Browsing by Author "Oyeleye, Sunday I."

Now showing 1 - 2 of 2
  • Thumbnail Image
    Item
    In vitro antioxidant activities of African birch (Anogeissus leiocarpus) leaf and its effect on the α-amylase and α-glucosidase inhibitory properties of acarbose
    (Elsevier, 2016-06-01) Adefegha, Stephen A.; Oboh, Ganiyu; Omojokun, Olasunkanmi S.; Jimoh, Tajudeen O.; Oyeleye, Sunday I.
    Objective This study sought to determine the antioxidant activities of African birch leaf, to assess its interaction with key enzymes relevant to type 2 diabetes (α-amylase and α-glucosidase) and to evaluate its effect on acarbose in vitro. Methods One milligram per milliliter of aqueous extract of African birch and acarbose were separately prepared. At the same time, both the African extract and acarbose solution (50:50 v/v) were thoroughly mixed until homogeneity was attained. The phenolic phytoconstituents and antioxidant properties of African birch leaf were subsequently determined. Finally, the effects of African birch extract, acarbose solution and a mixture of acarbose and African birch extract on α-amylase and α-glucosidase activities were assessed in vitro. Results The results showed that African birch extract demonstrated a remarkable antioxidant effect, as exemplified by its radical scavenging abilities, Fe2+ chelating ability and prevention of lipid peroxidation. Acarbose had significantly (p < 0.05) higher α-amylase (IC50 = 11.77 μg/ml) and α-glucosidase (IC50 = 9.05 μg/ml) activities compared to African birch extract [α-amylase (IC50 = 242.17 μg/ml); α-glucosidase (IC50 = 196.35 μg/ml)]. However, the combination of acarbose and African birch extract showed an additive effect on α-amylase inhibition, while a resultant synergistic action was observed against α-glucosidase inhibition. Conclusion The additive and synergistic actions of the combination of African birch extract and acarbose solution suggest effective, complementary and alternative strategies towards the management/treatment of hyperglycaemia associated with type 2 diabetes.
  • Thumbnail Image
    Item
    Inhibition of α-amylase, α-glucosidase and oxidative stress by some common apple varieties
    (Nutrafoods, 2016) Oboh, Ganiyu; Omojokun, Olasunkanmi S.; Oyeleye, Sunday I.; Akinyemi, Ayodele J.
    In recent times, the consumption of apples has been encouraged for the management of chronic diseases such as diabetes, but biochemical evidence to support this practice is lacking. Therefore, this study investigated α-amylase and α-glucosidase inhibitory activity, 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging ability, Fe2+-induced lipid peroxidation potential as well as the total phenol and flavonoid contents of aqueous extracts of the apple varieties Malus sylvestris (green apple), Malus pumila (red apple) and Syzygium samarangense (wax apple). The results showed that all apple varieties inhibited α-amylase (IC50=12.66–16.98 µg/ml) and α-glucosidase (13.55–16.23 µg/ml) in a dosedependent manner, with green apple showing the highest inhibitory activity while wax apple had the least. Similarly, all apple varieties showed dose-dependent DPPH radical scavenging activity (EC50=222.92–278.71 µg/ml) with green apple also showing the highest scavenging activity while wax apple showed the least. Furthermore, the aqueous extracts of the apple varieties dosedependently inhibited Fe2+-induced lipid peroxidation in rat pancreas (38.60–53.57 µg/ml), with wax apple exhibiting the highest inhibitory potential. Also, the total phenol content of the apple varieties ranged from 16.14 to 17.45 mg GAE/100g, while the flavonoid content ranged from 4.17 to 5.56 mg QUE/100 g, with green apple having the highest total phenolic and flavonoid contents. The biological activities exhibited by the apple varieties could be attributed to the presence of biologically active photochemicals. Furthermore, the apple variety (green apple) with the highest phenolic content showed the best overall activity, indicating the potent role of phenolic compounds in the management of diabetes, thereby providing biochemical support for the use of apples as a functional food in diabetes management.