Sodium Nitroprusside-induced Lipid Peroxidation Research Articles

Inhibitory Activity of <I>Tithonia diversifolia</I> (Hemsl.) A. Gray leaves on Some Pro-Oxidant Induced Oxidative Stress in Rat Brain

This study examines the antioxidant potentials and also the ability of the aqueous extract of Tithonia diversifolia (Hemsl.) A. Gray leaves to inhibit some pro-oxidants (Fe 2+ and sodium nitroprusside) induced lipid peroxidation in rat's brain homogenates in vitro . The ability of the extracts to inhibit 25 μM FeSO 4 and 7.0 μM sodium nitroprusside induced lipid peroxidation in isolated rat's brain determined. The antioxidative potentials of the extract as typified by the overall phenol content, reducing power, 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging ability and iron II chelating ability were cojointly determined. The results of the study discovered that each pro-oxidant (Fe 2+ and sodium nitroprusside) caused a considerably increase in (p < 0.05) malonaldehyde (MDA) content of the brain. Though, aqueous extracts of Tithonia diversifolia caused a substantial concentration-dependent decrease (p < 0.05) within the malonaldehyde (MDA) contents of the brain. Though, aqueous extracts from Tithonia diversifolia had an appreciably higher (p < 0.05) inhibitory impact on each Fe 2+ and sodium nitroprusside induced lipid peroxidation within the rat's brain homogenates. This higher inhibitory effect of Tithonia diversifolia may be attributed to its considerably higher (p < 0.05) total phenol content, iron (II) chelating ability, reducing power and free radical scavenging ability. Therefore, Fe 2+ and sodium nitroprusside induced oxidative stress within the brain may be probably managed by dietary intake of Tithonia diversifolia leaves. These antioxidant potentials of T. diversifolia extract could have contributed to the employment of the leaves in the management of disease.

Drying Methods Alter Angiotensin-I Converting Enzyme Inhibitory Activity, Antioxidant Properties, and Phenolic Constituents of African Mistletoe (Loranthus bengwensis L) Leaves.

This study investigated the most appropriate drying method (sun drying, oven drying, or air drying) for mistletoe leaves obtained from almond tree. The phenolic constituents were characterized using high-performance liquid chromatography-diode array detector, while the inhibitory effect of the aqueous extracts of the leaves on angiotensin-I converting enzyme (ACE) was determined in vitro as also the antioxidant properties. Oven-dried extract (kidney [276.09 μg/mL] and lungs [303.41 μg/mL]) had the highest inhibitory effect on ACE, while air-dried mistletoe extract (kidney [304.47 μg/mL] and lungs [438.72 μg/mL]) had the least. Furthermore, the extracts dose-dependently inhibited Fe(2+) and sodium nitroprusside-induced lipid peroxidation in rat's heart and kidney. Also, all extracts exhibited antioxidative properties as typified by their radical scavenging and Fe-chelating ability. Findings from this study revealed that oven drying is the best of the 3 drying methods used for mistletoe obtained from almond host tree, thus confirming that diversity in drying methods leads to variation in phenolic constituents and biological activity of plants.

Phenolic Composition and Evaluation of Methanol and Aqueous Extracts of Bitter Gourd (Momordica charantia L) Leaves on Angiotensin-I-Converting Enzyme and Some Pro-oxidant-Induced Lipid Peroxidation In Vitro.

This study sought to assess the effects of bitter gourd leaf extracts (methanol and aqueous) on enzyme linked with hypertension (angiotensin-I-converting enzyme and some pro-oxidants (iron sulfate, sodium nitroprusside, and cisplatin]-induced lipid peroxidation in rat kidney homogenates. Chromatographic analysis of the extract was done using high-performance liquid chromatography-diode array detection. The results revealed that methanol extract (IC50 = 109.63 µg/mL) had significantly (P < .05) higher angiotensin-I converting enzyme inhibitory activity than aqueous extract (IC50 = 182.95 µg/mL). Similarly, methanol extract had significantly (P < .05) higher inhibitory effect on Fe2+- and cisplatin-induced lipid peroxidation than aqueous extract. However, there was no significant (P > .05) difference in the inhibition of sodium nitroprusside-induced lipid peroxidation of both extracts. High-performance liquid chromatography-diode array detection analysis revealed the presence of quercetin, caffeic, gallic, and chlorogenic acids in the leaf. Thus, inhibition of angiotensin-I converting enzyme activity and the antioxidant properties of the extracts could be linked to the presence of phenolic phytochemicals.

