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to have both antioxidant and anticancer effects especially related to the G 0/G 1 block in the Jurkat E6.1 cell line (unpublished results).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 P. sidoides extracts was also isolated. In conclusion, the antioxidant and/or anticancer activity of the P. sidoides tincture may be attributed to the presence of these polyphenolics.