The effect on angiogenesis of constituents of Cajanus cajan leaves

Previous investigation of the leaves of Cajanus cajan from Nigeria had shown the existence of three cytotoxic compounds, the flavonoid pinostrobin, and the two stilbenes longistylin A and longistylin C [1]. Since stilbenes such as combretastain A4 are known to be angiogenesis inhibitors, it was considered of interest to test the three compounds isolated for this activity. Angiogenesis inhibition is receiving much current interest as an approach to restricting the growth of tumours, since the prevention of formation of blood vessels means that the cells in the tumour cannot receive adequate nutrients for continued growth. The three compounds were tested at concentrations of 1µg/mL and 5µg/mL using the angiogenesis kit (TCS Cellworks). Endothelial cells were cultured in a matrix of dermal fibroblasts and then treated with epithelial growth factor with and without the compounds. After 11 days the cells were fixed and any vessels formed were stained with CD31 so that the matrix could be imaged and pixels containing vessels could be quantified. Pinostrobin showed a dose-related stimulant effect on angiogenesis (95% increase compared with medium alone for 1µg/mL) but the two stilbenes showed marked inhibition with 45% and 74% angiogenesis compared to medium alone for longistylin A and C respectively at 1µg/mL and practically no angiogenesis observed at doses of 5µg/mL. The contradictory effects of the flavonoids and the stilbenes make an explanation of the traditional usage of the leaves difficult, although the longistylins are of interest as possible leads for novel antiangiogeneis drugs.

Acknowledgements: JAshidi thanks the Commonwealth Scholarship Commission for financial support.

References: 1. Ashidi, JS. (2006) Planta Med. 72:989.