Validation of Biosafety and Activity of Albizia antunesiana Lyophilised Leaf Extracts

Albizia antunesiana, from the Fabaceae family is a widespread plant species prevalent in tropical and subtropical regions of Africa. The plant is extensively utilized in traditional medicine for various ailments, particularly in the management of acute and chronic wounds. The use of Albizia antunesiana in traditional medicine has never been scientifically validated for its biosafety and activity. Our current study aimed to validate its biosafety and the pharmacological activity of the plant to ensure therapeutic efficacy while minimizing potential risks. Our investigations qualitatively and quantitatively determined the secondary metabolites of Albizia antunesiana, its activity as an anti-bacterial and anti-inflammatory agent as well as assessing the toxicity profile of the lyophilised leaf extract. The phytoscreening was done using various classical wet chemistry techniques. The biosafety study was based on an amended OECD guideline 425, using Sprague Dawley rat models. The anti-bacterial evaluations were done using a modified Kirby-Bauer test (disk diffusion test) on Pseudomonas aeruginosa, methicillin-sensitive Staphylococcus aureus, Escherichia coli, and Klebsiella pneumoniae with doxycycline as a standard. The egg albumin test was used to determine the anti-inflammatory potential of the plant. The phytoscreening assays confirmed the presence of numerous biomedically relevant secondary metabolites with high polyphenolic and flavonoid yields. The antibacterial tests demonstrated high antibacterial activity with an MIC of 300mg comparable to 10mg doxycycline and the anti-inflammatory activity at 8000mg/ was comparable to the standard diclofenac at 2000mg. The toxicity tests showed an LD50 above 2500mg/kg body weight. It was therefore concluded that the presence of bioactive secondary metabolites in lyophilized extracts of the aerial parts of Albizia antunesiana possess significant anti-inflammatory and antioxidant profiles. The extracts were also toxicologically safe according to the Hodge and Sterner toxicity scale, thereby supporting their continued use as an adjunct therapy in traditional medical practices in Southern Africa.