Sweet basil (Ocimum basilicum) leaf and seed extracts alleviate neuronal dysfunction in aluminum chloride-induced neurotoxicity in Drosophila melanogaster Meigen model

Ocimum basilicum is an important medicinal plant and culinary herb generally known as sweet basil (SB). These plants are effective radical scavengers, that have been employed in treatment of nervous system disorders, and thus, could be beneficial for the management of neurodegenerative diseases (NDs). Current clinical treatments for NDs present several side effects, therefore, there is need to develop new treatments that can mitigate these deadly diseases. Hence, this study investigated the neuroprotective activities of SB leaf and seed in aluminum chloride (AlCl3)-induced toxicity in Drosophila melanogaster. HPLC characterization of the leaves and seeds were carried out. AlCl3-diet was used to induce neurodegeneration and treated flies received SB leaf and seed extracts-supplemented diet. Survival and locomotor performance activities/levels of oxidative biomarkers [reactive oxygen species (ROS), thiobarbituric acid reactive species (TBARS), total thiol, catalase, superoxide dismutase (SOD) and glutathione-S-transferase (GST)], enzymes linked with neurodegeneration (acetylcholinesterase (AChE) and monoamine oxidase (MAO)) were investigated. SB leaf had significantly (p < 0.05) higher polyphenol contents; gallic acid and P-coumaric acid were the most abundant polyphenol in the leaf and seed respectively. Percentage survival and locomotor rates, level/activities of total thiol, catalase, SOD and GST were significantly (p < 0.05) reduced while ROS, TBARS, AChE and MAO activities were significantly (p < 0.05) increased in AlCl3-diet-fed flies. Treatment with SB leaf and seed diet lessened these observed impairments. However, SB leaf had better neuroprotective activities that could be related to the observed higher phenolic constituents. Hence, SB leaf diet may offer improved therapeutic effect in NDs.

Host-parasite relationship modulates the effect of African mistletoe leaves on the cholinergic, monoaminergic and carbohydrate hydrolyzing enzymes in fruit fly

OBJECTIVES

Mistletoe infests common plant trees of great medicinal values such as Moringa and Almond. According to folklore, mistletoe leaves have been found to have application as food and medicine in the alleviation of various degenerative diseases. Host-parasite relationship may possibly influence the phytochemical and biological activities of mistletoe leaves. Hence, we examined the polyphenol contents, antioxidant properties, α-amylase, α-glucosidase, acetylcholinesterase (AChE) and monoamine oxidase (MAO) inhibitory activities of African mistletoe leaves obtained from Moringa and Almond host plants in fruit fly in vitro.

METHODS

The phenolic constituents of the leaves were evaluated using HPLC system. The antioxidant activities were determined through the ABTS, DPPH and OH free radicals scavenging properties, ferric (Fe3+) and malondialdehyde (MDA) reducing abilities and Fe2+ chelation. The inhibitory effects of the leaves aqueous extracts on α-amylase, α-glucosidase, AChE and MAO activities were also assessed.

RESULTS

The HPLC characterization of the leaves revealed that host plants caused marked variation in their phenolic composition, however, Almond mistletoe leaves had significantly (p<0.05) greater amounts of phenolic constituents. Both Moringa and Almond mistletoe leaves reduced Fe3+ and MDA levels, scavenged free radicals, chelated Fe2+ and inhibited α-amylase, α-glucosidase, AChE and MAO activities with the Almond mistletoe leaves having significantly (p<0.05) higher antioxidant properties and enzyme inhibitory activities.

CONCLUSIONS

This present study indicated that host plants could positively modulate the phenolic profile of mistletoe leaves and this probably brought about the vivid noticeable changes in their antioxidant abilities, cholinergic, monoaminergic and carbohydrate hydrolyzing enzymes inhibitory activities.

Synergistic cardioprotective ability of co-administration of Moringa supplemented diets and acarbose in diabetic cardiomyopathy involves attenuation of cholinergic, purinergic, monoaminergic, renin-angiotensin system, and antioxidant pathways

One of the major complications of diabetes mellitus (DM) is diabetic cardiomyopathy (DCM) due to the multifaceted therapy involved. Here, we evaluated the combinatorial effect of Moringa leaf (ML) and seed (MS) supplemented diets plus acarbose (ACA) on cardiac acetylcholinesterase (AChE), adenosine triphosphatase (ATPase), adenosine deaminase (ADA), monoamine oxidase (MAO), arginase, angiotensin-I converting enzyme (ACE), and lactate dehydrogenase (LDH) activities, thiobarbituric acid reactive species (TBARS), and thiols levels. The diets and ACA (25 mg/kg) were administered for 14 days. The fasting blood glucose level (FBGL), cardiac AChE, ATPase, ADA, MAO, arginase, ACE, LDH activities, and TBARS and thiol levels were determined. Relative to the normal rats, the biomarkers were significantly increased in DM rats but were suppressed significantly in the diets plus ACA-treated rats while improving antioxidant status, with the 4% Moringa plus ACA proving outstanding compared to individual ML/MS and ACA. In addition, ML-supplemented diets with/without ACA had better effects compared to MS with/without ACA, respectively. In conclusion, the combination of ML/MS supplemented diets and ACA synergistically modulates the tested biochemicals. However, the effect on blood vessels and the nerves that control the heart, stiffness of left ventricular (LV) hypertrophy, fibrosis, cell signaling abnormalities, related gene expression, clinical trials, and echocardiology studies should be further investigated to affirm this claim. PRACTICAL APPLICATIONS: Moringa oleifera has been a vocal appetite in mitigating cardiovascular disease induced by diabetes, but the formulation of a medicinal diet as an ameliorative route of attention to the pathology is fairly addressed, not talking of its combination with the synthetic antidiabetic drug, such as ACA. Based on this experiment, it is imperative to explore such an idea. This research shows that co-administration of moringa leaf/seed formulated diets plus ACA exhibits a synergistic effect in DCM management. However, further research is needed in this field of experiment.

