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University of Namibia (2017)

Antibacterial, antioxidant and phytochemical investigation of Acacia Arenaria, Aloe Esculenta and Pechuel-Loeschea Leubnitziae

Ndongo, Daniel

Titre : Antibacterial, antioxidant and phytochemical investigation of Acacia Arenaria, Aloe Esculenta and Pechuel-Loeschea Leubnitziae

Auteur : Ndongo, Daniel

Université de soutenance  : University of Namibia

Grade : Master of Science (MS) (Biochemistry) 2017

Résumé
Natural products present in medicinal plants are an important source of therapeutic agents and many research groups are currently screening different biological activities of plants. This study aimed to investigate the antibacterial, antioxidant properties and phytochemical analysis of Acacia arenaria (Fabaceae), Aloe esculenta (Alliaceae) and Pechuel-Loeschea leubnitziae (Asteraceae) that are used in traditional settings. The antimicrobial activity of the methanol-dichloromethane (DCM) (1:1) extracts of these medicinal plants were tested against Shigella sonnei (ATCC 25931), Serratia marcescens (ATCC 8100), Enterococcus faecalis (ATCC 7080) and Alcaligenes faecalis (ATCC 8750). The minimum inhibitory concentration (MIC) of the extracts against afore mentioned microbes were determined. The antioxidant activity of the extracts was determined using α, α-diphenyl-β-picrylhydrazyl (DPPH) radical scavenging and reducing power assays. The phytochemical analysis of A. arenaria, A. esculenta and P. leubnitziae was done using qualitative and quantitative phytochemical analysis. Extracts demonstrated anti-microbial activity against S. sonnei, A. faecalis, E. faecalis and S. marcescens. The best activity was recorded with A. arenaria leaves extract, with MIC values ranging from 0.1 to 5.0 mg/mL against all tested bacteria. All extracts exhibited antioxidant activity for both assay techniques. The antioxidant activity correlated with the quantitative phytochemical presence of phenolic content ranging from 0.5 ± 0.1 to 5.7 ± 0.1 mg of GAE/g extract obtained in the extracts as well as condensed tannins ranging from 0.1 ± 0.0 to 72.6 ± 0.0 mg of TAC/g extract. Qualitative phytochemical analysis showed the presence of steroids, terpenoids, saponins, flavonoids, anthraquinones, coumarins, alkaloids, phenols and tannins. The results obtained in the present study indicated that the leaves, stem and roots of A. esculenta, and A. arenaria, P. leubnitziae are potential sources of natural antioxidants and antimicrobials. Further studies could look into the characterization of the bioactive compounds present in these plants.

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