Evaluating the effect of storage on the biological activity and chemical composition of three South African medicinal plants

Despite the popularity of traditional medicine in Africa, the continent remains behind in terms of the regulation, safety and quality control of its medicinal plant industry. There is heightened interest in essential aspects that affect the industry, with storage practices and consequent effects on plant efficacy being of high priority. Therefore, the effect of short-term storage on the efficacy and phytochemical content of three popular medicinal plants (Ocimum basilicum, Senna petersiana and Hypoxis hemerocallidea) was investigated. The antimicrobial and antioxidant activities of four solvent extracts of the selected plant (fresh and short-term stored) were compared. Phytochemical analysis of 50% methanol extracts of plant materials was determined using spectrophotometric methods. Fresh samples of the majority of the plant extracts indicated better antibacterial (Staphylococcus aureus and Escherichia coli) and antifungal (Candida albicans) activities in comparison to the stored samples. There was no specific pattern in antioxidant activity for both stored and fresh samples for the different plants. Phytochemical analysis pointed towards noticeable differences between fresh and stored samples of the various plant extracts with fresh samples showing higher chemical concentrations in many plant parts. In general, the current findings indicate that the degree of changes in the pharmacological and phytochemical activity due to storage was plant part- and species-specific.