Methanolic extracts of <it>Withania somnifera</it> leaves, fruits and roots possess antioxidant properties and antibacterial activities

• Main Authors: Alam Nadia (Author), Hossain Monzur (Author), Mottalib Md (Author), Sulaiman Siti (Author), Gan Siew (Author), Khalil Md (Author)
• Format: Book
• Published: BMC, 2012-10-01T00:00:00Z.
• Subjects: article
• Online Access: Connect to this object online.
• Notes: 10.1186/1472-6882-12-175; 1472-6882
• Keywords: Withania somnifera; Antioxidant; Antibacterial; Free radicals; FRAP; Other systems of medicine; RZ201-999
• Source: BMC Complementary and Alternative Medicine, Vol 12, Iss 1, p 175 (2012)

<p>Abstract</p> <p>Background</p> <p><it>Withania somnifera,</it> also known as ashwagandha, is an important herb in ayurvedic and indigenous medical systems. The present study was designed to evaluate the antioxidant and antibacterial activities of an 80% aqueous methanolic extract of <it>W. somnifera</it> roots (WSREt), fruits (WSFEt) and leaves (WSLEt).</p> <p>Methods</p> <p>Several assays were performed to determine the antioxidant properties of this herb including 1,1-diphenyl-2-picrylhydrazyl radical (DPPH) scavenging activity, ferric reducing antioxidant power (FRAP), ferrous chelation and inhibition of β-carotene bleaching.</p> <p>Results</p> <p>The values for DPPH, FRAP, ferrous chelation and inhibition of β carotene bleaching for the three types of extracts ranged from 101.73-801.93 μg/ml, 2.26-3.29 mM Fe/kg, 0.22-0.65 mg/ml and 69.87-79.67%, respectively, indicating that <it>W. somnifera</it>, particularly the leaves, possesses significant antioxidant properties. The mean ascorbic acid content was 20.60-62.60 mg/100 g, and the mean anthocyanin content was 2.86-12.50 mg/100 g. Antibacterial activities were measured using the agar well diffusion method and five pathogenic Gram-negative bacteria: <it>Escherichia coli</it>, <it>Salmonella typhi</it>, <it>Citrobacter freundii</it>, <it>Pseudomonas aeruginosa</it> and <it>Klebsiella pneumoniae</it>. The leaf extracts displayed the highest activity against <it>S. typhi</it> (32.00 ± 0.75 mm zone of inhibition), whereas the lowest activity was against <it>K. pneumoniae</it> (19.00 ± 1.48 mm zone of inhibition). The lowest minimum inhibitory concentration value was 6.25 mg/ml, which was against <it>S. typhi</it>, followed by 12.5 mg/ml against <it>E. coli</it>.</p> <p>Conclusion</p> <p>In addition to its antioxidant properties, <it>W. somnifer</it>a exhibited significant antibacterial activities against Gram-negative bacteria, particularly <it>S. typhi</it>.</p>