Welsh onion (Allium fistulosum L.) extracts alter vascular responses in rat aortae

Development of an analytic method for organosulfur compounds in Welsh onion and its use for nutritional quality analysis of five typical varieties in China

A reliable, simple, and sensitive method capable of quantifying six organosulfur compounds (OSCs) was established. The samples were extracted by water containing 3 % formic acid with a simple vortex, ultrasound, and centrifugation step, and the solutions were analyzed by ultra-high-performance liquid chromatography separation system coupled with a triple-quadrupole mass spectrometry (UHPLC - MS/MS). Then the method was applied for the analysis of six OSCs in five varieties of two types Welsh onions in China, and the moisture content, reducing sugar, total polyphenols, and 21 free amino acids were also analyzed to study the characters of these Welsh onions intensively. Multivariate statistical analysis was used to investigate the differences in OSCs and free amino acids profiles among the samples. This study showed that enzymatic inhibition method combined with UHPLC - MS/MS is an effective technique to analyze OSCs in Welsh onion, and could be valuable for the routine quantitation of OSCs in other foods.

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.

Natural Bioactive Cinnamoyltyramine Alkylamides and Co-Metabolites

Natural products are a vital source for agriculture, medicine, cosmetic and other fields. Among them alkylamides are a broad and expanding group found in at least 33 plant families. Frequently, they possess a simple carbon skeleton architecture but show broad structural variability and important properties such as immunomodulatory, antimicrobial, antiviral, larvicidal, insecticidal and antioxidant properties, amongst others. Despite to these several and promising biological activities, up to today, only two reviews have been published on natural alkylamides. One focuses on their potential pharmacology application and their distribution in the plant kingdom and the other one on the bioactive alkylamides specifically found in Annona spp. The present review is focused on the plant bioactive cinnamoyltyramine alkylamides, which are subject of several works reported in the literature. Furthermore, the co-metabolites isolated from the same natural sources and their biological activities are also reported.

Restorative effects of red onion (Allium cepa L.) juice on erectile function after-treatment with 5α-reductase inhibitor in rats

Benign prostatic hyperplasia (BPH) is one of the most prevalent conditions among aged men. The use of 5α-reductase inhibitors (5-ARIs) to treat BPH was linked to erectile dysfunction (ED). Many medicinal plants and secondary metabolites are used in the management of ED. Onion (Allium cepa L.) is an economically affordable vegetable with vital phytochemicals and biological functions. The study aimed to identify the beneficial effects of onion juice on dutasteride (a 5-ARI)-induced ED. Rats were divided into two groups (n = 5 per group): control and dutasteride-treated rats (0.5 mg/kg/day). Dutasteride was administered in drinking water for 12 weeks. Experiments were performed at the end of the 12th week. In vivo erectile responses were measured before and after intracavernosal injection of onion. Relaxant responses to onion juice were examined in the corpus cavernosum (CC). Acetylcholine (ACh)-, electrical field stimulation (EFS)-, sodium nitroprusside (SNP)-induced relaxation responses in CC tissues were evaluated in the absence and presence of onion juice. Total intracavernosal pressure (ICP) and ICP/ mean arterial pressure were significantly reduced in dutasteride-treated rats (1881.14 ± 249.72 mmHg, P < 0.001;0.26 ± 0.03, P < 0.01) as compared to control rats (4542.60 ± 429.19 mmHg, 0.51 ± 0.05), which was normalized after the intracavernous administration of onion (3288.60 ± 185.45 mmHg, 0.58 ± 0.04). Onion markedly induced relaxant responses in control (72.5 ± 4.7) and dutasteride-treated (66.5 ± 2.7) groups after precontraction with phenylephrine. Relaxation responses to onion were partially inhibited after precontraction with KCl (32.5 ± 3.1, P < 0.001). The relaxant responses to ACh (14.9 ± 4.2, P < 0.01) were diminished in dutasteride-treated CC) compared to control CC (59.8 ± 3.4), which was enhanced after the incubation with onion (36.6 ± 4.8). There were no differences in relaxation response to SNP among all groups. However, relaxation response to SNP was reduced in dutasteride-treated CC at 1 μM (P < 0.05) and 10 μM dosages (P < 0.001), which was partially increased after the incubation with onion at 10 μM dosage (P < 0.01). The presence of onion did not change the reduction in EFS-caused relaxation in the dutasteride-treated group. The current data suggest that red onion juice has a restorative effect on erectile function and endothelium-dependent relaxation response following the treatment of dutasteride.

