Unveiling the potential toxicity and mutagenicity of traditional remedies used for gynaecological and obstetric ailments in Maputaland, South Africa

Abstract

Medicinal plants play an important role in the primary healthcare of lay people around the world, including the rural community of Maputaland, South Africa. According to an ethnobotanical survey conducted in 2014, the lay people in northern Maputaland use plant species independently and in combination to treat gynaecology and obstetric ailments. These plant species were generally regarded as safe by the lay people except for one plant species, Trichilia dregeana Harv. & Sond. The aim of this study was to investigate the safety of 16 plant combinations using the brine shrimp lethality assay (BSLA) for toxicity and Ames test using S. typhimurium TA98 and TA100 strains for mutagenicity. Toxicity studies on 33 medicinal plant species independently needed to be analysed first in order to make a comparison of combined with single use. The aqueous and organic (1:1 methanol-dichloromethane) extracts were prepared from 51 plant samples (including leaf samples collected as a substitution for the roots). There were three plant species (Acalypha villicaulis Horchst. Ex A.Rich. root, Grewia occidentalis L. root and Gymnosporia senegalensis Loes. leaves) indicated neither toxicity nor mutagenicity when tested at 1 and 5 mg/ml using the BSLA and Ames test, respectively. Hermannia boraginiflora Hook., Sapium integerrimum (Hochst. ex Krauss), Scadoxus puniceus (L.) Friis Nordal and Tabernaemontana elegans Stapf demonstrated toxicity even after dilution to the lowest concentration of 0.031 mg/ml. The three plant combinations which were found to be non-toxic in the BSLA (both aqueous and organic extracts) were Euphobia tirucalli L. (root) with Ozoroa engleri R.Fern & A.Fern. (bark), S. puniceus (bulb) and Senecio serratuloides DC. (whole plant); Bridelia cathartica G.Bertol. (root) with Opuntia stricta Haw. (stem) with Searsia nebulosa (Schoenland) Moffett (bark); and B. cathartica (root) with Erythrina humeana Spreng (root). In the Ames test, the plant samples which appeared to be non-mutagenic against both S. typhimurium TA98 and TA100 strains were A. villicaulis root, Cyperus natalensis Hochst. ex Krauss root, Euclea natalensis A.DC. leaves, G. occidentalis root, Ochna natalitia Walp. leaves, S. integerrimum leaves and S. puniceus bulb. This study indicated that medicinal plant species (independently and in combination) may have toxic and/ or mutagenic effects, even without any obvious signs after consumption. More importantly, it was determined that toxicity can be reduced by carefully managing the dose.