Inhibitory Potential of Different Bilberry (Vaccinium myrtillus L.) Extracts on Human Salivary α-Amylase

Abstract

Recently, consumer preferences for bilberries have increased markedly. This fact is probably related to their natural constituents, such as phenolic compounds including anthocyanins and tannins, as well as the vitamins and minerals they contain. Phenolic compounds are known for their numerous beneficial effects on human health. Moreover, bilberry fruits have been shown to inhibit the activity of carbohydrate hydrolyzing enzymes, which can significantly decrease the postprandial increase in blood glucose levels. Thus, the aim of the present study is to investigate the inhibitory effect of Vaccinium myrtillus L. extracts on key enzyme α-amylase, linked to type 2 diabetes. No data have been published on the inhibitory properties of Vaccinium myrtillus L. fruits growing wild in Bulgaria against carbohydrate enzymes. Bilberry extracts were analyzed for total polyphenols, total anthocyanin content, antioxidant activity and their inhibitory properties against α-amylase. The contents of flavonols, anthocyanins and stilbenes were determined by HPLC analysis. The identified flavonols in the analyzed bilberry extracts were mainly represented by quercetin derivatives as rutinoside. The predominant anthocyanins for both aqueous and organic solvents were delphinidin-3-galactoside and malvidin-3-glucoside. The results revealed that bilberry extracts are effective inhibitors of α-amylase, with IC50 values from 20.8 to 194.8 μg GAE/mL. All the samples proved to have antioxidant activity measured by three different in vitro assays (FRAP, CUPRAC and DPPH). The inhibitory properties of V. myrtillus L. extracts may provide a new direction in the development and research of new pharmaceuticals for the suppression of postprandial hyperglycemia in diabetic patients.

Polyphenol Content, Antiradical Properties, and α-Amylase Inhibition Activity of Vaccinium myrtillus L. (Bilberry) and Vaccinium vitis-idaea L. (Lingonberry) Leaf and Aerial Parts Extracts

“…The α-amylase inhibition activity concentrations of α-amylase inhibitors in freezedried extracts were generally lower than those of ethanol extracts. The most effective inhibitors were found in freeze-dried VV aerial parts S and ethanol extracts of VV aerial parts D. Furthermore, according to Karcheva-Bahchevanska et al, the obtained data indicate no significant difference between the VM berries and leaves [10]. Therefore, leaves or aerial parts can serve as substitutes for berries.…”

“…Finding such inhibitory effects in VM and VV extracts could potentially slow down the digestion of carbohydrates, resulting in a slower release of glucose into the bloodstream [10]. This could be beneficial for individuals with T2DM by helping to manage blood sugar levels [11].…”

“…These plants have a history of being used to address various health concerns, including conditions related to metabolic imbalances [7,36]. Drawing on information from the scientific literature [10,17,36,37], our objectives were to characterise polyphenols and evaluate tannins, the total phenolic content, antioxidant activity, and the α-amylase inhibition activity of the leaves and the aerial parts of VM and VV in both ethanol extracts and freeze-dried samples. The plant samples were collected from two distinct locations: the Dekšāre district and the Sigulda district.…”

Anthocyanins and Type 2 Diabetes: An Update of Human Study and Clinical Trial

“…Current in vitro and animal studies have shown that anthocyanins are effective carbohydrate digestive enzyme inhibitors [ 13 , 46 , 47 , 48 , 49 , 50 , 51 , 52 ]. These mechanisms undoubtedly play a crucial role in their anti-diabetic properties, thereby reducing postprandial blood glucose levels.…”

“…In the last few years, the development of polyphenol research concerning their impact on diabetes has markedly progressed. Numerous in vivo and in vitro studies provide knowledge for a better understanding of the role of nutrition and its impact on diabetes treatment [ 11 , 12 , 13 , 14 ]. Natural compounds, such as flavonoids, have been extensively researched for their ability to target glucose metabolism and inflammatory processes by influencing signaling cascades and immune system cell responses [ 15 , 16 , 17 ].…”