EXTRACTS OF OCIMUM GRATISSIMUM LEAVES INHIBITS FE2+ AND SODIUM NITROPRUSSIDE INDUCED OXIDATIVE STRESS IN RAT LIVER

This study investigate the antioxidative properties and the ability of aqueous, ethanol and ethyl acetate extracts from Ocimum gratissimum (OG) leaves to inhibit some pro-oxidants (Fe and sodium nitroprusside) induced lipid peroxidation in rat’s liver homogenates in vitro. The ability of the extracts to inhibit 25 μM FeSO4 and 7.0 μM sodium nitroprusside induced lipid peroxidation in isolated rat’s liver was determined. The results of the study revealed that both pro-oxidants caused a significantly decrease in (p<0.05) accumulation of lipid peroxides. However, aqueous extract of Ocimum gratissimum shows a high ability to inhibit lipid production in the liver induced with SNP than Fe. Ethanol and ethyl acetate extract of Ocimum gratissimum which shows a high ability to inhibit lipid production more when induced with Fe than SNP. However, ethyl acetate fraction of Ocimum gratissimum shows a higher inhibitory effect on both Fe and SNP induced lipid peroxidation in rat’s liver. This might be as a result of its significantly higher extractable phytochemicals. Therefore, Fe II and sodium nitroprusside induced oxidative stress could be managed by dietary intake of Ocimum gratissimum leaves.

Antioxidant and inhibitory properties of Clerodendrum volubile leaf extracts on key enzymes relevant to non-insulin dependent diabetes mellitus and hypertension

ObjectiveTo characterize the interaction of phenolic (free and bound) extracts from white butterfly (Clerodendrum volubile P. Beauv) leaves with key enzymes relevant to non-insulin dependent diabetes mellitus (α-amylase and α-glucosidase) and hypertension (Angiotensin-I converting enzyme) and their antioxidant properties in vitro. MethodsThe effects of the extracts on enzymes [α-amylase, α-glucosidase, Angiotensin-I converting enzyme (ACE)], some pro-oxidant (Fe2+- and sodium nitroprusside-induced lipid peroxidation in the pancreas (in vitro)) and antioxidant properties and HPLC analysis of the extracts were investigated. ResultsThe phenolic extracts inhibited α-amylase, α-glucosidase, ACE and some pro-oxidants (Fe2+- and sodium nitroprusside-induced lipid peroxidation in the pancreas (in vitro)). Bound phenolics had significantly higher (P<0.05) α-glucosidase inhibitory effects compared to free phenolics and acarbose (a standard drug). However, captopril, a synthetic ACE inhibitor, showed a higher ACE inhibitory activity compared with both the free and bound phenolics, whereas there was no significant difference (P>0.05) in their α-amylase inhibitory activities. The stronger inhibition of α-glucosidase and ACE compared to α-amylase by both extracts may be of pharmacological relevance. Reversed-phase HPLC analysis of the extracts revealed the presence of quercetin, rutin, kaempferol, and chlorogenic and caffeic acids as the main components of both the free and bound extracts. ConclusionThe inhibitory properties of phenolic rich extracts on α-amylase, α-glucosidase, ACE, and Fe2+- and sodium nitroprusside-induced lipid peroxidation in the pancreas could be attributed to the antioxidant properties of the extracts and their phenolic composition. The stronger action of the bound phenolic extract on α-glucosidase may provide the possible bioactivity at the brush border end of the intestinal wall. This study may thus suggest that leaves represent a functional food and nutraceutical in the management of non-insulin dependent diabetes mellitus and hypertension.