Effect of Solanum vegetables on memory index, redox status, and expressions of critical neural genes in Drosophila melanogaster model of memory impairment

African eggplant (Solanum macrocarpon L) (AE) and Black Nightshade (Solanum nigrum L) (BN) leaves are green leafy vegetables with nutritional and ethnobotanical values. We have previously characterized the vegetables via HPLC/LC-MS to reveal notable phenolic acids, flavonoids and alkaloids. In this present study, we addressed the efficacy of the two vegetables in mitigating mercuric chloride (HgCl₂)-induced neurotoxicity and memory impairment in Drosophila melanogaster. Flies were exposed to HgCl₂ (0.30 mg/g) alone or in combination with the vegetables (0.1 and 1.0%) of both samples in their diets for seven days. The results showed that HgCl₂ (Hg)-exposed flies had significantly reduced survival rate and memory index, which were ameliorated in the Hg-exposed flies fed AE or BN. This was accompanied by increased reactive oxygen species (ROS) levels, reduced total thiol, as well as catalase, glutathione transferase (GST) and acetylcholine esterase (AChE) activities in Hg-exposed fly heads, but ameliorated in Hg-exposed flies fed dietary inclusions of the vegetables. In addition, the Hg-induced alterations in SOD, NF-ҝB/Relish, Dronc and Reaper mRNA levels were statistically indistinguishable from controls in Hg-treated flies fed diets containing AE or BN. Normalization of cnc/Nrf2 and FOXO were observed only in Hg-treated flies fed BN. These findings suggest that dietary AE or BN leaves offer protection against Hg-induced memory impairment and neurotoxicity in D. melanogaster, and further justify them as functional foods with neuroprotective properties.

Paving Plant-Food-Derived Bioactives as Effective Therapeutic Agents in Autism Spectrum Disorder

Autism spectrum disorder (ASD) is a neurodevelopmental disorder, where social and communication deficits and repetitive behaviors are present. Plant-derived bioactives have shown promising results in the treatment of autism. In this sense, this review is aimed at providing a careful view on the use of plant-derived bioactive molecules for the treatment of autism. Among the plethora of bioactives, curcumin, luteolin, and resveratrol have revealed excellent neuroprotective effects and can be effectively used in the treatment of neuropsychological disorders. However, the number of clinical trials is limited, and none of them have been approved for the treatment of autism or autism-related disorder. Further clinical studies are needed to effectively assess the real potential of such bioactive molecules.

Phenolic Bioactives as Antiplatelet Aggregation Factors: The Pivotal Ingredients in Maintaining Cardiovascular Health

Cardiovascular diseases (CVD) are one of the main causes of mortality in the world. The development of these diseases has a specific factor-alteration in blood platelet activation. It has been shown that phenolic compounds have antiplatelet aggregation abilities and a positive impact in the management of CVD, exerting prominent antioxidant, anti-inflammatory, antitumor, cardioprotective, antihyperglycemic, and antimicrobial effects. Thus, this review is intended to address the antiplatelet activity of phenolic compounds with special emphasis in preventing CVD, along with the mechanisms of action through which they are able to prevent and treat CVD. In vitro and in vivo studies have shown beneficial effects of phenolic compound-rich plant extracts and isolated compounds against CVD, despite that the scientific literature available on the antiplatelet aggregation ability of phenolic compounds in vivo is scarce. Thus, despite the current advances, further studies are needed to confirm the cardioprotective potential of phenolic compounds towards their use alone or in combination with conventional drugs for effective therapeutic interventions.

Phenolic constituents and inhibitory effects of the leaf of Rauvolfia vomitoria Afzel on free radicals, cholinergic and monoaminergic enzymes in rat's brain in vitro

OBJECTIVES

Rauvolfia vomitoria is a medicinal plant used traditionally in Africa in the management of several human diseases including psychosis. However, there is inadequate scientific information on the potency of the phenolic constituents of R. vomitoria leaf in the management of neurodegeneration. Therefore, this study characterized the phenolic constituents and investigated the effects of aqueous and methanolic extracts of R. vomitoria leaf on free radicals, Fe²⁺-induced lipid peroxidation, and critical enzymes linked to neurodegeneration in rat's brain in vitro.

METHODS

The polyphenols were evaluated by characterizing phenolic constituents using high-performance liquid chromatography coupled with diode array detector (HPLC-DAD). The antioxidant properties were assessed through the extracts ability to reduce Fe³⁺ to Fe²⁺; inhibit ABTS, DPPH, and OH radicals and Fe²⁺-induced lipid peroxidation. The effects of the extracts on AChE and MAO were also evaluated.

RESULTS

The phenolic characterization of R. vomitoria leaf revealed that there were more flavonoids present. Both aqueous and methanolic extracts of R. vomitoria leaf had inhibitory effects with the methanolic extract having higher significant (p≤0.05) free radicals scavenging ability coupled with inhibition of monoamine oxidases. However, there was no significant (p≤0.05) difference obtained in the inhibition of lipid peroxidation and cholinesterases.

CONCLUSION

This study suggests that the rich phenolic constituents of R. vomitoria leaf might contribute to the observed antioxidative and neuroprotective effects. The methanolic extract was more potent than the aqueous extract; therefore, extraction of R. vomitoria leaf with methanol could offer better health-promoting effects in neurodegenerative condition.

Dietary monosodium glutamate altered redox status and dopamine metabolism in lobster cockroach (Nauphoeta cinerea)

Monosodium Glutamate (MSG) is the most commonly utilized food additive in the world. However, data on possible biochemical reasons underlying the neurotoxic effects of dietary MSG is limited. Therefore, this study investigated the effects of dietary supplementation of MSG on redox status and neurochemical indices in lobster cockroach nymph. These were evaluated via assessment of enzymatic and nonenzymatic antioxidants, acetylcholinesterase and monoamine oxidase activities, and dopamine content in the cockroach nymph head homogenate. MSG supplemented diet caused dose-dependent significant (p < .05) reduction in % survival, thiol, GSH, dopamine contents, and GST activity, increased ROS, NO, Fe²⁺ , MDA contents, and MAO activity but no significant (p < .05) difference was obtained in GSH and TBARS contents, and AChE activity. Increased oxidative, cholinergic, and monoaminergic activities coupled with decreased dopamine level might be the plausible biochemical explanation for the neurotoxic effects observed during sub-chronic consumption of large amounts of MSG in diet. PRACTICAL APPLICATIONS: This study suggests that consumption of monosodium glutamate should be reduced to the barest minimum due to its capability to induce oxidative stress and nervous toxicological effects at high dosage.

