Methanolic extract of onion (Allium cepa) attenuates ischemia/hypoxia-induced apoptosis in cardiomyocytes via antioxidant effect

An ethnopharmacological, phytochemical, and pharmacological overview of onion (Allium cepa L.)

ETHNOPHARMACOLOGICAL RELEVANCE

Onion (Allium cepa L.) is one of the most widely distributed species within the Allium genus of family Amaryllidaceae. Onion has been esteemed for its medicinal properties since antiquity. It has been consumed for centuries in various indigenous cultures for the management of several ailments including microbial infections, respiratory, gastrointestinal, skin and cardio-vascular disorders, diabetes, renal colic, rheumatism, sexual impotence, menstrual pain, and headache. However, so far, there is a scarcity of recent data that compiles the plant chemistry, traditional practices, biological features, and toxicity.

AIM OF THE WORK

The aim of this review is to provide a comprehensive and analytical overview of ethnopharmacological uses, phytochemistry, pharmacology, industrial applications, quality control, and toxicology of onion, to offer new perspectives and broad scopes for future studies.

MATERIALS AND METHODS

The information gathered in this review was obtained from various sources including books, scientific databases such as Science Direct, Wiley, PubMed, Google Scholar, and other domestic and foreign literature.

RESULTS

Onion has a long history of use as a traditional medicine for management of various conditions including infectious, inflammatory, respiratory, cardiovascular diseases, diabetes, and erectile dysfunction. More than 400 compounds have been identified in onion including flavonoids, phenolic acids, amino acids, peptides, saponins and fatty acids. The plant extracts and compounds showed various pharmacological activities such as antimicrobial, antidiabetic, anti-inflammatory, anti-hyperlipidemic, anticancer, aphrodisiac, cardioprotective, and neuroprotective activities. In addition to its predominant medicinal uses, onion has found various applications in the functional food industry.

CONCLUSION

Extensive literature analysis reveals that onion extracts and bioactive constituents possess diverse pharmacological activities that can be beneficial for treating various diseases. However, the current research primarily revolves around the documentation of ethnic pharmacology and predominantly consists of in vitro studies, with relatively limited in vivo and clinical studies. Consequently, it is imperative for future investigations to prioritize and expand the scope of in vivo and clinical research. Additionally, it is strongly recommended to direct further research efforts towards toxicity studies and quality control of the plant. These studies will help bridge the current knowledge gaps and establish a solid basis for exploring the plant's potential uses in a clinical setting.

Natural Products in Cardiovascular Diseases: The Potential of Plants from the Allioideae Subfamily (Ex-Alliaceae Family) and Their Sulphur-Containing Compounds

Cardiovascular diseases (CVDs) are the leading cause of mortality worldwide and, together with associated risk factors such as diabetes, hypertension, and dyslipidaemia, greatly impact patients' quality of life and health care systems. This burden can be alleviated by fomenting lifestyle modifications and/or resorting to pharmacological approaches. However, due to several side effects, current therapies show low patient compliance, thus compromising their efficacy and enforcing the need to develop more amenable preventive/therapeutic strategies. In this scenario, medicinal and aromatic plants are a potential source of new effective agents. Specifically, plants from the Allioideae subfamily (formerly Alliaceae family), particularly those from the genus Allium and Tulbaghia, have been extensively used in traditional medicine for the management of several CVDs and associated risk factors, mainly due to the presence of sulphur-containing compounds. Bearing in mind this potential, the present review aims to gather information on traditional uses ascribed to these genera and provide an updated compilation of in vitro and in vivo studies validating these claims as well as clinical trials carried out in the context of CVDs. Furthermore, the effect of isolated sulphur-containing compounds is presented, and whenever possible, the relation between composition and activity and the mechanisms underlying the beneficial effects are pointed out.

