Lyophilized tea extracts of Brickellia cavanillesii (Asteraceae): in vitro characterization of biological activity

Lyophilized Brickellia cavanillesii (LBC) tea extracts and identified chemical compounds of LBC were examined using in vitro human carcinoma liver (HepG2) cells with and without fetal bovine serum (FBS). Cells were incubated for 24 h with varying concentrations of FBS and LBC, respectively; cytotoxicity was determined spectrophotometrically using MTT (Formazan 3-(4,5-dimethyl-thiazol-2-yl)-2, 5-diphenyl-tetrazolium bromide) assay. Furthermore, the potential hypoglycemic activity of LBC tea extracts was investigated using glucose transport and metabolism proteins biomarkers. FBS (0% to 10%) increased the viability of HepG2 cells steadily with increasing concentration. Possible therapeutic effects of LBC were concentration dependent with and without FBS. The cytotoxicity of 12 identified compounds from the LBC extract suggests that the individual compounds inhibited the proliferation of HepG2 cells differentially and do not reflect the inhibition of the whole aqueous LBC. Western blot analysis of glucose facilitated transporter protein 2 (GLUT 2) expression of HepG2 cells exposed to 0 mg/mL (Control) and 0.2 mg/mL LBC for 2, 4, 6, and 24 h suggests that GLUT 2 expression was increased. Increase in GLUT 2 expression in the absence of FBS was statistically significant with time of exposure. Significant difference was observed for GLUT 2 expression between 6 and 24 h and also between 4 and 24 h at 0.2 mg/mL LBC. Results obtained indicate that LBC may exhibit antidiabetic activity. However, further studies will be necessary to clearly delineate LBC potential therapeutic benefit and biological activities in animal studies as well as other in vitro models.

Brickellia cavanillesii (Asteraceae) is a herbal plant widely used (Central America, Mexico and South-Western U.S.A.) in Type 2 diabetes mellitus therapy. Unfortunately, there is insufficient scientific data to validate its presumed pharmacological properties. This study examines the cytotoxic properties of whole, and certain identified chemical compounds in B. cavanillesii. It also investigates the potential hypoglycemic activity of lyophilized B. cavanillesii using glucose transport and metabolism proteins as biomarkers.