RESUMO
INTRODUCTION: Cancer causes about 13% of all deaths. According to the American Cancer Society, world-wide cancer deaths were 7.6 million in 2007. African Americans and other minorities are disproportionately affected. Effective cancer chemotherapy is scarce. This study is part of an ongoing search for potential cancer-fighting agents in medicinal herbs. In previous in-vitro studies, we have shown that the aqueous extracts of the medicinal herb Ocimum gratissimum (Og) inhibit the proliferation of several cancer cell lines, especially prostate adenocarcinoma (PC-3) cells. Therefore, Og leaf extracts may harbor novel cancer-fighting compounds that need to be isolated, purified and characterized. METHODS: Partially purified Og fractions were obtained from sequential extraction of Og powder with organic solvents of different polarities. The hypothesis that the anti-proliferation activity of the fractions will be significantly greater than that of either aqueous or ethanol extracts was tested by treating PC-3 cells with 1.61 mg/mL of each fraction. Spectral analysis of the fractions was also conducted. RESULTS: Activity of the fractions was P2>P(3-2)>P(4-2)>P(3-1)>P(4-1). Fractions P2, P(3-2) and P(4-2) were 725, 75 and 2.3 times more active than the aqueous extract, respectively. Spectral analysis revealed peaks for: P(3-2) and aqueous extract at 208 nm, P2 and P(4-2) at 210 nm, and P(3-1) at 220 nm. CONCLUSIONS: These findings suggest that fractions P2, P(3-2) and P(4-2) could be potential sources of Og's bioactive component(s) that warrant further purification and characterization.