Inhibition of α-amylase, α-glucosidase and oxidative stress by some common apple varieties

In recent times, the consumption of apples has been encouraged for the management of chronic diseases such as diabetes, but biochemical evidence to support this practice is lacking. Therefore, this study investigated α-amylase and α-glucosidase inhibitory activity, 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging ability, Fe2+-induced lipid peroxidation potential as well as the total phenol and flavonoid contents of aqueous extracts of the apple varieties Malus sylvestris (green apple), Malus pumila (red apple) and Syzygium samarangense (wax apple). The results showed that all apple varieties inhibited α-amylase (IC50=12.66–16.98 µg/ml) and α-glucosidase (13.55–16.23 µg/ml) in a dosedependent manner, with green apple showing the highest inhibitory activity while wax apple had the least. Similarly, all apple varieties showed dose-dependent DPPH radical scavenging activity (EC50=222.92–278.71 µg/ml) with green apple also showing the highest scavenging activity while wax apple showed the least. Furthermore, the aqueous extracts of the apple varieties dosedependently inhibited Fe2+-induced lipid peroxidation in rat pancreas (38.60–53.57 µg/ml), with wax apple exhibiting the highest inhibitory potential. Also, the total phenol content of the apple varieties ranged from 16.14 to 17.45 mg GAE/100g, while the flavonoid content ranged from 4.17 to 5.56 mg QUE/100 g, with green apple having the highest total phenolic and flavonoid contents. The biological activities exhibited by the apple varieties could be attributed to the presence of biologically active photochemicals. Furthermore, the apple variety (green apple) with the highest phenolic content showed the best overall activity, indicating the potent role of phenolic compounds in the management of diabetes, thereby providing biochemical support for the use of apples as a functional food in diabetes management

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

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

Phenolic Extract from Moringa oleifera

This study was designed to determine the antioxidant properties and inhibitory effects of extract from Moringa oleifera leaves on angiotensin-I-converting enzyme (ACE) and arginase activities in vitro. The extract was prepared and phenolic (total phenols and flavonoid) contents, radical (nitric oxide (NO), hydroxyl (OH)) scavenging abilities, and Fe2+-chelating ability were assessed. Characterization of the phenolic constituents was done via high performance liquid chromatography-diode array detection (HPLC-DAD) analysis. Furthermore, the effects of the extract on Fe2+-induced MDA production in rats’ penile tissue homogenate as well as its action on ACE and arginase activities were also determined. The extract scavenged NO∗, OH∗, chelated Fe2+, and inhibited MDA production in a dose-dependent pattern with IC50 values of 1.36, 0.52, and 0.38 mg/mL and 194.23 µg/mL, respectively. Gallic acid, chlorogenic acid, quercetin, and kaempferol were the most abundant phenolic compounds identified in the leaf extract. The extract also inhibited ACE and arginase activities in a dose-dependent pattern and their IC50 values were 303.03 and 159.59 µg/mL, respectively. The phenolic contents, inhibition of ACE, arginase, and Fe2+-induced MDA production, and radical (OH∗, NO∗) scavenging and Fe2+-chelating abilities could be some of the possible mechanisms by which M. oleifera leaves could be used in the treatment and/or management of erectile dysfunction

Distribution of Phenolic Contents, Antidiabetic Potentials, Antihypertensive Properties, and Antioxidative Effects of Soursop (Annona muricata L.) Fruit Parts In Vitro

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 ( -amylase and -glucosidase) and hypertension [angiotensin-I converting enzyme (ACE)]. Radicals scavenging and Fe 2+ chelation abilities and reducing property as well as phenolic contents of the extracts were also determined. Our data revealed that the extracts inhibited -amylase and -glucosidase and ACE activities dose-dependently. The effective concentration of the extract causing 50% antioxidant activity (EC 50 ) revealed that pericarp extract had the highestamylase (0.46 mg/mL), -glucosidase (0.37 mg/mL), and ACE (0.03 mg/mL) inhibitory activities while the seed extract had the least [ -amylase (0.76 mg/mL); -glucosidase (0.73 mg/mL); and ACE (0.20 mg/mL)]. Furthermore, the extracts scavenged radicals, reduced Fe 3+ to Fe 2+ , and chelated Fe 2+ . 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

Aqueous extract from Ficus capensis leaves inhibits key enzymes linked to erectile dysfunction and prevent oxidative stress in rats' penile tissue

