Inhibitory potentials of phenolic-rich extracts from Bridelia ferruginea on two key carbohydrate-metabolizing enzymes and Fe(2+)-induced pancreatic oxidative stress.

The current study was designed to evaluate the various antioxidant potentials and inhibitory effects of phenolic-rich leaf extracts of Bridelia ferruginea (BF) on the in vitro activities of some key enzymes involved in the metabolism of carbohydrates. In this study, BF leaf free and bound phenolic-rich extracts were used. We quantified total phenolic and flavonoid contents, and evaluated several antioxidant activities using assays for ferric reducing antioxidant power, total antioxidant activity (phosphomolybdenum reducing ability), 1,1-diphenyl-2-picrylhydrazyl and thiobarbituric acid reactive species. Also, extracts were tested for their ability to inhibit α-amylase and α-glucosidase activity. The total phenolic and total flavonoid contents in the free phenolic extract of BF were significantly greater than in the bound phenolic extract. Also, all the antioxidant activities considered were significantly greater in the free phenolic extract than in the bound phenolic extract. In the same vein, the free phenolic-rich extract had a significantly higher percentage inhibition against α-glucosidase activity (IC50 = 28.5 µg/mL) than the bound phenolic extract (IC50 = 340.0 µg/mL). On the contrary, the free phenolic extract (IC50 = 210.0 µg/mL) had significantly lower inhibition against α-amylase than the bound phenolic-rich extract (IC50 = 190.0 µg/mL). The phenolic-rich extracts of BF leaves showed antioxidant potentials and inhibited two key carbohydrate-metabolizing enzymes in vitro.

Afolabi OB ，Oloyede OI ，Agunbiade SO 《Journal of Integrative Medicine-JIM》

In vitro inhibition activity of polyphenol-rich extracts from Syzygium aromaticum (L.) Merr. & Perry (Clove) buds against carbohydrate hydrolyzing enzymes linked to type 2 diabetes and Fe(2+)-induced lipid peroxidation in rat pancreas.

Adefegha SA ，Oboh G 《Asian Pacific Journal of Tropical Biomedicine》

Phenolic-rich extracts from selected tropical underutilized legumes inhibit α-amylase, α-glucosidase, and angiotensin I converting enzyme in vitro.

Ademiluyi AO ，Oboh G 《-》

Medicinal properties of Ocotea bullata stem bark extracts: phytochemical constituents, antioxidant and anti-inflammatory activity, cytotoxicity and inhibition of carbohydrate-metabolizing enzymes.

This study evaluates the phytochemical constituents, antioxidant and anti-inflammatory activity, cytotoxicity, and inhibitory activity against carbohydrate metabolism of extracts from Ocotea bullata stem bark. Hexane, ethyl acetate, methanol and water were used to extract the air-dried sample. The phytochemical investigation and antioxidant assays were carried out on the extracts using standard procedures. The antidiabetic and anti-inflammatory potentials were evaluated using α-amylase, α-glucosidase and 5-lipoxygenase enzymes respectively. Vero cells were employed to determine the cytotoxicity of the extracts. The ethyl acetate extract showed higher phenolic contents (8.97 mg/g gallic acid) while methanol displayed higher flavonoid (36.06 mg/g quercetin) and flavonol (153.44 mg/g rutin) contents than other extracts. Hexane extract had the greatest capacity to scavenge 1,1-diphenyl-2-picryl-hydrazyl (0.19 mg/mL), hydroxyl (25.77 mg/mL) and 2,2-azino-bis(3-ethylbenzothiazoline)-6-sulfonic acid (0.07 mg/mL) radicals, while ethyl acetate extract exhibited stronger inhibition (P < 0.05) against superoxide anion (0.41 mg/mL) and ferric ion-reducing power (2.36 mg/mL) compared to other extracts and standards. Aqueous extract (27.02 mg/mL) exhibited strong metal-chelating activity (P < 0.05) compared to other extracts and gallic acid. The aqueous extract demonstrated the greatest inhibition of α-glucosidase (1.45 mg/mL) and α-amylase (2.43 mg/mL) compared to other extracts and acarbose. There were no significant differences (P < 0.05) in half-maximum inhibitory concentration (IC50) values of all tested extracts and indomethacin in the inhibition of 5-lipoxygenase activity. The aqueous extract was nontoxic to Vero cells with an IC50 value of 0.38 mg/mL. O. bullata stem bark contains active phytochemicals with diverse pharmacological potentials that could be beneficial in managing diabetes and inflammation.

Ogundajo AL ，Adeniran LA ，Ashafa AO 《Journal of Integrative Medicine-JIM》

Soybean phenolic-rich extracts inhibit key-enzymes linked to type 2 diabetes (α-amylase and α-glucosidase) and hypertension (angiotensin I converting enzyme) in vitro.

This study sought to assess the inhibitory activities of phenolic-rich extracts from soybean on α-amylase, α-glucosidase and angiotensin I converting enzyme (ACE) activities in vitro. The free phenolic extract of the soybean was obtained by extraction with 80% acetone, while that of the bound phenolic extract was done by extracting the alkaline and acid hydrolyzed residue with ethyl acetate. The inhibitory action of these extracts on the enzymes activity as well as their antioxidant properties was assessed. Both phenolic-rich extracts inhibited α-amylase, α-glucosidase and ACE enzyme activities in a dose dependent pattern. However, the bound phenolic extract exhibited significantly (P < 0.05) higher α-amylase and ACE inhibition while the free phenolic extract had significantly (P < 0.05) higher α-glucosidase inhibitory activity. Nevertheless, the free phenolic extract had higher α-glucosidase inhibitory activity when compared to that of α-amylase; this property confer an advantage on soybean phenolic-rich extracts over commercial antidiabetic drugs with little or no side effect. And inhibition of ACE suggests the antihypertension potential of soybean phenolic-rich extracts. Furthermore, the enzyme inhibitory activities of the phenolic-rich extracts were not associated with their phenolic content. Therefore, phenolic-rich extracts of soybean could inhibit key-enzyme linked to type 2 diabetes (α-amylase and α-glucosidase) and hypertension (ACE) and thus could explain in part the mechanism by which soybean renders these health promoting effect.

Ademiluyi AO ，Oboh G 《-》