Ganiyu Oboh

Comparative Study on the Inhibitory Effect of Caffeic and Chlorogenic Acids on Key Enzymes Linked to Alzheimer’s Disease and Some Pro-oxidant Induced Oxidative Stress in Rats’ Brain-In Vitro

This study sought to investigate and compare the interaction of caffeic acid and chlorogenic acid on acetylcholinesterase (AChE) and butyrylcholinesterase (BChE), and some pro-oxidants (FeSO4, sodium nitroprusside and quinolinic acid) induced oxidative stress in rat brain in vitro. The result revealed that caffeic acid and chlorogenic acid inhibited AChE and BChE activities in dose-dependent manner; however, caffeic acid had a higher inhibitory effect on AChE and BChE activities than chlorogenic acid. Combination of the phenolic acids inhibited AChE and BChE activities antagonistically. Furthermore, pro-oxidants such as, FeSO4, sodium nitroprusside and quinolinic acid caused increase in the malondialdehyde (MDA) contents of the brain which was significantly decreased dose-dependently by the phenolic acids. Inhibition of AChE and BChE activities slows down acetylcholine and butyrylcholine breakdown in the brain. Therefore, one possible mechanism through which the phenolic acids exert their neuroprotective properties is by inhibiting AChE and BChE activities as well as preventing oxidative stress-induced neurodegeneration. However, esterification of caffeic acid with quinic acid producing chlorogenic acid affects these neuroprotective properties.

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.

Caffeic and chlorogenic acids inhibit key enzymes linked to type 2 diabetes (in vitro): a comparative study

Abstract Background: Chlorogenic acid is a major phenolic compound that forms a substantial part of plant foods and is an ester of caffeic acid and quinic acid. However, the effect of the structures of both chlorogenic and caffeic acids on their antioxidant and antidiabetic potentials have not been fully understood. Thus, this study sought to investigate and compare the interaction of caffeic acid and chlorogenic acid with α-amylase and α-glucosidase (key enzymes linked to type 2 diabetes) activities in vitro. Methods: The inhibitory effect of the phenolic acids on α-amylase and α-glucosidase activities was evaluated. Thereafter, their antioxidant activities as typified by their 1,1-diphenyl-2 picrylhydrazyl radical scavenging ability and ferric reducing antioxidant properties were determined. Results: The results revealed that both phenolic acids inhibited α-amylase and α-glucosidase activities in a dose-dependent manner (2–8 μg/mL). However, caffeic acid had a significantly (p<0.05) higher inhibitory effect on α-amylase [IC50 (concentration of sample causing 50% enzyme inhibition)=3.68 μg/mL] and α-glucosidase (IC50=4.98 μg/mL) activities than chlorogenic acid (α-amylase IC50=9.10 μg/mL and α-glucosidase IC50=9.24 μg/mL). Furthermore, both phenolic acids exhibited high antioxidant properties, with caffeic acid showing higher effects. Conclusions: The esterification of caffeic acid with quinic acid, producing chlorogenic acid, reduces their ability to inhibit α-amylase and α-glucosidase activities. Thus, the inhibition of α-amylase and α-glucosidase activities by the phenolic acids could be part of the possible mechanism by which the phenolic acids exert their antidiabetic effects.

Nutrient enrichment of cassava peels using a mixed culture of Saccharomyces cerevisae and Lactobacillus spp solid media fermentation techniques

Cassava pulp was fermented with pure strains of Saccharomyces cerevisae and two bacteria namely Lactobacillus delbruckii and Lactobacillus coryneformis for 3 days. The squeezed liquid from the fermented pulp was used to ferment cassava peels for 7 days. Analysis of the dried fermented peels revealed that there was a significant ( P ( 21.5%) when compared with the unfermented cassava peel (8.2%). Moreover, the treatment equally brought about a significant ( P

Antioxidant and inhibitory effect of red ginger (Zingiber officinale var. Rubra) and white ginger (Zingiber officinale Roscoe) on Fe2+ induced lipid peroxidation in rat brain in vitro

