Trimer procyanidin oligomers contribute to the protective effects of cinnamon extracts on pancreatic β-cells in vitro

Abstract

Aim: Cinnamon extracts rich in procyanidin oligomers have shown to improve pancreatic β-cell function in diabetic db/db mice. The aim of this study was to identify the active compounds in extracts from two species of cinnamon responsible for the pancreatic β-cell protection in vitro. Methods: Cinnamon extracts were prepared from Cinnamomum tamala (CT-E) and Cinnamomum cassia (CC-E). Six compounds procyanidin B2 (cpd1), (-)-epicatechin (cpd2), cinnamtannin B1 (cpd3), procyanidin C1 (cpd4), parameritannin A1 (cpd5) and cinnamtannin D1 (cpd6) were isolated from the extracts. INS-1 pancreatic β-cells were exposed to palmitic acid (PA) or H 2 O 2 to induce lipotoxicity and oxidative stress. Cell viability and apoptosis as well as ROS levels were assessed. Glucose-stimulated insulin secretion was examined in PA-treated β-cells and murine islets. Results: CT-E, CC-E as well as the compounds, except cpd5, did not cause cytotoxicity in the β-cells up to the maximum dosage using in this experiment. CT-E and CC-E (12.5-50 μg/mL) dose-dependently increased cell viability in both PA-and H 2 O 2 -treated β-cells, and decreased ROS accumulation in H 2 O 2 -treated β-cells. CT-E caused more prominent β-cell protection than CC-E. Furthermore, CT-E (25 and 50 μg/mL) dose-dependently increased glucose-stimulated insulin secretion in PA-treated β-cells and murine islets, but CC-E had little effect. Among the 6 compounds, trimer procyanidins cpd3, cpd4 and cpd6 (12.5-50 μmol/L) dose-dependently increased the cell viability and decreased ROS accumulation in H 2 O 2 -treated β-cells. The trimer procyanidins also increased glucose-stimulated insulin secretion in PA-treated β-cells. Conclusion: Trimer procyanidins in the cinnamon extracts contribute to the pancreatic β-cell protection, thus to the anti-diabetic activity.

Screening active components from Rubus amabilis for pancreatic β-cells protection

“…Similar findings have been reported by other research groups. Trimer procyanidins and cinnamtannin D-1, an A-type procyanidin oligomer isolated from cinnamon extracts, were verified to protect b-cells from PA and H 2 O 2 -induced dysfunction and apoptosis (Wang et al 2014;Sun et al 2016). Furthermore, we studied the mechanism involved in the prevention of b-cell apoptosis by PCs.…”

Cinnamon – Differentiation of Four Species by Linking Classical Botany to an Automated Chromatographic Authentication System

“…The cinnamon species have differing chromatographic profiles of procyanidins, polyphenols composed of catechin, and/or epi-catechin oligomers, in particular, doubly linked type-A procyanidins (21). These cinnamon procyanidins function as antioxidants and have been shown to exhibit other pharmacological activities, including insulin potentiation and impact on glucose intolerance and diabetes (4,5,(11)(12)(13)(22)(23)(24).…”

Antidiabetic Effects of Flavan-3-ols and Their Microbial Metabolites

“…The effect of flavan-3-ols directly on beta cell viability was also assessed. Cinnamtannin B1, procyanidin C1, and cinnamtannin D1 from cinnamon extracts were shown to dose-dependently protect INS-1 cells from palmitic acid and H 2 O 2 -induced reduction in terms of cell viability [ 34 ]. At 25 μmol/L, they enhanced insulin secretion in lipotoxic INS-1 cells [ 34 ].…”

“…Cinnamtannin B1, procyanidin C1, and cinnamtannin D1 from cinnamon extracts were shown to dose-dependently protect INS-1 cells from palmitic acid and H 2 O 2 -induced reduction in terms of cell viability [ 34 ]. At 25 μmol/L, they enhanced insulin secretion in lipotoxic INS-1 cells [ 34 ]. However, the flavan-3-ols EC and procyanidin B2 had no significant effects [ 34 ].…”