A review of the protective effects of quercetin-rich natural compounds for treating ischemia-reperfusion injury

Ischemia-reperfusion (IR) injury causes dysfunction of tissues and organs, and oxidative stress plays an important role. During IR, reactive oxygen species (ROS) are increased. Antioxidants are used to decrease ROS associated with IR. We review the protective effects of quercetin-rich natural antioxidants against IR. We searched PubMed, ScienceDirect, Scopus and Cochrane databases using the keywords: ischemic reperfusion, quercetin, antioxidant and herbal medicine. The effects of quercetin during IR have been reported for animal models in vitro and in vivo. Quercetin-rich plants including Abelmoschus esculentus, coriander, Hypericum perforatum, onion, Psidium guajava, buckwheat and Rosa laevigata Michx have been used to reduce oxidative stress damage to various organs during IR.

Pharmacological Properties of Allium cepa, Preclinical and Clinical Evidences; A Review

Onion or Allium cepa (A. cepa) is one of the most important condiment plants grown and consumed all over the world. This plant has various therapeutic effects attributed to its constituents, such as quercetin, thiosulphinates and phenolic acids. In the present article, various pharmacological and therapeutic effects of A. cepa were reviewed. Different online databases using keywords such as onion, A. cepa, therapeutic effects, and pharmacological effects until the end of December 2019 were searched for this purpose. Onion has been suggested to be effective in treating a broad range of disorders, including asthma, inflammatory disorders, dysentery, wounds, scars, keloids and pain. In addition, different studies have demonstrated that onion possesses numerous pharmacological properties, including anti-cancer, anti-diabetic and anti-platelet properties as well as the effect on bone, cardiovascular, gastrointestinal, nervous, respiratory, and urogenital systems effects such as anti-osteoporosis, anti-hypertensive, antispasmodic, anti-diarrheal, neuro-protective, anti-asthmatic and diuretic effects. The present review provides detailed the various pharmacological properties of onion and its constituents and possible underlying mechanisms. The results of multiple studies suggested the therapeutic effect of onion on a wide range of disorders.

Advances in the Protective Mechanism of NO, H2S, and H2 in Myocardial Ischemic Injury

Myocardial ischemic injury is among the top 10 leading causes of death from cardiovascular diseases worldwide. Myocardial ischemia is caused mainly by coronary artery occlusion or obstruction. It usually occurs when the heart is insufficiently perfused, oxygen supply to the myocardium is reduced, and energy metabolism in the myocardium is abnormal. Pathologically, myocardial ischemic injury generates a large number of inflammatory cells, thus inducing a state of oxidative stress. This sharp reduction in the number of normal cells as a result of apoptosis leads to organ and tissue damage, which can be life-threatening. Therefore, effective methods for the treatment of myocardial ischemic injury and clarification of the underlying mechanisms are urgently required. Gaseous signaling molecules, such as NO, H₂S, H₂, and combined gas donors, have gradually become a focus of research. Gaseous signaling molecules have shown anti-apoptotic, anti-oxidative and anti-inflammatory effects as potential therapeutic agents for myocardial ischemic injury in a large number of studies. In this review, we summarize and discuss the mechanism underlying the protective effect of gaseous signaling molecules on myocardial ischemic injury.

Effects of Phenolic-Rich Onion (Allium cepa L.) Extract on the Growth Performance, Behavior, Intestinal Histology, Amino Acid Digestibility, Antioxidant Activity, and the Immune Status of Broiler Chickens

