BIOACTIVE POTENTIAL OF SOUTH AFRICAN MEDICINAL PLANT ASPARAGUS SUAVEOLENS: PHYTOCHEMICAL SCREENING, ANTIOXIDANT, AND ANTIBACTERIAL ACTIVITIES

Abstract

Objective: To evaluate the phytochemical composition, antioxidant, and antibacterial activities of root extracts of A. suaveolens. Methods: The roots of A. suaveolens were collected from Bolahlakgomo village in Zebediela subregion, Limpopo province (South Africa) and ground into powder after drying. The ground plant material was extracted sequentially with hexane, dichloromethane (DCM), methanol (MeOH), and water (H2O). The resultant extracts were then subjected to phytochemical screening, thin-layer chromatography (TLC) fingerprinting, and gas chromatography – mass spectrometry (GC–MS) for the detection of different classes of compounds. Antioxidant activity was assessed using 1,1-diphenyl-2-picrylhydrazyl(DPPH) free radical scavenging, hydrogen peroxide (H2O2) scavenging, and ferric chloride (FeCl3)reducing power assays. Antibacterial activity was evaluated against four pathogenic bacterial strains (Pseudomonas aeruginosa, Staphylococcus aureus, Escherichia coli, and Streptococcus pyogenes) using a minimum inhibitory concentration (MIC) assay and TLC-bioautography. Results: Extraction with methanol yielded the highest extract mass, followed by H2O, DCM, and hexane extracts, indicating predominant extraction of polar compounds. Phytochemical screening of the root extracts revealed the presence of alkaloids, flavonoids, phenols, tannins, terpenoids, and other secondary metabolites. TLC fingerprinting confirmed the presence of diverse vanillin-sulfuric acid reagent reactive compounds, while GC–MS. Analysis enabled the identification of phytoconstituents with known antioxidant and antibacterial properties. Water extract showed the strongest antioxidant activity, half maximal effective concentration (EC50) (EC₅₀ = 0.058 mg/ml), surpassing ascorbic acid and BHT, followed by methanol extract (EC₅₀ = 0.152 mg/ml). DCM and methanol extracts exhibited notable antibacterial activity against S. pyogenes (MICs of 0.078 and 0.312 mg/ml, respectively) but were largely inactive against the other tested strains. Conclusion: This study represents the first report on the phytochemical profile and bioactivities of A. suaveolens roots. The findings demonstrate strong antioxidant potential and selective antibacterial activity that support the plant’s usage in traditional medicine and highlight its potential as a source of natural therapeutic agents. Further studies should focus on isolating bioactive constituents and elucidating their mechanisms of action.