Planta Med 2014; 80 - SL26
DOI: 10.1055/s-0034-1394514

Green synthesis of silver nanoparticles using Withania somnifera extract and their incorporation into a cream with antibacterial activity

M Gregory 1, RK Selvakesavan 1, G Franklin 1, B Sarmento 2, 3, ACP Dias 1
  • 1Centre for the Research and Technology of Agro-Environment and Biological Sciences (CITAB-UM), AgroBioPlant Group, Department of Biology, University of Minho, Portugal
  • 2INEB – Instituto de Engenharia Biomédica, University of Porto, Portugal
  • 3CICS, Department of Pharmaceutical Sciences, Instituto Superior de Ciências da Saúde-Norte, Gandra, Portugal

Withania somnifera (L) Dunal, (Solanaceae), commonly known as ashwagandha, winter cherry or Indian ginseng, is one of the distinguished medicinal plants in Indian Ayurvedic medicine [1]. Although W. somnifera was known for its medicinal uses since ancient times, it received much more attention in the recent years from pharmaceutical companies and local Baidyas due to confirmation of its multipurpose medicinal uses [2]. Several pharmacological studies have demonstrated that W. somnifera is efficacious in the treatment of arthritis, geriatric, behavioural and stress related problems [3]. In the present study, we have biosynthesised silver nanoparticles (AgNPs) using W. somnifera aqueous leaf extract, incorporated them into a cream formulation and evaluated the anti-bacterial potential of the cream against several pathogenic bacteria (Stapylococous aureus, Pseudomonas aruginosa, Candida albicans, Proteus vulgarius, Escherichia coli, Agrobacterium tumefaciens). The formation, size and shape of biosynthesized AgNPs were confirmed by physical-chemical techniques such as UV-Visible spectroscopy, Laser Doppler anemometry, Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM), X-ray diffraction (XRD) and X-ray energy dispersive spectroscopy (EDX). AgNPs exhibited significantly higher antibacterial activity (up to 200x) against human as well as plant pathogens compared to AgNO3 solution or W. somnifera leaf extract. The cellular interaction study coupled with SEM analysis revealed the effective disruption of bacterial cell by AgNPs. The incorporation of AgNO3 and AgNPs into a cream was done. The AgNPs-cream did not provoque significant changes in physical properties and stability of the cream, when compared with control, but have a significant higher antibacterial activity (Figure 1).

Fig. 1: Antibacterial activity of silver nanoparticles incorporated cream. (a) S. aureus treated with water (b) S. aureus treated with empty cream (control) (c) S. aureus treated with AgNO3-cream (d) S. aureus treated with AgNPs-cream.

Acknowledgements: This work was supported by Fundação para a Ciência e Tecnologia (FCT), projects PTDC/AGR-ALI/105169/2008, PTDC/AGR-GPL/119211/2010, and project PEst-OE/AGR/UI4033/2014. Marslin Gregory is supported by a FCT PhD fellowship (SFRH/BD/72809/2010).

Keywords: Withania somnifera, green silver nanoparticles, antibacterial activity, cream

References:

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