The effect of phenolic-rich onion extract (PROE), as a feed additive, was evaluated on the growth, carcass traits, behavior, welfare, intestinal histology, amino acid ileal digestibility "AID%," and the immune status of broiler chicks for 35 days. A total number of 400, 1-day-old broiler chicks (45.38 g ± 1.35) were allocated to four different treatments with 10 replicates each (100 chicks/treatment) consisting of: T1, basal diet without additives (control treatment) (PROE0); T2, basal diet + phenolic-rich onion extract (1 g/kg diet) (PROE1); T3, basal diet + phenolic-rich onion extract (2 g/kg diet) (PROE2); and T4, basal diet + phenolic-rich onion extract (3 g/kg diet) (PROE3). An increase in the final body weight "FBW," bodyweight gain "BWG," and feed consumption was observed (P < 0.05) at different PROE levels. Also, the thymus and bursa percentages were increased in the PROE2 and PROE3 treatments (P < 0.05). The chicks fed on PROE supplemented diets had increased frequency of feeding and drinking and showed comfortable behavior (P < 0.05) with lesser aggression (P < 0.05). Additionally, an increase was observed in the antioxidant enzyme activity, phagocytic %, phagocytic index, and serum lysozyme activity in PROE supplemented treatments, with the best outcome reported in the PROE3 treatment (P < 0.01). IgM was increased in the birds fed with PROE2 and PROE3 diets (P < 0.01). PROE supplementation increased the AID% of lysine and methionine (P <0.01), PROE3 treatment increased the AID% of threonine (P < 0.05), and PROE2 and PROE3 treatments increased the AID% of leucine and isoleucine (P < 0.05). Besides, PROE2, and PROE3 treatments increased the villus height and width, mucosal thickness, and goblet cell count from the duodena, jejuna, and ilea (P < 0.05) compared to control treatment. Based on these results, we concluded that the dietary addition of phenolic-rich onion extracts can improve the growth rate of broiler chicken by improving the AID% of amino acids and intestinal histology. Also, it can improve the welfare, antioxidant enzymes activity, and immune status of the birds. Phenolic-rich onion extracts can be used as a natural growth promoter in the poultry feed for good health and improved performance.

Protective effect of Nelumbo nucifera (Gaertn.) against H2O2-induced oxidative stress on H9c2 cardiomyocytes

Ischemic heart disease (IHD), a severe condition of myocardium facing impediment in the supply of basic needs for cellular metabolism is caused by atherosclerosis. Though statin drugs could control the use of surgery on IHD patients, the complete rehabilitation or prophylaxis can be achieved through herbal-based medicines viz. either in the form of crude extract or pure phytocompounds. In the present study, pretreatment with leaf extract of Nelumbo nucifera Gaertn. was investigated for cardioprotective activity-in vitro by mitigating H₂O₂-induced oxidative stress. Analysis such as estimation of antioxidants, lipid peroxidation, and DNA fragmentation assay revealed significant protective effect of plant extract on cardiomyocytes. Reactive oxygen species detection was done by using 2',7'-dichlorofluorescein diacetate, apoptosis detection with Acridine Orange/Ethidium Bromide and nuclear damage detection by diamidino-2-phenylindole which confirmed the protective effect of N. nucifera extract. In addition, gene expression studies of apoptotic regulatory genes (Bcl2 and Cas-9) resulted in significant protection of nucifera extract pretreated and maintained cells. To conclude, in vitro cardioprotective activity of N. nucifera against H₂O₂ induced oxidative stress was achieved at the concentration of 50 µg/ml. Therefore, major phytocompounds present in extract could be beneficial in managing cardiac complications in the future.

Biological Properties and Bioactive Components of Allium cepa L.: Focus on Potential Benefits in the Treatment of Obesity and Related Comorbidities

Common onion (Allium cepa L.) is one of the oldest cultivated plants, utilized worldwide as both vegetable and flavouring. This species is known to contain sulphur amino acids together with many vitamins and minerals. A variety of secondary metabolites, including flavonoids, phytosterols and saponins, have also been identified. Despite the predominant use of this plant as food, a wide range of beneficial effects have also been proved. Different biological properties, such as antioxidant, antimicrobial and antidiabetic, have been reported. The aim of this review is to provide an overview of the studies concerning the beneficial effects of this species against obesity and its related comorbidities, such as hyperlipidaemia, hypertension and diabetes. Both in vitro and in vivo results about onion dietary supplementation have been taken into account. Furthermore, this review examines the possible role of onion bioactive components in modulating or preventing weight-gain or related diseases, as well as the possible mechanisms behind their activity.