Comparative study of the phenolic profile, antioxidant properties, and inhibitory effects of Moringa (Moringa oleifera Lam.) and Almond (Terminalia catappa Linn.) leaves on acetylcholinesterase and monoamine oxidase activities in the head region of Fruitfly (Drosophila melanogaster Meigen) in vitro

Moringa and Almond are medicinal plants used traditionally as food and medicine to prevent and/or treat a wide array of metabolic and neurodegenerative diseases, however, Almond leaf is underutilized. Therefore, this study investigated and compared the polyphenol constituents, antioxidant capacities, and neurochemical indices of the aqueous extracts of Moringa and Almond leaves in fruitfly head tissue homogenate in vitro. The polyphenols were evaluated by characterization using HPLC-DAD, antioxidant properties were assessed through extracts ability to inhibit ABTS, DPPH, OH, and NO radicals, reduce Fe³⁺ and MDA, and chelate Fe²⁺ . The neurochemical indices were evaluated through AChE and MAO inhibitory activities. Almond leaf had significant (p < .05) higher polyphenols and antioxidant properties. However, Moringa leaf had significant (p < .05) higher AChE inhibition and no significant (p < .05) difference was obtained in MAO inhibitory activities. Thus, Almond leaf might be more effective in managing diseases related with oxidative stress and neurodegeneration. PRACTICAL APPLICATIONS: This present study has shown that Almond leaf might offer better health promotion due to its higher phenolic constituents and antioxidant activities when compared with Moringa leaf, however, both Moringa and Almond leaves could be taken as functional foods to alleviate the symptoms of oxidative stress and neurodegenerative diseases.

Modulatory effects of moringa (Moringa oleifera L.) leaves infested with African mistletoe (Tapinanthus bangwensis L.) on the antioxidant, antidiabetic, and neurochemical indices in high sucrose diet-induced diabetic-like phenotype in fruit flies (Drosophila melanogaster M.)

Moringa is a common medicinal plant tree with mistletoe infestation and its leaf is widely used as food and traditional medication in alleviating several metabolic and neurodegenerative diseases. Hence, this study investigated the influence of African mistletoe on the antioxidant, antidiabetic, and neuroprotective activities of infested moringa leaf in sucrose induced diabetes in Drosophila melanogaster model. Glucose and triglycerides were evaluated in the flies' hemolymph and all other parameters were evaluated in the tissues. A significant (p < .05) decrease in survival rate and increase in the level of glucose and triglycerides in flies fed with 30% of sucrose when compared with control was obtained. Treated flies had significant (p < .05) positive alteration in the level of glucose, triglycerides, antioxidants (both enzymatic and nonenzymatic), and enzyme activities when compared with normal and sucrose control flies. This study suggests that mistletoe infestation did not alter the antioxidant, antidiabetic, and neuroprotective effects of the moringa leaf. PRACTICAL APPLICATIONS: This present study has shown that mistletoe infestation did not alter the protective activities of moringa leaf, hence, moringa with or without mistletoe infestation could be taken as functional food to mitigate several metabolic diseases.

Impact of drying processes on Bryophyllum pinnatum phenolic constituents and its anti-inflammatory and antioxidative activities in human erythrocytes

The effect of drying on the phytoconstituents, antioxidative, and anti-inflammatory properties of Bryophyllum pinnatum leaves was investigated. The phenolic constituents were characterized using HPLC-DAD. The aqueous extraction was done and various assays (Inhibition of membrane stabilization, albumin Denaturation and heat-induced hemolysis, malondialdehyde (MDA), and reduced glutathione (GSH) contents, as well as superoxide dismutase (SOD) activity), were carried out on human erythrocytes. The fresh portion (89.12 µg/ml) exhibited the highest potential to inhibit heat-induced hemolysis compared to the standard drug-Diclofenac (91.51 µg/ml). Freeze-dried sample showed the highest inhibitory potential on albumin denaturation ([Freeze-dried-330.72 µg/ml], [Diclofenac-318.63 µg/ml]) and membrane destabilization ([Freeze-dried-331.93 µg/ml], [Diclofenac-289.57 µg/ml]) when compared with Diclofenac. Similarly, the freeze-dried sample showed the highest GSH and SOD level and lowest MDA level when human erythrocytes challenged with tertiary butyl hydroperoxide (tBHP) were treated with the extract. This study confirms the retention of a considerable quantity of bioactive constituents of plants when freeze-dried. PRACTICAL APPLICATIONS: The ideal method of drying Bryophyllum pinnatum and possible anti-inflammatory potential was investigated. This work may apply to the development of anti-inflammatory agents from a natural source with little or no side effect in managing inflammation.

Solanum leaves extracts exhibit antioxidant properties and inhibit monoamine oxidase and acetylcholinesterase activities (in vitro) in Drosophila melanogaster

Background This study sought to determine the in vitro antioxidant, anti-monoamine oxidase and anticholinesterase properties of extracts (aqueous and alkaloid) of two tropical vegetables from Solanum spp- African eggplant (Solanum macrocarpon L) and black nightshade (Solanum nigrum L) as indices of their neuroprotective properties. Methods Both aqueous and alkaloid extracts of African eggplant (AE) and black nightshade (BN) were prepared by solvent extraction according to standard methods. Thereafter, the inhibitory effects of the extracts on monoamine oxidase (MAO) and acetylcholinesterase (AChE) activities, as well as their free radical-scavenging and reducing abilities were assessed. Also, phytochemical analysis for phenols, flavonoids, and alkaloids were carried out. Results The results showed that the extracts inhibited MAO and AChE activities dose dependently, with aqueous extracts showing significantly higher MAO inhibition that the alkaloid extracts from both samples, but in all, BN showed higher MAO inhibitory effect compared to AE; the reverse was however, observed for AChE inhibition. Furthermore, the aqueous extracts showed significantly higher antioxidant properties than the alkaloid extracts, while BN had higher antioxidant properties compared to AN. The phytochemical analysis also showed that BN had significantly higher amount of phenols, flavonoids, and alkaloids than AE. Conclusions The anti-monoamine oxidase, anticholinesterase, and antioxidant properties exhibited by extracts from both samples could contribute to their neuroprotective abilities. Thus, these vegetables can be potential sources of functional foods and nutraceuticals in the management of neurodegenerative diseases, especially in the tropics.

Fluted pumpkin (Telfairia occidentalis) seed modulates some markers of erectile function in isolated rat's corpus cavernosum: Influence of polyphenol and amino acid constituents

Pumpkin seeds are often used in traditional medicine in the management of erectile dysfunction. However, there is insufficient information about the possible biochemical rationale behind this practice. Hence, this study investigated the influence of fluted pumpkin seed on critical enzymes involved in erectile function in isolated rats' corpus cavernosum in vitro. The phenolics and amino acid contents of fluted pumpkin seed were determined using HPLC-DAD and GC-PFPD analyses respectively. The aqueous extract of the fluted pumpkin seed significantly (p < .05) scavenged free radicals and inhibited PDE-5, arginase, AChE, and ACE in rats' corpus cavernosum in a concentration-dependent pattern. Quercitrin and luteolin were the most dominant phenolics, while arginine, aspartate, and cysteine were the most aboundant amino acid constituents. The positive modulatory effect of the fluted pumpkin seed on these critical markers of erectile function could be attributed to its polyphenolics and amino acid constituents. PRACTICAL APPLICATIONS: This study brought to limelight the medicinal importance of fluted pumpkin seed in erectile functions. Therefore, this seed could be used as a functional food ingredient in the management of erectile dysfunctions and also in improving erectile functions in men. In addition, the dominant phenolics and amino acid constituents of this seed might be an effective nutraceutical in enhancing erections in men.

