The Appropriate Growing Stage for Harvesting of Senna alata (L.) Roxb Leaves Contained High Yield of Hydroxyanthracene Derivatives according to Standard Criteria

Abstract

Chum-Het-Thet is an herbal medicine listed in the national list of essential medicines as a remedy to relieve constipation. The varied amount of an active constituent was reported and their proportions can affect the quality and efficacy of the herb for treatment. The ‎World Health Organization recommends that harvesting herbs at the appropriate growing stage is a good way to obtain qualified raw materials. The aim of this research was to study the appropriate growth stage for harvesting Chum-Het-Thet leaves in order to obtain high yield of total hydroxyanthracene derivatives in order to comply with standard criteria. Plants used in this experiment were propagated from seed before transplanting into the field where they were maintained and the leaves were continuously harvested over 2 years. Total hydroxyanthracene derivatives were analyzed monthly using spectrophotometry. Thai Herbal Pharmacopoeia recommends that leaves must contain total hydroxyanthracene derivatives no less than 1.0% of dry weight. In this research, this plant was well grown and looked strong throughout this study. For the first year of the growing season of the plant, Chum-Het-Thet leaves were found to have high content of total hydroxyanthracene derivatives which were compiled using the standard criteria. The leaves at the 4th and 6th months growing, which were a prior flowering period, showed yields of 1.59±0.014% and 1.07±0.080%, respectively calculated on the dried basis. The leaves were obtained from the 9th and 10th months of plant growth, a flowering period. The amount of total hydroxyanthracene derivatives were found at 1.51±0.096% and 1.26±0.057%, respectively calculated on the dried basis. For the second year of growing season, the leaves were also showing a large amount of total hydroxyanthracene derivatives from February. Then, the compounds showed continually high yield until November (1.05±0.058% to 2.09±0.013% on dried basis); that was the growing period of this plant. In conclusion, the appropriate harvesting time to get the high yield of total hydroxyanthracene derivatives was the prior flowering, during the blooming, and also the post blooming period of the plant growth. The collecting time in the prior flowering stage should be considered the plant age.