In Vitro Studies on the Antioxidant Property and Inhibition of α-Amylase, α-Glucosidase, and Angiotensin I-Converting Enzyme by Polyphenol-Rich Extracts from Cocoa (Theobroma cacao) Bean

GC-MS fingerprinting, nutritional composition, in vitro pharmacological activities and molecular docking studies of Piper chaba from Uttarakhand region

This study aimed to evaluate the potential therapeutic effects of Piper chaba (PC) growing in the northern region of India, having differences in the phytochemicals, nutritional content, antimicrobial and antioxidant properties by reducing power assay (RPA), 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay, phosphomolybdate assay, and antidiabetic potential by α-amylase assay with change in the geographical location. Outcomes of the gas chromatography-mass spectrometry (GC-MS) analysis revealed that phytochemicals such as piperine (46.69%), kusunokinin (8.9%), and sitostenone (7.57%) are the prominent compounds found in PC. The plant has also shown a good nutritional value, i.e., iron (11.25 mg), calcium (147 mg), and vitamin C (9.30 mg) per 100 g. PC has a higher phenolic content than other species (⁓ 13.75 g/100 g plant powder). Among the four tested bacterial strains, the extract is best responsive toward Escherichia coli (35 ± 0.68 mm) which is more than the standard ciprofloxacin (24 ± 0.8 mm). Similarly, among two tested fungal strains, Saccharomyces cerevisiae shows the best zone of inhibition (ZOI) (27.5 ± 0.8 mm), which is greater than tat of standard amphotericin (20.25 ± 0.28 mm). The DDPH method demonstrated the highest antioxidant activity (⁓ 42.61 ± 1.82 µg/ml). IC50 for the antidiabetic potential of PC was found to be 23.09 ± 0.3 µg/ml against α-amylase assay. A molecular docking study revealed that three compounds, piperine, sitostenone and kusunokinin, showed strong binding affinity toward bacterial tyrosyl-tRNA synthetases, fungal dihydrofolate reductase, and α-amylase, respectively. Therefore, the findings of the current study indicate that PC can be considered as a source of food and medicines, either in the form of traditional preparations or as pure active constituents.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13205-024-03996-7.

Chromatographic Fingerprinting of Cacao Pod Husk Extracts (Theobroma cacao L.): Exploring Antibacterial, Antioxidant, and Antidiabetic Properties with In Silico Molecular Docking Analysis

Natural drugs derived from plants are becoming more popular because of their apparent biological efficacy, affordability, and safety. A byproduct of cocoa farms, cocoa pod husk (CPH), is often disregarded yet contains an abundance of phenolic chemicals that have antimicrobial and antioxidant features, which has led to intensive investigation into possible biomedical applications. In order to identify crucial functional groups and phytochemical components, we carefully examined the 80% ethanol and dichloromethane extracts of CPH using gas chromatography-mass spectrometry (GC-MS) and HPLC. The antibacterial and antioxidant properties of such extracts and their impact on cytotoxicity and α-glucosidase were explored. According to our results, the 80% ethanol and dichloromethane extracts contained 19 and 12 phytochemical components, respectively. Interestingly, at 250 µg/mL, all CPH extracts showed strong antibacterial properties that totally prevented the bacterial growth. At 66.6% and 82.7%, respectively, the ethanol and dichloromethane extracts showed impressive antioxidant and DPPH scavenging capabilities where the ethanol extract showed a substantially lower IC50 value of 35.26 µg/mL than the dichloromethane extract, which had an IC50 value of 23.88 µg/mL. Furthermore, the α-glucosidase inhibitory effect of the dichloromethane extract was found to be better, as shown by its IC50 value of 126.5 µg/mL, which was lower than that of the ethanol extract at 151.3 µg/mL. The extracts' compatibility was verified by cytotoxicity tests, which revealed no appreciable alterations in the cell lines. Additionally, novel in silico molecular docking experiments were performed on 25 discovered compounds, providing insight into their possible bioactivity. Broad-spectrum activities of extracts were confirmed by molecular docking investigations aimed at interacting with α-glucosidase proteins. Our thorough analysis makes CPH extracts seem like the excellent candidates for biomedical uses. These results provide new insights into the therapeutic potential of CPH extracts and pave the way for the development of innovative medications and natural remedies.