Phenolic analysis and erectogenic function of African Walnut (Tetracarpidium conophorum) seeds: The impact of the seed shell on biological activity

This study investigated the erectogenic potential of African walnut seed (AWS). The extract from AWS cooked with/without shell interacted with phosphodiesterase-5 (PDE-5), arginase, angiotensin-I converting enzymes (ACE), and acetylcholinesterase (AChE); enzymes associated with erectile dysfunction (ED) and Fe²⁺ -induced malonaldehyde (MDA) production in the isolated penile tissue. The results showed that the extracts inhibited the enzymes and MDA production, but Walnut cooked with shell had the highest effect. This agreed with increased phenolic acids and flavonoids, found in the AWS cooked with the shell, compared with that cooked without shell. The inhibition of enzymes and antioxidative potentials could be among the possible mechanisms of actions of AWS in the management/treatment of ED. However, cooking walnut seed with the shell seem to be a contributing factor, as this could prevent possible leaching out of the phytochemicals that could be responsible for these biological effects. PRACTICAL APPLICATIONS: Walnut seed possesses a high content of phenolic compounds and inhibit enzymes relevant to the management of erectile dysfunction. Traditionally, Walnut seed is being cooked with/without the shell and consumed for the purpose of alternative medicine in folklore. Our investigation revealed the possible mechanism underlying the therapeutic effect Walnut seed in the management of ED, but the impact of the shell during cooking contributes to this effect. This result will inform the consumers and food scientist on the importance of cooking Walnut seed with the shell in order to maximize its nutraceutical values.

Drying alters the phenolic constituents, antioxidant properties, α-amylase, and α-glucosidase inhibitory properties of Moringa (Moringa oleifera) leaf

Moringa oleifera leaf is a popular green leafy vegetable which has found its usefulness in the preparation of traditional stews and soups. Like most green leafy vegetable which are not around year-round, the leaf is usually dried and pulverized for storage and easier handling, and despite the popularity of this processing technique, there is dearth of information on how drying affects the health-promoting properties of the leaves. Hence, this study sought to investigate the effect of some drying methods (freeze-drying, sun, air and oven drying) on the phytoconstituents, antioxidant properties, and biological activities of moringa leaf. This study revealed that drying methods significantly altered the phytoconstituents (phenolics, flavonoids, vitamin C, tannin, saponin, phytate, oxalate, alkaloid, cardenolides, and cardiac glycosides), antioxidant capacities (reducing power, Fe2+chelating, ABTS •+, DPPH, and • OH scavenging abilities), and enzyme inhibitory (α-amylase and α-glucosidase) effects of the leaf, with freeze-drying being the most promising method for preserving the nutraceutical properties of moringa leaf. However, for practical application, the order of preference of the drying methods which ensures adequate retention of phytoconstituents and possibly biological activities of the leaf as observed in this study is freeze-drying > air drying > sun drying > oven drying, in the order of decreasing magnitude.

Green leafy vegetables from two Solanum spp. (Solanum nigrum L and Solanum macrocarpon L) ameliorate scopolamine-induced cognitive and neurochemical impairments in rats

This study examined the modulatory effect of Black nightshade (Solanum nigrum L) and African eggplant (Solanum macrocarpon L) leaves on cognitive function, antioxidant status, and activities of critical enzymes of monoaminergic and cholinergic systems of neurotransmission in scopolamine-administered rats. Cognitive impairment was induced in albino rats pretreated with dietary inclusions of Black nightshade (BN) and African eggplant (AE) leaves by single administration (i.p.) of scopolamine (2 mg/kg body weight). Prior to termination of the experiment, the rats were subjected to spontaneous alternation (Y-maze) test to assess their spatial working memory. Thereafter, activities of acetylcholinesterase (AChE), butyrylcholinesterase (BChE), monoamine oxidase (MAO), arginase, and antioxidant enzymes (catalase, SOD, and GST) of rat brain homogenate were determined. Also, the malondialdehyde (MDA), nitrite, and GSH contents of the homogenate were determined. The results showed that pretreatment with dietary inclusions of AE and BN significantly reversed the impairment in the rats' spatial working memory induced by scopolamine. Similarly, elevations in activities of AChE, BChE, and MAO induced by scopolamine were significantly reversed in rats pretreated with dietary inclusions of AE and BN. In addition, impaired antioxidant status induced by scopolamine was reversed by pretreatment with dietary inclusions of AE and BN. This study has shown that dietary inclusions of AE and BN could protect against cognitive and neurochemical impairments induced by scopolamine, and hence, these vegetables could be used as a source of functional foods and nutraceuticals for the prevention and management of cognitive impairments associated diseases such as Alzheimer's disease.

Local condiments from fermented tropical legume seeds modulate activities of critical enzymes relevant to cardiovascular diseases and endothelial function

Investigation into modulatory effects of local condiments produced from fermented legume (African locust bean and soybean) seeds on activities of enzymes relevant to endothelial function and cardiovascular disease (arginase, phosphodiesterase-5, acetylcholinesterase, and, ecto 5'-nucleotidase) in vitro was the focus of this study. The condiments were prepared according to traditional methods of fermentation. Thereafter, modulatory effects of aqueous extracts from the condiments on activities of the enzymes were subsequently carried out. Results showed the extracts significantly inhibited activities of arginase, phosphodiesterase-5 and acetylcholinesterase, while the activity of ecto 5'-nucleotidase was stimulated at sample concentrations tested. Thus, the observed enzyme modulatory properties exhibited by the condiments could be novel mechanisms to support their use as functional foods and nutraceuticals for the management of cardiovascular disease and associated endothelial dysfunction.

