Opeyemi B. Ogunsuyi

Attenuation of gentamycin-induced nephrotoxicity in rats by dietary inclusion of ginger (Zingiber officinale) and turmeric (Curcuma longa) rhizomes

This study sought to investigate the modulatory effects of dietary inclusion of ginger (Zingiber officinale) and turmeric (Curcuma longa) rhizomes on antioxidant status and renal damage induced by gentamycin in rats. Renal damage was induced in albino rats pretreated with dietary inclusion of ginger and turmeric (2% and 4%) by intraperitoneal (i.p.) administration of gentamycin (100 mg/kg body weight) for three days. Assays for renal damage biomarkers (plasma creatinine, plasma urea, blood urea nitrogen and plasma uric acid), malondialdehyde (MDA) content and reduced glutathione (GSH) content as well as renal antioxidant enzymes (catalase, glutathione-S-transferase (GST), glutathione peroxidase (GPx) and superoxide dismutase (SOD)) were carried out. The study revealed significant (p < 0.05) increases in renal damage biomarkers following gentamycin administration with severe alteration in kidney antioxidant status. However, pretreatment with ginger and turmeric rhizome (2% and 4%) prior to gentamycin administration significantly (p < 0.05) protected the kidney and attenuated oxidative stress by modulating renal damage and antioxidant indices. This finding therefore suggests that dietary inclusion of ginger and turmeric rhizomes may protect against gentamycin-induced nephrotoxicity and oxidative stress.

Quercetin and Its Role in Chronic Diseases

Quercetin, a member of the flavonoid class of polyphenol, is one of the most abundantly distributed flavonoids found in various food sources such as fruits, vegetables, nuts, wine and seeds. Quercetin and quercetin-rich foods have been reported to have wide range of health promoting effects, especially in the prevention and management of several diseases; however, the subject of its solubility and bioavailability has limited its use. This section will therefore, consider quercetin as a food-rich flavonoid, the various food sources, the limitations in its use and new approaches at improving its solubility and bioavailability. The therapeutic potentials of quercetin at the prevention/management of some degenerative diseases such as diabetes, hypertension and neurodegenerative diseases, as well as the underlying biochemical mechanisms such as free radical scavenging and enzyme inhibition will also be discussed.

Phenolic profile and Enzyme Inhibitory activities of Almond (Terminalia catappa) leaf and Stem bark

ABSTRACT Almond (Terminalia catappa) is a species used in Nigerian folkloric medicine because of its antihypertensive property. In this study, the acetylcholinesterase, arginase, phosphodiesterase-5 and angiotensin-1-converting enzyme inhibition and antioxidant properties of the phenolic-rich extracts from almond leaf and stem bark were determined. The chemical composition was evaluated using high-performance liquid chromatography. The total phenol and flavonoid contents were estimated and the antihypertensive potential was estimated by the determination of acetylcholinesterase, arginase, phosphodiesterase-5 and angiotensin-1-converting enzyme inhibition in vitro. Three assays were used for the evaluation of antioxidant properties of the extracts. Eleven and eight phenolic compounds were detected in leaf and stem bark respectively. The phenolic-rich extracts showed remarkable enzyme inhibition activity in concentration dependent manner, with high antioxidant activities. Almond leaf and stem bark can serve as potential natural source for the development of a novel antihypertensive agent.

Effect of caffeine, caffeic acid and their various combinations on enzymes of cholinergic, monoaminergic and purinergic systems critical to neurodegeneration in rat brain— In vitro

HIGHLIGHTSIn vitro neuromodulatory effects of proportion of caffeine to caffeic acid as obtained in most foods were investigated.These combinations modulate activities of some enzymes critical to neurodegeneration in rat brain structures.The combinations also exhibited Fe2+ and Cu2+ chelating abilities.However, a higher proportion of caffeine to caffeic acid produced significantly higher enzyme modulatory effects.These opined that food rich in higher caffeine‐caffeic acid ratio could offer more neuroprotective potentials. ABSTRACT Caffeine and caffeic acid are two bioactive compounds that are present in plant foods and are major constituent of coffee, cocoa, tea, cola drinks and chocolate. Although not structurally related, caffeine and caffeic acid has been reported to elicit neuroprotective properties. However, their different proportional distribution in food sources and possible effect of such interactions are not often taken into consideration. Therefore, in this study, we investigated the effect of caffeine, caffeic acid and their various combinations on activities of some enzymes [acetylcholinesterase (AChE), monoamine oxidase (MAO) ecto‐nucleoside triphosphate diphosphohydrolase (E‐NTPase), ecto‐51‐nucleotidase (E‐NTDase) and Na+/K+ ATPase relevant to neurodegeneration in vitro in rat brain. The stock concentration of caffeine and caffiec acid and their various proportional combinations were prepared and their interactions with the activities of these enzymes were assessed (in vitro) in different brain structures. The Fe2+ and Cu2+ chelating abilities of the samples were also investigated. The results revealed that caffeine, caffeic acid and their various combinations exhibited inhibitory effect on activities of AChE, MAO, E‐NTPase and E‐NTDase, but stimulatory effect on Na+/K+ ATPase activity. The combinations also exhibited Fe2+ and Cu2+ chelating abilities. Considering the various combinations, a higher caffeine to caffeic acid ratio produced significantly highest enzyme modulatory effects; these were significantly lower to the effect of caffeine alone but significantly higher than the effect of caffeic acid alone. These findings may provide new insight into the effect of proportional combination of these bioactive compounds as obtained in many foods especially with respect to their neuroprotective effects.