Effect of Enzymatic Biotransformation on the Hypotensive Potential of Red Grape Pomace Extract

Hypertension is a widespread health risk, affecting over a billion people and causing 9 million deaths per year. The Renin-Angiotensin-Aldosterone System (RAAS) is a primary target for hypertension treatment, and it is primarily treated through drugs that inhibit the Angiotensin I-Converting Enzyme (ACE). In addition to pharmacological treatment, various plants are recommended in traditional medicine for blood pressure regulation. This study aimed to produce high-phenolic-content extracts with and without enzymatic assistance from red grape pomace and evaluate their antioxidant capacity and ACE inhibitory potential. The total phenolic content (TPC) was measured, and phenolic identification was performed using HPLC analysis. In addition, the antioxidant capacity and anti-hypertensive potential were determined via in vitro assays. There was no statistical difference in the TPC antioxidant capacity between the extraction methods. Otherwise, when considering the extraction yield, the enzymatic process recovered around 70% more phenolic compounds from the pomace, and the phenolic profile was changed. Enzymatic assistance also significantly increased the ACE inhibitory potential in the grape pomace extract. This study demonstrates the viability of upcycling grape pomace to obtain bioactive compounds and to reduce their environmental impact, and highlights the influence of the enzymatic extraction on the hypotensive potential of the extract.

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.

Theobroma cacao and Theobroma grandiflorum: Botany, Composition and Pharmacological Activities of Pods and Seeds

Cocoa and cupuassu are evergreen Amazonian trees belonging to the genus Theobroma, with morphologically distinct fruits, including pods and beans. These beans are generally used for agri-food and cosmetics and have high fat and carbohydrates contents. The beans also contain interesting bioactive compounds, among which are polyphenols and methylxanthines thought to be responsible for various health benefits such as protective abilities against cardiovascular and neurodegenerative disorders and other metabolic disorders such as obesity and diabetes. Although these pods represent 50-80% of the whole fruit and provide a rich source of proteins, they are regularly eliminated during the cocoa and cupuassu transformation process. The purpose of this work is to provide an overview of recent research on cocoa and cupuassu pods and beans, with emphasis on their chemical composition, bioavailability, and pharmacological properties. According to the literature, pods and beans from cocoa and cupuassu are promising ecological and healthy resources.

Evaluation of chemical composition, in vitro antioxidant, and antidiabetic activities of solvent extracts of Irvingia gabonensis leaves

Irvingia gabonensis commonly referred to as wild mango or ogbono is a tropical plant with both nutritional and medicinal uses. The present study was designed to evaluate the chemical composition, in vitro antioxidant activity, and inhibitory activity of carbohydrate hydrolyzing enzymes related to diabetes by different extracts of the plant. From the results of the study, Total Phenolic Content (TPC) was highest in the aqueous and ethanol extracts (367.30 ± 00 mg/100g GAE) compared to the chloroform and n-hexane extracts whereas the Total Flavonoid Content (TFC) was highest (230.69 ± 0.18 mg/100g QE) in the ethanol extract. Analysis of the in vitro antioxidant activity showed that the ethanol extract also possessed the highest 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity (IC₅₀: 21.42 ± 0.05 μg/ml) and hydroxyl radical scavenging activity (81.43 ± 0.11%) compared to other solvent extracts. The aqueous extract had the highest (23.91 ± 0.04 mM Fe++ equivalent) ferric antioxidant reducing power (FRAP). However, the antioxidant activity of the extracts was significantly lower than that of the reference compounds used for the study (butylated hydroxytoluene and Gallic acid). In vitro antidiabetic activity of the extracts was measured based on inhibition of α-amylase and α-glucosidase. The aqueous extract had the highest α-amylase and α-glucosidase inhibitory activity followed by the ethanol extract compared to the chloroform and n-hexane extracts. The inhibitory activity of the aqueous extract against both enzymes was higher compared to the reference compound Acarbose. Gas Chromatography-Mass Spectrometry analysis of the extracts revealed the presence of chemical constituents including fatty acids, vitamin, phytosterols, aromatic compounds, glycosides. The interaction of these compounds with α-amylase and α-glucosidase was evaluated in silico by molecular docking. Phytosterols namely, campesterol, stimasterol and γ-sitosterol had the best binding affinities to α-amylase and α-glucosidase. In conclusion, the results of this study revealed that the aqueous and ethanol extracts of Irvingia gabonensis had the highest phenolic content, antioxidant activity, and in vitro antidiabetic activity. These results offer a scientific explanation for the mode of preparation and traditional use of the plant in the treatment of diabetes.

