Cooking enhances the antioxidant properties of some tropical green leafy vegetables

Most leafy vegetables undergo cooking before consumption in tropical Africa. Therefore, this study sought to evaluate the effect of cooking on the vitamin C, total phenolics, total flavonoid and antioxidant properties [1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical and 2,2- azinobis -3-ethylbenzo-thiazoline- 6-sulfonate radical (ABTS*) scavenging abilities, reducing property and Fe2+ chelating ability] of some tropical green leafy vegetables; Talinium triangulare, Ocimum gratissimum, Amaranthus hybridus, Telfairia occidentalis, Ipomea batata, Cnidoscolous aconitifolius, Baselia alba and Senecio biafrae leaves. The results of the study revealed that cooking causes a significant (P <0.05) decrease in the vitamin C [raw (321.4 - 842.0), cooked (198.2 - 638.4 mg/100 g)] content. Conversely, there was a significant (P < 0.05) increase in the total phenol [raw (146.9 - 693.8), cooked (272.9 - 1037.5 mg/100 g)] , total flavonoid [raw (8.2 - 53.0), cooked (12.9 - 57.4 mg/100 g)], DPPH radical scavenging ability [raw (15.7 - 61.8), cooked (52.8 - 92.7 %)], reducing property [raw (28.3 - 61.8), cooked (43.9 – 71.6 mg/100g AAE)], Fe2+ chelating ability [raw (17.4 – 75.4), cooked (22.8 - 89.2%)] and ABTS* scavenging ability [raw (17.4 - 87.3), cooked (57.5 - 113.2 mmol/100 gTEAC)]. In view of this, it could be concluded that cooking decreases the vitamin C contents in all the vegetables, while it increased the phenolic content and antioxidant activities.Key words: Vegetables, cooking, antioxidant, phenolic, vitamin C

Modulatory effect of protocatechuic acid on cadmium induced nephrotoxicity and hepatoxicity in rats in vivo

Introduction: This study sought to investigate the effect of protocatechuic acid (PCA); a phenolic compound readily available in most plant foods on cadmium-induced nephrotoxicity and hepatoxicity in rats. Case description: Thirty six adult male rats weighing about 150–160 g were acclimatized for 2 weeks and subsequently divided into six groups: Group 1 rats received normal saline (control group), group 2 rats were administered 5 mg Cd/kg body weight in form of solution orally (induced group), groups 3 and 4 received cadmium solution and different doses of PCA (10 and 20 mg/kg body weight) respectively, while groups 5 and 6 were the normal rats administered different doses of PCA (10 and 20 mg/kg) respectively in an experiment that lasted for twenty one days. The animals were sacrificed, the blood was collected and the serum was subsequently prepared. Furthermore, the liver was excised, homogenized and centrifuged to obtain the tissue homogenate used for the analyses. The serum was used for the determination of the total protein, urea, creatinine and uric acid levels while the liver homogenate was used for the estimation of alanine aminotransferase (ALT), aspartate transaminase (AST), and alkaline phosphatase (ALP). Discussion and evaluation: The result revealed that total protein level was reduced in cadmium induced toxicity rat group which was elevated upon treatment with PCA. Conversely, the elevated levels of urea, uric acid and creatinine in cadmium induced toxicity kidney rats were significantly (p < 0.05) reduced in PCA treated groups. Similarly, marked elevation in the ALT, AST and ALP activity were observed in cadmium induced toxicity rat group when compared with the control group. However, significant (p < 0.05) decrease in ALT, AST and ALP activity were noticed in groups administered different doses of PCA. Conclusions: The results from this study suggest that PCA may protect against cadmium-induced toxicity in the kidney and liver

Alterations of Na+/K+-ATPase, cholinergic and antioxidant enzymes activity by protocatechuic acid in cadmium-induced neurotoxicity and oxidative stress in Wistar rats