Modulatory Effects of Ferulic Acid on Cadmium-Induced Brain Damage

Studies have shown the pharmacological relevance of phenolics like ferulic acid (FA) in promoting health. This study sought to investigate the modulatory effects of FA on cadmium-induced brain damage in rats. Brain damage was induced in Wistar strain rats by oral administration of cadmium (5 mg/kg body weight) for 21 days. Assays for malondialdehyde (MDA) content, acetylcholinesterase (AChE), butyrylcholinesterase (BChE), monoamine oxidase (MAO), and Na+/K+-ATPase activities were carried out. The study revealed significant (P < .05) increases in the MDA content and all enzymes’ (AChE, BChE, MAO, and Na+/K+-ATPase) activity investigated following cadmium administration. However, rats administered FA (10 and 20 mg/kg body weight) alongside cadmium significantly (P < .05) protected the brain by reversing the level of lipid peroxidation as measured by the MDA content as well as the enzymes’ activity. This study, therefore, substantiates the neuroprotective potentials of FA especially in the management of cadmium-induced toxicity.

Polyphenolic compositions and in vitro angiotensin-I-converting enzyme inhibitory properties of common green leafy vegetables: A comparative study

This study compared the phenolic compositions of common green leafy vegetable extracts from Vernonia amygdalina (VA), Telfairia occidentalis (TO), Talinium triangulare (TT), and Amaranthus hybridus (AH) and their effects on the angiotensin-I-converting enzyme (ACE) and cisplatin-induced malonylaldehyde (MDA) production in an isolated rat kidney homogenate. HPLC confirmed the presence of phenolic compounds in the extracts. Furthermore, all extracts inhibited ACE activity dosedependently; however, the extract from VA exhibited the highest ACE activity while TT exhibited the least. Incubation of the kidney homogenate with 1mM cisplatin caused an increase in MDA production; however, all the extracts inhibited the level of MDA produced. Nevertheless, VA extract exhibited the highest inhibition. These activities of the vegetable extracts could be attributed to their phenolic compositions and may suggest some possible mechanism of the actions. However, VA appeared to be the most potent among the vegetables tested.

Jimson weed (Datura stramonium L.) alkaloid extracts modulate cholinesterase and monoamine oxidase activities in vitro: possible modulatory effect on neuronal function

Despite the well-established medicinal values of Jimson weed (Datura stramonium L.), this medicinal plant has been associated with neurological effects such as hallucination and anxiety in folklore. This study examined the effect of alkaloid extracts from the leaf and fruit of Jimson weed on critical enzymes of the monoaminergic [monoamine oxidase (MAO)] and cholinergic [acetylcholinesterase (AChE) and butyrylcholinesterase (BChE)] systems of neurotransmission. Alkaloid extracts were prepared by solvent extraction method and their interaction with the activities of MAO, AChE, and BChE were assessed (in vitro). Gas chromatography coupled with mass spectroscopic (GC-MS) characterization of the extracts was also carried out. The results revealed that the extracts inhibited the activity of the enzymes assayed for in a concentration-dependent manner. Considering the IC50 values, the fruit extract had more potent (P < 0.05) inhibitory effect on the enzymes’ activities, compared to the leaf extract. GC-MS characterization revealed the presence of atropine, scopolamine, amphetamine, 3-methoxyamphetamine, 3-ethoxyamhetamine cathine, spermine, phenylephrine, and 3-piperidinemethanol, among others in the extracts. The alteration of activities of these critical enzymes of the cholinergic and monoaminergic signaling may be responsible for the reported neurological effects of this medicinal plant in folklore; nevertheless, the fruit extract exhibited more neuromodulatory effect than the leaf.

