The Effects of Storage Time on the Antibacterial Activity of Terminalia sericea Burch. ex DC. Extracts

Introduction: The recent development of extensively antibiotic resistant bacteria has necessitated the search for novel antibacterial therapies. An examination of aromatic plants and traditional medicines is an attractive option for drug discovery. Terminalia sericea Burch. ex DC. is a southern African native species, which has been reported to have antibacterial activity, although the effects of storage on the activity is yet to be determined. Materials and Methods: The ability of T. sericea leaf extracts to inhibit the growth of a panel of bacterial triggers of autoimmune diseases was quantified by disc diffusion and liquid dilution MIC assays. The potency of extracts prepared using fresh and stored leaves was compared. Toxicity was examined using the Artemia franciscana nauplii bioassay. Results: The T. sericea leaf methanolic and aqueous extracts displayed noteworthy growth inhibitory activity towards all bacterial pathogens tested. However, a substantial decrease in activity was seen when extracts were prepared using leaves that had been stored for two years, indicating that the leaves become less useful therapeutically over time. All extracts were non-toxic in the Artemia nauplii bioassay following 24hr exposure. Conclusion: The T. sericea leaf extracts had noteworthy antibacterial activity, although the potency decreased substantially following storage of the leaf material.