Review of Natural Resources With Vasodilation: Traditional Medicinal Plants, Natural Products, and Their Mechanism and Clinical Efficacy

For decades, chronic diseases including cardiovascular and cerebrovascular diseases (CCVDs) have plagued the world. Meanwhile, we have noticed a close association between CCVDs and vascular lesions, such as hypertension. More focus has been placed on TMPs and natural products with vasodilation and hypotension. TMPs with vasodilatory and hypotensive activities are mainly from Compositae, Lamiaceae, and Orchidaceae (such as V. amygdalina Del., T. procuinbens L., M. glomerata Spreng., K. galanga L., etc.) whereas natural products eliciting vasorelaxant potentials were primarily from flavonoids, phenolic acids and alkaloids (such as apigenin, puerarin, curcumin, sinomenine, etc.). Furthermore, the data analysis showed that the vasodilatory function of TMPs was mainly concerned with the activation of eNOS, while the natural products were primarily correlated with the blockage of calcium channel. Thus, TMPs will be used as alternative drugs and nutritional supplements, while natural products will be considered as potential therapies for CCVDs in the future. This study provides comprehensive and valuable references for the prevention and treatment of hypertension and CCVDs and sheds light on the further studies in this regard. However, since most studies are in vitro and preclinical, there is a need for more in-depth researches and clinical trials to understand the potential of these substances.

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.

Onion bulb extract reduces colitis severity in mice via modulation of colonic inflammatory pathways and the apoptotic machinery

ETHNOPHARMACOLOGICAL RELEVANCE

The use of nutraceutical-based products has increased in recent years due to their demonstrated efficacy and their good safety profile. Onion is one of the most commonly used plants in the traditional medicine for the management of various conditions including inflammatory and gastrointestinal diseases. However, little is known regarding the molecular mechanism of the anti-inflammatory effects of onion particularly in inflammatory bowel disease (IBD).

AIM OF THE STUDY

To test the anti-inflammatory effects of onion bulb extract (OBE) in an IBD mouse model and the molecular mechanisms responsible for these effects such as modulation of the expression and/or the activity profile of various pro-inflammatory molecules.

MATERIALS AND METHODS

Colitis was induced in mice by dextran sulfate sodium (DSS) daily administration for 5 days. Animals were sacrificed, colons were removed and the severity of the inflammation was determined by the gross and histological assessments. The colonic level/activity of various cytokines and chemokines were measured using proteome profiling-based assay, western blotting, and immunofluorescence techniques.

RESULTS

DSS-induced colitis was significantly reduced by the daily OBE treatment and 5-aminosalicylic acid (5-ASA, positive control), particularly at 100-200 mg/kg doses, at both the gross and histological levels. OBE was also shown to reduce colonic expression and activity of several pro-inflammatory molecules and signaling pathways, such as mitogen activated protein kinase family, mammalian target of rapamycin, cyclooxygenase-2, and tissue inhibitors of metalloproteinases. In addition, OBE reduced the expression of interferon-γ, various C-C and C-X-C chemokines, and molecules involved in the apoptotic machinery such as cytochrome c, caspase-3 and -8, B-cell lymphoma-extra-large and -2.

CONCLUSIONS

OBE showed anti-inflammatory actions in IBD mouse model, which is attributed, in part, to the modulation of the expression and the activity of important pro-inflammatory molecules and signaling pathways involved in the inflammatory response. These data suggest that OBE may be a promising lead in the therapeutic management of IBD.

Effect of Heating on Onion (Allium cepa L.) Antiplatelet Activity and Pungency Sensory Perception

