Age-dependent variations in bioactive compounds in the roots of Himalayan peony (Paeonia emodi Royle)

Abstract

Himalayan peony (Paeonia emodi Royle) is a popular herbaceous plant known for its medicinal and therapeutic potential in indigenous and traditional systems of medicine. The fleshy roots of P. emodi are most frequently uses in uterine diseases, rheumatic pain, sciatica, muscle cramps, epilepsy, and nervous affection. Phytochemical compounds like phenolics, monoterpenes, triterpenes, steroids, and various organic acids are also present in the roots of P. emodi. In the present study, for the first time, the root age of P. emodi determined using growth rings and corresponding paeoniflorin, albiflorin, polyphenolics, and antioxidant content were evaluated. Based on the paraffin sectioning method, 1–7-year-old roots were identified, followed by quantification of bioactive compounds. The maximum content of gallic acid (79.15 ± 3.93 mg/100 g D.W.), naringin (158.82 ± 9.49 mg/100 g D.W.), chlorogenic acid (29.45 ± 2.60 mg/100 g D.W.), and p-hydroxybenzoic acid (37.69 ± 1.92 mg/100 g D.W.) were recorded from 5, 4, 6, and 7-year-old roots. The maximum content of catechin (176.82 ± 6.66 mg/100 g D.W.) and salicylic acid (24.15 ± 3.18 mg/100 g D.W.) were recorded from 3-year-old roots. The maximum content of paeoniflorin (20.51 ± 0.16 mg/g D.W.) and albiflorin (2.96 ± 0.65 mg/g D.W.) were recorded from 5 and 7-year-old roots, respectively. Maximum FRAP (12.75 ± 0.003 mg/g D.W.) and DPPH activity (18.67 ± 0.004 mg/g D.W.) were recorded in 6-year-old roots; while ABTS activity (13.54 ± 0.81 mg/g D.W.) was found maximum in 7-year-old roots. The Pearson correlation analysis showed that plant age demonstrated significant positive relationships (p < 0.01) with paeoniflorin, albiflorin, p-hydroxybenzoic acid, FRAP, and ABTS. The study showed that the amounts of bioactive compounds increased with the age of P. emodi. However, to harness and maintain the quality of raw materials in herbal or pharmaceutical industries, it is necessary to identify the material with the same age root of the target species for subsequent use.