Cytotoxic, antioxidant and antimicrobial effects of nine species of woundwort (Stachys) plants

Context: Woundwort (Stachys) plants from the Lamiaceae family have been used in folk medicine for various purposes. Objective: This study was designed to analyze cytotoxic, antioxidant and antimicrobial activities of Stachys plants, because these fields have extensively benefited of drug discovery from natural sources. Materials and methods: Nine Stachys plants were collected from different regions of Iran. Cytotoxic activities of methanol, 80% methanol and dichloromethane (DCM) extracts of these plants were assessed on three human cancer cell lines (HL-60, K562 and MCF-7 cells) with the MTT assay, while antioxidant and antimicrobial activities were determined on methanol extracts by DPPH and nutrient broth micro-dilution assays, respectively. Results: DCM extract of St. pilifera Benth. had the lowest IC50 in three cancer cell lines ranging from 33.1 to 48.2 mu g/ml, followed by the 80% methanol extract of St. persica S.G.Gmel. ex C.A.Mey. (IC50 range: 62.1-104.1 mu g/ml) and DCM extract of St. byzantina C. Koch (IC50 range: 62.7-131.0 mu g/ml). St. byzantina, St. lavandulifolia Vahl., St. acerosa Boiss., St. obtusicrena Boiss. and St. persica showed lowest IC50 values in the DPPH scavenging assay (135.1, 162.6, 164.7, 169.4 and 172.4 mu g/ml, respectively), while their total phenolic contents were 23.9, 18.2, 18.6, 20.4, 27.8 mg equivalent of gallic acid in 1 g dry plant, respectively. The methanol extracts of St. byzantina and St. persica inhibited all six tested Gram-negative and Gram-positive bacterial strains. Conclusion: Various Stachys species (especially St. byzantina and St. persica) are valuable sources of natural compounds with important biological properties.