Context: Ficus capensis Thunb (Moraceae) is a medicinal plant widely grown in tropical and subtropical regions with the leaf decoction commonly taken in traditional folklore as fertility agent in men for ages. Aim: This study investigated the effects of aqueous extract from Ficus capensis leaves on angiotensin-I-converting enzyme (ACE), acetylcholinesterase (AChE) and arginase activities in vitro. The antioxidant properties of the extract as typified by the abilities to scavenge radicals [nitric oxide (NO), hydroxyl (OH)], chelate Fe2+  and inhibit Fe2+ -induced lipid peroxidation were also assessed. Methods: The aqueous extract (1:10 w/v) of Ficus capensis leaves was prepared and the ability of the extract to inhibit arginase, angiotensin I –converting enzyme (ACE), acetylcholinesterase (AChE) and antioxidant properties of the extract in rat’s penile tissue in vitro was investigated using various spectrophotometric methods. Phenolic constituent was carried-out using high performance liquid chromatography coupled with diode array detection (HPLC - DAD). Results: The extract inhibited ACE (IC50 = 52.17), AChE (IC50 = 172.60 μg/mL) and arginase (IC50 = 112.50 μg/mL) activities in a dose-dependent pattern. Gallic acid, quercetin, caffeic acid, ellagic acid, rutin and chlorogenic acid were the most abundant phenolic compounds identified in the sample. Furthermore, extract scavenged NO (IC50 = 0.12 μg/mL) and OH (IC50 = 0.53 μg/mL) radicals, chelated Fe2+  (IC50 = 0.16 μg/mL) and inhibited Fe2+  lipid peroxidation (IC50 = 435.17 μg/mL) dose-dependently. Conclusion: Inhibition of ACE, AChE, arginase, Fe2+ -induced lipid peroxidation as well as radical scavenging and Fe2+ -chelating abilities could be some of the possible mechanisms by which F. capensis leaves could be used in the treatment/management of erectile dysfunction (ED). Keywords: Ficus capensis, Erectile dysfunction, ACE, Arginase, AChE, Polyphenol

Phenolic characterization, antioxidant activities, and inhibitory effects of Physalis angulata and Newbouldia laevis on enzymes linked to erectile dysfunction

This study reports the phenolic composition, antioxidant activity, and capacity of Physalis angulata and Newbouldia laevis leaves to inhibit enzymes (phosphodiesterase-5′ [PDE-5′], arginase, acetylcholinesterase [AChE], and angiotensin-I converting enzyme [ACE]) linked to erectile dysfunction. High-performance liquid chromatography–diode array detector analysis of the aqueous extracts revealed the presence of phenolic acids (caffeic, ellagic, chlorogenic, and gallic acids) and flavonoids (quercetin, rutin, isoquercitrin, kaempferol, and quercitrin). N. laevis exhibited significantly higher inhibitory effects on PDE-5′, arginase, and ACE activities compared to P. angulata. There was no significant (P < 0.05) difference in the AChE inhibitory activities of both extracts. Furthermore, P. angulata exhibited lower radical scavenging and chelating abilities compared to N. laevis. These findings revealed that P. angulata and N. laevis leaves are good candidates for the development of functional foods with potentials to improve erectile function

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

In vitro neuroprotective potentials of aqueous and methanol extracts from Heinsia crinita leaves

This study was designed to determine the neuroprotective potentials of aqueous and methanol extracts from Heinsia crinita leaves in vitro. The total phenol and flavonoid contents of the extracts were determined using colorimetric method while phenolic characterization of the leaf was analyzed via high performance liquid chromatography-diode array detector (HPLC-DAD). The effects of the extracts on Fe2+-induced lipid peroxidation in rats’ brain homogenate, monoamine oxidase (MAO), Na+/K+-ATPase, acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) activities were also assessed. The aqueous extract had higher total phenol and flavonoid contents than the methanol extract. HPLC-DAD revealed that quercetin ellagic, chlorogenic and caffeic acids were the most abundant phenolic compounds in the leaves. The aqueous extract had higher inhibitory effects on MAO, AChE and BChE activities while there was no significant difference between their Fe2+-induced lipid peroxidation inhibitory effects. Furthermore, both extracts stimulated Na+/K+-ATPase activity; however, methanol extract had higher stimulatory effect. The neuroprotective properties of H. crinita leaves could be associated with its inhibitory effects on Fe2+-induced lipid peroxidation and modulation of MAO, Na+/K+-ATPase, AChE, and BChE activities. Therefore, H. crinita leaves could be used as a functional food and dietary intervention for the management of some neurodegenerative diseases. Nevertheless, the aqueous extracts exhibited better neuroprotective properties