Inhibitory Effect of Garlic, Purple Onion, and White Onion on Key Enzymes Linked with Type 2 Diabetes and Hypertension

Spices are used in soup preparation in many homes and serve as ingredients in the preparation of several traditional delicacies endowed with natural antioxidants such as polyphenols. The aim of this study is to evaluate the effect of aqueous extract of garlic, white onion, and purple onion on angiotensin-converting enzyme, α-amylase, and α-glucosidase activity in vitro and determine their antioxidant properties via various antioxidant assays such as OH^*, Fe²⁺ chelation, and 2, 2'-azino-bis 3-ethylbenzothiazoline-6-sulphonic acid (ABTS) radical-scavenging assays. The results reveal that aqueous extract of garlic, purple onion, and white onion inhibited angiotensin-converting enzyme, α-amylase, and α-glucosidase in a concentration-dependent manner (0-4 mg/ml). However, purple onion (IC₅₀ = 0.59 mg/ml) had higher inhibitory effect on angiotensin-converting enzyme than white onion (IC₅₀ = 0.66 mg/ml) and purple onion (IC₅₀ = 0.96 mg/ml). Furthermore, white onion had significantly (p < .05) stronger inhibitory effect on α-amylase (IC₅₀ = 3.93 mg/mL) than garlic (IC₅₀ = 8.19 mg/ml) and purple onion (IC₅₀ = 8.27 mg/ml). Conversely, garlic (IC₅₀ = 4.50 mg/ml) had no significantly higher inhibitory effect on α-glucosidase activity than white onion and purple onion. In addition, the aqueous extracts were able to scavenge 2,2- diphenyl-1-picrylhydrazyl (DPPH^*) free radical and reduce Fe³⁺ to Fe²⁺ in a dose-dependent manner. Therefore, a possible mechanism by which garlic, white onion, and purple onion exert antidiabetes and antihypertensive properties could be through the inhibitory effect on ACE, α-amylase, and α-glucosidase coupled with their ability to prevent lipid peroxidation in the pancreas and heart, which justify their strong antioxidant properties.

Phenolic extracts and amino acids content from Cucumeropsis mannii naudin and Citrullus lanatus inhibit relevant enzymes of erectile dysfunction in rat's penile tissue

•A focused on the erectogenic potentials of two tropical pumpkin seeds was established.•The antioxidant properties of these seed varieties were also discussed.•The inhibitory effects of the seeds on key enzymes relevant to ED were critically explored.•The potentials of the seeds to manage ED were recommended.

Aqueous extracts of avocado pear (Persea americana Mill.) leaves and seeds exhibit anti-cholinesterases and antioxidant activities in vitro

BACKGROUND

Avocado pear (Persea americana Mill.) leaves and seeds are used in traditional medicine for the treatment/management of Alzheimer disease (AD); however, information on the mechanism of actions is limited. This study sought to investigate the effect of P. americana leaf and seed aqueous extracts on some enzymes linked with AD (acetylcholinesterase [AChE] and butyrylcholinesterase [BChE] activities) and their antioxidant potentials in vitro.

METHODS

The inhibitory effects of extracts on AChE and BChE activities and antioxidant potentials (inhibition of Fe2+- and sodium nitroprusside-induced thiobarbiturate reactive species [TBARS] production in rat brain homogenates, radicals [1,1-diphenyl-2-picrylhydrazyl, hydroxyl, and nitric oxide] scavenging and iron [Fe] chelation abilities) were investigated. Phenolic content and phytochemical screening were carried out. Alkaloid profile was also determined using gas chromatography coupled with flame ionization detector (GC-FID).

RESULTS

The extracts inhibited AChE and BChE activities and prooxidant-induced TBARS production in a dose-dependent manner, with the seed extract having the highest inhibitory effect and the leaf extract exhibiting higher phenolic content and radical scavenging abilities, but lower Fe chelation ability compared with that of the seed. The phytochemical screening revealed the presence of saponins, alkaloids, and terpenoids in both extracts, whereas the total alkaloid profile was higher in the seed extract than in the leaf extract, as revealed by GC-FID.

CONCLUSIONS

The anti-cholinesterase and antioxidant activities of avocado leaf and seed could be linked to their phytoconstituents and might be the possible mechanisms underlying their use as a cheap and natural treatment/management of AD. However, these extracts should be further investigated in vivo.

Local salt substitutes "Obu-otoyo" activate acetylcholinesterase and butyrylcholinesterase and induce lipid peroxidation in rat brain

Evidence has shown that ingestion of heavy metals can lead to neurodegenerative diseases. This study aimed to investigate the neurotoxic potential of salt substitutes (Obu-Otoyo); salt A (made by burning palm kernel shaft then soaked in water overnight and the extract from the resulting residue is used as the salt substitute) and salt B (an unrefined salt mined from a local site at Ilobu town, Osun-State, Nigeria) by assessing their effect on some key enzymes linked with neurodegenerative disease [acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) activities] as well as on malondialdehyde (MDA) content of the rat brain. Salt substitutes were fed to normal rats as dietary inclusion at doses of 0.5 and 1.0% for 30 days. Thereafter, the effect of the salt substitutes on AChE and BChE activities as well as on MDA level in the rat brain was determined. The results revealed that the salt substitutes caused a significant (p<0.05) increase in both AChE and BChE activity and also induced lipid peroxidation in the brain of rats in vivo as well as under in vitro condition in a dose-dependent manner. The effect of the salt substitutes on AChE and BChE activities could be attributed to the presence of some toxic heavy metals. Therefore, the ability of the salt substitutes to induce lipid peroxidation and activate AChE and BChE activities could provide some possible mechanism for their neurotoxic effect.

Alkaloid extracts from Jimson weed (Datura stramonium L.) modulate purinergic enzymes in rat brain

Although some findings have reported the medicinal properties of Jimson weed (Datura stramonium L.), there exist some serious neurological effects such as hallucination, loss of memory and anxiety, which has been reported in folklore. Consequently, the modulatory effect of alkaloid extracts from leaf and fruit of Jimson weed on critical enzymes of the purinergic [ecto-nucleoside triphosphate diphosphohydrolase (E-NTPDase), ecto-5'-nucleotidase (E-NTDase), alkaline phosphatase (ALP) and Na⁺/K⁺ ATPase] system of neurotransmission was the focus of this study. Alkaloid extracts were prepared by solvent extraction method and their interaction with the activities of these enzymes were assessed (in vitro) in rat brain tissue homogenate and in vivo in rats administered 100 and 200mg/kg body weight (p.o) of the extracts for thirty days, while administration of single dose (1mg/kg body weight; i.p.) of scopolamine served as the positive control. The extracts were also investigated for their Fe²⁺ and Cu²⁺ chelating abilities and GC-MS characterization of the extracts was also carried out. The results revealed that the extracts inhibited activates of E-NTPDase, E-NTDase and ALP in a concentration dependent manner, while stimulating the activity of Na⁺/K⁺ ATPase (in vitro). Both extracts also exhibited Fe²⁺ and Cu²⁺ chelating abilities. Considering the EC₅₀ values, the fruit extract had significantly higher (P<0.05) modulatory effect on the enzymes' activity as well as metal chelating abilities, compared to the leaf extract; however, there was no significant difference (P>0.05) in both extracts' inhibitory effects on E-NTDase. The in vivo study revealed reduction in the activities of ENTPDase, E-NTDase, and Na⁺/K⁺ ATPase in the extract-administered rat groups compared to the control group, while an elevation in ALP activity was observed in the extract-administered rat groups compared to the control group. GC-MS characterization revealed the presence of atropine, scopolamine, amphetamine, 3-methyoxyamphetamine, 3-ethoxyamhetamine cathine, spermine, phenlyephirine and 3-piperidinemethanol, among others in the extracts. Hence, alterations of activities of critical enzymes of purinergic signaling (in vitro and in vivo) by alkaloid extracts from leaf and fruit of Jimson weed suggest one of the mechanisms behind its neurological effects as reported in folklore.

