An in vitro study of the effect of Centella asiatica [Indian pennywort] on enteric pathogens

B Mamtha¹, K Kavitha¹, KK Srinivasan², PG Shivananda¹,  
¹ Department of Microbiology, Kasturba Medical College, Manipal - 576119, India
² Department of Pharmaceutical Chemistry, Kasturba Medical College, Manipal - 576119, India

Correspondence Address:
B Mamtha
Department of Microbiology, Kasturba Medical College, Manipal - 576119
India

Full Text

Sir,

Diarrhea is a major public health problem in developing countries. The present study was undertaken to find the antibacterial activity of Centella asiatica against a battery of enteric pathogens. Centella asiatica, also known as gotukola is a very useful medicinal plant described by Charaka as an anti-aging plant. This plant is found in marshy areas all over India, Sri Lanka, and Madagascar. It is mainly used to treat mental and neurological disturbances. Apart from its role as a brain tonic, its efficacy in treating tuberculosis, syphilis, amoebic dysentery and common cold is well documented in the literature.[1],[2]

Multiple drug resistance among enteropathogens in various geographic regions presents a major threat in the control of diarrhea. Therefore indigenous medicinal plants as an alternative to antibiotics are said to play a significant role here. This particular aspect of using medicinal plants as a remedy or home cure for diarrhea is applied in our present study.

The ethanol extract of Centella asiatica was prepared according to the method of Nair et al with certain modifications.[3] In the present study, 4 ATCC Standard bacterial strains [E coli ATCC 25922, Staphylococcus aureus ATCC 25923, Vibrio parahaemolyticus ATCC 17802 and Pseudomonas aeruginosa ATCC 27853] and 45 fresh clinical isolates like Vibrio cholerae 01, V cholerae 0139, species of Shigella, Salmonella typhimurium, Aeromonas hydrophila, Entero-aggregative E coli and Candida albicans were used.

Punch well and agar dilution methods along with viable cell count were carried out.[4],[5] The working concentrations of the extracts were 100, 200, 300 and 400 mg/ml respectively.

Broad spectrum activity of the herb was observed at concentrations of 100, 200, 300 and 400 mg/ml against a battery of enteric pathogens as shown in [Table:1]. But the inhibitory effect of the extract was best demonstrated at a concentration of 400 mg/ml of the agar. Of the two methods used, the punch well method yielded better results than the agar dilution method. Viable cell count method was used to study whether the observed inhibition was bactericidal or bacteriostatic in action. In case of Vibrio cholerae 01, Shigella species and Staphylococcus aureus, the alcoholic extract was bactericidal within 2 h.

Considerable work has been carried out on the phytochemical properties of the plant which has been reviewed and it is reported to consist of triterpenoid glycosides, free acids, volatile oils and flavonoids. It has been found that the activity of this plant extract against the microorganisms is mainly concentrated on the triterpene asiaticoside. The triterpenes weaken the membranous tissues which results in dissolving the cell walls of the microorganisms so that they can be more efficiently eliminated.[6],[7],[8]

The results of our study demonstrate the antimicrobial activity of Centella asiatica against the enteropathogens. Its potential as an antidiarrheal drug is worth studying.

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