Cereal‐derived phenolic acids and intestinal alpha glucosidase activity inhibition: Structural activity relationship

Abstract

Phenolic acids are thought to be involved in modulating the activity of intestinal α‐glucosidase which is desirable in the treatment and management of diabetes. However, limited data exist on the structural activity relationship between phenolic acid derivatives and intestinal α‐glucosidase activity inhibition. Thus five (5) hydroxycinnamic and six (6) hydroxybenzoic acid derivatives and four (4) hydroxycinnamic acid conjugates common in cereal grains were used to investigate the structural activity relationship and the kinetics of enzyme inhibition. α‐Glucosidase activity was inhibited by 4%–55% in the presence of the phenolic acid derivatives. The inhibition potency was dependent on the number of hydroxyl and methoxy groups present in the aromatic ring. Conjugation to other compounds did not affect their inhibition potency. The Lineweaver–Burk plots suggest mixed, competitive and uncompetitive types of inhibition. These results suggest that some derivatives of phenolic acid could play a significant role in prevention and management of diabetes. Practical Applications Phenolic acids, a group of biologically active compounds, present in cereal grains are thought to be involved in the prevention and management of diabetes through inhibiting the activities of enzymes in the intestine (such as α‐glucosidase). Intestinal α‐glucosidase is one of the enzymes required to breakdown sugars before their absorption into blood. This work investigated how the structure of phenolic acids found in cereal grain affects the activity of this enzyme. The results suggest that the number of hydroxyl and methoxy groups present in the main structure of phenolic acid decides to what extent the activity of the enzyme (α‐glucosidase) is inhibited. Understanding of this structure–activity relationship will help in identifying the type or variety of cereal grain that has the highest efficacy in preventing or managing diabetes based on their phenolic acid profile.

Antioxidant, Anti-Inflammatory, and Anti-Diabetic Activity of Phenolic Acids Fractions Obtained from Aerva lanata (L.) Juss.

“…As reported by other authors, sinapic, gallic, protocatechuic, gentistic, vanillic, and syringic acids have α-glucosidase inhibitory activity [56,57], which was also confirmed by our research. There are also many in vitro and in vivo reports on the anti-diabetic effects of gallic, protocatechuic, syringic, salicylic, ferulic, caffeic, p-coumaric, sinapic, and rosmarinic acids [29].…”

Inhibitors of α‐amylase and α‐glucosidase: Potential linkage for whole cereal foods on prevention of hyperglycemia

“…Quercetin, and ferulic and p-coumaric acids are reported to have high α-glucosidase inhibitory activity by mixed noncompetitive inhibition (Adisakwattana et al, 2009;Li et al, 2009). The results of Mishra et al (2017) had shown that organic rye varieties have higher ferulic acid content and α-amylase inhibitory activity, while traditional rye varieties have higher catechin content and α-glucosidase The structure-activity relationship suggests that the number of hydroxyl and methoxy groups present in the aromatic ring phenolic acids decides the inhibitory activity (Malunga et al, 2018).…”

“…The enzyme inhibition potency of individual phenolic compounds through mixed, uncompetitive, and competitive type is highly correlated with their structures (Di Stefano et al., 2018; Kim et al., 2019; Malunga et al., 2018; Tadera et al., 2006). Hydroxycinnamic acids are reported to be more potent on inhibition of α‐glucosidase compared with their corresponding hydroxybenzoic acid derivatives.…”

“…Hydroxycinnamic acids are reported to be more potent on inhibition of α‐glucosidase compared with their corresponding hydroxybenzoic acid derivatives. The structure–activity relationship suggests that the number of hydroxyl and methoxy groups present in the aromatic ring phenolic acids decides the inhibitory activity (Malunga et al., 2018). Furthermore, flavonoids appeared to have a better α‐glucosidase inhibitory activity than phenolic acids due to the additional hydroxyl groups in flavone skeleton, which is most likely responsible for the more pronounced inhibitory activity (Di Stefano et al., 2018; Tadera et al., 2006).…”

Changes in phenolics, γ‐aminobutyric acid content and antioxidant, antihypertensive and hypoglycaemic properties during ale white sorghum (Sorghum bicolor (L.) Moench) brewing process

“…Strong positive significant correlations ( P < 0.05) were found with 4‐hydroxybenzoic acid ( r : 0.9799), vanillic acid ( r : 0.9756), p‐coumaric acid ( r : 0.9928) and ferulic acid ( r : 0.9808). It is known that cereal‐derived phenolic acids could inhibit α‐glucosidase (Malunga et al ., ).…”