CONTEXT : Pelargonium sidoides DC (Geraniaceae) is an important medicinal plant indigenous to South Africa and Lesotho. Previous studies have shown root extracts rich in polyphenolic compounds with antibacterial, antiviral and immunomodulatory activities. Little is known regarding the anticancer properties of Pelargonium sidoides extracts. OBJECTIVE : This study evaluates the anti-proliferative effects of a Pelargonium sidoides radix mother tincture (PST).
MATERIALS AND METHODS : The PST was characterized by LC-MS/MS. Anti-proliferative activity was evaluated in the pre-screen panel of the National Cancer Institute (NCI-H460, MCF-7 and SF-268) and the Jurkat leukemia cell line at concentrations of 0-150 μg/mL. Effect on cell growth was determined with sulforhodamine B and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium
bromide assays after 72 h. Effect on cell cycle and apoptosis induction in Jurkat cells was determined by flow cytometry with propidium iodide and Annexin V: fluorescein isothiocyanate staining. RESULTS : Dihydroxycoumarin sulfates, gallic acid as well as gallocatechin dimers and trimers were characterized in PST by mass spectrometry. Moderate anti-proliferative effects with GI50 values between 40 and 80 μg/mL observed in the NCI-pre-screen panel. Strong activity observed with Jurkat cells with a GI50 of 6.2 μg/mL, significantly better than positive control 5-fluorouracil (GI50 of 9.7 μg/mL). The PST arrested Jurkat cells at G0/G1 phase of the cell cycle and increased the apoptotic cells from 9% to 21%, while the dead cells increased from 4% to 17%. CONCLUSION : We present evidence that Pelargonium sidoides has cancer cell type specific antiproliferative effects and may be a source of novel anticancer molecules.