EFFECT OF SEASONAL VARIATION ON SECONDARY METABOLITES OF MEDICINAL PLANTS

Seasonal fluctuations are periodical series, and have impact on availability of active principles in medicinal plants hence, therapeutic efficacy also get influenced. The survey of several scientific studies published in scientific journals of international repute indicates this fact. The studies reported that essential oil component shows a rhythmic increase in oil production throughout the growing season and then a steady decline towards the winter hence, recommended late summer as the best collection time. In contrast other researchers concluded the winter as a best season for harvesting of essential oils containing plant parts. It is not only essential oil that influenced by the season but other important constituents like polyphenol, flavonoids, glycosides, alkaloids etc are also influenced significantly by seasons.  There is no general rule for the harvesting time for better yield of specific secondary metabolites. Although several studies have been published indicating the effect of seasons on secondary metabolites but there is no compiled information representing the optimized season for the collection of pharmaceutically important constituents from different plant sources. Therefore, present review has been targeted the information of best possible season for the harvesting of plant material for the maximum output with respect to pharmaceutically important chemicals from the plants.