A comparative study on antihypertensive and antioxidant properties of phenolic extracts from fruit and leaf of some guava (Psidium guajava L.) varieties

Investigation of antihypertensive and antioxidant properties of fruit and leaf extracts from four varieties (giant white, small white, stripped and pink) of guava (Psidium guajava L.) in vitro was the focus of this study. Consequently, methanol/1 M HCl (20:1 v/v) extraction of fruit and leaf of the guava varieties were carried out. Thereafter, the extracts were assayed for their angiotensin I converting enzyme (ACE) inhibitory effect, total phenol and flavonoid contents, reducing property, radicals (DPPH, ABTS•+, hydroxyl and nitric oxide) scavenging ability, Fe2+ chelating ability, and inhibition of Fe2+ and Sodium nitroprusside (SNP) induced lipid peroxidation reactions (in vitro). Furthermore, the phenolic constituents of the extracts were characterised with gas chromatography (GC). The results showed that all the extracts significantly (P < 0.05) inhibited ACE activity, scavenged (DPPH, ABTS•+, nitric oxide and hydroxyl) radicals, chelated Fe2+ and also inhibited Fe2+ and SNP induced lipid peroxidation in rat heart (in vitro). Nevertheless, the pink guava variety had the highest ACE inhibitory and antioxidant properties. In addition, Rosmarinic acid, eugenol, carvacrol, catechin and caffeic acid were the dominant phenolics found in the extracts. The ACE inhibitory effects and antioxidant properties of the guava extracts, which correlates significantly with their phenolic constituents, could largely contribute to their antihypertensive properties as obtained in traditional medicine.

Free radical scavenging in vitro and biological activity of diphenyl diselenide-loaded nanocapsules: DPDS-NCS antioxidant and toxicological effects.

Selenium compounds, such as diphenyl diselenide (DPDS), have been shown to exhibit biological activity, including antioxidant effects. However, the use of DPDS in pharmacology is limited due to in vivo pro-oxidative effects. In addition, studies have shown that DPDS-loaded nanocapsules (DPDS-NCS) have greater bioavailability than free DPDS in mice. Accordingly, the aim of this study was to investigate the antioxidant properties of DPDS-NCS in vitro and biological activity in mice. Our in vitro results suggested that DPDS-NCS significantly reduced the production of reactive oxygen species and Fe(II)-induced lipid peroxidation (LPO) in brain. The administration of DPDS-NCS did not result in death or change the levels of endogenous reduced or oxidized glutathione after 72 hours of exposure. Moreover, ex vivo assays demonstrated that DPDS-NCS significantly decreased the LPO and reactive oxygen species levels in the brain. In addition, the highest dose of DPDS-NCS significantly reduced Fe(II)- and sodium nitroprusside-induced LPO in the brain and Fe(II)-induced LPO in the liver. Also, δ-aminolevulinate acid dehydratase within the brain was inhibited only in the highest dose of DPDS-NCS. In conclusion, our data demonstrated that DPDS-NCS exhibited low toxicity in mice and have significant antioxidant characteristics, indicating that nanoencapsulation is a safer method of DPDS administration.

Antioxidant, hypolipidemic, and anti-angiotensin-1-converting enzyme properties of lemon (Citrus limon) and lime (Citrus aurantifolia) juices

Lemon (Citrus limon) and lime (Citrus aurantifolia) juices are used in folk medicine for the management of hypertension and other cardiovascular diseases, but the mechanism of action by which they exert their therapeutic action is unclear. The aim of this study is to investigate the effect of lemon and lime juices on angiotensin-1-converting enzyme (ACE) activity in vitro and investigate the hypocholesterolemic properties of the juices in a high-cholesterol diet rat model. The phenolic content and antioxidant properties of the manually squeezed juices were also determined. Lemon juice had higher total phenol content (64.5 mg/l), while lime juice had higher total flavonoid content (29.5 mg/l). Both juices inhibited ACE activity in a dose-dependent manner and also exhibited antioxidant activities as typified by their ferric reducing power, and radicals (DPPH·, ABTS·, OH·, and NO·) scavenging abilities, as well as inhibition of Fe2+- and sodium nitroprusside-induced lipid peroxidation in rat’s liver in vitro. Administration of the juices to rats fed with a high-cholesterol diet caused a significant reduction in plasma total cholesterol, triglyceride, and LDL-cholesterol levels and an increase in plasma HDL-cholesterol levels. The inhibition of ACE activity in vitro and in vivo hypocholesterolemic effect of the juices could explain the use of the juices in the management of cardiovascular diseases.

