Activity markers of the anti-breast carcinoma cell growth fractions of Vernonia amygdalina extracts.

Vernonia amygdalina (VA) is an edible plant of the Asteraceae family used in many herbal formulations prescribed by herbalists for many diseases. We have previously reported that aqueous VA extracts inhibit the growth of estrogen receptor-positive human breast cancerous cells in vitro. Activity markers of the VA extracts have not been previously identified or characterized. Hence, the objective of this study was to identify activity markers of the VA extracts associated with cell growth inhibition. Extraction of VA with multiple solvents of various polarity indexes yielded three fractions (A-1-2, B-1-3) that significantly inhibited cell growth (P < 0.05) at 0.1 mg/ml concentration. At a higher concentration of 1 mg/ml, six fractions of hexane, chloroform, butanol, and ethyl acetate (A-1-3, B-1-4) inhibited DNA synthesis by 76%, 98%, 94%, 98%, 98%, and 96%, respectively. These fractions were UV-detected from 250-730 nm; and all showed three distinct peaks around 410, 431, and 664 nm. Furthermore, HPLC analysis of the fractions revealed similar retention times of 2.213, 2.167, and 2.151 min, respectively. Bioactivity assays showed that HPLC retention of approximately 2 min is required for cell growth-inhibitory activity of VA fractions. Interestingly, all active fractions exhibited HPLC peaks at approximately 2 min. Therefore, the UV and HPLC peaks may be used as predictive tools to determine VA extracts activities.