Modulatory effects of Aqueous extract from Tetracarpidium conophorum leaves on key enzymes linked to erectile dysfunction and oxidative stress-induced lipid peroxidation in penile and testicular tissues -

Tetracarpidium conophorum (walnut) is used in folk medicine for the treatment of erectile dysfunction but the mechanism remains unclear. This study evaluated the effect of aqueous extract from T conophorum leaves on oxidative stress-induced penile damage and key enzymes linked to erectile dysfunction. The inhibitory effect of the extract on sodium nitroprusside (SNP)-induced lipid peroxidation, arginase, angiotensin I-converting enzyme (ACE) and acetylcholinesterase (AChE) activities in penile and testicular tissue homogenates were determined via colorimetric method. The aqueous extract inhibited SNP-induced lipid peroxidation in rats penile and testicular homogenates in a dose dependent manner. The highest inhibitory effect was obtained in the penis at a concentration of 0.5 mg/mL. Furthermore, the extract inhibited arginase activity in a dose dependent pattern. The IC50 revealed that the extract had significantly (P

Modulatory Effects of Alkaloid Extract from Gongronema latifolium (Utazi) and Lasianthera africana (Editan) on Activities of Enzymes Relevant to Neurodegeneration

ABSTRACT Most alkaloids are produced by plants as a defense mechanism against herbivores. Since alkaloids are known to possess pharmacological effects, this study sought to investigate the in vitro modulatory effect of alkaloid obtained from two commonly consumed vegetables in southern Nigeria, Lasianthera africana (editan) and Gongronema latifolium (utazi), on some enzyme activities relevant to neurodegeneration. Effects of the alkaloids on cholinesterases (acetylcholinesterase [AChE] and butyrylcholinesterase [BChE]) and monoamine oxidase (MAO) activities were determined in vitro. In addition, Fe2+ chelating ability as well as radical-scavenging abilities were determined. Alkaloid profile was also determined using gas chromatography coupled with flame ionization detector (GC-FID). The results revealed that the alkaloids inhibited AChE, BChE, and MAO activities in a concentration-dependent manner, such that the alkaloid from G. latifolium showed higher enzyme inhibition (AChE [IC50 = 87.39 µg/ml], BChE [IC50 = 118.65 µg/ml], and MAO [IC50 = 61.37 µg/ml]) than L. africana (AChE = 115.60 µg/ml; BChE = 169.48 µg/ml; MAO = 73.72 µg/ml). In addition, GC-FID analysis revealed abundance of choline in both extracts. Gongronema latifolium and Lasianthera africana alkaloid extracts inhibit enzymes (acetylcholinesterase, butyrylcholinesterase, and monoamine oxidase) implicated in neurodegenerative diseases. Hence, these vegetables could offer dietary supplement in the management of neurodegenerative diseases.

Phenolic constituents and modulatory effects of Raffia palm leaf ( Raphia hookeri ) extract on carbohydrate hydrolyzing enzymes linked to type-2 diabetes

This study sought to investigate the effects of Raffia palm (Raphia hookeri) leaf extract on enzymes linked to type-2 diabetes mellitus (T2DM) and pro-oxidant induced oxidative stress in rat pancreas. The extract was prepared and its α-amylase and α-glucosidase inhibitory effects were determined. Radical [2,2-diphenyl-1-picrylhydrazyl (DPPH)] scavenging and Fe2+-chelating abilities, and inhibition of Fe2+-induced lipid peroxidation in rat pancreas homogenate were assessed. Furthermore, total phenol and flavonoid contents, reducing property, and high performance liquid chromatography diode array detector (HPLC-DAD) fingerprint of the extract were also determined. Our results revealed that the extract inhibited α-amylase (IC50 = 110.4 μg/mL) and α-glucosidase (IC50 = 99.96 μg/mL) activities in concentration dependent manners which were lower to the effect of acarbose (amylase: IC50 = 18.30 μg/mL; glucosidase: IC50 = 20.31 μg/mL). The extract also scavenged DPPH radical, chelated Fe2+ and inhibited Fe2+-induced lipid peroxidation in rat pancreas all in concentration dependent manners with IC50 values of 402.9 μg/mL, 108.9 μg/mL and 367.0 μg/mL respectively. The total phenol and flavonoid contents were 39.73 mg GAE/g and 21.88 mg QAE/g respectively, while the reducing property was 25.62 mg AAE/g. The HPLC analysis revealed the presence of chlorogenic acid (4.17 mg/g) and rutin (5.11 mg/g) as the major phenolic compounds in the extract. Therefore, the ability of the extract to inhibit carbohydrate hydrolyzing enzymes and protect against pancreatic oxidative damage may be an important mechanisms supporting its antidiabetic properties and could make Raffia palm leaf useful in complementary/alternative therapy for management of T2DM. However, further studies such as in vivo should be carried out.