In vitro and in vivo protocols of antimicrobial bioassay of medicinal herbal extracts: A review

Antimicrobial susceptibility testing against pathogenic microorganisms is the most significant task of clinical microbiology laboratory. The present study was therefore designed to review the in vitro and in vivo protocols of antimicrobial bioassays of various medicinal herbal extracts against a diversity of pathogenic microorganisms. Plants have a broad variety of antimicrobial agents which are extensively used as herbal drugs against different microbes. The review covers the antimicrobial techniques and antimicrobial bioassays of medicinal herbal extracts against different bacterial and fungal strains from 2000 onward. Plants have diverse concentrations of bioactive constituents such as alkaloids, saponins, tannins, terpenoids, steroids, carbohydrates, proteins and lipids. These phytochemicals are used against an extensive range of bacteria (Escherichia coli, Mycobacterium, Corynebacterium pervum, Bordetella pertusis, Klebsiella pneumoniae, Salmonella typhi), viruses (simian-virus, retrovirus) and fungi (Pseudomonas aeruginosa, Aspergillus fumigatus, Aspergillus flavus, Fusarium solani). A variety of antibiotics (tetracycline, terramycin, ampicillin) has also been isolated from different medicinal plants. This review was therefore intended to explore the techniques used for antimicrobial activities of herbal medicinal extracts.