Inhibition of Key Enzymes Linked to Type 2 Diabetes and Sodium Nitroprusside Induced Lipid Peroxidation in Rats' Pancreas by Phenolic Extracts of Avocado Pear Leaves and Fruit

Persea americana fruit and leaves had been known in folk medicine for their anti-diabetic prowess. Therefore, this study sought to investigate the inhibitory effect of phenolic extract from avocado pear (Persea americana) leaves and fruits on some key enzymes linked to type 2 diabetes (α-amylase and α-glucosidase); and sodium nitroprusside (SNP) induced lipid peroxidation in rats' pancreas in vitro. The phenolic extracts of Persea americana fruit and leaves were extracted using methanol and 1M HCl (1:1 v/v). Thereafter, their inhibitory effects on sodium nitroprusside induced lipid peroxidation and key enzymes linked to type 2 diabetes (α-amylase and α-glucosidase) were determined in vitro. The result revealed that the leaves had fruit of avocado pear inhibit both α-amylase and α-glucosidase activities in a dose dependent manner. However, the Peel had the highest α-amylase inhibitory activity while the leaf had the highest α-glucosidase inhibitory activity as revealed by their IC50 value. Furthermore, incubation of the rat pancreas in the presence of 5 mM SNP caused an increase in the malondialdehyde (MDA) content in the tissue, however, introduction of the phenolic extracts inhibited MDA produced in a dose dependent manner. The additive and/or synergistic action of major phenolic compounds such as syringic acid, eugenol, vnillic acid, isoeugenol, guaiacol, kaemferol, catechin, p-hydroxybenzoic acid, ferulic acid, apigenin, naringenin, epigallocatechin, epicatechin, lupeol and epigallocatechin-3-O-gallate in avocado pear using gas chromatography (GC) could have contributed to the observed medicinal properties of the plant. Therefore, inhibition of some key enzymes linked to type 2 diabetes and prevention of oxidative stress in the pancreas could be some of the possible mechanism by which they exert their anti-diabetic properties.

Antioxidant activities and inhibitory effects of dietary plants against sodium nitroprusside induced lipid peroxidation in the mouse brain and liver

The antioxidant properties of aqueous extracts of 6 medicinal plants, Phyllanthus emblica, Terminalia chebula (black and yellow), Terminalia arjuna, Balsamodendron Mukul, and Alium sativum against lipid peroxidation in mouse tissues were investigated. Extracts showed inhibition against thiobarbituric acid reactive species (TBARS) induced by pro-oxidant (5 µM sodium nitroprusside) in the mouse brain and liver. Extracts displayed high free radical scavenging activities against DPPH (IC50, 23.23±1.2 µg/ mL, P. emblica), 20.24±0.9 µg/mL (T. chebula yellow), 17.33±1.1 µg/mL (T. chebula black), 19.44±0.45 µg/mL (T. arjuna), 56.59±2.1 µg/mL (Balsamo-dendron Mukul), and higher than 200 µg/mL (A. sativum). Higher antioxidant and inhibitory effects of T. chebula black are attributed to a higher phenolic content, Fe(II) chelating ability, reducing ability, nitric oxide radical scavenging, and free radical scavenging activity. Oxidative stress in the brain and liver could potentially be managed/prevented by dietary intake of these plants.