Staff PublicationBackground: This study assessed the possible protective mechanisms of protocatechuic acid (PCA) against cadmium (Cd)-induced oxidative stress and neurotoxicity in rats. Methods: Male wistar strain rats weighing between 150–160 g were purchased and acclimatized for two weeks. The rats were divided into seven groups of seven each; NC group received normal saline, CAD group received 6 mg/kg of Cd-solution, CAD + PSG group received Cd-solution and prostigmine (5 mg/kg), CAD + PCA-10 and CAD + PCA-20 groups received Cd-solution and PCA (10 mg/kg and 20 mg/kg) respectively, PCA-10 and PCA-20 groups received 10 mg/kg and 20 mg/kg PCA each. Animals were administered normal saline, Cd and PCA daily by oral gavage for 21 days. After which the animals were sacrificed, the brain excised, homogenized and centrifuged. The activities of enzymes (Na+/K+-ATPase, cholinesterases, catalase, glutathione peroxidase, superoxide dismutase) and levels of oxidative stress markers (lipid peroxidation and reduced glutathione) linked to neurodegeneration were subsequently assessed. Results: Significant (p < 0.05) alterations in the enzyme activities and levels of oxidative stress markers were observed in CAD group when compared to the NC group. However, the activities of the enzymes were reversed in CAD + PSG and CAD + PCA groups. Conclusions: PCA may protect against cadmium-induced neurotoxicity by altering the activities of Na+/K+- ATPase, acetylcholinesterase, butyrylcholinesterase and endogenous antioxidant enzymes

In vitro antioxidant activities of African birch (Anogeissus leiocarpus) leaf and its effect on the α-amylase and α-glucosidase inhibitory properties of acarbose

Objective This study sought to determine the antioxidant activities of African birch leaf, to assess its interaction with key enzymes relevant to type 2 diabetes (α-amylase and α-glucosidase) and to evaluate its effect on acarbose in vitro. Methods One milligram per milliliter of aqueous extract of African birch and acarbose were separately prepared. At the same time, both the African extract and acarbose solution (50:50 v/v) were thoroughly mixed until homogeneity was attained. The phenolic phytoconstituents and antioxidant properties of African birch leaf were subsequently determined. Finally, the effects of African birch extract, acarbose solution and a mixture of acarbose and African birch extract on α-amylase and α-glucosidase activities were assessed in vitro. Results The results showed that African birch extract demonstrated a remarkable antioxidant effect, as exemplified by its radical scavenging abilities, Fe2+ chelating ability and prevention of lipid peroxidation. Acarbose had significantly (p < 0.05) higher α-amylase (IC50 = 11.77 μg/ml) and α-glucosidase (IC50 = 9.05 μg/ml) activities compared to African birch extract [α-amylase (IC50 = 242.17 μg/ml); α-glucosidase (IC50 = 196.35 μg/ml)]. However, the combination of acarbose and African birch extract showed an additive effect on α-amylase inhibition, while a resultant synergistic action was observed against α-glucosidase inhibition. Conclusion The additive and synergistic actions of the combination of African birch extract and acarbose solution suggest effective, complementary and alternative strategies towards the management/treatment of hyperglycaemia associated with type 2 diabetes

Distribution of Phenolic Contents, Antidiabetic Potentials, Antihypertensive Properties, and Antioxidative Effects of Soursop ( Annona muricata

Soursop fruit has been used in folklore for the management of type-2 diabetes and hypertension with limited information on the scientific backing. This study investigated the effects of aqueous extracts (1 : 100 w/v) of Soursop fruit part (pericarp, pulp, and seed) on key enzymes linked to type-2 diabetes (α-amylase and α-glucosidase) and hypertension [angiotensin-I converting enzyme (ACE)]. Radicals scavenging and Fe2+ chelation abilities and reducing property as well as phenolic contents of the extracts were also determined. Our data revealed that the extracts inhibited α-amylase and α-glucosidase and ACE activities dose-dependently. The effective concentration of the extract causing 50% antioxidant activity (EC50) revealed that pericarp extract had the highest α-amylase (0.46 mg/mL), α-glucosidase (0.37 mg/mL), and ACE (0.03 mg/mL) inhibitory activities while the seed extract had the least [α-amylase (0.76 mg/mL); α-glucosidase (0.73 mg/mL); and ACE (0.20 mg/mL)]. Furthermore, the extracts scavenged radicals, reduced Fe3+ to Fe2+, and chelated Fe2+. The phenolic contents in the extracts ranged from 85.65 to 560.21 mg/100 g. The enzymes inhibitory and antioxidants potentials of the extracts could be attributed to their phenolic distributions which could be among the scientific basis for their use in the management of diabetes and hypertension. However, the pericarp appeared to be most promising

