A novel Gymnema sylvestre extract stimulates insulin secretion from human islets in vivo and in vitro

Many plant‐based products have been suggested as potential antidiabetic agents, but few have been shown to be effective in treating the symptoms of Type 2 diabetes mellitus (T2DM) in human studies, and little is known of their mechanisms of action. Extracts of Gymnema sylvestre (GS) have been used for the treatment of T2DM in India for centuries. The effects of a novel high molecular weight GS extract, Om Santal Adivasi, (OSA®) on plasma insulin, C‐peptide and glucose in a small cohort of patients with T2DM are reported here. Oral administration of OSA® (1 g/day, 60 days) induced significant increases in circulating insulin and C‐peptide, which were associated with significant reductions in fasting and post‐prandial blood glucose. In vitro measurements using isolated human islets of Langerhans demonstrated direct stimulatory effects of OSA® on insulin secretion from human ?‐cells, consistent with an in vivo mode of action through enhancing insulin secretion. These in vivo and in vitro observations suggest that OSA® may provide a potential alternative therapy for the hyperglycemia associated with T2DM. Copyright © 2010 John Wiley & Sons, Ltd.     

人参白虎汤对2型糖尿病大鼠血糖、血脂及其胰岛素耐量的影响

目的:探讨人参白虎汤治疗2型糖尿病的作用及其机制.方法:高脂饲料喂养大鼠4周,腹腔注射链脲佐菌素(STZ)制备2型糖尿病大鼠模型.糖尿病大鼠随机分为模型组、人参白虎汤高(15 g·kg-1)、中(7.5 g·kg-1)、低剂量组(3.7 g·kg-1)和二甲双胍组(0.2 g·kg-1).人参白虎汤高、中、低剂量组分别ig不同剂量的人参白虎汤,二甲双胍组ig二甲双胍,模型组与对照组ig等量自来水.给药4周后取血,测定血糖(Glu)、血脂、糖耐量、糖化血红蛋白(HbA1c)、胰岛素(Ins)和胰岛素耐量的变化.结果:人参白虎汤能明显降低糖尿病大鼠的Glu(P＜0.05或P＜0.01)、胆固酵(TC)(P＜0.05或P＜0.01)、甘油三酯(TG)(P＜0.05或P＜0.01)含量,升高高密度脂蛋白(胆固醇HDL-C)含量(P＜0.05),改善糖耐量(P ＜0.05或P＜0.01),增强糖尿病大鼠Ins敏感性(P＜0.05或P＜0.01),但对Ins含量影响不明显.结论:人参白虎汤在降血糖、降血脂、改善糖耐量、增强Ins敏感性方面作用显著,其降糖作用可能与增强大鼠对Ins敏感性有关.     

丹酚酸B改善2型糖尿病大鼠糖脂代谢及 胰岛素抵抗的实验研究

目的:观察丹酚酸B对实验性2型糖尿病大鼠血糖、血脂、肾功能、血清胰岛素水平以及胰岛素耐量和葡萄糖耐量的影响.方法:采用高糖高脂饲料喂养1个月加小剂量的链脲佐菌素(30 mg·kg-1,ip)的方法建立实验性2型糖尿病大鼠模型,分为正常组、模型组、达美康组(26.7 mg·kg-1)和丹酚酸B组(187 mg-kg-1),连续ig 4周,测定空腹m糖,糖化血红蛋白、甘油三酯、总胆固醇、肌酐、尿素氮及血清胰岛素水平,计算胰岛素敏感指数,并采用胰岛素耐量和葡萄糖耐量等实验评价模型动物的胰岛素敏感性.结果:丹酚酸B和达美康均能显著降低实验性2型糖尿病大鼠的空腹血糖水平(P＜0.01),降低血脂含量,改善肾功能(P＜0.0S～0.01),降低胰岛素和糖化血红蛋白水平(P＜0.05),升高胰岛素敏感性(P＜0.01),改善胰岛素耐量以及糖耐量异常,与模型组比较有显著性差异.结论:丹酚酸B对实验性2型糖尿病大鼠模型有降低血糖,调节血脂,保护肾脏,改善糖脂代谢紊乱及胰岛素抵抗的作用.     