Tissue-Specific Accumulation of Sulfur Compounds and Saponins in Different Parts of Garlic Cloves from Purple and White Ecotypes

This study set out to determine the distribution of sulfur compounds and saponin metabolites in different parts of garlic cloves. Three fractions from purple and white garlic ecotypes were obtained: the tunic (SS), internal (IS) and external (ES) parts of the clove. Liquid Chromatography coupled to High Resolution Mass spectrometry (LC-HRMS), together with bioinformatics including Principal Component Analysis (PCA), Hierarchical Clustering (HCL) and correlation network analyses were carried out. Results showed that the distribution of these metabolites in the different parts of garlic bulbs was different for the purple and the white ecotypes, with the main difference being a slightly higher number of sulfur compounds in purple garlic. The SS fraction in purple garlic had a higher content of sulfur metabolites, while the ES in white garlic was more enriched by these compounds. The correlation network indicated that diallyl disulfide was the most relevant metabolite with regards to sulfur compound metabolism in garlic. The total number of saponins was almost 40-fold higher in purple garlic than in the white variety, with ES having the highest content. Interestingly, five saponins including desgalactotigonin-rhamnose, proto-desgalactotigonin, proto-desgalactotigonin-rhamnose, voghieroside D1, sativoside B1-rhamnose and sativoside R1 were exclusive to the purple variety. Data obtained from saponin analyses revealed a very different network between white and purple garlic, thus suggesting a very robust and tight coregulation of saponin metabolism in garlic. Findings in this study point to the possibility of using tunics from purple garlic in the food and medical industries, since it contains many functional compounds which can be exploited as ingredients.

Protective Effect of Tempol Against Hypoxia-Induced Oxidative Stress and Apoptosis in H9c2 Cells

Background

Hypoxia-induced oxidant stress and cardiomyocyte apoptosis are considered essential processes in the progression of heart failure. Tempol is a nitroxide compound that scavenges many reactive oxygen species (ROS) and has antioxidant and cardioprotective effects. This study aimed to investigate the protective effect of Tempol against hypoxia-induced oxidative stress and apoptosis in the H9c2 rat cardiomyoblast cell line, in addition to related mechanisms.

Material/Methods

H9c2 cells were pre-treated with Tempol, followed by hypoxia (37°C, 5% CO₂, and 95% N₂) for 24 h. Cell viability was detected using MTT assay. ROS level was evaluated using DCFH-DA. Lactate dehydrogenase (LDH), creatinine kinase (CK), malondialdehyde (MDA), catalase (CAT), and superoxide dismutase (SOD) were evaluated using the relevant kits. Cell apoptosis was determined by Annexin V/7-AAD double labelling. The expression of apoptosis-related molecules was assessed with RT-PCR analysis and Western blotting.

Results

Tempol protected H9c2 cells against hypoxia-induced injury, with characteristics of increased the cell viability and reduced LDH and CK release. Tempol also reduced oxidant stress by inhibiting ROS generation and lipid peroxidation, as well as enhancing antioxidant enzyme activity. Moreover, Tempol pretreatment upregulated the expression of Bcl-2 and downregulated the expression of Bax and caspase-3, thereby reducing hypoxia-induced apoptosis in H9c2 cells.

Conclusions

These results indicate that Tempol reduces the hypoxia-induced oxidant stress and apoptosis in H9c2 cells by scavenging free radicals and modulating the expression of apoptosis-related proteins.

Therapeutic Role of Functional Components in Alliums for Preventive Chronic Disease in Human Being

Objectives. Functional components in alliums have long been maintained to play a key role in modifying the major risk factors for chronic disease. To obtain a better understanding of alliums for chronic disease prevention, we conducted a systematic review for risk factors and prevention strategies for chronic disease of functional components in alliums, based on a comprehensive English literature search that was conducted using various electronic search databases, especially the PubMed, ISI Web of Science, and CNKI for the period 2007-2016. Allium genus especially garlic, onion, and Chinese chive is rich in organosulfur compounds, quercetin, flavonoids, saponins, and others, which have anticancer, preventive cardiovascular and heart diseases, anti-inflammation, antiobesity, antidiabetes, antioxidants, antimicrobial activity, neuroprotective and immunological effects, and so on. These results support Allium genus; garlic and onion especially may be the promising dietotherapeutic vegetables and organopolysulfides as well as quercetin mechanism in the treatment of chronic diseases. This review may be used as scientific basis for the development of functional food, nutraceuticals, and alternative drugs to improve the chronic diseases.

