qNMR quantification of phenolic compounds in dry extract of Myrcia multiflora leaves and its antioxidant, anti-AGE, and enzymatic inhibition activities.

Myrcia multiflora (Lam.) DC. is often used in Brazilian folk medicine to control diabetes. Analysis using HPLC-HRMS and NMR of the dry extract from the infusion of leaves of this species revealed twelve phenolic compounds. Among these compounds, chlorogenic acid (1), 4-O-caffeoylquinic acid (2), corilagin (3), chebulagic acid (4), pedunculagin (5), quercetin-3-O-ß-2″-galloylglucoside (7), and kaempferol-3-O-rhamnoside (12) are described for the first time in this matrix. Furthermore, six compounds were quantified using qNMR. The compounds in the dry extracts are 3, 6 (myricetin-3-O-d-glucoside), 8 (myricitrin), 9 (hyperoside), 10 (guaijaverin) and 11 (quercitrin). These compounds may be considered chemical markers in this matrix. In addition, this extract presents activities of α-glucosidase inhibition (IC50 = 79.9 µg mL-1) and glycation in vitro (IC50 = 10.2 µg mL-1), in addition to antioxidant activity against DPPH and ABTS radicals (1,856.7 and 1,032.0 µmol TEq, respectively). This extract did not show significant cytotoxicity in human fibroblasts. Therefore, the enzymatic inhibition, anti-AGE (advanced glycation end-products) and antioxidant activities of Myrcia multiflora leaves corroborated its antidiabetic therapeutic potential and instigates future preclinical studies aimed at the treatment of diabetes mellitus and its complications.