Abstract:
Infectious diseases are the world’s leading cause of death. The rapid growth of drug resistance
microbes are unable to treat by the existing antibiotics. Plants are considered rich sources of
bioactive compounds used to overcome those pathogens. Thus, this study was aimed to evaluate
the antibacterial activity of ethanol, methanol, and chloroform crude leaf extracts of Withania
somnifera, Solanum incanum and their mixtures against six selected pathogenic bacteria such as
Escherichia coli (ATCC35218), Klebsiella pneumonia (ATCC700603), Staphylococcus aureus
(ATCC25923) and their clinical isolates. Agar well diffusion was used to determine the
inhibition zone of extracts, and broth dilution and agar well diffusion methods were used to
determine the minimum inhibitory concentration and minimum bactericidal concentration
(MBC). The inhibition zone of Withania somnifera extracts were range from to
; whereas the inhibition zone of Solanum incanum ranges from to
. The greatest inhibition zone ( mm) was recorded in S. aureus
(clinical isolate) subjected to methanol leaf extract of the plant mixture. The inhibition zone of
the mixture was significantly (P≤0.05) greater than the separated plant extracts; and also most
extracts of Withania somnifera were significantly (P≤0.05) greater than inhibition zones of
Solanum incanum. Methanol extracts showed the highest inhibition zone against most of the
tested bacterial strains, because it extracts a variety of bioactive compounds sufficiently. The
crude extracts were showed different ranges of minimum inhibitory concentration and minimum
bactericidal concentration. Moreover, the crude extracts were revealed the presence and
absence of some bioactive constituents of the plant. Thus, the present finding supports the
traditional use of Withania somnifera and Solanum incanum to treat different ailments.
However, a detailed in vitro scientific study is needed to come up with comprehensive
conclusions on the use of their synergistic extracts as alternative medicine.
Key words: Antibacterial activity, Inhibition zone, MBC, MIC, S. incanum, synergetic effect, W.
somnifera.
