Flavonol glucosides in Allium species: A comparative study by means of HPLC–DAD–ESI-MS–MS

Diversity of the Morphometric and Biochemical Traits of Allium cepa L. Varieties

Several Allium cepa L. varieties, representing a versatile set of vegetables widely utilized by consumers, are appreciated for their bioactive properties, including antimicrobial, anticarcinogenic, and antioxidant capacities. The aim of this study is to compare the morphometric characteristics and biochemical profiles of four cultivars of A. cepa, two of them represented by the perennial Sicilian landrace "Cipudda agghiarola" (Allium × proliferum (Moench) Schrader), widely known as the Egyptian walking onion (WO), and by the landrace "Cipudduzza" belonging to the variety known as aggregatum (ON), which were compared with two commercial cultivars of A. cepa var. cepa (onion), Stoccarda (OS) and Rossa Carmen (OR). The experimental trial was conducted in Catania (Sicily), following organic growing practices. The randomized complete block experimental design was adopted with one experimental factor, the genotype (GE) effect. The harvested plants were characterized for their main morphometric parameters, according to the International Plant Genetic Resources (IGPR) descriptors. The biochemical activity was assessed by analyzing the total phenolic content (TPC) and the total flavonoid content (TFC). The antioxidant capacity was determined by 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging, ferric reducing antioxidant power (FRAP), and oxygen radical absorbance capacity (ORAC). The sugar profile (total sugars, sucrose, glucose, fructose, and fructooligosaccharides-FOS) and the volatile compounds by headspace-gas chromatography/mass spectrometry (HS-GC/MS) were also determined. The OR bulb exhibited the highest TPC (16.3 mg GAE/g d.w., p < 0.01) and TFC (8.5 mg QE/g d.w., p < 0.01), with the highest antioxidant capacity measured by the FRAP (27.1 µmol TE/g d.w., p < 0.01) and DPPH assays (46.2 µmol TE/g d.w., p < 0.01). The ON bulb showed the highest ORAC value (209 µmol TE/g d.w., p < 0.01). Generally, the bulbs were richer in sugars (584 mg/g d.w., p < 0.01) than the leaf blade (239 mg/g d.w., p < 0.01), except for OR. Significant interaction between the genotype and plant organ was noted in the volatile compound profiles (p < 0.05) except for total ketones and carboxylic acids, where higher content was observed in the leaf blade compared to the bulb, regardless of the genotype. These findings highlight WO's potential for use in ready-to-eat products, enhancing its market value.

Towards a natural treatment for mania: red onion husk extract modulates neuronal resilience, redox signalling, and glial activation

BACKGROUND

Red onion husk, a readily available agricultural waste material, contains diverse bioactive compounds with potential health benefits. This study aimed to assess the safety and therapeutic potential of red onion husk extract in managing manic-like symptoms and associated neurochemical dysfunctions.

METHODS

Acute and repeated oral dose studies were conducted in mice and rats to evaluate the safety profile of the extract. FT-IR analysis identified functional groups in the extract, while GC-MS analysis identified specific bioactive compounds in the flavonoid-rich fraction. A ketamine-induced manic behaviour model in Wistar rats was employed to assess the extract's efficacy in attenuating manic-like symptoms. Behavioural and neurochemical analyses were performed to further investigate the extract's effects.

RESULTS

The extract demonstrated a favourable safety profile in both acute and repeated dose studies. FT-IR analysis revealed a complex mixture of organic compounds, including hydroxyl groups, alkynes/nitriles, aromatic and non-aromatic C = C bonds, amines, and polysaccharides. GC-MS analysis identified 17 bioactive compounds, including five-methyl-2-phenylindolizine, methadone N-oxide, and 3-phenylthiane, S-oxide. Ketamine administration significantly increased oxidative stress markers, TBARS, and suppressed antioxidant enzyme activities (SOD, GPx, CAT) in both the cerebral cortex and hippocampus, alongside elevated acetylcholinesterase (AchE) activity, indicating enhanced neuronal excitability. Pre-treatment with FRF (25 mg/kg) effectively mitigated ketamine-induced oxidative stress, as evidenced by reduced TBARS levels and partially restored SOD and GPx activities. Interestingly, FRF significantly increased CAT activity (p < 0.001), potentially suggesting an additional compensatory mechanism. Notably, FRF pre-treatment also counteracted ketamine-upregulated AchE activity, offering neuroprotection against heightened neuronal excitability.

CONCLUSION

Red onion husk extract exhibits a favourable safety profile and exerts potent antioxidant and neuroprotective effects, possibly through modulating Nrf2 signalling pathways. Its ability to counteract ketamine-induced oxidative stress and neuronal hyperactivity highlights its potential as a complementary therapeutic strategy for managing manic episodes in bipolar disorder. Further research is warranted to elucidate the precise molecular mechanisms underlying FRF's action and explore its clinical efficacy in human studies.

Exploring the Immunomodulatory Properties of Red Onion (Allium cepa L.) Skin: Isolation, Structural Elucidation, and Bioactivity Study of Novel Onion Chalcones Targeting the A2A Adenosine Receptor

Onions are versatile and nutritious food widely used in various cuisines around the world. In our ongoing pursuit of bioactive substances with health benefits from red onion (Allium cepa L.) skin, a comprehensive chemical investigation was undertaken. Consequently, a total of 44 compounds, including three previously unidentified chalcones (1-3) were extracted from red onion skin. Of these isolates, chalcones 1-4 showed high affinity to A2A adenosine receptor (A2AAR), and chalcone 2 displayed the best binding affinity to A2AAR, with the IC50 value of 33.5 nM, good A2AAR selectivity against A1AR, A2BAR, and A3AR, and high potency in the cAMP functional assay (IC50 of 913.9 nM). Importantly, the IL-2 bioassay and the cell-mediated cytotoxicity assay demonstrated that chalcone 2 could boost T-cell activation. Furthermore, the binding mechanism of chalcone 2 with hA2AAR was elucidated by molecular docking. This work highlighted that the active chalcones in red onion might have the potential to be developed as A2AAR antagonists used in cancer immunotherapy.