Acute Effects of Cocoa Flavanols on Blood Pressure and Peripheral Vascular Reactivity in Type 2 Diabetes Mellitus and Essential Hypertension

Background: Type 2 diabetes mellitus (T2DM) is associated with a high risk of vascular complications. Interestingly, cocoa flavanols (CF) can exert beneficial vascular effects in non-diabetic subjects. However, these effects have only been scarcely studied in T2DM. Therefore, we performed a study to assess the effects on vascular reactivity of a single dose of CF (790 mg) in T2DM and whether certain antihypertensive drugs may modulate these effects. Methods: 24 non-diabetic and 11 T2DM subjects were studied in a cross-over design. Fasting blood samples, blood pressure (BP), and arterial vasoreactivity (flow-mediated dilation) were assessed before and 70 min after capsule ingestion. Muscle microvascular reactivity was only assessed after capsule ingestion. Age, waist-to-hip ratio, BP at baseline, and the use of antihypertensive drugs were regarded as covariates in a mixed models analysis. Results: CF ingestion did not affect any parameter. However, independent of the type of capsules ingested, a decrease in diastolic BP by 3 mmHg (95% CI: −4.0; −2.0) and an increase in the change in brachial artery diameter (pre vs. post occlusion) by 0.06 mm (95% CI: 0.01; 0.12) were detected in the non-diabetic group, while they remained unchanged in the T2DM group. Conclusion: No beneficial effects of CF were detected on vascular reactivity parameters in T2DM and non-diabetic participants.

Starch composition, glycemic indices, antioxidant properties and carbohydrate hydrolyzing enzymes activities of African star apple fruit parts

Background

African star apple (Chrysophyllum albidum) is a traditonal fruit, which is predominant in tropical regions with the fruit parts consumed by the populace and used in folklore to manage diabetes. However, the likely activity mechanism is still undetermined. The current study examined and compared the inhibitory abilities of African star apple fruit parts on selected key enzymes related to diabetes mellitus in the pancreas tissue of rat.

Methods

Inhibitory effect of aqueous extract (1:10 w/v) of African star apple fruit parts (pulp, cotyledon, seed coat and pulp coat) on the activities of α-amylase, α-glucosidase, as well as their starch composition, phenolic constituents, estimated glycemic index, and antioxidant properties were assessed.

Results

The fruit parts showed low sugar, eGI, amylose, and amylopectin contents. The analysis also showed that the fruit parts inhibited α-glucosidase and α-amylase activities and exhibited antioxidant properties. Furthermore, the fruit parts contain high concentrations of beta-amyrin acetate, eleagine, epicatechin, epigallocatechin, skatole, stigmasterol and tetrahydro − 2- methylharman as revealed by HPLC-DAD.

Conclusion

The fruit part low estimated glycemic indices, strong antioxidant properties, inhibition of α-amylase and α-glucosidase activities exhibited might be related to the bioactive compounds contained in the extract. This could also be a potential mechanism for the use in the prevention and management of type-2 diabetes. Nevertheless, the African star apple pulp coat displayed the highest property in comparison to other parts of the fruit.

Microencapsulation as a tool to counteract the typical low bioavailability of polyphenols in the management of diabetes

Polyphenols are secondary metabolites widely distributed in many plant foods, such a tea, coffee, chocolate and fruits. The consumption of these compounds is related to the improvement or amelioration of many diseases, including diabetes. Nevertheless, the great barrier to the therapeutic use of polyphenols is the low bioavailability of these compounds once ingested. For that reason, the encapsulation of polyphenols in different matrices may protect them from digestion and improve their release and subsequent absorption to obtain target-specific health effects. Some studies have reported the beneficial effect of encapsulation to increase both bioavailability and bioaccessibility. However, these works have mostly been carried out in vitro and few studies are specifically addressed at improving diabetes. In the current work, an overview of the knowledge related to nanoparticles and their use in the diabetic condition has been reviewed.

Medicinal plants with concomitant anti-diabetic and anti-hypertensive effects as potential sources of dual acting therapies against diabetes and hypertension: A review

ETHNOPHARMACOLOGICAL RELEVANCE

Diabetes and hypertension are pathophysiologically related diseases that co-exist with a wider complex of metabolic diseases having similar set of risk factors. There are numerous ethnopharmacological evidences on the anti-diabetic and/or anti-hypertensive properties of medicinal plants from various parts of the world, which are used as therapies to concomitantly manage diabetes and hypertension.