Interaction of Some Commercial Teas with Some Carbohydrate Metabolizing Enzymes Linked with Type-2 Diabetes: A Dietary Intervention in the Prevention of Type-2 Diabetes

This study is aimed at assessing the inhibitory effect of teas on key enzymes (α-amylase and α-glucosidase) linked with type-2 diabetes and their antioxidant properties. Four samples of three brands were used; infusions of green tea (GT), 2 brands of black tea (BT), and a formulated herbal preparation for diabetes (ADT) (white tea, Radix Puerariae, Radix ophiopogonis, hawthorn berry, Chinese yam, and fragrant Solomon seal rhizome) were prepared and subsequently analyzed for their total phenol, ascorbic acid contents, antioxidant properties (2,2-Azizobis (3-Ethylbenzo-Thiazoline~6-sulfonate) “ABTS” scavenging ability and ferric reducing antioxidant property), and inhibition of pancreatic-α-amylase and intestinal-α-glucosidase in vitro. The study revealed that GT had the highest total phenol content, ascorbic acid content, ABTS∗ scavenging ability, and ferric reducing ability. Furthermore, all the teas inhibited Fe2+ and sodium nitroprusside induced lipid peroxidation in pancreas, with GT having the highest inhibitory effect. Conversely, there was no significant difference (P > 0.05) in the inhibitory effects of the teas on α-amylase and α-glucosidase. The antidiabetic property of the teas could be attributed to their inhibitory effect on carbohydrate hydrolyzing enzymes implicated in diabetes and their antioxidant activities.

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)

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. 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. 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. 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.

Antioxidant properties of aqueous extracts of unripe Musa paradisiaca on sodium nitroprusside induced lipid peroxidation in rat pancreas in vitro

ObjectiveTo evaluate and compare antioxidant activities of the aqueous extracts of unripe plantain (Musa paradisiaca), assess their inhibitory action on sodium nitroprusside induced lipid peroxidation in rat pancreas in vitro and to characterize the main phenolic constituents of the plantain products using gas chromatography analysis. MethodsAqueous extracts of plantain products (raw, elastic pastry, roasted and boiled) flour of 0.1 g/mL (each) were used to determine their total phenol, total flavonoid, 1,1 diphenyl-2 picrylhydrazyl (DPPH) and hydroxyl (OH) radical scavenging ability. The inhibitory effect of the extracts on sodium nitroprusside induced lipid peroxidation was also determined. ResultsThe results revealed that all the aqueous extracts showed antioxidant activity. The boiled flour had highest DPPH and OH radical scavenging ability while raw flour had the highest Fe2+ chelating ability, sodium nitroprusside inhibitory effect and vitamin C content. The antioxidant results showed that elastic pastry had the highest total phenol and total flavonoid content. Characterization of the unripe plantain products for polyphenol contents using gas chromatography showed varied quantity of apigenin, myricetin, luteolin, capsaicin, isorhaemnetin, caffeic acid, kampferol, quercetin, p-hydroxybenzoic acid, shogaol, glycitein and gingerol per product on the spectra. ConclusionsConsidering the antioxidant activities and ability to inhibit lipid peroxidation of unripe plantain, this could justify their traditional use in the management/prevention of diseases related to stress.

Compound Isolated from the Leaves of Phyllostachys nigra Protects NMDA-Induced Retinal Degeneration

