Extraction, Isolation And Evaluation Of Antimicrobial Activity Of Tanzanian Medicinal Plants: Cleome Gynandra And Zanthoxylum Chalybeum

ABSTRACT

Antimicrobial resistance could cause approximately 10 million of people‟s deaths

worldwide yearly by 2050 (Sutherland, 2017). Thus, this study was aimed to

evaluate the antimicrobial activity of Cleome gynandra and Zanthoxylum

chalybeum. The extracts of roots and flowers of Cleome gynandra; root barks, stem

barks and leaves of Zanthoxylum chalybeum were used for investigation.

The powdered plant materials were macerated in petroleum ether, ethyl acetate, nbutanol

and aqueous methanol, then concentrated in vacuum using rotary

evaporator. The antimicrobial activity of extracts was evaluated using disc diffusion

and macrodilution methods. Phytochemical screening was done by TLC and

Chemical test. The cytotoxicity of the extracts was determined by brine shrimp

assay.

The most extracts contain alkaloids, anthraquinones, flavonoids, phenols, saponin,

steroids, tannins and terpenoids, which cause bioactivities against tested species. The

least MIC of 0.3125 mg/mL was shown by nBECGR against Staphylococcus aureus

with TA (67.2 mL/g), IZ (7.93 ± 0.15) mm AI (0.22), followed by AMECGR with

MIC of 0.625 mg/mL, TA of 89.28 mL/g against E. coli, nBEZCL with MIC of

0.625 mg/mL, TA of 36.8 mL/g against Escherichia coli, nBEZCS with MIC of

0.625 mg/mL and TA of 3.04 mL/g against Staphylococcus aureus. The rest extracts

show the range of 1.25-10 mg/mL.

The nBECGR have highest cytotoxicity with LC50 (18.01 ± 0.38) μg/mL but less

than Cyclophosphamide with LC50 of 16.3 μg/mL (Moshi et al., 2010) and nontoxic

was shown by PETECGF with LC50 (160.95 ± 2.16) μg/mL. Antimicrobial activities

of root extracts of Cleome gynandra and their cytotoxicity are reported for the first

time.

The observed antimicrobial activity and cytotoxicity of the extracts indicated that the

compounds of these species may possess higher antimicrobial efficacy. Therefore,

further phytochemical and antimicrobial investigation of isolated compounds is

required, and determination of acute toxicity of the extracts and compounds is

important.