Chlorogenic acid analogues from Gynura nepalensis protect H9c2 cardiomyoblasts against H2O2-induced apoptosis

AIM

Chlorogenic acid has shown protective effect on cardiomyocytes against oxidative stress-induced damage. Herein, we evaluated nine caffeoylquinic acid analogues (1-9) isolated from the leaves of Gynura nepalensis for their protective effect against H₂O₂-induced H9c2 cardiomyoblast damage and explored the underlying mechanisms.

METHODS

H9c2 cardiomyoblasts were exposed to H₂O₂ (0.3 mmol/L) for 3 h, and cell viability was detected with MTT assay. Hoechst 33342 staining was performed to evaluate cell apoptosis. MMPs (mitochondrial membrane potentials) were measured using a JC-1 assay kit, and ROS (reactive oxygen species) generation was measured using CM-H₂ DCFDA. The expression levels of relevant proteins were detected using Western blot analysis.

RESULTS

Exposure to H₂O₂ markedly decreased the viability of H9c2 cells and catalase activity, and increased LDH release and intracellular ROS production; accompanied by a loss of MMP and increased apoptotic rate. Among the 9 chlorogenic acid analogues as well as the positive control drug epigallocatechin gallate (EGCG) tested, compound 6 (3,5-dicaffeoylquinic acid ethyl ester) was the most effective in protecting H9c2 cells from H₂O₂-induced cell death. Pretreatment with compound 6 (1.56-100 μmol/L) dose-dependently alleviated all the H₂O₂-induced detrimental effects. Moreover, exposure to H₂O₂ significantly increased the levels of Bax, p53, cleaved caspase-8, and cleaved caspase-9, and decreased the level of Bcl-2, resulting in cell apoptosis. Exposure to H₂O₂ also significantly increased the phosphorylation of p38, JNK and ERK in the H9c2 cells. Pretreatment with compound 6 (12.5 and 25 μmol/L) dose-dependently inhibited the H₂O₂-induced increase in the level of cleaved caspase-9 but not of cleaved caspase-8. It also dose-dependently suppressed the H₂O₂-induced phosphorylation of JNK and ERK but not that of p38.

CONCLUSION

Compound 6 isolated from the leaves of Gynura nepalensis potently protects H9c2 cardiomyoblasts against H₂O₂-induced apoptosis, possibly by inhibiting intrinsic apoptosis and the ERK/JNK pathway.

Allium cepa Extract and Quercetin Protect Neuronal Cells from Oxidative Stress via PKC-ε Inactivation/ERK1/2 Activation

Oxidative stress plays an important role in the pathophysiology of various neurologic disorders. Allium cepa extract (ACE) and their main flavonoid component quercetin (QCT) possess antioxidant activities and protect neurons from oxidative stress. We investigated the underlying molecular mechanisms, particularly those linked to the antioxidant effects of the ACE. Primary cortical neuronal cells derived from mouse embryos were preincubated with ACE or QCT for 30 min and exposed to L-buthionine sulfoximine for 4~24 h. We found that ACE and QCT significantly decreased neuronal death and the ROS increase induced by L-buthionine-S, R-sulfoximine (BSO) in a concentration-dependent manner. Furthermore, ACE and QCT activated extracellular signal-regulated kinase 1/2 (ERK1/2), leading to downregulation of protein kinase C-ε (PKC-ε) in BSO-stimulated neuronal cells. In addition, ACE and QCT decreased the phosphorylated levels of p38 mitogen-activated protein kinase. Our results provide new insight into the protective mechanism of ACE and QCT against oxidative stress in neuronal cells. The results suggest that the inactivation of PKC-ε induced by phosphorylating ERK1/2 is responsible for the neuroprotective effect of ACE and QCT against BSO-induced oxidative stress.

