Phytochemical and Antimicrobial Evaluation of Lauridia tetragona (L.F) R.H. Archer: A Medicinal Plant Used for the Management of Dysentery in the Eastern Cape Province of South Africa

Objective: The present investigation evaluated the in vitro phytochemical and antimicrobial potential of the methanol and acetone leaf extracts of Lauridia tetragona (L.F), a plant consumed as a herb in South Africa. Materials and Methods: Spectrophotometry assays using Folin–Ciocalteu, aluminum chloride, and vanillin–hydrochloric acid were used for the determination of phenols, flavonoids, and proanthocyanidin contents of the extracts, respectively. The agar dilution technique was used for the antimicrobial evaluation. The inhibitory activity of the extracts was tested on five Gram‑negative and five Gram‑positive bacteria and four fungi. Results: The methanol extract had a higher phenol (54.87 ± 4.01 mg gallic acid equivalent [GAE]/g) and proanthocyanidin (78.55 ± 0.83 mg catechin equivalent [CE]/g) content than the acetone extracts with 45.27 ± 3.93 mg GAE/g and 63.54 ± 1.67 mg CE/g, respectively. The acetone extract, however, had higher flavonoid content (462.45 ± 1.93 mg quercetin equivalent [QE]/g) than the methanol extract (412.20 ± 3.85 mg QE/g). The minimum inhibitory concentration (MIC) of the antibacterial assay ranged from 2.5 to 5 mg/mL. All the bacteria except Staphylococcus aureus were susceptible to the acetone extract. Five bacteria, three Gram positive and two Gram negative, were resistant while the remaining five were susceptible to the methanol extract. Conversely, all the fungi tested were susceptible to both extracts with a MIC which ranged from 0.63 to 10 mg/mL. Conclusion: The results obtained revealed that Gram‑positive and Gram‑negative bacteria and fungi showed some degree of susceptibility to the plant extracts. This gives an indication of broad‑spectrum activity exhibited by the crude extracts of L. tetragona and supports its ethnomedicinal usage.