Modulatory Effects of Ferulic Acid on Cadmium-Induced Brain Damage

Staff PublicationStudies 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 Naþ/Kþ-ATPase activities were carried out. The study revealed significant (P < .05) increases in the MDA content and all enzymes’ (AChE, BChE, MAO, and Naþ/Kþ- 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

In vivo antioxidant activity of phenolic compounds: facts and gaps

Background: Numerous diseases have been related with free radicals overproduction and oxidative stress. Botanical preparations possess a multitude of bioactive properties, including antioxidant potential, which has been mainly related with the presence of phenolic compounds. However, the mechanisms of action of these phytochemicals, in vivo effects, bioavailability and bio-efficacy still need research. Scope and Approach: The present report aims to provide a critical review on the aspects related with the in vivo antioxidant activity of phenolic extracts and compounds from plant origin. Key findings: Biological functions beyond the human metabolism were discussed, comparing in vivo vs. in vitro studies, as also focusing the conditioning factors for phenolic compounds bioavailability and bio-efficacy. Furthermore, an upcoming perspective about the use of phytochemicals as life expectancy promoters and anti-aging factors in human individuals was provided. Conclusions: Overall, and despite all of those advances, the study of the biological potential of numerous natural matrices still remains a hot topic among the scientific community. In fact, the available knowledge about the responsible phytochemicals for the biological potential, their mechanisms of action, the establishment of therapeutic and prophylactic doses, and even the occurrence of biochemical inter-relations, is considerable scarce.The authors are grateful to Foundation for Science and Technology (FCT, Portugal) for N. Martins grant (SFRH/BD/87658/2012), L. Barros researcher contract under "Programa Compromisso com Ciencia - 2008" and financial support to the research centre CIMO (strategic project Pest-OE/AGR/UI0690/2014)

The use of plants in the traditional management of diabetes in Nigeria: Pharmacological and toxicological considerations

Ethnopharmacological relevance: The prevalence of diabetes is on a steady increase worldwide and it is now identified as one of the main threats to human health in the 21st century. In Nigeria, the use of herbal medicine alone or alongside prescription drugs for its management is quite common. We hereby carry out a review of medicinal plants traditionally used for diabetes management in Nigeria. Based on the available evidence on the species׳ pharmacology and safety, we highlight ways in which their therapeutic potential can be properly harnessed for possible integration into the country׳s healthcare system. Materials and methods: Ethnobotanical information was obtained from a literature search of electronic databases such as Google Scholar, Pubmed and Scopus up to 2013 for publications on medicinal plants used in diabetes management, in which the place of use and/or sample collection was identified as Nigeria. ‘Diabetes’ and ‘Nigeria’ were used as keywords for the primary searches; and then ‘Plant name – accepted or synonyms’, ‘Constituents’, ‘Drug interaction’ and/or ‘Toxicity’ for the secondary searches. Results: The hypoglycemic effect of over a hundred out of the 115 plants reviewed in this paper is backed by preclinical experimental evidence, either in vivo or in vitro. One-third of the plants have been studied for their mechanism of action, while isolation of the bioactive constituent(s) has been accomplished for twenty three plants. Some plants showed specific organ toxicity, mostly nephrotoxic or hepatotoxic, with direct effects on the levels of some liver function enzymes. Twenty eight plants have been identified as in vitro modulators of P-glycoprotein and/or one or more of the cytochrome P450 enzymes, while eleven plants altered the levels of phase 2 metabolic enzymes, chiefly glutathione, with the potential to alter the pharmacokinetics of co-administered drugs. Conclusion: This review, therefore, provides a useful resource to enable a thorough assessment of the profile of plants used in diabetes management so as to ensure a more rational use. By anticipating potential toxicities or possible herb–drug interactions, significant risks which would otherwise represent a burden on the country׳s healthcare system can be avoided

Data for: Comparative Effects of Horseradish (Moringa oleifera) Leaves and Seeds on Blood Pressure and Crucial Enzymes Relevant to Hypertension in Rat

All figures and table