The luteolin 6-C-(6″-O-trans-caffeoylglucoside) (PN6) isolated from Phyllostachys nigra is effective against both the negative influence of N-methyl-D-aspartate (NMDA) to the rat retina and the oxidative stress induced transformed retinal ganglion cells (RGC-5) death. The PN6 concentration-dependently inhibited sodium nitroprusside-induced lipid peroxidation. Treatment of the RGC-5 with PN6 decreased the apoptotic proteins of poly (adenosine diphosphate-ribose) polymerase (PARP) and cleaved caspase-3, and increased the antioxidant proteins of superoxide dismutase (SOD)-2, catalase and glutathione peroxidase (GPx-1) expressions by Western blot analysis. The PN6 reduced the thickness of the inner plexiform layer using hematoxylin and eosin staining and decreased the number of terminal deoxynucleotidyl transferase 2′-deoxyuridine 5′-triphosphate nick-end labeling (TUNEL)-positive cells using TUNEL kit assay. Moreover, PN6 attenuated upregulation of apoptotic proteins (PARP and cleaved caspase-3) and downregulation of antioxidant proteins (SOD-2, catalase and GPx-1) caused by NMDA in the rat retina. Practical Applications The aim of this study was to determine whether the luteolin 6-C-(6″-O-trans-caffeoylglucoside) (PN6) previously isolated from Phyllostachys nigra is effective at blunting the negative influence of N-methyl-D-aspartate (NMDA)-induced excitotoxicity in situ. The treatment of the PN6 was evaluated by lipid peroxidation studies, which showed that PN6 significantly inhibited lipid peroxidation with an half maximal inhibitory concentration (IC50) of 1.05 μM. PN6 decreased the upregulation of poly (adenosine diphosphate-ribose) polymerase (PARP) and cleaved caspase-3 and the downregulation of superoxide dismutase (SOD-2), catalase and glutathione peroxidase (GPx -1) in retinal ganglion cells. Intravitreal injection of NMDA to the rat retina reduced the thickness of the inner plexiform layer and increased the number of terminal deoxynucleotidyl transferase 2′-deoxyuridine 5′-triphosphate nick-end labeling-positive cells, which was partially, but significantly blunted by the presence of PN6. Moreover, PN6 blunted the changes in PARP, cleaved caspase-3, SOD-2, catalase and GPx-1 proteins in the rat retina. Evidence is therefore provided to show that P. nigra can be considered as a candidate neuroprotectant for the treatment of various neurodegenerative diseases.

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

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

Assessment of antioxidant capacity, proximate composition and inhibitory activity of unripe plantain (Musa paradisiaca) products on Fe2+ and sodium nitroprusside -induced oxidative stress in vitro

This study sought to assess the proximate composition, antioxidant and inhibitory effect of unripe false horn plantain (Musa paradisiaca) products on Fe2+ and sodium nitroprusside (SNP) induced lipid peroxidation in rat’s pancreas. The EC50 of Fe2+ chelating, 2,2-diphenyl-1picrylhydrazyl (DPPH) and OH free radical scavenging ability were also determined. A portion of the unripe false horn plantain pulps were roasted to form a local meal called ‘boli’ while the other was boiled in water. Thereafter, each portion was sundried and milled into flour. The aqueous extracts of roasted flour (Rf) and boiled flour (Bf) samples were prepared (1 g/20 mL). Proximate composition showed that the Rf had higher ash and fibre content while the Bf had higher carbohydrate, fat, protein and moisture content. The Bf had higher phenolic contents, reducing power, DPPH and OH free radical scavenging ability. The Rf flour had higher vitamin C content, 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), and Fe2+ chelating ability. Bf had higher inhibitory effect on both the Fe2+and SNP induced lipid peroxidation in pancreas at the concentration tested (1.25 to 6.25 mg/mL). Their strong inhibitory activities, coupled with the antioxidant properties suggest that they could be a cheap source of natural antioxidants and also a means of restoring antioxidant status. Key words: Antioxidant capacity, Musa paradisiaca, lipid peroxidation, oxidative stress, 2,2-diphenyl-1picrylhydrazyl (DPPH).

Rotenone-Induced Death of RGC-5 Cells is Caspase Independent, Involves the JNK and p38 Pathways and is Attenuated by Specific Green Tea Flavonoids