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

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.

Dietary supplementation with fermented legumes modulate hyperglycemia and acetylcholinesterase activities in Streptozotocin-induced diabetes

The study investigated the hypoglycemic and anticholinesterase activities of some fermented legumes (bambara groundnut and locust bean) in Streptozotocin (STZ)-induced diabetic rats. The rats were made diabetic by intraperitoneal administration of STZ (35mg/kg b.w.) and were fed diets containing fermented legumes (10% inclusion) for 14 days. The effect of the diets on blood glucose, pancreatic glutathione peroxidase (GPx) activity, reduced glutathione (GSH) and malondialdehyde (MDA) contents, α-amylase, intestinal α-glucosidase and acetylcholinesterase activities were studied. Significant (P<0.05) increase in blood glucose, pancreatic MDA, α-amylase, intestinal α-glucosidase and acetylcholinesterase activities with concomitant decrease in pancreatic GPx and GSH contents were observed in diabetic rats. However, this trend was reversed in rats fed fermented legumes supplemented diets for 14 days. The HPLC-DAD finger printing revealed the presence of gallic acid, catechin, caffeic acid, epicatechin, rutin, isoquercitrin, quercitrin, quercetin and kaempferol as the dominant phenolic compounds of the fermented legumes. However, possible contributing role of some bioactive peptides could not be ruled out. Hence, the hypoglycemic and antiacetylcholinesterase activities of the fermented legume condiments could be attributed to their constituent phytochemicals.

Sorghum [Sorghum bicolor (L.) Moench] leaf sheath dye protects against cisplatin-induced hepatotoxicity and oxidative stress in rats

This study sought to determine the protective effect of dietary inclusion of sorghum leaf sheath dye on cisplatin-induced hepatotoxicity and oxidative stress in rats. Adult male rats were randomly divided into four groups with six animals in each group. Groups I and II were fed a basal diet, while groups III and IV were fed diets containing 0.5% and 1% sorghum leaf sheath dye, respectively, for 20 days before cisplatin administration. Hepatotoxicity was induced by a single dose of cisplatin (7 mg/kg body weight, i.p.), and the experiment was terminated at 3 days after cisplatin injection. The liver and plasma were studied for hepatotoxicity and antioxidant capacity. Cisplatin caused a significant (P<.05) alteration in plasma and liver enzymatic (catalase, glutathione-S-transferase [GST], and superoxide dismutase [SOD]) and nonenzymatic (glutathione [GSH] and vitamin C) antioxidant indices with a concomitant increase in the malondialdehyde (MDA) content; however, there was a significant (P<.05) restoration of the antioxidant status coupled with a significant (P<.05) decrease in the tissue MDA content, after consumption of diets containing sorghum leaf sheath dye. Furthermore, dietary inclusion of sorghum leaf sheath dye caused a marked reduction in the activities of alanine aminotransferase and aspartate aminotransferase after cisplatin administration. However, the ability of the dye to prevent significant cisplatin-induced alteration of both plasma and liver antioxidant indices suggests an antioxidant mechanism of action. Hence, this protective effect of Sorghum bicolor leaf sheath dye against cisplatin-induced hepatotoxicity in rats reflects its potential and beneficial role in the prevention of liver damage associated with cisplatin administration.

Inhibition of key enzymes linked to type 2 diabetes and sodium nitroprusside-induced lipid peroxidation in rat pancreas by water-extractable phytochemicals from unripe pawpaw fruit (Carica papaya)

BACKGROUND

Various parts of unripe pawpaw (Carica papaya Linn) fruit have been reportedly used for the management or treatment of diabetes mellitus in folklore medicine. Therefore, the present study sought to investigate the inhibitory effects of the aqueous extract of different parts of unripe pawpaw fruit on key enzymes linked to type 2 diabetes (α-amylase and α-glucosidase) and sodium nitroprusside (SNP)-induced lipid peroxidation in rat pancreas in vitro.

METHODS

The aqueous extracts of the unripe pawpaw (C. papaya) fruit parts were prepared (1:20 w/v) and the ability of the extracts to inhibit α-amylase, α-glucosidase and SNP-induced lipid peroxidation in rat pancreas in vitro was investigated.

RESULTS

The results revealed that all the extracts inhibited α-amylase (IC50=0.87-1.11 mg/mL), α-glucosidase (IC50=1.76-2.64 mg/mL) and SNP-induced lipid peroxidation (IC50=1.99-2.42 mg/mL) in a dose-dependent manner. However, combination of the flesh, seed and peel in equal amounts had the highest inhibitory effect on α-amylase and α-glucosidase activities.

CONCLUSIONS

Strong inhibitory activities of the unripe pawpaw fruit against key enzymes linked to type 2 diabetes and SNP-induced lipid peroxidation in rat pancreas could be part of the mechanism by which unripe pawpaw is used in the management/prevention of diabetes mellitus in folk medicine. However, combining the unripe pawpaw fruit parts in equal amounts exhibited synergistic properties on α-amylase and α-glucosidase inhibitory activities.

Phenolic compounds from sandpaper (ficus exasperata) leaf inhibits angiotensin 1 converting enzyme in high cholesterol diet fed rats

ETHNOPHARMACOLOGICAL RELEVANCE

Sandpaper [Ficus exasperata Vahl (Moraceae)] leaf has been reportedly used in folklore for the management/treatment of cardiovascular diseases with little/or no scientific basis for their action. This study sought to investigate the effect of dietary supplementation of sandpaper leaf on angiotensin-I converting enzyme (ACE) activity in hypercholesterolemia as well as the effect of their phenolic extract on this enzyme in vitro.

MATERIALS AND METHODS

The phenolic extract was prepared, then, the inhibitory effect of the leaf extract on ACE was determined in vitro. Thereafter, the effect of dietary supplementation of sandpaper leaf on angiotensin-I converting enzyme (ACE) activity in high cholesterol diet fed rats for 14 days was evaluated as well as some biochemical parameters.