Identification and Quantification of Flavonoids from Two Southern Italian Cultivars of Allium cepa L., Tropea (Red Onion) and Montoro (Copper Onion), and Their Capacity to Protect Human Erythrocytes from Oxidative Stress

Onions (Allium cepa) are consumed worldwide and represent an important source of dietary phytochemicals with proven antioxidant properties, such as phenolic acids, flavonoids, thiosulfinates, and anthocyanins. Epidemiological and experimental data suggest that regular consumption of onions is associated with a reduced risk of degenerative disorders. Therefore, it is of interest to investigate the biological properties of different varieties of onions. Here, we characterized for the first time a variety of onion, called Ramata di Montoro (coppery onion from Montoro), grown in a niche area in southern Italy, and compared its phenolic profile and antioxidant properties to a commercial ecotype of red onion, Tropea, also present in southern Italy. An analytical method based on high-performance liquid chromatography coupled with UV detection and mass spectrometry was used to separate and characterize the phenolic fraction (anthocyanins and flavonols) extracted from both coppery and red types. The main compounds detected in the two ecotypes were quercetin and quercetin glucosides, isorhamnetin glucosides, kaempferol glucoside, and, among anthocyanins, cyanidin glucosides. Tropea ecotype onion showed a higher content of flavonols (632.82 mg/kg fresh weight) than Montoro type onion (252.91 mg/kg fresh weight). Accordingly, the antioxidant activity of the former was 2.8-fold higher compared to the latter. More pronounced were the differences existing between the four anthocyanins detected in the two ecotypes, with those in the Tropea ecotype onion present at concentrations 20-230-fold higher than in the Montoro type onion. Both extracts reduced LDL oxidation about 6-fold and protected human erythrocytes from oxidative damage induced by HClO by about 40%. In addition, as a consequence of HClO treatment, glutathione concentration in erythrocytes was reduced about 50% and pretreatment with onion extracts induced a recovery of glutathione level by about 15-22%. Qualitative differences highlighted in the chemical composition of the two phenolic extracts, especially the total content of anthocyanins, which was 30-fold higher in Montoro type onion compared to Tropea ecotype, can be associated with the protective effects measured against oxidative damage induced in human erythrocytes.

Lycopene protects against apoptosis in hypoxia/reoxygenation‑induced H9C2 myocardioblast cells through increased autophagy

Lycopene (Ly), the most common type of antioxidant in the majority of diet types, provides tolerance to ischemia/reperfusion injury. However, the underlying mechanism of the protective effects observed following Ly administration remains poorly investigated. The aim of the current study was to investigate whether Ly prevents damage to hypoxia/reoxygenation (HR)‑induced H9C2 myocardioblasts in an autophagy‑dependent manner. The levels of autophagic markers were detected using western blotting, the level of apoptosis was detected using western blotting and flow cytometry. The activation of autophagy was impaired via knockdown of the expression of 'microtubule‑associated protein 1‑light chain 3β (MAP1LC3B)' and 'Beclin 1'. After 16 h hypoxia, followed by 2 h reoxygenation, the expression levels of the microtubule‑associated protein 1A/1B‑light chain 3 (LC3) and Βeclin 1 autophagic biomarkers, and cell viability were reduced, whereas the percentage of apoptotic cells, and the expression levels of the Bax/B‑cell lymphoma 2 (Bcl‑2) and active caspase‑3 apoptotic biomarkers were increased. Pre‑incubation of the cells with different Ly concentrations reversed the HR‑induced inhibition of autophagy and cell viability, and the HR‑induced elevation in apoptotic levels. The induction of autophagy was accompanied by reduced apoptosis, and decreased expression levels of Bax/Bcl‑2 and active caspase‑3. In addition, the impairment of autophagy by silencing the expression of MAP1LC3B and Beclin 1 accelerated HR‑induced H9C2 cell apoptosis and the Ly‑mediated protective effects disappeared. Furthermore, Bax/Bcl‑2 and active caspase‑3 expression levels were increased. Moreover, Ly‑induced autophagy was associated with increased adenosine monophosphate kinase (AMPK) phosphorylation. Suppressed AMPK phosphorylation using compound C terminates Ly‑mediated cytoprotective effects. Ly treatment improves cell viability and reduces apoptosis as a result of the activation of the adaptive autophagic response on HR‑induced H9C2 myocardioblasts. AMPK phosphorylation may be involved in the progression.

