抗糖尿病作用。此外，体外测定活性部位的α-糖苷酶抑制活性，并测定各部位的化学成分，包括皂苷、总黄酮和总糖。
用正丁醇从乙醇提取物中萃取，然后用石油醚和乙酸乙酯萃取，得到富含皂苷的正丁醇部分，该部分在 HepG2 细胞摄取葡萄糖实验中显示出最强的抗糖尿病作用，其次是富含黄酮类化合物的乙酸乙酯部分。进一步用大孔树脂柱（D101）对富含皂苷的部分进行分离，用水、40%和 60%乙醇洗脱，分别得到多糖、黄酮和皂苷富分，其在 HepG2 细胞摄取葡萄糖和 STZ 诱导的糖尿病大鼠中的抗糖尿病作用顺序为皂苷富分>黄酮富分>多糖富分。对严重糖尿病大鼠的长期治疗试验（60d）表明，皂苷富分可显著改善糖尿病的临床症状，包括血糖升高、体重减轻以及摄食量和饮水量增加，而黄酮富分比皂苷富分更能提高大鼠血浆中超氧化物歧化酶（SOD）活性，降低丙二醛（MDA）水平。此外，皂苷富分和黄酮富分均具有α-糖苷酶抑制活性，IC50 值分别为 2.05±0.32 和 3.92±0.65mg/ml。
结果表明，该植物中的皂苷比黄酮在发挥抗糖尿病活性方面更为重要，而黄酮在体内的抗氧化活性方面更为重要。