RESULTS

The result revealed that under in vitro condition, the phenolic extract inhibited ACE (IC50=14.7µg/mL) in a dose-dependent manner (0-10µg/mL). Feeding high cholesterol diets to rats caused a significant (P<0.05) increase in the ACE activity. However, there was a significant (P<0.05) decrease in the ACE activity as a result of supplementation with the sand paper leaves. Furthermore, there was a significant (P<0.05) increase in the plasma lipid profile with a concomitant increase in malondialdehyde (MDA) content in rat liver and heart tissues. However, supplementing the diet with sandpaper leaf (either 10% or 20%) caused a significant (P<0.05) decrease in the plasma total cholesterol (TC), triglyceride (TG), very low density lipoprotein-cholesterol (VLDL-C), and low-density lipoprotein-cholesterol levels (LDL-C), and in MDA content in the tissues. Conversely, supplementation caused a significant (P<0.05) increase in plasma high-density lipoprotein-cholesterol level when compared with the control diet. Reversed phase HPLC analysis of the extract revealed Quercitrin (43.7mg/g), chlorogenic acid (42.8mg/g) and caffeic acid (33.9mg/g) as the major phenolics in the leaf.

CONCLUSION

The inhibition of ACE activity and prevention of hypercholesterolemia by sandpaper leaf could be part of the possible mechanism underlying its anti-hypertensive property which could lay credence to its use in folk medicine. However, these activities may be directly/indirectly attributed to the polyphenolics present.

Inhibitory effect of polyphenolic-rich extract from Cola nitida (Kolanut) seed on key enzyme linked to type 2 diabetes and Fe(2+) induced lipid peroxidation in rat pancreas in vitro

OBJECTIVE

To investigate the inhibitory effect of phenolic-rich extracts from Cola nitida (C. nitida) seeds on key enzymes linked with type-2 diabetes and Fe(2+) induced oxidative stress in rat pancreas.

METHODS

The phenolic extract was prepared with 80% acetone (v/v). Subsequently, the antioxidant properties and inhibitory effect of the extract on α - amylase and α - glucosidase as well as on Fe(2+) induced lipid peroxidation in rat pancreas were determined in vitro.

RESULTS

The result revealed that C. nitida extract inhibited α-amylase (EC50=0.34 mg/mL) and α-glucosidase (EC50=0.32 mg/mL) activities as well as Fe(2+) induced lipid peroxidation in rat pancreas in a dose dependent manner. In addition, the extract had high DPPH radical scavenging ability (EC50=2.2 mg/mL) and reducing power (8.2 mg AAE/g). Characterization of the main phenolic compounds of the extract using gas chromatography analysis revealed catechin (6.6 mg/100 g), epicatechin (3.6 mg/100 g), apigenin (5.1 mg/100 g) and naringenin (3.6 mg/100 g) were the main compounds in the extract.

CONCLUSIONS

This antioxidant and enzyme inhibition could be some of the possible mechanism by which C. nitida is use in folklore for the management/treatment of type-2 diabetes. However, the enzyme inhibitory properties of the extract could be attributed to the presence of catechin, epicatechin, apigenin and naringenin.

Dietary inclusion of sorghum (Sorghum bicolour) straw dye protects against cisplatin-induced nephrotoxicity and oxidative stress in rats

CONTEXT

Sorghum straw (dried leaves and stem fiber) extracts and infusion are employed in the management of several ailments in folklore, and it is also a natural dye source used in food preparation.

OBJECTIVE

This study sought to investigate the modulatory effect of dietary inclusion of Sorghum straw dye on cisplatin-induced nephrotoxicity and antioxidant status in rats.

MATERIALS AND METHODS

Adult male rats were randomly divided into four groups of six animals each. Groups I (normal rats) and II (control rats) were fed with basal diet while Groups III and IV were fed with diets containing 0.5% and 1% sorghum straw dye, respectively. Nephrotoxicity was induced in Groups I-IV on the 20th day by the administration of a single dose of cisplatin solution (7 mg/kg body weight, i.p.) and the experiment was terminated 3 d after. Thereafter, the kidney and plasma of the rats were analyzed for kidney function (creatinine, urea, uric acid, and blood urea nitrogen) and antioxidant indices [superoxide dismutase (SOD), catalase, glutathione-S-transferase (GST), malondialdehyde (MDA), vitamin C, and reduced glutathione (GSH)].

RESULTS

The average feed intake of the rats in all the groups ranged from 9.0 to 9.5 (g/rat/day). Furthermore, the result indicated that administration of cisplatin caused significant (p < 0.05) elevation in plasma creatinine (2.2 mg/dL), uric acid (39.3 mg/dL), urea (81.4 mg/dL), and blood urea nitrogen (38.0 mg/dL) as well as a concomitant decrease in kidney antioxidant indices in control rats as against the normal rats. However, diets supplemented with 0.5 and 1.0% sorghum straw dye significantly reversed the plasma creatinine and the kidney antioxidant indices to near normal levels.

DISCUSSION AND CONCLUSION

The study suggests that dietary inclusion of sorghum straw dye as colorants could protect against oxidative stress and cisplatin-induced nephrotoxicity.

Dietary inclusion of local salt substitutes induces oxidative stress and renal dysfunction in rats

Our earlier report has shown that salt substitutes (Obu-Otoyo) contain some toxic heavy metals. This study, therefore, investigated the effect of the dietary inclusion of salt substitutes (Obu-Otoyo), namely, salt "A" and "B", on biomarkers of oxidative stress and renal function in rats. Salt "A", which has a gray color, is the product of a process in which ash is produced by burning palm kernel shaft soaked in water overnight and extracting the residue to produce the salt substitute while Salt "B", which has a white color, is a rock salt mined from a local site at Ilobu town, Osun-State, Nigeria. Salt substitutes were fed to normal rats as dietary inclusion at 0.5% and 1.0% for 21 days. The dietary inclusion of the salt substitutes caused a significant (p<0.05) increase in plasma activities of creatinine, urea, uric acid, and blood urea nitrogen compared with the control. Meanwhile, the dietary inclusion of the salt substitutes caused a significant (p<0.05) decrease in renal superoxide dismutase, catalase, reduced glutathione level, glutathione-S-transferase, and glutathione peroxidase activities with a concomitant increase in the malondialdehyde level compared with the control. Furthermore, there was a significant (p<0.05) increase in the concentrations of heavy metals, such as Pb, Co, Cu, Fe, Zn and Cr, in kidney of rats fed with the salt substitute Obu-Otoyo. Therefore, this finding indicates that Obu-Otoyo induces nephrotoxicity in rats. The nephrotoxicity of Obu-Otoyo could be attributed to the induction of oxidative stress as a result of the presence of some heavy metals, suggesting possible health hazards in subjects who consume it.