AIM OF THE REVIEW

This article reviewed findings on medicinal plants with both anti-diabetic and anti-hypertensive effects reported in same experimental study to facilitate the development of dual-acting therapies against diabetes and hypertension.

MATERIALS AND METHODS

A literature search was carried out on different scientific search engines including, but not limited to "PubMed", "Google Scholar", "Scopus" and ScienceDirect to identify published data in which plants in same experimental studies were reported to possess both anti-hyperglycemic and anti-hypertensive effects. Subsequently, the anti-diabetic/anti-hypertensive potency ratio (ψ) of the medicinal plants was computed.

RESULTS

Sixty-four studies with 102 plant species matched the selection criteria. Members of the Fabaceae family were the most investigated plants, while the ψ greatly varied across the plants, with only 11 plants having a ψ ≃ 1. Withania somnifera Dunal was the only plant reported to show blood glucose-lowering and diuretic effects in humans, comparable to daonil. Caffeic acid, chlorogenic acid, caftaric acid, cichoric acid, verbascoside, leucosceptoside A, isoacteoside, fucoxanthin and nicotinamide were the reported dual acting anti-diabetic and anti-hypertensive compounds identified and/or isolated in the plants.

CONCLUSIONS

This review suggests that medicinal plants possess varied therapeutic dynamics against hypertension and diabetes that could be exploited for the discovery of therapeutic preparation(s) or agent(s) for treating the two diseases.

Cardioprotective Mechanisms of Cocoa

Cardiovascular diseases are the main cause of deaths in highly developed countries. Dietetic interventions that involve recommendations for consumption of products with a confirmed health-improving action are an important aspect of prevention of cardiovascular diseases. Cocoa is an alimentary product with significant cardioprotective potential due to its high content of bioactive compounds. The aim of the present study was to review the most recent literature concerning the effectiveness and mechanisms of action of compounds contained in cocoa with regard to selected cardiovascular risk factors and cardiometabolic markers. Study results indicate that cocoa consumption, especially in the form of dark chocolate with high flavonoid content, may be a good strategy to diminish cardiovascular risk due to its beneficial effect on platelet aggregation, decreasing blood pressure, diminishing dyslipidemia, and decreasing blood plasma glucose concentration. Many studies have shown that cocoa-derived flavonoids have antioxidant and anti-inflammatory activity and also play a significant role in preventing insulin resistance. However, in order to completely confirm the potential cardiovascular benefits, it is necessary to conduct larger and longer studies, also with regard to potential dangers associated with long-term consumption of large amounts of flavonoids and determination of a safe and effective dose. Key teaching points Cocoa consumption may be a good strategy in diminishing cardiovascular risk. Beneficial effects on platelet aggregation, blood pressure, dyslipidemia, glycemia, as well as antioxidant and anti-inflammatory activity are observed. There is a need to conduct larger and longer studies to determine a safe and effective dose of cocoa flavonoids.

Evaluation of free radical scavenging capacity of methoxy containing-hybrids of thiosemicarbazone-triazole and their influence on glucose transport

Background

Diabetes mellitus is a metabolic disease in which the body is unable to produce insulin or respond to insulin production, consequently leading to abnormal metabolism of carbohydrates, lipids and proteins causing elevation of glucose in the blood. Oxidative stress, an imbalance between the production of free radicals and body antioxidant system has been implicated in the pathogenesis of diabetes. Free radicals attack important macromolecules leading to cell damage. Antioxidants are intimately involved in the prevention of damage caused by free radicals.

Methods

The anti-diabetic effects of hybrid compounds (2a-h) of thiosemicarbazone and triazole containing methoxy groups at C (4) positions were tested against genes involved in glucose metabolism (Glut-4, Mef2a and Nrf-1) using quantitative real time PCR (qPCR). Free radical scavenging capacity (FRAP, TEAC, DPPH and ORAC) of the hybrids was also carried out by using established antioxidant capacity assays.

Results

From the results, hybrid compounds 2b and 2h showed more pronounced effects in up-regulating diabetes associated genes which are important in the up-regulation of glucose uptake. All the hybrid compounds also showed free radical scavenging abilities.

Conclusion

In conclusion, hybrid compounds (2b and 2h) can be useful as potential drugs for the management of diabetes mellitus.

