Antibacterial and antifungal activity of Terminalia arjuna Wight&Arn.bark against multi-drug resistant clinical isolates

Objective:To evaluate antimicrobial activity of Terminalia arjuna(T.arjuna)bark against clinical strains of multi-drug resistant bacteria,and Candida spp.isolated from patients,as well as the corresponding reference strains.Methods:The antimicrobial activity of water,methanol and chloroform extracts of T.arjuna bark were evaluated by agar-well diffusion method,followed by determination of minimum inhibitory concentration(MIC)by broth micro-dilution method.The clinical isolates were studied for antibacterial susceptibility by Kirby and Bauer disk diffusion technique.Results:The water and methanolic extracts of T.arjuna bark produced significant zones of inhibition against twenty-two tested bacteria including eight uropathogens.MIC values against the bacteria were found in the range of 0.16 to 2.56 mg/mL.The chloroform extract did not exhibit antibacterial activity.The polar extracts of T.arjuna also demonstrated strong antifungal effect against eight species of Candida,with MIC between 0.16 and 0.64 mg/mL.The antimicrobial efficacy of the polar extracts was found to be commensurate with high polyphenol content in contrast to the non-polar(chloroform fraction).Conclusions:This study has revealed the therapeutic prospect of T.arjuna bark for the treatment of microbial diseases.The polar fraction of the bark could be used for development of novel antimicrobial agents,particularly against urinary tract infections,and candidiasis/candidaemia.

Antimicrobial activity and DNA-fragmentation effect of isoflavonoids isolated from seeds of Millettia ferruginea,an endemic legume tree in Ethiopia

Objective:To investigate the seeds of Millettia ferruginea(M.ferruginea)to unravel its antibacterial,antifungal,antitubercular,and antileishmanial potential for the first time.Methods:M.ferruginea seeds were refluxed separately with chloroform,methanol and water to prepare the three extracts,which were tested against the reference strains of Gram-positive and Gram-negative bacteria,yeast cells,Mycobacterium tuberculosis and Leishmania donovani(L.donovani)promastigotes.Next,the seeds were chemically analysed to isolate three constituent compounds,viz.,barbigerone,calopogonium isoflavone-A and durmillone,which were purified,characterised and evaluated for antibacterial and antileishmanial activity.Further,Comet assay was conducted to observe DNA fragmentation effects on human peripheral blood mononuclear cells pretreated with the isoflavonoid compounds.Results:The chloroform and methanol extracts of M.ferruginea seeds exhibited antibacterial and antileishmanial activity.The pure compounds also showed inhibitory activity against Gram-negative ATCC strains(minimum inhibitory concentration~0.5μmol/L),and L.donovani promastigotes(IC_(50)8.2-87.3μg/mL).However,they had little or no activity against yeast cells and tubercle bacilli.The DNA fragmentation study showed that the isoflavonoid constituents of M.ferruginea seeds were safe at therapeutic doses.Conclusions:The antibacterial efficacy of the non-aqueous extracts of M.ferruginea seed was observed against both Gram-positive and Gram-negative ATCC strains.Moreover,the constituents isoflavonoids,viz.,barbigerone,calopogonium isoflavone-A and durmillone,exhibited inhibitory activity against Gram-negative ATCC strains and L.donovani promastigotes.The comet assay showed that the compounds were safe to be considered for human consumption.