Onion, in its raw form, is recognized as an antiplatelet agent that may contribute to the prevention of cardiovascular disease. In raw onions, the content of pyruvate, is significantly correlated with antiplatelet activity (AA) and the sensory perception of pungency. However, onion is generally cooked before consumption. Herein, we examine the effect of heating — using different boiling intensities — on the in vitro antiaggregatory activity (IVAA), the pyruvate concentration and the flavor (pungency) of crushed-onion samples. In general, heating is detrimental for onion AA. Boiling for 3 min has no significant effect on platelet aggregation, as compared to raw onion. Heating for 46 min completely suppresses IVAA, whereas samples boiled for > 20 min have pro-aggregatory effects. Significant differences in AA are found between the blood donors. Pyruvate content is not reduced after 30 min boiling. Pungency ratings decrease with the intensity of the heat treatment. Strong significant positive correlations are found between IVAA and pungency, but not between pyruvate and the former two variables. Our results suggest that: (i) in order to obtain the maximum health benefits onions should be eaten raw or moderately cooked, (ii) extensive heating may result in pro-aggregatory effects, (iii) pyruvate is not a good indicator of AA in cooked onions, (iv) the decrease in IVAA and pungency during onion cooking may be due to degradation of sulfur compounds (e.g. thiosulfinates) which are, likely, less tolerant than pyruvate to the high temperatures.

Antioxidative and Antihypertensive Effects of Welsh Onion on Rats Fed with a High-Fat High-Sucrose Diet

The effects of Welsh onion on the development of hypertension and autoxidation were studied in 6-week-old male Sprague-Dawley rats. The rats were fed with a control diet or a high-fat high-sucrose (HFS) diet with or without 5% Welsh onion (green-leafy type or white-sheath type) for 4 weeks. The systolic blood pressure was elevated and the thiobarbituric acid reactive substances (TBARS) in plasma were increased in the rats fed with the HFS diet without Welsh onion. The rats fed with the HFS diet containing Welsh onion, especially the green-leafy type, had lower blood pressure. They also had a higher level of nitric oxide (NO) metabolites in both the urine and plasma, lower activity of NADH/NADPH oxidase in the aorta, and suppressed angiotensin II production. The effect of white Welsh onion on decreasing the blood pressure was not significant, although the effects on increasing NO metabolites in the urine and decreasing NADH oxidase activity in the aorta were significant. The TBARS value in the plasma was lowered in the rats fed with either green or white Welsh onion, but the in vitro radical scavenging and ferric reducing antioxidative activities were much higher with green Welsh onion than with the white type. These results suggest that the green-leafy Welsh onion, but not the white type, reduced superoxide generation by suppressing the angiotensine II production and then the NADH/NADPH oxidase activity, increasing the NO availability in the aorta, and consequently lowering the blood pressure in the rats fed with the HFS diet. The radical scavenging and reducing antioxidative activities of green Welsh onion may also be effective in decreasing superoxide.

Activation of immune responses in mice by an oral administration of bunching onion (Allium fistulosum) mucus

Bunching onion [Allium fistulosum L. (Liliaceae)] secretes mucus in the cavities of its green leaves. The effects of the mucus, which is consumed as food, were examined. The mucus augmented the production of tumor necrosis factor (TNF)-α and monocyte chemotactic protein (MCP)-1 from RAW 264 cells and of interleukin (IL)-12 from J774.1 cells; however, extracts from green leaves and white sheaths did not. An oral administration of this mucus to mice augmented the immune functions of peritoneal cells by increasing TNF-α and IL-12 production and phagocytosis. It also augmented interferon (IFN)-γ production from spleen cells and natural killer (NK) activity. These results suggest that an oral administration of the A. fistulosum mucus can enhance natural immunity.

Dietary administration of scallion extract effectively inhibits colorectal tumor growth: cellular and molecular mechanisms in mice

Colorectal cancer is a common malignancy and a leading cause of cancer death worldwide. Diet is known to play an important role in the etiology of colon cancer and dietary chemoprevention is receiving increasing attention for prevention and/or alternative treatment of colon cancers. Allium fistulosum L., commonly known as scallion, is popularly used as a spice or vegetable worldwide, and as a traditional medicine in Asian cultures for treating a variety of diseases. In this study we evaluated the possible beneficial effects of dietary scallion on chemoprevention of colon cancer using a mouse model of colon carcinoma (CT-26 cells subcutaneously inoculated into BALB/c mice). Tumor lysates were subjected to western blotting for analysis of key inflammatory markers, ELISA for analysis of cytokines, and immunohistochemistry for analysis of inflammatory markers. Metabolite profiles of scallion extracts were analyzed by LC-MS/MS. Scallion extracts, particularly hot-water extract, orally fed to mice at 50 mg (dry weight)/kg body weight resulted in significant suppression of tumor growth and enhanced the survival rate of test mice. At the molecular level, scallion extracts inhibited the key inflammatory markers COX-2 and iNOS, and suppressed the expression of various cellular markers known to be involved in tumor apoptosis (apoptosis index), proliferation (cyclin D1 and c-Myc), angiogenesis (VEGF and HIF-1α), and tumor invasion (MMP-9 and ICAM-1) when compared with vehicle control-treated mice. Our findings may warrant further investigation of the use of common scallion as a chemopreventive dietary agent to lower the risk of colon cancer.

