Ethylacetate extract of red onion (Allium cepa L.) tunic affects hemodynamic parameters in rats

Phycocyanin attenuates skeletal muscle damage and fatigue via modulation of Nrf2 and IRS-1/AKT/mTOR pathway in exercise-induced oxidative stress in rats

Prolonged strenuous exercise induces oxidative stress, leading to oxidative damage, skeletal muscle fatigue, and reduced exercise performance. The body compensates for oxidative stress through antioxidant actions, while related enzymes alone may not overcome excessive oxidative stress during prolonged strenuous exercise. Phycocyanin is an important antioxidant supplement derived from blue-green algae, which may be helpful in this type of situation. This study determined the effects of phycocyanin on exercise performance from prolonged strenuous exercise. Forty Sprague Dawley male rats were divided into 5 groups (n = 8 /group); Control group (C), Exercise group (E), and Exercise with supplement groups receiving low dose (Phycocyanin = 100 mg/kg BW; ELP) and high dose (Phycocyanin = 200 mg/kg BW; EHP) or vitamin C (Vitamin C = 200 mg/kg BW; VC). Phycocyanin was found to decrease oxidative damage markers, muscle fatigue, and muscle atrophy through the activated AKT/mTOR pathway. This was also found to have greater increases in antioxidants via Nrf2 signaling and increases ATP synthesis, GLUT4 transporters, and insulin signaling due to increased IRS-1/AKT signaling. In conclusion, phycocyanin was found to reduce oxidative damage and muscle atrophy, including an increase in insulin signaling in skeletal muscles leading to increased exercise performance in rats.

Phytochemical constituents of sterol-rich fraction from Allium cepa L. and its cytotoxic effect on human embryonic kidney (HEK293) cells

The present study investigates the cytotoxic effect of the chemical fractions of Allium cepa (yellow variety) on Human Embryonic Kidney (HEK293) cells. Allium cepa was blended into paste and macerated in distilled water before subjecting to liquid-liquid fractionation, yielding the dichloromethane, ethyl acetate (EtOAc), butanol, and aqueous fractions. Their cytotoxicity on HEK293 cells were evaluated via MTT assay. The cytotoxic fraction (EtOAc) was further evaluated for its oxidative, pro-inflammatory, and apoptotic effects on the cells. The incubation of cells with EtOAc led to depleted level of GSH, SOD, and catalase activities, and elevated levels of malondialdehyde, nitric oxide, and myeloperoxidase as well as apoptotic activities. GC-MS analysis of EtOAc revealed allyl ionone, pentadecanoic acid, and phytol acetate as the predominant fatty acids, while ergost-7-en-3β-ol, campesterol, cycloartenol-3β acetate, sitosterol, and fucosterol as the predominant sterols. These results portray the cytotoxic effect of the EtOAc fraction of A. cepa on HEK293 cells. PRACTICAL APPLICATIONS: There have been increasing concerns in the toxicity and safety of foods. Allium cepa (onions) is among the common globally grown and consumed plant food. This study investigated its cytotoxic effect on normal Human Embryonic Kidney (HEK293) Cells. Although only the ethyl acetate fraction was cytotoxic against the cell line, it, however, portrays a need for caution in its usage.

Allium Flavonols: Health Benefits, Molecular Targets, and Bioavailability

Allium species are revered worldwide as vegetables, condiments, and spices as well as the therapeutic agents in traditional medicine. The bioactive compounds in alliums mainly include organosulfur compounds, polyphenols, dietary fibers, and saponins. Flavonoids, particularly flavonols from alliums, have been demonstrated to have the antioxidant, anticancer, hypolipidemic, anti-diabetic, cardioprotective, neuroprotective, and antimicrobial activities. However, flavonols are mostly characterized from onions and have not been comprehensively reviewed across different species. This article therefore focuses on flavonol profiles from different Allium species, their health effects, underlying molecular mechanisms, and bioavailability. Intriguingly, the functional health effects of flavonols were mainly ascribed to their antioxidant and anti-inflammatory activities involving a cascade of multiple signaling pathways. Although the Allium-derived flavonols offer tremendous potential in preventing chronic disease risks, in-depth studies are needed to translate their clinical application.

Alleviation of Cardiac Damage by Dietary Fenugreek (Trigonella foenum-graecum) Seeds is Potentiated by Onion (Allium cepa) in Experimental Diabetic Rats via Blocking Renin-Angiotensin System

