Inhibition of Digestive Enzymes and Antioxidant Activity of Extracts from Fruits of Cornus alba, Cornus sanguinea subsp. hungarica and Cornus florida-A Comparative Study

Abstract

The fruits of some Cornus species (dogwoods) are used in traditional medicine and considered potential anti-diabetic and hypolipemic agents. The aim of the study was to determine the ability of extracts from Cornus alba (CA), Cornus florida (CF), and Cornus sanguinea (CS) to inhibit digestive enzymes namely α-amylase, pancreatic lipase, and α-glucosidase, as well as isolation of compounds from plant material with the strongest effect. In addition, the phytochemical profile and antioxidant activity of extracts from three dogwoods were compared with HPLC-DAD-MS/MS and DPPH scavenging assay, respectively. Among the aqueous-ethanolic extracts, the activity of α-amylase was the most strongly inhibited by the fruit extract of CA (IC₅₀ = 115.20 ± 14.31 μg/mL) and the activity of α-glucosidase by the fruit of CF (IC₅₀ = 38.87 ± 2.65 μg/mL). Some constituents of CA fruit extract, such as coumaroylquinic acid, kaempferol, and hydroxytyrosol derivatives, were isolated. Among the three species of dogwood studied, the greatest biological potential was demonstrated by CA extracts, which are sources of phenolic acids and flavonoid compounds. In contrast, iridoid compounds or flavonoid glycosides found in fruits of CF or CS extracts do not play a significant role in inhibiting digestive enzymes but exert antioxidant activity.

Keywords: Siberian dogwood; diabetes; digestive enzymes; obesity; polyphenols.

Figure 1

HPLC chromatograms of the ethanolic extracts from fruits of Cornus alba (CA) (10 mg/mL) acquired at 240 nm and 325 nm. HPLC conditions: Kinetex XB-C₁₈ column (150 × 2.1 mm, 1.7 μm), mobile phase A: 0.1% HCOOH/H₂O; B: 0.1% HCOOH/MeCN, and the gradient was as follows: 0–50 min. 5–26% B; 50–60 min. 26–95% B.

Figure 2

HPLC chromatograms of the ethanolic extracts from fruits of Cornus sanguinea (CS) (10 mg/mL) acquired at 240 nm and 325 nm. HPLC conditions: Kinetex XB-C₁₈ column (150 × 2.1 mm, 1.7 μm), mobile phase A: 0.1% HCOOH/H₂O; B: 0.1% HCOOH/MeCN, and the gradient was as follows: 0–50 min. 5–26% B; 50–60 min. 26–95% B.

Figure 3

HPLC chromatograms of the ethanolic extracts from fruits of Cornus florida (CF) (10 mg/mL) acquired at 240 nm and 325 nm. HPLC conditions: Kinetex XB-C₁₈ column (150 × 2.1 mm, 1.7 μm), mobile phase A: 0.1% HCOOH/H₂O; B: 0.1% HCOOH/MeCN, and the gradient was as follows: 0–50 min. 5–26% B; 50–60 min. 26–95% B.