The aim of the present studies was to characterise cell death following inhibition of mitochondrial complex I with rotenone in a transformed cell line (RGC-5 cells) and to examine the neuroprotective properties of the flavonoids genistein, epigallocatechin gallate (EGCG), epicatechin (EC) and baicalin. Rotenone-induced cell death of RGC-5 cells results in a generation of reactive oxygen species, a breakdown of DNA, the translocation of membrane phosphatidylserine, an up-regulation of haemoxygenase-1 and is unaffected by necrostatin-1 (inhibitor of necroptosis), z-VAD-fmk (pan caspase inhibitor) or NU1025 (PARP inhibitor) but attenuated with SP600125 (JNK inhibitor). Rotenone-induced toxicity of RGC-5 cells also caused an activation of mitogen-activated kinases indicated by an up-regulation and translocation into mitochondria of p-c-Jun, pJNK and pp38. Exposure of RGC-5 cells to rotenone does not affect apoptosis inducing factor or significantly stimulate caspase-3 activity. EGCG and EC both significantly blunt rotenone toxicity of RGC-5 cells at concentrations of 50 μM while genistein and baicalin were without effect. Significantly, genistein is approximately 20 times less efficacious than EGCG (IC(50) 2.5 μM) and EC (IC(50) 1.5 μM) at inhibiting sodium nitroprusside-induced lipid peroxidation. These studies show that rotenone toxicity of RGC-5 cells is neither necroptosis nor caspase-dependent apoptosis but involves the activation of mitogen-activated kinases and is inhibited by a JNK inhibitor, EGCG and EC. Genistein attenuates lipid peroxidation less efficaciously than EC and EGCG and does not affect rotenone toxicity of RGC-5 cells.

PHENOLIC EXTRACTS FROM GRAPEFRUIT PEELS (CITRUS PARADISI) INHIBIT KEY ENZYMES LINKED WITH TYPE 2 DIABETES AND HYPERTENSION

Thisstudysoughttocharacterizetheinteractionof phenolicextractfromgrapefruit peels with a-amylase, a-glucosidase and angiotensin-I-converting enzyme (ACE) activities.Thefreephenolicofgrapefruitpeelswasextractedwith80%acetone,while theboundphenolicwasextractedfromthealkalineandacid-hydrolyzedresiduewith ethyl acetate; and their interaction with the enzymes were assessed. The phenolic extractsinhibited a-amylase,a-glucosidaseandACEenzymeactivities;however,free phenolichadsignificantlyhigher(P 0.05)in their ACE inhibitory activities. Nevertheless, the extracts were strong inhibitor of a-glucosidase when compared to a-amylase. The phenolic inhibited sodium nitroprusside-induced lipid peroxidation in pancreas in a dose-dependent manner. Therefore, free and bound phenolic extracts from grapefruit peels could be used as nutraceuticalforthemanagementofhypertensionandtype2diabetes.

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

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

Antioxidant and Inhibitory Effects of Aqueous Extracts of Salvia officinalis Leaves on Pro-Oxidant-Induced Lipid Peroxidation in Brain and Liver In Vitro

The present study sought to determine the antioxidant activity and protective ability of water-extractable phytochemicals from Salvia officinalis leaves (strongly aromatic leaves used in flavoring cooked foods) on lipid peroxidation induced by some pro-oxidants in rat brain and liver homogenates in vitro. Aqueous extracts of the leaves were prepared, and the ability of the extract to inhibit 25 microM FeSO(4)- and 7 microM sodium nitroprusside-induced lipid peroxidation in isolated rat brain and liver was determined. Subsequently, the ascorbic acid content, total phenol content, reducing power, Fe(II) chelating, and .OH radical scavenging ability of the extracts were determined as indices of antioxidant activity. The results of the study revealed that the extract inhibited malondialdehyde (MDA) production in basal and pro-oxidant-induced lipid peroxidation in the brain and liver in a dose-dependent manner. The percentage induction of lipid peroxidation by Fe(II) and sodium nitroprusside was higher in the brain than the liver; however, the level of inhibition of MDA production in the brain was significantly (P < .05) higher than the liver. The ascorbic acid (10.3 +/- 2.5 mg/g) and total phenol (7.6 +/- 1.2 mg/g) contents of the leaves were high; likewise, the aqueous extract had high reducing power and Fe(II) chelating ability but low .OH radical scavenging ability. This antioxidant and protective effect of this leaf could be harnessed in the management and prevention of degenerative diseases associated with oxidative stress.