Evaluation of in vitro glucose metabolism potential of sterols and essential oil extracts from Erythroxylum monogynum Roxb. using cell lines and enzyme inhibition models

Abstract

The present research purports screening of extracts, essential oils and isolated sterols from Erythroxylum monogynum for in vitro anti-diabetic activity through in vitro cell line model and also by in vitro enzyme inhibition models. The MTT assay for the cytotoxic studies in vitro of isolated sterols on HepG2 cells at varied concentrations from 0-200 µg/ml revealed that all the tested extracts and compounds displayed low level of toxicity at all concentrations in a dose-dependent manner. The 4-methyl ergosta-7, 23-dien-3β-ol and 4-methyl ergosta-7, 24 (28)-dien-3β-ol exhibited considerable increase in the uptake of glucose in HepG2 cells at both the tested concentration (dose dependent behaviour) compared to the negative control (untreated) but not with the positive control, metformin. Further, the two sterols offered a safety profile to the cells as revealed from the assay wherein, at 25 and 100 µg/ml were also not toxic and exhibited <10% cell death. Moreover, the sterols also showed marked increase in triglyceride accumulation of 127% and 125% at 50 µg/ml when compared to the negative control (100%) but less than the positive control, Rosiglitazone (145%). No substantial increase in the glucose metabolism of INS-1 cells and a significant increase in the total cells (108-114%) were observed. Surprisingly, the sterols inhibited all the investigated enzymes such as sucrase, lipase, dipeptidyl peptidase IV, collagenase and protein tyrosine phosphatase 1B with IC50 values comparable to that of standard compounds. The results obtained were remarkable suggesting that these sterols and extracts might be the future lead molecules for the management of diabetes.