The Water Fraction of Calendula officinalis Hydroethanol Extract Stimulates In Vitro and In Vivo Proliferation of Dermal Fibroblasts in Wound Healing

The active fraction and/or compounds of Calendula officinalis responsible for wound healing are not known yet. In this work we studied the molecular target of C. officinalis hydroethanol extract (CEE) and its active fraction (water fraction of hydroethanol extract, WCEE) on primary human dermal fibroblasts (HDF). In vivo, CEE or WCEE were topically applied on excisional wounds of BALB/c mice and the rate of wound contraction and immunohistological studies were carried out. We found that CEE and only its WCEE significantly stimulated the proliferation as well as the migration of HDF cells. Also they up‐regulate the expression of connective tissue growth factor (CTGF) and α‐smooth muscle actin (α‐SMA) in vitro. In vivo, CEE or WCEE treated mice groups showed faster wound healing and increased expression of CTGF and α‐SMA compared to placebo control group. The increased expression of both the proteins during granulation phase of wound repair demonstrated the potential role of C. officinalis in wound healing. In addition, HPLC‐ESI MS analysis of the active water fraction revealed the presence of two major compounds, rutin and quercetin‐3‐O‐glucoside. Thus, our results showed that C. officinalis potentiated wound healing by stimulating the expression of CTGF and α‐SMA and further we identified active compounds. Copyright © 2016 John Wiley & Sons, Ltd.     

石榴果实乙酸乙酯提取物对胰岛素抵抗大鼠血糖及血脂的干预作用

目的:观察石榴果实乙酸乙酯提取物(PGFEAE)对正常大鼠及胰岛素抵抗(IR)大鼠模型血糖、血脂的干预作用,评价其改善胰岛素抵抗的药理作用。方法:高糖高脂饲料喂养加链脲佐菌素(STZ)2次ip(30 mg·kg-1)建立胰岛素抵抗大鼠模型。分别以PGFEAE 100,200,300 mg·kg-1ig干预4周后,检测空腹血糖(FBG)、空腹胰岛素水平(FINS)、胰岛素敏感指数(ISI)、血清游离脂肪酸(FFA)浓度、甘油三酯(TG)浓度。结果:与正常组相比,模型组FBG,FINS,FFA,TG水平显著上升,胰岛素(INS)水平下降(P0.05,P0.01);造模4周后,正常组与模型组大鼠FBG,FINS,TG分别为5.94,30.71,0.57mmol·L-1;13.05,42.36,1.62 mmol·L-1;给药4周后,与模型组相比,PGFEAE各剂量组均可有效降低胰岛素抵抗大鼠模型FBG,FINS,FFA,TG水平,使胰岛素抵抗大鼠模型INS水平升高(P0.05,P0.01)。结论:PGFEAE可有效改善胰岛素抵抗大鼠血糖、血脂偏高的症状,其对正常大鼠血糖、血脂无干预作用。     

Extracts from Leonurus sibiricus L. increase insulin secretion and proliferation of rat INS-1E insulinoma cells

Ethnopharmacological relevance

Traditional Mongolian medicine (TMM) uses preparations from herbs as one form of medication for the treatment of a diversity of diseases including diabetes mellitus (DM). We evaluated the effect of extracts from the plant Leonurus sibiricus L. (LS), used in TMM to treat typical symptoms of type 2 DM, on insulin secretion, electrophysiological properties, intracellular calcium concentration and cell proliferation of INS-1E insulinoma cells under standard cell culture conditions (SCC; 11.1 mM glucose).

Materials and methods

Insulin secretion was measured by ELISA, electrical properties were assessed by whole cell patch clamping, intracellular calcium concentration (Ca_i) by Fluo-4 time lapse imaging, insulin receptor expression was verified by RT-PCR and cell proliferation assessed by CellTiter-Glo® cell viability assay.

Results

Insulin released from INS-1E cells into the culture medium over 24 h was significantly increased in presence of 500 mg/L aqueous LS extract (LS OWE) as well as methanolic LS extract (LS MeOH/H2O) but not in the presence of the butanol-soluble extract (LS MeOH/BuOH). Acute application of LS OWE resulted in a depolarization of the cell membrane potential paralleled by an initial increase and subsequent decline and silencing of action potential frequency, by KATP channel inhibition, persisting depolarization and an increase in Ca_i. The electrophysiological effects were comparable to those of 100 μM tolbutamide, which, however failed to elevate insulin secretion under SCC. Furthermore all LS extracts stimulated INS-1E cell proliferation.

Conclusions

The finding that extracts from Leonurus sibiricus L. enhance insulin secretion and/or foster cell proliferation may provide possible explanations for the underlying therapeutic principles in the empirical use of LS-containing formulations in DM and DM-related disorders as applied in TMM.