Effect of processing and cooking conditions on onion (Allium cepa L.) induced antiplatelet activity and thiosulfinate content

Allium vegetables serve as sources of antiplatelet agents that may contribute to the prevention of cardiovascular disease. However, onion and garlic, the major Allium species, are usually cooked before consumption. Here, we examined the effect of cooking on onion in vitro antiplatelet activity (IVAA). Two different cooking systems (convection oven and microwaves) and several time-temperature variables were tested on whole bulbs, quarters of bulbs, and completely crushed bulbs, monitoring the degradation of sulfur antiplatelet compounds (e.g., thiosulfinates) by analysis of pyruvate levels. Although heating was, in general, detrimental for onion IVAA, the extent of this effect varied greatly, from unaffected antiplatelet activity (AA) (i.e., similar to raw onion) to a complete lost of activity, depending upon the manner in which onions were prepared prior to heating, the cooking method, and the intensity of the heat treatment. "Whole", "quarters", and "crushed" onions lost their IVAA after 30, 20, and 10 min of oven heating, respectively. The longer retainment of AA in intact bulbs was attributed to a later alliinase inactivation. Proaggregatory effects observed in samples subjected to the most intense oven and microwave heat treatments suggest that extensively cooked onions may stimulate rather than inhibit platelet aggregation. The efficacy of Allium species as antiplatelet agents, as affected by preparation and cooking conditions, is discussed.

Effects of typheramide and alfrutamide found in Allium species on cyclooxygenases and lipoxygenases

Typheramide (N-caffeoyltyramine) and alfrutamide (N-feruloyltyramine) are phenylpropenoic acid amides found in plants. In this article, typheramide and alfrutamide were isolated from Allium sativum (garlic) and Allium fistulosum (green onion), their chemical structures were confirmed using nuclear magnetic resonance spectroscopic methods, and the potential effects on cyclooxygenases (COXs) (COX 1 and 2) and lipoxygenases (LOXs) (5- and 15-LOX) were investigated. Typheramide and alfrutamide inhibited COX 1 by 74% (P < .01) and 60% (P < .01), respectively, at the concentration of 0.1 μM; at the same concentration, they also inhibited COX 2 by 68% (P < .02) and 54% (P < .02), respectively. Typheramide was slightly stronger than alfrutamide in inhibiting COX enzymes, and the inhibition patterns of COX 1 and 2 were uncompetitive with K(i) = 0.032 and 0.047 μM, respectively. However, typheramide and alfrutamide were not able to inhibit 5-LOX, and they only moderately inhibited 15-LOX by 27% (P < .02) and 17% (P < .02), respectively, at the relatively high concentration of 25 μM. Altogether, the data suggest that typheramide and alfrutamide from garlic and green onions are likely to be significant inhibitors for COX 1 and 2 rather than 5- and 12-LOX.

A systematic review of mechanisms by which natural products of plant origin evoke vasodilatation

This article reviews the body of work aimed at elucidating the mechanisms of action by which natural products of plant origin exert a vasodilatory effect at the level of the vasculature. The search was restricted to 4 mechanisms: the nitric oxide system and (or) reactive oxygen species, the eicosanoid system, potassium channel function, and calcium channel function. The National Library of Medicine database was searched using "PubMed" without restriction to language. The search generated 266 references on 15 November 2005. Most studies were in vitro in nature and of these, most involved studies in the rat aorta. Many of the natural products evoked vasodilatation through an endothelium-dependent mechanism. The vasodilatation was attenuated or abolished by a nitric oxide synthase inhibitor and, in some of these studies, by an inhibitor of guanylate cyclase. A few studies reported a cyclooxygenase component, but most found no effect of the cyclooxygenase inhibitor, indomethacin. The vasorelaxation evoked by several natural products was attenuated by various potassium channel blocking agents, suggesting that some natural products exerted their effect either directly or indirectly through activation of potassium channels. Finally, a significant number of natural products evoked vasodilatation either through blockade of calcium channels or by inhibiting the release of calcium from intracellular stores. Many natural products evoked vasodilatation through multiple mechanisms. The information in this review on mechanisms of action should facilitate good clinical practice by increasing the predictive capabilities of the practitioner, notably the ability to predict adverse effects and interactions among medications. The knowledge should also help to provide leads to the ultimate goal of developing new therapeutic medications.

