Antioxidant and Glycemic Regulatory Properties Potential of Different Maturity Stages of Leaf of Ceylon Cinnamon (Cinnamomum zeylanicum Blume) In Vitro

Dichloromethane:methanol (1:1, v/v) extracts of different maturity stages (immature, partly mature, and mature) of authenticated leaves of Ceylon cinnamon (CC) were used in this study. Antioxidant properties [total polyphenolic content (TPC) and total flavonoid content (TFC), 1, 1-diphenyl-2-picryl-hydrazyl (DPPH), 2-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid (ABTS)), oxygen radical absorbance capacity (ORAC), and ferric reducing antioxidant power (FRAP)] and glycemic regulatory properties [antiamylase (AA); antiglucosidase (AG)] were evaluated using 96-well microplate based bio assays in vitro (TPC, TFC, DPPH, ABTS, ORAC n=4 each; FRAP, AA, AG n=3 each). Results clearly revealed significant differences (p<0.05) among different maturity stages of leaf of CC for both antioxidant and glycemic regulatory properties (except AG activity). The mean antioxidant and glycemic regulatory activities of immature, partly mature, and mature leaves ranged from TPC: 0.68 ± 0.02–22.35 ± 0.21 mg gallic acid equivalents/g of sample (GS); TFC: 0.85 ± 0.01–4.68 ± 0.06 mg quercetin equivalents/GS; DPPH: 0.42 ± 0.01–27.09 ± 0.65 mg Trolox equivalents (TE)/GS; ABTS: 3.57 ± 0.10–43.91 ± 1.46 TE/GS; ORAC: 0.71 ± 0.01–18.70 ± 0.26 TE/G, FRAP: 0.31 ± 0.02–69.16 ± 0.52 TE/GS; and AA: 18.05 ± 0.24–36.62 ± 4.00% inhibition at 2.5 mg/mL. Mature leaf had the highest antioxidant and AA activities for all the assays investigated. In contrast, immature leaf had the lowest. The order of potency for antioxidant and AA activities was mature leaf > partly mature leaf > immature leaf. This is the first study to report on antioxidant and glycemic regulatory properties of different maturity stages of leaf of Ceylon cinnamon and highlights its potential use in management of oxidative stress-associated chronic diseases including diabetes mellitus.