Effect of cooking on glycemic index, antioxidant activities, α-amylase, and α-glucosidase inhibitory properties of two rice varieties

This study was designed to investigate the influence of cooking on the glycemic index (GI), amylose, and amylopectin contents of two rice varieties. Two rice varieties (foreign long rice and ofada) were sourced for, divided into two, one portion cooked and the other used raw. The sugar, starch, amylose, and amylopectin contents as well as glycemic indices, antioxidant properties, and the ability of the rice to inhibit carbohydrate-hydrolyzing enzymes (α-amylase and α-glucosidase) were determined. In addition, polyphenol content was determined. The results revealed that cooking caused a significant increase in starch content of the rice varieties. In the same vein, cooking increases the amylopectin content but has no effect on the amylose content. In addition, cooking shows no effect on polyphenol content but significantly increases radical scavenging ability of rice varieties used in this study. Furthermore, cooking lower the α-amylase and α-glucosidase inhibitory properties of two rice varieties except for foreign rice. However, the inhibitory effect of both cooked and raw foreign and ofada rice on α-amylase and α-glucosidase coupled with their low GI may explain their important role in controlling blood glucose level.

Inhibitory Reactivity of Capsaicin with α-Amylase and α-Glucosidase Related to Antidiabetes using Molecular Docking and Quantum Calculation Methods

This work aims to investigate the inhibitory activity of capsaicin, which is one of capsaicinoid compounds, on these enzymes using a molecular docking and quantum calculation. Acarbose, a commercial diabetes drug, was also investigated for comparison. The docking results revealed that acarbose yields better inhibition efficiency with binding free energy (ΔGbinding) of about -8.2 to -11.9 kcal/mol, and inhibition constant (Ki) of about 0.0002 to 0.4 µM, whereas capsaicin provided the ΔGbinding of -5.8 to -6.1 kcal/mol and Ki of 23.7 to 45.9 µM. The total binding energy (ΔEbinding) between each inhibitor and amino acids in active site of enzyme obtained from quantum calculation with MP2/6-31G(d,p) level is in agreement with the ΔGbinding, i.e. the ΔEbinding of acarbose was larger negative than that of capsaicin. The amino acids interacting with inhibitor as hydrogen bond mainly contribute to the total binding energy. Nevertheless, it could be concluded that capsaicinoids have high potential to be developed as an alternative drug for diabetes disease.

Cocoa, Blood Pressure, and Vascular Function

Cardiovascular disease (CVD) represents the most common cause of death worldwide. The consumption of natural polyphenol-rich foods, and cocoa in particular, has been related to a reduced risk of CVD, including coronary heart disease and stroke. Intervention studies strongly suggest that cocoa exerts a beneficial impact on cardiovascular health, through the reduction of blood pressure (BP), improvement of vascular function, modulation of lipid and glucose metabolism, and reduction of platelet aggregation. These potentially beneficial effects have been shown in healthy subjects as well as in patients with risk factors (arterial hypertension, diabetes, and smoking) or established CVD (coronary heart disease or heart failure). Several potential mechanisms are supposed to be responsible for the positive effect of cocoa; among them activation of nitric oxide (NO) synthase, increased bioavailability of NO as well as antioxidant, and anti-inflammatory properties. It is the aim of this review to summarize the findings of cocoa and chocolate on BP and vascular function.

Oxidative stress and food supplementation with antioxidants in therapy dogs

The objective of this study was to evaluate the ability of a long-term antioxidant-supplemented diet to regulate the oxidative stress and general health status of dogs involved in animal-assisted intervention (AAI) programs. Oxidative stress is a consequence of the accumulation of reactive oxygen species (ROS). Exercise-induced oxidative stress can increase muscle fatigue and fiber damage and eventually leads to impairment of the immune system. A randomized, placebo-controlled, crossover clinical evaluation was conducted with 11 healthy therapy dogs: 6 females and 5 males of different breeds and with a mean age of 2.7 ± 0.8 y (mean ± SEM). The dogs were divided into 2 groups, 1 fed a high quality commercial diet without antioxidants (CD) and the other a high quality commercial diet supplemented with antioxidants (SD) for 18 wk. After the first 18 wk, metabolic parameters, reactive oxygen metabolite-derivatives (d-ROMs), and biological antioxidant potential (BAP) levels were monitored and showed a significant reduction of d-ROMs, triglycerides, and creatinine values in the SD group (P < 0.05) and a significant increase in amylase values in the CD group (P < 0.01). At the end of this period, groups were crossed over and fed for another 18 wk. A significant decrease in amylase and glutamate pyruvate transaminase (GPT) values was observed in the CD and SD group, respectively (P < 0.05). In conclusion, a controlled, balanced antioxidant diet may be a valid approach to restoring good cell metabolism and neutralizing excess free radicals in therapy dogs.

