03-08-2013, 04:47 PM
TLC Bioautography Technique: A Boon for Isolation of Antimicrobial Compounds from Botanicals
ABSTRACT
Diseases are taking heavy toll of field crops every year. Spectrum of chemical pesticides available in the market is used as frontline strategy to protect the crops from diseases. However their reckless application and associated health and environmental problems are now raising global concerns on their use. Secondary metabolites present in botanicals are well known for their role in plant defence response against invasion by insect-pests. Growing evidence indicate that these secondary metabolites can be useful ingredient for development of commercial pesticide formulations. However in order to achieve this, the first and the fore most requirements is the selection of plant material and target organism. Using simple fractionation procedures it is possible to separate the chemical compounds present in the mother extract derived from the plant material into different solvent factions based on polarity. After achieving this, an appropriate bioassay which is sensitive, reproducible and suffers from minimum false positives should be employed. In this direction, Thin Layer Chromatography based bioautography (TLC-Bioautography) technique holds promise for isolation of antimicrobial compounds from botanicals. This technique clearly indicates the antimicrobial compounds on the TLC plate which can be isolated using simple preparative TLC (Prep TLC) procedure. Choice of the test organism is central to the TLC bioautography procedure. However, once the antimicrobial compound is isolated using TLC bioautography, its broad spectrum antimicrobial activity can be followed by employing battery of potential target organisms using other screening methods.