In Vitro Investigation of Anti-Diabetic Effect of Taxus cuspidate Extracts by Ultrasound Assisted Method

Abstract

Extracting active components from Chinese medicinal herbs efficiently is a key step in the investigation of their pharmacological effects and modes of action. In this project, we compared the ultrasound-assisted method and the conventional solvent method for extracting the active compound of Taxus cuspidate (dong bei hong dou shan). Through the analysis of various extractions with a quadruple time-of-fight (Q-TOF) LC/MS, we demonstrated that the ultrasound-assisted method reduced solvent consumption and had shorter extraction time, while the extraction yields of the active compound (taxol) were equivalent to or even higher than those obtained with the conventional solvent extraction method. Through the comparison of Taxus cuspidate extracts (TCEs) with different concentrations of acetone and ethanol, we proved that 50% ethanol was an optimal solvent for extracting taxol from Taxus cuspidate. Based on traditional Chinese medicine (TCM) literature, we further determined whether TCEs possess antidiabetic effects by testing glucose uptake in 3T3-L1 adipocytes treated with TCEs from Taxus cuspidate bark and twigs under insulin stimulation (100 nM). The results showed that neither taxol (10 μg/ml) nor TCEs (1 and 0.1 mg/ml) changed glucose uptake significantly compared with insulin alone. This study demonstrated that the ultrasound-assisted method with 50% ethanol is a highly efficient approach for extracting Taxus cuspidate, which may be applicable for extraction of other Chinese medicinal herbs. Extracts of Taxus cuspidate bark and twigs had no effect on insulin stimulated-glucose uptake in vitro. This result conflicts with the description in TCM literature. Further in vivo study to clarify Taxus cuspidate's metabolic actions is necessary.