Neurodegerative diseases have been linked to oxidative stress arising from peroxidation of membrane biomolecules and high levels of Fe have been reported to play an important role in neurodegenerative diseases and other brain disorder. Malondialdehyde (MDA) is the end-product of lipid peroxidation and the production of this aldehyde is used as a biomarker to measure the level of oxidative stress in an organism. The present study compares the protective properties of two varieties of ginger [red ginger (Zingiber officinale var. Rubra) and white ginger (Zingiber officinale Roscoe)] on Fe(2+) induced lipid peroxidation in rat brain in vitro. Incubation of the brain tissue homogenate in the presence of Fe caused a significant increase in the malondialdehyde (MDA) contents of the brain. However, the aqueous extract from both varieties of ginger caused a significant decrease in the MDA contents of the brain in a dose-dependent manner. However, the aqueous extract of red ginger had a significantly higher inhibitory effect on both Fe(2+)-induced lipid peroxidation in the rat brain homogenates than that of white ginger. This higher inhibitory effect of red ginger could be attributed to its significantly higher phytochemical content, Fe(2+) chelating ability, OH scavenging ability and reducing power. However, part of the mechanisms through which the extractable phytochemicals in ginger (red and white) protect the brain may be through their antioxidant activity, Fe(2+) chelating and OH scavenging ability. Therefore, oxidative stress in the brain could be potentially managed/prevented by dietary intake of ginger varieties (red ginger and white ginger rhizomes).

Inhibition of acetylcholinesterase activities and some pro-oxidant induced lipid peroxidation in rat brain by two varieties of ginger (Zingiber officinale).

Ginger has been reportedly used for the management or treatment of Alzheimers disease in folklore medicine. Therefore, this study sought to investigate the inhibitory effects of water extractable phytochemicals of red and white ginger on acetylcholinesterase activities, and sodium nitroprusside (SNP) and quinolinic acid (QA)-induced lipid peroxidation in rat brain -in vitro. Both extracts inhibited acetylcholinesterase (AChE) activities in a dose-dependent manner; however, white ginger had higher acetylcholinesterase inhibitory activity than red ginger. Combination of the ginger inhibited acetylcholinesterase activities synergistically. Furthermore, SNP and QA caused a significant increase in the malondialdehyde (MDA) contents of the brain; however, the extracts significantly decrease the SNP and QA elevated brain MDA contents in a dose-dependent manner. Nevertheless, there was no significant difference (P>0.05) in the inhibition of the SNP and QA-induced lipid peroxidation by both extracts. The inhibitory effect of ginger extracts on acetylcholinesterase activities and some prooxidants induced lipid peroxidation in rats brain could be attributed to the presence of phytochemicals such as flavonoids, tannins, alkaloids and terpenoids. Therefore, some possible mechanism by which ginger extracts exert anti-Alzheimer properties could be through the inhibition of acetylcholinesterase activities and prevention of lipid peroxidation in the brain.

Antihyperglycemic, hypolipidemic, hepatoprotective and antioxidative effects of dietary clove (Szyzgium aromaticum) bud powder in a high‐fat diet/streptozotocin‐induced diabetes rat model

BACKGROUND Syzygium aromaticum (L.) Merr. & Perry (clove) bud is an important spice used in the preparation of several delicacies and in folklore for diabetes management. The present study was convened to assess the effects of dietary clove bud powder (CBP) on biochemical parameters in a type 2 diabetes rat model, induced by a combination of high-fat diet and low-dose streptozotocin (35 mg kg⁻¹) for 30 days. RESULTS Diabetic rats were placed on dietary regimen containing 20-40 g kg⁻¹ clove bud powder. The results revealed that there was no significant (P > 0.05) difference in the average feed intake and weight changes between the rat groups. Furthermore, supplementation with CBP gradually reduced blood glucose level in diabetic rat compared to control diabetic rats without CBP supplementation (DBC). Moreover, reduced activity of α-glucosidase was observed in CBP and metformin-treated rat groups when compared to that of the DBC rat group. In addition, the DBC group had significantly (P < 0.05) higher lipid concentrations (except for high-density lipoprotein cholesterol) when compared to all other groups. Furthermore, CBP had significantly (P < 0.05) reduced activity of liver enzymes (alanine aminotransferase, aspartate aminotransferase and alkaline phosphatase) and showed elevated levels of antioxidant status (glutathione, ascorbic acid, superoxide dismutase and catalase). CONCLUSION The results suggest that the clove bud diet may attenuate hyperglycemia, hyperlipidemia, hepatotoxicity and oxidative stress in the type 2 diabetic condition.

Inhibition of key enzymes linked to type 2 diabetes and sodium nitroprusside-induced lipid peroxidation in rat pancreas by water extractable phytochemicals from some tropical spices