Hyperglycemia is one of the metabolic and homeostatic abnormalities that increase the cardiovascular mortality in diabetic patients by increased oxidative stress. We have recently reported amelioration of oxidative stress in cardiac tissue by dietary fenugreek (Trigonella foenum-graecum) seeds and onion (Allium cepa) in streptozotocin-induced diabetic rats. The mechanistic aspects of the cardio-protective influence of dietary fenugreek seeds (10%) and onion (3% powder) both individually and in combination on hyperglycemia-mediated cardiac damage was further investigated in this study on streptozotocin-induced diabetic rats. Cardio-protective influence of these dietary spices was evidenced by their blocking potential on renin-angiotensin system. This might be the consequence of reduced activation of angiotensin-converting enzyme (ACE) and angiotensin type 1 receptor (AT₁) in cardiac tissue. The combination produced an additive effect on ACE and AT₁ protein and mRNA expressions. Increased expression of type IV collagen, fibronectin, Bax, 4-hydroxynonenal, iNOS and metabolites of nitric oxide (nitrate/nitrite) along with disturbed PUFA-to-SFA ratio and activities of cardiac marker enzymes in blood confirmed the myocardial damage. Dietary fenugreek seed, onion and fenugreek + onion were found to ameliorate these pathological changes in the cardiovascular system. The beneficial effect being higher with the combination sometime amounting to additive (iNOS expression) or even a synergistic (cardiac Bax and type IV collagen expression and circulatory marker enzymes) in diabetic rats. Thus, the results of present investigation suggested that the combination of fenugreek seeds and onion offers higher beneficial influence in ameliorating cardiac damage accompanying diabetes.

Inhibition of Enzymatic Browning by Onion (Allium cepa L.): Investigation on Inhibitory Mechanism and Identification of Active Compounds

Presence of browning or black-spot in fresh foods can adversely affect consumer acceptance. Onion has been reported to exert inhibitory activity against browning reaction. This research aimed to uncover the mechanism and identify active compounds in onion responsible for PPO inhibitors based on metabolomic approach. Onion was fractioned using different solvents, i.e n-hexane; chloroform; ethyl acetate; water, respectively. As a result, ethyl acetate fraction (EAF) of the onion demonstrated the strongest inhibition to PPO in comparison with other fractions, i.e. n-hexane, chloroform, and water. The reversible inhibitory activity of PPO by EAF occurred with presence of L-DOPA as substrate through competitive inhibition and Cu chelation in the active side of the PPO. Based on 1H-NMR (X) score plot and PPO inhibition (Y) using OPLS, NMR signals revealed that active compounds accounting for inhibition of PPO included quercetin, kaempferol, cyanidin 3.4’-di-O-β-glucopyranoside, quercetin 4-O-β-D-glucopyranoside, cyanidin 7-O-(3”-O-glucosyl-6”-O-malonyl-β-glucopyrano-side)-4’-O-β-glucopyranoside, cyanidin 3-(6”-O-malonyl) laminaribioside’.

Angiotensin-1-converting enzyme inhibition, antioxidant activity, and modulation of cerebral Na+/K+ ATPase by free phenolics of African locust bean (Parkia biglobosa)

AIMS

To investigate the antioxidant activities and effects of free phenols (FPPB) and bound phenols (BPPB) of Parkia biglobosa leaves on some enzymes of neuro-cardiovascular relevance.

METHODS AND RESULTS

HPLC-DAD fingerprinting of FPPB and BPPB, and the antihemolytic, radical (1,1-diphenyl-2 picrylhydrazyl, DPPH; 2,2-azino-bis(3-ethylbenzthiazoline-6-sulphonic acid), ABTS) scavenging and ferric reducing antioxidant properties of extracts, were assessed. In addition, the effects of the phenolics on angiotensin-1-converting enzyme (ACE), cerebral acetylcholinesterase/butyrylcholinesterase (AChE/BuChE), and Na+/K+ATPase were determined in vitro. FPPB was more potent than BPPB in terms of ABTS (EC50:4.06 ± 0.3 vs 24.07 ± 2.1 μg/mL) and DPPH (EC50:3.82 ± 0.2 vs 10.22 ± 0.1 μg/mL) radicals scavenged, respectively. The free phenolic extract was a better DPPH. scavenger than ascorbic acid (EC50 = 12.58 ± 0.4 μg/mL; DPPH reference) and compared well with Trolox (EC50:4.44 ± 0.08 μg/mL; ABTS reference). The anti-hemolytic effect of FPPB (36%) and BPPB (53%) was highest at 15 μg/mL but lower than that recorded for ascorbic acid (67% at 10 μg/mL). Even though FPPB (IC50 = 15.35 ± 4.0 μg/mL) and BPPB (IC50 = 46.85 ± 3.3 μg/mL) showed considerably lower ACE-inhibitory effect than ramipril (IC50:0.173 ± 0.04 μg/mL), both extracts demonstrated dose-dependent, significant (p < 0.01/p < 0.05) inhibition of the enzyme. FPPB increased cerebral Na+/K+ATPase activity but neither phenolic extract affects cerebral AChE/BuChE activities. HPLC-DAD revealed catechin, caffeic acid, and quercetin, respectively, as the major phenolics (mg/g) in FPPB (29.85, 30.29, and 17.10) and BPPB (32.70, 30.51, and 19.25).

CONCLUSION

The effects of P biglobosa on ACE and cerebral ATPase are related to its constituent phenolics. ACE inhibition could be an important mechanism underlying the documented hypotensive effect of the plant.