More than just a drink

By Biplab Das
Published: Tuesday 31 March 2009

It can kill bacteria harmful to humans

coconut water--the clear liquid found inside young, green coconuts--is a cool drink to look forward to in the summer months. Sweet and nutritious, it is popular in the tropics especially in Asia and Latin America. Not just a beverage though, coconut water has medicinal properties. It is used to treat diarrhoea. It is good for the heart. Now researchers say that it can also kill harmful bacteria.

Over the years pathogenic bacteria have turned stronger at resisting commercial antibiotics. To solve this problem, scientists turned towards basic immunity providers--proteins. When a bacterium attacks, immune cells release antibodies which are made of proteins. Researchers around the world isolated a variety of antimicrobial proteins or amps from different plant tissues like flowers, tubers, leaves, roots and seeds. Of them, the ones isolated from common guava and blackeyed pea seeds showed significant anti-bacterial activity. Given the medicinal value of coconut water, researchers from West Bengal and Brazil decided to explore its antimicrobial properties.

The researchers collected coconut water from the local markets in Kharagpur. They purified the liquid and divided it into three fractions which were exposed to four bacterial strains-- Escherichia coli (inhabits the human gut), Staphylococcus aureus and Bacillus subtilis (cause food poisoning) and Pseudomonus aeruginosa (turns milk and meat toxic).

All three fractions displayed antibacterial activity against all the bacterial strains. It is probably an electrostatic bonding, between the positively charged amps and the negatively charged substances present on the surface of the bacterial cell which kills the bacterium, said the study. "These are three new classes of peptides with different properties," said Octavio L Franco who led a team of researchers from the Universidade Catolica de Brasilia, DF, Brazil and Department of Biotechnology and School of Medical Science and Technology, Indian Institute of Technology, Kharagpur. "They are small and stable and probably will control infections which other peptides succumb to," Franco added.

This report, published in the December 6 issue of Peptides, is the first description of antimicrobial peptides in coconut water found effective against pathogenic bacteria. These peptides could be potential drug ingredients to generate future antibiotics.

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