Onions--a global benefit to health

Onion (Allium cepa L.) is botanically included in the Liliaceae and species are found across a wide range of latitudes and altitudes in Europe, Asia, N. America and Africa. World onion production has increased by at least 25% over the past 10 years with current production being around 44 million tonnes making it the second most important horticultural crop after tomatoes. Because of their storage characteristics and durability for shipping, onions have always been traded more widely than most vegetables. Onions are versatile and are often used as an ingredient in many dishes and are accepted by almost all traditions and cultures. Onion consumption is increasing significantly, particularly in the USA and this is partly because of heavy promotion that links flavour and health. Onions are rich in two chemical groups that have perceived benefits to human health. These are the flavonoids and the alk(en)yl cysteine sulphoxides (ACSOs). Two flavonoid subgroups are found in onion, the anthocyanins, which impart a red/purple colour to some varieties and flavanols such as quercetin and its derivatives responsible for the yellow and brown skins of many other varieties. The ACSOs are the flavour precursors, which, when cleaved by the enzyme alliinase, generate the characteristic odour and taste of onion. The downstream products are a complex mixture of compounds which include thiosulphinates, thiosulphonates, mono-, di- and tri-sulphides. Compounds from onion have been reported to have a range of health benefits which include anticarcinogenic properties, antiplatelet activity, antithrombotic activity, antiasthmatic and antibiotic effects. Here we review the agronomy of the onion crop, the biochemistry of the health compounds and report on recent clinical data obtained using extracts from this species. Where appropriate we have compared the data with that obtained from garlic (Allium sativum L.) for which more information is widely available.

Effects of Welsh onion extracts on human platelet function in vitro

Welsh onion has been consumed for prevention of cardiovascular disorders. However, its underlying mechanisms are still unclear. This study investigated whether Welsh onion extracts can alter human platelet function (ie, platelet adhesion, aggregation, and thromboxane release). To clarify the underlying mechanisms, we also measured the intracellular calcium ([Ca2+]i) and cyclic nucleotide levels in platelets. Our results showed that 1) boiled extracts directly induced platelet aggregation in a dose-dependent manner; 2) raw extracts inhibited platelet adhesion and ADP-evoked platelet aggregation, while boiled extracts enhanced them; 3) raw green extract suppressed ADP-stimulated platelet [Ca2+]i elevation and thromboxane production, whereas boiled green extract enhanced them; 4) raw green extract elevated platelet cAMP level, whereas boiled green extract had no effect on cAMP level. Furthermore, the boiled green extract, but not the raw extract, induced pronounced platelet morphological changes. In conclusion, raw extracts of Welsh onion inhibit platelet function in vitro while boiled extracts activate platelets.

Chronic consumption of raw but not boiled Welsh onion juice inhibits rat platelet function

Welsh onion has been consumed for prevention of cardiovascular disorders. To study if it has antithrombotic effects, 9-wk-old male Sprague-Dawley rats were studied. Some rats were fed raw or boiled Welsh onion juice (2 g. kg(-1). d(-1)) for 4 wk, and the remaining acted as the control. Before and after feeding, their systolic blood pressure was measured by a tail-cuff method. Two days after the treatment period, tail bleeding time, platelet function (including platelet aggregation and adhesion), plasma levels of prostaglandins, and platelet cyclic nucleotide levels were determined. In comparison to the control, raw Welsh onion juice consumption significantly (1) lowered resting systolic blood pressure; (2) prolonged the bleeding time; (3) diminished platelet adhesion on a fibrinogen-coated surface, ADP-evoked platelet aggregation and ADP-stimulated thromboxane release; (4) elevated the concentration of cyclic AMP, but not cyclic GMP, in platelets; (5) increased the plasma level of 6-keto-prostaglandin F(1alpha), the stable prostacyclin metabolite, but not the plasma nitrite level. On the contrary, boiled Welsh onion juice consumption was totally ineffective. In conclusion, consuming raw Welsh onion juice, but not boiled juice, has blood pressure lowering and antithrombotic effects in rats. These effects may be mediated by PGI(2)-cAMP pathway.