Metabolite profiling of Drynariae Rhizoma using ¹H NMR and HPLC coupled with multivariate statistical analysis

Drynariae Rhizoma has been used to treat bone diseases and kidney deficiency in traditional medicine. Recently its aqueous extract was reported to enhance memory function. Although the Japanese standards for non-Pharmacopoeial crude drugs 2022 prescribed Drynaria roosii as the botanical origin, some counterfeits and both raw and stir-fired crude drugs are available in markets. To distinguish Drynariae Rhizoma derived from D. roosii appropriately from others and verify the validity of uses of stir-fried ones, ¹H NMR-based metabolite profiling coupled with HPLC were performed. Raw samples derived from D. roosii contained naringin (1), neoeriocitrin (2), 5,7-dihydroxychromone-7-O-neohesperidoside (3), caffeic acid 4-O-β-D-glucoside (4), protocatechuic acid (5), trans-p-coumaric acid 4-O-β-D-glucoside (6), and kaempferol 3-O-α-L-rhamnoside 7-O-β-D-glucoside (8). Stir-fried samples were characterized by presence of 5-hydroxymethyl-2-furaldehyde (13), and were divided into two types; one possessing similar composition to raw samples (Type I) and another without above components except 5 (Type II). Quantitative analyses using qHNMR and HPLC, followed by principal component analysis demonstrated that the raw samples had higher contents of 1 (0.93-9.86 mg/g), 2 (0.74-7.59 mg/g), 3 (0.05-2.48 mg/g), 4 (0.27-2.51 mg/g), 6 (0.14-1.26 mg/g), and 8 (0.04-0.52 mg/g), and Type II had a higher content of 5 (0.84-1.32 mg/g). The counterfeit samples derived from Araiostegia divaricata var. formosana were characterized by higher content of ( -)-epicatechin 3-O-β-D-allopyranoside (10) (1.44-11.49 mg/g) without 1 and 2. These results suggested that Drynariae Rhizoma samples derived from other botanical origins and Type II stir-fried samples cannot substitute for D. roosii rhizome.