Protective effects of onion extract on cadmium-induced oxidative stress, histological damage, and apoptosis in rat heart

To date, there is no available information on the protective effect of onion (Allium cepa) extract (AcE) on cadmium (Cd)-induced cardiotoxicity. The present study was performed to assess the possible antioxidant and anti-apoptotic roles of AcE in Cd-induced cardiotoxicity in rats. A Cd group was injected subcutaneously with CdCl2 dissolved in saline at a dose of 2 ml/kg/day for 30 days, resulting in a dosage of 1 mg/kg Cd. The rats in the AcE-treated group were given 1 ml of AcE via intragastric intubation for 30 days. The rats intoxicated with Cd for 30 days showed increased tissue malondialdehyde (MDA) levels and decreased levels of the enzymatic antioxidants superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and catalase (CAT) in cardiac tissue. AcE attenuated these adverse effects of Cd. After Cd exposure, histological abnormalities were observed, including myofibrillar loss, vacuolization of cytoplasm and irregularity of myofibrils. These histological alterations were effectively attenuated by the treatment with AcE. Furthermore, our data indicate a significant reduction of apoptosis in the cardiomyocytes of the Cd group treated with AcE therapy. Animal studies show antioxidant effects of AcE. But to date, no study reported the effect of AcE on biochemical and histopathological changes due to Cd induced on rat heart. Our study showed that AcE therapy reduced Cd-induced oxidative stress and apoptosis, possibly through its antioxidant and anti-apoptotic activity.

Protective effects of onion-derived quercetin on glutamate-mediated hippocampal neuronal cell death

Background:

Neurodegenerative diseases are characterized by progressive neuron degeneration in specific functional systems of the central or peripheral nervous system. This study investigated the protective effects of quercetin isolated from onion on neuronal cells and its protective mechanisms against glutamate-induced apoptosis in HT22 cells.

Materials and Methods:

HT22 cells were cultured to study the neuroprotective mechanism of quercetin against glutamate-mediated oxidative stress. The intracellular reactive oxygen species (ROS) level and mitochondrial membrane potential (ΔΨ_m) were measured. The protein expression of calpain, spectrin, Bcl-2, Bax, Bid, cytochrome c, and mitogen-activated protein kinases (MAPKs) was evaluated by Western blotting.

Results:

Quercetin had a protective effect by reducing both intracellular ROS overproduction and glutamate-mediated Ca²⁺ influx. These effects were due to the downregulation of several apoptosis-related biochemical markers. Calpain expression was reduced and spectrin cleavage was inhibited by quercetin in glutamate-exposed HT22 cells. Disruption of the mitochondrial membrane potential (ΔΨ_m), activation of the pro-apoptotic proteins Bid and Bax, and cytochrome c release in response to glutamate-induced oxidative stress were reduced. Quercetin also suppressed phosphorylation of MAPKs.

Conclusion:

This is the first report on the detailed mechanisms of the protective effect of quercetin on HT22 cells. Onion extract and quercetin may be useful for preventing or treating neurodegenerative disorders.

In vitro antioxidant synergism and antagonism between food extracts can lead to similar activities in H2O2-induced cell death, caspase-3 and MMP-2 activities in H9c2 cells

BACKGROUND

The cardio-health-promoting activity of some foods may be due to their specific antioxidant content. The antioxidant activity of a mixture of plant extracts has been shown to differ from the activity of the individual extracts. As a result, the activity of the mixture can be described as synergistic, antagonistic or additive. This in vitro study evaluated the relationship between the in vitro antioxidant capacity of mixtures and their bioactivity when cardiomyocytes (H9c2) were challenged with H(2)O(2).

RESULTS

A mixture of raspberry and adzuki bean extracts produced a synergistic response and a mixture of broccoli and soybean extracts produced an antagonistic response in chemical-based antioxidant assays. When these extracts were tested in cell cultures, individually and in mixtures, the mixture of raspberry and adzuki bean protected the cardiomyocytes from H(2)O(2)-induced cell damage significantly better than the individual extracts. Conversely, the mixture of broccoli and soybean extracts was less effective in protecting H9c2 cells. The synergistic and antagonistic effects of the mixtures in protecting cell damage were brought about by enhanced or reduced ability in attenuating caspase-3 and matrix metalloproteinase-2 activities elevated by H(2)O(2).

CONCLUSION

Food mixtures with synergistic antioxidant activity and protective property against reactive oxygen species-induced cell death can potentially be incorporated into novel functional foods or beverages with optimum health benefit. The antagonistic effect of food mixtures can be a health concern and thus should be avoided.