Dietary Phytochemicals: Natural Swords Combating Inflammation and Oxidation-Mediated Degenerative Diseases

Cumulatively, degenerative disease is one of the most fatal groups of diseases, and it contributes to the mortality and poor quality of life in the world while increasing the economic burden of the sufferers. Oxidative stress and inflammation are the major pathogenic causes of degenerative diseases such as rheumatoid arthritis (RA), diabetes mellitus (DM), and cardiovascular disease (CVD). Although a number of synthetic medications are used to treat these diseases, none of the current regimens are completely safe. Phytochemicals (polyphenols, carotenoids, anthocyanins, alkaloids, glycosides, saponins, and terpenes) from natural products such as dietary fruits, vegetables, and spices are potential sources of alternative medications to attenuate the oxidative stress and inflammation associated with degenerative diseases. Based on in vitro, in vivo, and clinical trials, some of these active compounds have shown good promise for development into novel agents for treating RA, DM, and CVD by targeting oxidative stress and inflammation. In this review, phytochemicals from natural products with the potential of ameliorating degenerative disease involving the bone, metabolism, and the heart are described.

Antioxidative and Antidiabetic Effects of Natural Polyphenols and Isoflavones

Many polyphenols that contain more than two phenolic hydroxyl groups are natural antioxidants and can provide health benefits to humans. These polyphenols include, for example, oleuropein, hydroxytyrosol, catechin, chlorogenic acids, hesperidin, nobiletin, and isoflavones. These have been studied widely because of their strong radical-scavenging and antioxidative effects. These effects may contribute to the prevention of diseases, such as diabetes. Insulin secretion, insulin resistance, and homeostasis are important factors in the onset of diabetes, a disease that is associated with dysfunction of pancreatic β-cells. Oxidative stress is thought to contribute to this dysfunction and the effects of antioxidants on the pathogenesis of diabetes have, therefore, been investigated. Here, we summarize the antioxidative effects of polyphenols from the perspective of their radical-scavenging activities as well as their effects on signal transduction pathways. We also describe the preventative effects of polyphenols on diabetes by referring to recent studies including those reported by us. Appropriate analytical approaches for evaluating antioxidants in studies on the prevention of diabetes are comprehensively reviewed.

Effect of olive oil phenolic compounds on the expression of blood pressure-related genes in healthy individuals

PURPOSE

To investigate whether the ingestion of olive oil having different phenolic contents influences the expression of blood pressure-related genes, involved in the renin-angiotensin-aldosterone system, in healthy humans.

METHODS

A randomized, double-blind, crossover human trial with 18 healthy subjects, who ingested 25 mL/day of olive oils (1) high (366 mg/kg, HPC) and (2) low (2.7 mg/kg, LPC) in phenolic compounds for 3 weeks, preceded by 2-week washout periods. Determination of selected blood pressure-related gene expression in peripheral blood mononuclear cells (PBMNC) by qPCR, blood pressure and systemic biomarkers.

RESULTS

HPC decreased systolic blood pressure compared to pre-intervention values and to LPC, and maintained diastolic blood pressure values compared to LPC. HPC decreased ACE and NR1H2 gene expressions compared with pre-intervention values, and IL8RA gene expression compared with LPC.

CONCLUSIONS

The introduction to the diet of an extra-virgin olive oil rich in phenolic compounds modulates the expression of some of the genes related to the renin-angiotensin-aldosterone system. These changes could underlie the decrease in systolic blood pressure observed.

Inhibitory Effect of Heracleum persicum and Ziziphus jujuba on Activity of Alpha-Amylase

