Antibacterial activity of Zingiber officinale against selected bacteria

BHMH Lakshani¹, N Ravimannan²

Department of Botany, faculty of science, University of Jaffna

¹lakshani202@gmail.com

Abstract

The usage of plants for the preparation of medicines has been increased in the world due to the presence of antimicrobial agents in the plants. Antimicrobial agent is a compound which selectively destroys or inhibits the growth of microorganisms. Herbal medicine is a source of health maintenance and cure of diseases for the increasing population in the world. Misuse and overuse of antimicrobial agents has led microorganisms to develop resistance against antimicrobial agents. So the constant discovery of new antibiotic agents has become necessary in the world. Green plants produce secondary metabolites which have the antimicrobial compounds like terpenes, sesquiterpenes and phenolic compounds etc. All these chemicals cannot be synthesized in laboratories. Many secondary metabolites of plant are commercially important and find use in a number of pharmaceutical compounds. Gingerol, shogaol, zingerone and paradol are the major bioactive compounds present in ginger rhizome. Those parts can be used for the preparation of medicine. Secondary metabolites of plants are also important for defense against abiotic stresses (e.g.UV-B exposure) and for the communication of the plants with other organisms.

For the experimental studies five bacterial species were used. They were Escherichia coli, Bacillus subtilis, Pseudomonas aeruginisa, Staphylococcus aureus and Proteus vulgaris. Here the antimicrobial activity of ginger extracts from three different zones in Sri Lanka (wet, dry and intermediate zone) was tested. Extracts were prepared using fleshy part of ginger and dried powder of ginger. Water, methanol and chloroform were the solvents used. For the fleshy part, sterile water (25g/100ml) and for dried ginger, methanol and chloroform (10g/100ml) were used as solvents. The method used to test the antibacterial activity was well diffusion method. The results were analyzed with tukey test (p<0.05) using statistical software R i386. 4.0.5.

The extract from fleshy part of ginger from wet zone inhibited Staphylococcus aureus, Pseudomonas aeruginosa and Proteus vulgaris. It showed highest zone of inhibition against Staphylococcus aureus (20±2.82 mm) and lowest zone of inhibition against Proteus vulgaris (16±1.41 mm). Fresh ginger extract from wet zone also showed inhibition against Pseudomonas aeruginosa (18±0 mm). The fresh extract from dry zone inhibited Proteus vulgaris (13±0 mm). Fresh extract from intermediate zone inhibited Bacillus subtilis (14±1.41 mm) and Proteus vulgaris (13±0.70 mm). Bacillus subtilis was the only species which was inhibited by dried ginger extracts of both methanol and chloroform from the three different zones. Dried ginger from wet zone extracted with methanol showed highest inhibition (14±0 mm) than that of dried ginger from wet zone extracted with chloroform. (11±2.12 mm). The dried ginger from dry zone extracted with chloroform showed highest inhibition (15±0.70 mm) than dried ginger from wet zone extracted with methanol (14±0 mm). Dried ginger from intermediate zone extracted in both methanol and chloroform showed similar inhibitions (12±0 mm). All the extracts used in this study did not inhibit the growth of E. coli.

Key words: antibacterial activity, Zingiber officinale, bacteria