International Journal of Food Safety and Public Health

Activity guided isolation and characterization of antioxidant and antibacterial agents from some local Nigerian plants

Sanusi Wara Hassan¹*, Surjeet Verma², Santosh Kumar Srivastava², Suaib Luqman³,

Usha Gupta⁴ and Nusrat Masood³

¹Department of Biochemistry, Usmanu Danfodiyo University, Sokoto, Nigeria.

²Medicinal Chemistry Department, Central Institute of Medicinal and Aromatic plants, Lucknow, India.

³Molecular Bioprospection Department, Biotechnology Division, Central Institute of Medicinal and Aromatic plants, Lucknow, India.

⁴Molecular Bioprospection Department, Central Institute of Medicinal and Aromatic plants, Lucknow, India.

*Corresponding author. E-mail: [email protected]. Tel: +2348036355866.

Accepted 10 October, 2013

Abstract

This study aimed to present the activity guided fractionation, isolation and characterization of antioxidants and antibacterial agents from combined mixture of plants (Vitex doniana, Diospyros mesipiliformis, Acacia polycantha, Pirinari macrophylla, Ficus sycomorus and Parkia biglobosa) and that of Pergularia tomentosa. Combined Mixture of Plants (CMP) is used locally in ratio of 1:1 for the treatment of bacterial infections. The CMP and P. tomentosa were extracted with methanol separately; the residues obtained were also separately suspended in water and successively fractionated with hexane, ethylacetate and n-butanol. All the fractions obtained were screened for antimicrobial and antioxidant activities. For CMP, only the ethyl acetate fraction (EF) indicated marginal antibacterial activity with 8.0, 7.0 and 7.0 mm zone of inhibition against Micrococcus luteus (MTCC 2470), Bacillus subtilis (MTCC 121) and Salmonella typhimurium, respectively. Minimum inhibitory concentration (MIC) for the CMP was greater than 1000 for M. luteus and S. typhimurium and 87.5 μg/ml for B. subtilis. The CMP fraction was subjected to chromatographic separations which resulted in the isolation and characterization of five bioactive constituents, gallic acid, 3β-OH-α-amyrin, 5,7,3’.4’,5’-pentahydroxy-3-O-glucophyranoside flavones (myricetin 3-O-β-rhamnopyranoside), 5,7,3’,4’ tetrahydroxy-3-O-glucopyranoside flavone (quercetin 3-O-β-rhamnopyranoside) and 3,5,7,3’,4’-pentahydroxy flavones (quercetin). They were characterized with the help of ESI-MS, IR, ¹H C¹³, HMBC/HSQC and COSY-NMR data. These compounds did not show antibacterial activity when tested separately but exhibited appreciable antioxidant activities in different manner. Chromatographic fractionation of hexane extract of P. tomentosa resulted in the isolation of lupeol acetate (LA) with marginal but selective activity against M. luteus and the activity is due to LA rather than the combined constituents. These findings suggest that the fractions of the extracts and pure compounds possess antibacterial and antioxidant properties.

Key words: Antioxidant properties, antibacterial activity, NMR data, Pergularia tomentosa, combined mixture of plants.