Inhibition of angiogenesis by a common herb: Ocimum sactum

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Ocimum sanctum (OS), also known as holy basil, or tulsi, has been used in European and Asian countries, mainly India, as a medicinal herb since ancient times. Experimental evidence has shown it to possess chemopreventive, radiation protecting, and free radical scavenging properties. We prepared crude aqueous extract from the leaves of OS and performed in vitro and in vivo studies. Our results show that OS extracts inhibited breast cancer cell (MDA-MB-435) migration towards Matrigel significantly at 0.1 and 0.2% concentrations (w/v). Similarly, it inhibited the migration of human umbilical vein endothelial cells (HUVEC) towards galectin-3 at a concentration of 0.2% (w/v). However, no significant inhibition in migration was observed at the same concentration towards Matrigel and fibronectin indicating the specificity of inhibition. OS extract also inhibited the induction of cycloxygenase COX-2 in MDA-MB-231 breast cancer cells treated with tetradecanoyl phorbol acetate (TPA). In vitro capillary tube formation in the 3 dimensional cultures of HUVEC on Matrigel was inhibited by the leaf extracts at 0.02, 0.05 and 0.1% concentrations (w/v). Matrigel plug assay using MDA-MB-231 cells in the presence or absence of 0.01 and 0.1% OS leaf extracts showed a significant reduction in the number of blood vessels and COX-2 expression. Our results suggest that OS leaf extract can be used as an anti-tumorigenic and anti-angiogenic agent in breast cancer models.