Carotenoid compositions of coloured tomato cultivars and contribution to antioxidant activities and protection against H(2)O(2)-induced cell death in H9c2

The carotenoid compositions, antioxidant activities and the potential cardio-protective role of 13 tomato cultivars with distinct colour were studied. Colour coordinates were evaluated by colorimeter and the carotenoid compositions were analysed by UPLC. Red tomatoes had the highest total carotenoid contents (TCC) and antioxidant activities, followed by purple, orange, pink and yellow ones. The TCC were 120.5-278.0 μg/gDW, and the antioxidant activities were 21.32-40.07 μmolTE/gDW (PCL), 64.42-89.98% (DPPH) and 10.47-13.76 μmolTE/g DW (ORAC), respectively. The lipophilic extracts were also found to prevent cell death in a cell-based model system using cardiac H9c2 cells and H(2)O(2), via attenuation of the caspase-3 and matrix metalloproteinase-2 activities. The extracts of different tomatoes showed strong but different antioxidant activities. Roles of total and individual carotenoids in the antioxidant activities were studied and lycopene showed the highest correlation. Results of this study can be used to guide the development of new tomato cultivars and functional foods, and benefit the consumers.

Protective effect of grape seed extract against oxidative stress-induced cell death in a staurosporine-differentiated retinal ganglion cell line

OBJECTIVE

Grape seed extract (GSE) is a potent antioxidant. We examined the effect of GSE on oxidative stress-induced cell death in a transformed retinal ganglion cell line, RGC-5.

METHODS

Staurosporine-differentiated RGC-5 (ssdRGC-5) cells obtained by treating RGC-5 cells with 1 µM staurosporine were incubated with GSE for 2 h and then exposed to buthionine sulfoximine plus glutamate (B/G) for 24 h. Cell death was detected using the LIVE/DEAD viability assay and the type of cell death was evaluated using fluorescein isothiocyanate-conjugated Annexin-V/propidium iodide staining. To investigate the mechanism underlying cell death, we determined the caspase-3 activity and level of reactive oxygen species (ROS) formation.

RESULTS

Treatment of ssdRGC-5 cells with B/G increased intracellular ROS and induced apoptosis (not necrosis) with increasing caspase-3 activity. GSE rescued the ssdRGC-5 cells from oxidative stress-induced cell death by inhibiting both intracellular ROS production and caspase-3 activation.

CONCLUSION

GSE had a neuroprotective effect against oxidative stress-induced apoptotic death in ssdRGC-5 cells.

Onion (Allium cepa) extract attenuates brain edema

OBJECTIVE

This study investigated the potential beneficial effects of onion extract on brain ischemia-induced edema and blood-brain barrier (BBB) dysfunction. The possible underlying mechanisms are investigated, especially those linked to the antioxidant effects of the onion extract.

METHODS

Brain ischemia was induced by middle cerebral artery occlusion (MCAO) for 2 h followed by reperfusion in mice. Mice were treated intravenously with onion extract 30 min before MCAO. Brain edema and BBB hyperpermeability were evaluated by the measurement of the brain water content and Evans blue extravasation, respectively. The disruption of tight junction proteins was examined by immunohistochemical staining. The level of malondialdehyde was determined using the thiobarbituric acid method. The activities of glutathione peroxidase and catalase were determined by spectrophotometric assay.

RESULTS

Brain water content in the ischemic hemisphere was significantly reduced by treatment with onion extract. Onion extract also had a significant effect on both the decrease in Evans blue extravasation and the inhibition of zonula occludens-1 and occludin disruption caused by brain ischemia. In addition, onion extract significantly prevented brain ischemia-induced reduction in catalase and glutathione peroxidase activities and elevation of malondialdehyde level in the brain tissue.

CONCLUSION

The results from this study demonstrate that onion extract prevents brain edema, BBB hyperpermeability, and tight junction proteins disruption, possibly through its antioxidant effects in the mouse MCAO model. This study suggests that onion extract may be a beneficial nutrient for the prevention of BBB function during brain ischemia.