Anthocyanin - Rich Red Dye of Hibiscus Sabdariffa Calyx Modulates Cisplatin-induced Nephrotoxicity and Oxidative Stress in Rats

This study sought to investigate the protective effect of dietary inclusion of Hibiscus sabdariffa calyx red dye on cisplatin-induced nephrotoxicity and antioxidant status in rats. Adult male rats were randomly divided into four groups of six animals each. Groups I and II were fed basal diet while groups III and IV were fed diets containing 0.5% and 1% of the dye respectively for 20 days prior to cisplatin administration. Nephrotoxicity was induced by a single dose intraperitoneal administration of cisplatin (7 mg/kg b.w) and the experiment was terminated 3 days after. The kidney and plasma were studied for nephrotoxicity and oxidative stress indices. Cisplatin administration caused a significant (P<0.05) increase in creatinine, uric acid, urea, and blood urea nitrogen (BUN) levels as well as kidney malondialdehyde (MDA) content, with concomitant decrease in kidney vitamin C and GSH contents. Furthermore, activities of kidney antioxidant enzymes such as, SOD, Catalase, and GST were significantly (P<0.05) altered in cisplatin administered rats. However, consumption of diets supplemented with the dye for 20 days prior to cisplatin administration protected the kidney and attenuates oxidative stress through modulation of in vivo antioxidant status. The determined anthocyanin content of the dye is 121.5 mg Cyanidin-3-rutinoside equivalent/100 g, thus, the observed nephroprotective effect of H. sabdariffa dye could be attributed to its anthocyanin content.

Aqueous extracts of two varieties of ginger (Zingiber officinale) inhibit angiotensin I-converting enzyme, iron(II), and sodium nitroprusside-induced lipid peroxidation in the rat heart in vitro

Ginger has reportedly been used in folk medicine for the management and prevention of hypertension and other cardiovascular diseases. Therefore, this study sought to investigate the inhibitory effect of aqueous extracts of two varieties of ginger on a key enzyme linked to hypertension (angiotensin I-converting enzyme [ACE]), and on pro-oxidants [Fe(2+) and sodium nitroprusside (SNP)] which have been shown to induce lipid peroxidation in the rat's isolated heart in vitro. Aqueous extracts (0.05 mg/mL) of red ginger (Zingiber officinale var. Rubra) and white ginger (Zingiber officinale Roscoe) were prepared and the ability of the extracts to inhibit ACE along with Fe(2+)- and SNP-induced lipid peroxidation was determined in rat's heart in vitro. Results revealed that both extracts inhibited ACE in a dose-dependent manner (25-125 μg/mL). However, red ginger extract (EC50=27.5 μg/mL) had a significantly (P<.05) higher inhibitory effect on ACE than white ginger extract (EC50=87.0 μg/mL). Furthermore, incubation of the rat's heart in the presence of Fe(2+) and SNP caused a significant increase (P<.05) in the malondialdehyde (MDA) content of the heart homogenates, while the introduction of the ginger extracts (78-313 μg/mL) caused a dose-dependent decrease in the MDA content of the stressed heart homogenates. This suggests that the possible mechanism through which ginger exerts its antihypertensive properties may be through inhibition of ACE activity and prevention of lipid peroxidation in the heart. Furthermore, red ginger showed stronger inhibition of ACE than white ginger. Additionally, it should be noted that these protective properties of the ginger varieties could be attributed to their polyphenol contents.

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.

Aqueous extracts of Roselle (Hibiscus sabdariffa Linn.) varieties inhibit α-amylase and α-glucosidase activities in vitro

This study sought to investigate the inhibitory effect of aqueous extracts of two varieties (red and white) of Hibiscus sabdariffa (Roselle) calyces on carbohydrate hydrolyzing enzymes (α-amylase and α-glucosidase), with the aim of providing the possible mechanism for their antidiabetes properties. Aqueous extracts were prepared (1:100 w/v) and the supernatant used for the analysis. The extracts caused inhibition of α-amylase and α-glucosidase activities in vitro.The IC(50) revealed that the red variety (25.2 μg/mL) exhibited higher α-glucosidase inhibitory activity than the white variety (47.4 μg/mL), while the white variety (90.5 μg/mL) exhibited higher α-amylase inhibitory activity than the red variety (187.9 μg/mL). However, the α-glucosidase inhibitory activities of both calyces were higher than that of their α-amylase. In addition, the red variety possessed higher antioxidant capacity as exemplified by the (•)OH scavenging abilities, Fe(2+) chelating ability, and inhibition of Fe(2+)-induced pancreatic lipid peroxidation in vitro. The enzyme inhibitory activities and antioxidant properties of the roselle extracts agreed with their phenolic content. Hence, inhibition of α-amylase and α-glucosidase, coupled with strong antioxidant properties could be the possible underlying mechanism for the antidiabetes properties of H. sabdariffa calyces; however, the red variety appeared to be more potent.

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.

Inhibition of α-amylase and α-glucosidase activities by ethanolic extract of Telfairia occidentalis (fluted pumpkin) leaf

OBJECTIVE

To investigate the inhibitory effect of Telfairia occidentalis Hook f. (Curcubitaceae) (T. occidentalis) leaf on key enzyme linked to type-2 diabetes (α - amylase and α - glucosidase) as well as assess the effect of blanching (a commonly practiced food processing technique) of the vegetable on these key enzymes.

METHODS

Fresh leaves of T. occidentalis were blanched in hot water for 10 minutes, and the extracts of both the fresh and blanched vegetables were prepared and used for subsequent analysis. The inhibitory effect of the extract on α - amylase and α - glucosidase activities as well as some antioxidant parameter was determined in vitro.

RESULTS

The result revealed that unprocessed T. occidentalis leaf reduce Fe(3+) to Fe(2+) and also inhibited α - amylase and α - glucosidase activities in a dose dependent manner. However, blanching of the leafy vegetables caused a significant (P<0.05) increase in the antioxidant properties but decrease their ability to inhibit α - amylase and α - glucosidase activities.

CONCLUSIONS

This antioxidant properties and enzyme inhibition could be part of the mechanism by which they are used in the treatment/prevention of type-2 diabetes. However, the blanched vegetable reduces their ability to inhibit both α - amylase and α - glucosidase activity in vitro.

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 Alzheimer's 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 rat's 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.