Activity of Stachys germanica L. subsp. salviifolia (Ten.) Gams on mutagenesis

Stachys germanica L. subsp. salviifolia (Ten.) Gams (Lamiaceae) is an herbaceous plant widespread in Central and Southern Italy [1]. The fresh plant was used against wart and pustule but few references deal with this plant, perhaps because the subsp. salvifolia wasn't distinguished from the other subspecies of the S. germanica. There isn't any reference about the biological activity of the plant. Aerial parts were extracted with dichloromethane or subjected to sequential extraction with n-hexane, chloroform, chloroform/methanol (1:1) and methanol. To assess their genotoxic/antigenotoxic properties, the extracts were tested in vitro by applying the alkaline single-cell microgel-electrophoresis (comet) assay on HepG2 cells. These hepatic cells, originating by a primary hepatoblastoma, retain many of the morphological characteristics of liver parenchymal cells, and contain phase I and phase II drug metabolizing enzymes which play an essential role in the activation/detoxification of promutagens/procarcinogens [3]. The following approaches were performed: (i) co-treatment, (ii) pre-treatment and (ii) post-treatment protocol by challenging the extracts with the model mutagen 4-nitroquinoline-N-oxyde (4NQO). The tested extracts neither affected cell viability nor induced DNA damage, except chloroform extract which was highly cytotoxic and genotoxic (2.5µg/mL). As regard the antigenotoxic properties, the dichloromethane extract was active in the co-exposure experiments (2.5µg/mL) and in the post- exposure experiments (20µg/mL); the n-hexane extract was active only in the co- exposure experiments (2.5µg/mL); the chloroform/methanol extract was active in the co- and post- exposure experiments (2.5µg/mL and 10µg/mL respectively); the methanol extract was active only in the co- exposure experiments (10µg/mL).

References: [1] Conti, F., et al. (2005) An annotated checklist of the italian vascular flora, Palombi ed., Roma [2] Knasmüller et al. (1998) Mutat. Res. 18: 402, 185–202