Effect of NPK Fertilizers on Chemical Constituents of Aloe vera Leaves

A field study was conducted in Aloe vera syn Aloe barbadensis with an objective to determine the effect of various levels of synthetic fertilizers (10:10:10: 20:20:20: 40:40:40: 80:80:80: N:P₂O₅:K₂O kg/ha) on chemical constituents at the inflorescence stage of the plant (12 months old). The active principles were assessed from the gel (mucilaginous tissue of leaf) and juice (yellow exudate from the base of leaf). The results suggested that free o-glycones and o-glycosides were not affected by levels of NPK nutrients applied, but c-glycosides, anhydrous barbaloin and hydroxy anthroquinone derivatives were significantly affected with application of NPK fertilizers at 40:40:40 or 80:80:80 N:P₂O₅:K₂O kg/ha. The recovery of total polysaccharides from gel ranged from 0.52% from control to 0.89% in 40:40:40 applied plots. Anhydrous barbaloin content estimated using HPLC technique and colorimetric methods were comparable Aloe emodin was found absent in all samples. Aloesin content ranged from 10.60 to 13.10% in Aloe juice and there was no significant difference across treatments. The recovery of Aloe juice ranged from 0.050 to 0.066% on dry weight basis.