Activity-guided isolation and identification of the major antioxidant and anticancer compounds from a commercial Pelargonium sidoides tincture

Abstract

Extracts prepared from the roots of Pelargonium sidoides (DC) are commercially available for the treatment of respiratory related conditions. Recently, a commercial radix mother tincture of this plant was shown to have both antioxidant and anticancer effects especially related to the G0/G1 block in the Jurkat E6.1 cell line (unpublished results). Fractions were prepared by semi-preparative HPLC, and their antioxidant and anticancer activities were determined. The more hydrophilic fractions isolated namely F6-F12 were all found to have strong reducing capacities and were able to scavenge peroxyl radicals. In the human lung cell line, NCI-H460, significant cellular antioxidant effects were observed. Anticancer activity was evaluated in the NCI-pre-screen panel (NCI-H460, MCF-7 and SF-268) and the Jurkat E6.1 cell line. Fractions F7, F9 and F12 were found to inhibit the cell growth of these four cell-lines (p < 0.05), especially the Jurkat E6.1 cell line with the sulforhodamine B assay. Mass spectrometry analysis revealed that these active fractions contained several polyphenolic compounds such as gallic acid, trihydroxycoumarin, dihydroxycoumarin sulfates, proanthocyanidins and phenolic glycosides. A phenolic acid glycoside sulfate not previously shown in Pelargonium sidoides extracts was also isolated. In conclusion, the antioxidant and/or anticancer activity of the Pelargonium sidoides tincture may be attributed to the presence of these polyphenolics.