In vitro biological activities of South African Pelargonium (Geraniaceae) species

AbstractDespite commercial interest and ethnobotanical data, the pharmacological activities of a number of indigenous Pelargonium species hitherto remain poorly explored. The acetone extracts of twenty-one Pelargonium species (section Pelargonium) were included in this study. Using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay, potent anti-oxidant activity was observed for the crude extracts of P. betulinum and P. crispum (IC50 values of 4.13±0.14 μg/ml and 4.49±0.18 μg/ml, respectively compared to ascorbic acid, IC50=4.72±0.14 μg/ml). The antimicrobial (both bacterial and fungal) potential of the extracts was evaluated by using the minimum inhibitory assay. The crude extracts of P. glutinosum (SBG), P. pseudoglutinosum, P. scabrum and P. sublignosum exhibited considerable antimicrobial activity against the Gram-positive test bacteria, with P. pseudoglutinosum demonstrating the highest inhibitory activity (MIC=39 μg/ml); however the aforementioned species were also relatively cytotoxic. The 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT) cellular viability assay was used to determine the toxicity of the acetone extracts against transformed human kidney epithelial (Graham) cells. The acetone extracts of P. sublignosum and P. citronellum (NBG) displayed the highest toxicities (IC50=11.89±1.54 μg/ml and 19.14±0.98 μg/ml, respectively). The results from the toxicity assay suggested that the antimicrobial activity of the extracts may be ascribed to general cytotoxic effects. Considering all the results collectively, Pelargonium cordifolium appears to be the most promising species requiring further investigation

Interactive efficacies of Elephantorrhiza elephantina and Pentanisia prunelloides extracts and isolated compounds against gastrointestinal bacteria

Elephantorrhiza elephantina (Burch.) Skeels (Fabaceae) and Pentanisia prunelloides (Klotzsch ex Eckl. & Zeyh.) Walp. (Rubiaceae) are two medicinal plants used extensively in southern Africa to treat various ailments. Often, decoctions and infusions from these two plants are used in combination specifically for stomach ailments. The antimicrobial activities of the methanol and aqueous extracts of the rhizomes of the two plants, as well as the two active ingredients from the plants [(−)-epicatechin and palmitic acid] have been determined apart and in combination against Enterococcus faecalis (ATCC 29212), Escherichia coli (ATCC 8739) and Bacillus cereus (ATCC 11778). The minimum inhibitory concentration (MIC) values for the aqueous (0.50–16.00 mg/mL) and methanol (0.20–16.00 mg/mL) extracts independently demonstrated varied efficacies depending on the pathogen of study. When the two plants were combined in 1:1 ratios, synergistic to additive interactions (ΣFIC values 0.19–1.00) were noted. Efficacy for the two major compounds ranged between 0.13–0.63 mg/mL and mainly synergistic interactions were noted against E. faecalis and E. coli. The predominantly synergistic interactions noted between E. elephantina and P. prunelloides and major compounds, when tested in various ratios against these pathogens, provide some validation as to the traditional use of these two plants to treat bacterial gastrointestinal infections