Postprandial hyperglycemia plays an important role in the development of type 2 diabetes. Inhibition of alpha-amylase was led to a delay in breaks down of starch and glycogen and prevented a rapid rise in blood sugar. Alpha-amylase was isolated by gel filtration chromatography Sephadex G-75 from bovine pancreas. Then, total methanolic extracts of plants were prepared and IC50 values of extracts on alpha-amylase were obtained and compared with acarbose IC50. The polyphenolic content of extracts and antioxidant capacity were determined by Folin-Ciocalteu test and DPPH test, respectively. The specific activity of alpha-amylase was 48.2 U/mg. For inhibition of alpha-amylase, IC50 values of H. persicum, Z. jujuba, and acarbose were 307, 827, and 113 μg/ml, respectively. For inhibition of DPPH radical, IC50 values of extracts were 235 and 701 μg/ml. Total phenolic contents of methanol extracts were 73.8±3.2 and 44.2±1.8 μg tannic acid equivalent/mg extract. Acarbose causes gastrointestinal symptoms and liver toxicity, but H. persicum and Z. jujuba decrease these side effects and prevent gastrointestinal disorders. Due to the high polyphenolic content and antioxidant capacity of these plants and significant inhibitory effect of the plants on alpha-amylase, these plants can be proposed for treatment of diabetic patients.

Phenolic content and anti-hyperglycemic activity of pecan cultivars from Egypt

CONTEXT

Pecans are commonly used nuts with important health benefits such as anti-hyperglycemic and anti-hyperlipidemic effects.

OBJECTIVE

A comparative investigation of the antihyperglycemic and total phenolic content of the leaves and shells of four pecan cultivars growing in Egypt was carried out. The selected cultivars (cv.) were Carya illinoinensis Wangneh. K. Koch. cv. Wichita, cv. WesternSchely, cv. Cherokee, and cv. Sioux family Juglandaceae.

MATERIALS AND METHODS

Total phenolic and flavonoid contents of the leaves and shells of pecan cultivars were carried out using Folin-Ciocalteu's and aluminum chloride assays, respectively. Moreover, HPLC profiling of phenolic and flavonoid contents was carried out using RP-HPLC-UV. In addition, in vivo anti-hyperglycemic activity of the ethanolic extracts (125 mg/kg bw, p.o.) of C. illinoinensis cultivars was carried out using streptozotocin (STZ)-induced diabetes in Sprague-Dawley rats for 4 weeks.

RESULTS AND DISCUSSION

Phenolic contents were higher in shells than leaves in all studied cultivars, while flavonoids were higher in leaves. Leaves and shells of cv. Sioux showed the highest phenolics (251.7 µg gallic acid equivalent (GAE)/g), and flavonoid contents (103.27 µg rutin equivalent (RE)/g and 210.67 µg quercetin equivalent (QE)/g), respectively. The HPLC profiling of C. illinoinensis cultivars resulted in the identification of eight flavonoids (five of these compounds are identified for the first time from pecan), and 15 phenolic acids (six are identified for the first time from pecan). Leaves of cv. Sioux revealed the most potent decrease in blood glucose and glycated hemoglobin (HbA1c%) (194.9 mg/dl and 6.52%, respectively), among other tested cultivars. Moreover, leaves of cv. Sioux significantly elevated serum total antioxidant capacity (TAC) and reduced glutathione (GSH) (0.33 mMol/l and 30.68 mg/dl, respectively), and significantly suppressed the markers of both lipid peroxidation (malondialdehyde, MDA) and protein oxidation (protein carbonyl, PC) (14.25 µmol/ml and 3.18 nmol/mg protein, respectively).

CONCLUSION

Different pecan cultivars showed significant variation in its phenolic and flavonoid contents and consequently their antioxidant and anti-hyperglycemic effects.

An Antioxidant Dietary Supplement Improves Brain-Derived Neurotrophic Factor Levels in Serum of Aged Dogs: Preliminary Results

Biological aging is characterized by a progressive accumulation of oxidative damage and decreased endogenous antioxidant defense mechanisms. The production of oxidants by normal metabolism damages proteins, lipids, and nucleotides, which may contribute to cognitive impairment. In this study 36 dogs were randomly divided into four groups and fed croquettes of different compositions for 6 months. We monitored derivatives of reactive oxygen metabolites (dROMs) and biological antioxidant potential (BAP) levels in dogs' plasma samples as well as brain-derived neurotrophic factor (BDNF) serum levels at the beginning and at the end of the dietary regime. Our results showed that a dietary regime, enriched with antioxidants, induced a significant decrease of plasma levels of dROMs (p < 0.005) and a significant increase in BDNF serum levels (p < 0.005) after six months. Thus, we hypothesized a possible role of the diet in modulating pro- and antioxidant species as well as BDNF levels in plasma and serum, respectively. In conclusion the proposed diet enriched with antioxidants might be considered a valid alternative and a valuable strategy to counteract aging-related cognitive decline in elderly dogs.