How can crude plant extracts be standardised?
Plant extracts contain multiple compounds which in combination contribute to its efficacy. Variation in plant constituents caused by environmental factors affect the efficacy of extracts and also makes standardisation difficult. Several approaches have been used but there are limitations to these conventional approaches. The new approach of metabolomics is therefore currently being explored. Therein a fingerprint of the extract is obtained and an attempt is made to correlate it to the efficacy of the extract.
At FMR, this approach to standardisation is being tested on the guava leaf extract which exhibits anti-diarrhoeal activity. Leaves were collected from individual trees in 3 seasons from 3 locations. We used two methods for obtaining the fingerprint of these 90 extracts, viz., Nuclear Magnetic Resonance (NMR) and High-performance liquid chromatography (HPLC). These extracts were also screened using eight bioassays, against different diarrhoea causing microorganisms and representing various stages of diarrhoea. Correlating the fingerprints with activity based on the bioassays we observed segregation of extracts with good (green) and poor (red) activity (Fig.1) and were able to identify peaks in the fingerprint which were predominantly present in extracts with good (green) or poor (red) activity with respect to individual bioassays (Fig.2).
This shows that metabolomics is useful in the standardisation of herbal extracts, especially using HPLC fingerprinting since this equipment is widely available. This, in turn, would benefit industry to undertake standardisation of botanicals and market products with uniform quality and efficacy — a boost to the traditional Indian system of medicine.