Context: Spices have been used as food adjuncts and in folklore for ages. Inhibition of key enzymes (α-amylase and α-glucosidase) involved in the digestion of starch and protection against free radicals and lipid peroxidation in pancreas could be part of the therapeutic approach towards the management of hyperglycemia and dietary phenolics have shown promising potentials. Objective: This study investigated and compared the inhibitory properties of aqueous extracts of some tropical spices: Xylopia aethiopica [Dun.] A. Rich (Annonaceae), Monodora myristica (Gaertn.) Dunal (Annonaceae), Syzygium aromaticum [L.] Merr. et Perry (Myrtaceae), Piper guineense Schumach. et Thonn (Piperaceae), Aframomum danielli K. Schum (Zingiberaceae) and Aframomum melegueta (Rosc.) K. Schum (Zingiberaceae) against α-amylase, α-glucosidase, 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals and sodium nitroprusside (SNP)-induced lipid peroxidation in rat pancreas - in vitro using different spectrophotometric method. Materials and methods: Aqueous extract of the spices was prepared and the ability of the spice extracts to inhibit α-amylase, α-glucosidase, DPPH radicals and SNP-induced lipid peroxidation in rat pancreas - in vitro was investigated using various spectrophotometric methods. Result: All the spice extracts inhibited α-amylase (IC50 = 2.81–4.83 mg/mL), α-glucosidase (IC50 = 2.02–3.52 mg/mL), DPPH radicals (EC50 = 15.47–17.38 mg/mL) and SNP-induced lipid peroxidation (14.17–94.38%), with the highest α-amylase & α-glucosidase inhibitory actions and DPPH radical scavenging ability exhibited by X. aethiopica, A. danielli and S. aromaticum, respectively. Also, the spices possess high total phenol (0.88–1.3 mg/mL) and flavonoid (0.24–0.52 mg/mL) contents with A. melegueta having the highest total phenolic and flavonoid contents. Discussion and conclusion: The inhibitory effects of the spice extracts on α-amylase, α-glucosidase, DPPH radicals and SNP-induced lipid peroxidation in pancreas (in vitro) could be attributed to the presence of biologically active phytochemicals such as phenolics and some non-phenolic constituents of the spices. Furthermore, these spices may exert their anti-diabetic properties through the mechanism of enzyme inhibition, free radicals scavenging ability and prevention of lipid peroxidation.

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

OBJECTIVE To investigate and compare the inhibitory properties of free and bound phenolic extracts of clove bud against carbohydrate hydrolyzing enzymes (alpha-amylase & alpha-glucosidase) and Fe(2+)-induced lipid peroxidation in rat pancreas in vitro. METHODS The free phenolics were extracted with 80% (v/v) acetone, while bound phenolics were extracted from the alkaline and acid hydrolyzed residue with ethyl acetate. Then, the interaction of the extracts with alpha-amylase and alpha-glucosidase was subsequently assessed. Thereafter, the total phenolic contents and antioxidant activities of the extracts were determined. RESULTS The result revealed that both extracts inhibited alpha-amylase and alpha-glucosidase in a dose-dependent manner. However, the alpha-glucosidase inhibitory activity of the extracts were significantly (P<0.05) higher than their alpha-amylase inhibitory activity. The free phenolics (31.67 mg/g) and flavonoid (17.28 mg/g) contents were significantly (P<0.05) higher than bound phenolic (23.52 mg/g) and flavonoid (13.70 mg/g) contents. Both extracts also exhibited high antioxidant activities as typified by their high reducing power, 1,1 diphenyl-2- picrylhydrazyl (DPPH) and 2, 2-azinobis-3-ethylbenzo-thiazoline-6-sulfonate (ABTS) radical scavenging abilities, as well as inhibition of Fe(2+)-induced lipid peroxidation in rat pancreas in vitro. CONCLUSIONS This study provides a biochemical rationale by which clove elicits therapeutic effect on type 2 diabetes.

Shaddock peels (Citrus maxima) phenolic extracts inhibit α-amylase, α-glucosidase and angiotensin I-converting enzyme activities: A nutraceutical approach to diabetes management

In this study, the interactions of free and bound phenolic-rich extracts from shaddock peels (popular in folklore for the management of diabetes and hypertension) with α-amylase and α-glucosidase (key enzymes linked to type-2 diabetes) and angiotensin I-converting enzyme (ACE) (key enzyme linked to hypertension) were assessed. The free phenolics of shaddock (Citrus maxima) peels were extracted with 80% acetone, while the bound phenolics were extracted from the alkaline and acid hydrolyzed residue with ethyl acetate; and their interaction with the enzymes were assessed. The phenolic extracts inhibited α-amylase, α-glucosidase and ACE enzyme activities in a dose-dependent manner; however, bound phenolics had significantly higher (P<0.05) α-amylase inhibitory activities, than free phenolics, which had significantly higher (P<0.05) ACE inhibitory activities. There was no significant difference (P>0.05) in their α-glucosidase inhibitory activities. The stronger inhibition of α-glucosidase when compared to α-amylase is of great pharmaceutical importance. The phenolic inhibited sodium nitroprusside induced lipid peroxidation in pancreas in a dose dependent manner. Therefore, free and bound phenolic extracts from shaddock peels could be used as nutraceutical for the management of hypertension and type-2 diabetes.