HPLC-Mass spectrometry analysis of phenolics comparing traditional bilberry and blueberry liqueurs

The purpose of this study was to investigate the differences between the phenolics compositions of bilberry and blueberry liqueurs, to determine whether these are comparable. Both bilberry and blueberry liqueurs have the same name on the market, however they differ in phenolic composition and content. A total of 43 compounds were identified, 36 in the bilberry liqueur, and 21 in the blueberry liqueur. High performance liquid chromatography coupled with mass spectrometry (HPLC-MS) was used to identify and quantify these compounds, where they were fragmented to the MS4 fragments. Anthocyanins were the major phenolics group detected in the bilberry liqueurs, but only the second most abundant phenolics group in the blueberry liqueurs. The most abundant phenolics group in the blueberry liqueurs was hydroxycinnamic acids. The lowest content of individual phenolic compounds was for blueberry liqueur made from whole fruit. This study will provide valuable data to consumers in their choice of a more expensive bilberry liqueur or a cheaper blueberry liqueur.

Size Does Matter: The Influence of Bulb Size on the Phytochemical and Nutritional Profile of the Sweet Onion Landrace "Premanturska Kapula" (Allium cepa L.)

The Mediterranean area is especially rich in old, both sweet and pungent, varieties of onion. The synthesis of phytochemicals takes place concurrently with the overall development and maturation of vegetables; however, it is unclear whether there is a correlation between onion bulb size and antioxidant compound content, antioxidant capacity, and nutritional parameters and what the origin of these variations is. The aim of this work was to investigate the biochemical and nutritional aspects of the sweet onion landrace "Premanturska kapula", as well as to investigate the influence of onion bulb size on onion phytochemical and nutritional profile. The sweet onion landrace "Premanturska kapula" has a high soluble sugar content, a high antioxidant capacity, and a high phenolic compound content. Quercetin-3,4'-diglucoside and quercetin-4'-glucoside were the major flavonols, while protocatehuic acid was the major phenolic acid detected. The choice of onion bulb size can impact the profile of the sugars present, with large bulb sizes favoring higher sucrose and fructooligosaccharides content compared to small bulb sizes which were more abundant in glucose. The total sugars or bulb dry matter were not affected by bulb size. Phenolic compounds were more abundant in smaller bulb sizes, thus indicating a link between bulb development and phenolic compound allocation within the plant. This link possibly derived from agronomic practices such as bare-root transplants, or even open pollination which causes a broader genetic variability. From a consumer perspective, it can be a choice between the small and medium bulb sizes on one hand, which are more abundant in polyphenolics and simple sugars, or on the other hand, the larger bulbs which are more abundant in fructooligosaccharides known to carry excellent health benefits.

In Vitro and In Vivo Antibiofilm Activity of Red Onion Scales: An Agro-Food Waste

Red onion wastes (ROW) are valuable sources of bioactive metabolites with promising antimicrobial effects. Methicillin-resistant Staphylococcus aureus (MRSA) infections are a growing risk in hospitals and communities. This study aims to investigate the in vitro and in vivo antibiofilm activities of the acidified ethanolic extract of red onion scales (RO-T) and its fractions against an MRSA vaginal colonization model. The RO-T extract, as well as its anthocyanin-rich fraction (RO-P) and flavonoid-rich fraction (RO-S), recorded a promising antibacterial activity against highly virulent strains of bacteria (MRSA, Acinetobacter baumannii, Escherichia coli and Pseudomonas aeruginosa). RO-S showed the highest antibacterial activity (MBC of 0.33 ± 0.11 mg/mL) against MRSA USA300 and significantly eradicated its biofilm formation with an IC₅₀ of 0.003. Using a rat model, in vivo assessment on all samples, which were formulated as a hydrogel, revealed a significant reduction of MRSA bacterial load recovered from an infected vagina compared to that of the negative control group (NCG). RO-T extract and vancomycin groups recorded the highest antibacterial activity with a bacterial load 2.998 and 3.358 logs lower than the NCG, respectively. The histopathological investigation confirmed our findings. RO-T and RO-S were standardized for their quercetin content. Finally, ROW offers a new potent antibiofilm agent mostly due to its high quercetin content.

The Phytochemical and Nutritional Composition of Shallot Species (Allium × cornutum, Allium × proliferum and A. cepa Aggregatum) Is Genetically and Environmentally Dependent

Shallots are a perennial plant from the Alliaceae family, classified with the common onion under the name of the Allium cepa Aggregatum group. The term shallot is also used for diploid and triploid viviparous onions, known as Allium × proliferum (Moench) Schrad and Allium × cornutum Clementi ex Vis., respectively. In this study, we compared the dry matter, pyruvic acid content, sugar content, flavonoid content, antioxidant capacity and mineral composition of 34 shallot accessions falling into three shallot species (Allium × cornutum, Allium × proliferum and A. cepa Aggregatum). Shallot accessions belonging to the A.× cornutum and A. × proliferum groups are characterized by high dry matter content (around 25%), of which a little less than 50% is formed of inulin-type sugars, polysaccharides, considered an excellent prebiotic with beneficial effects on human health. On the other hand, accessions belonging to the A. cepa Aggregatum group have lower dry matter content and, as a result, lower pungency (measured as pyruvic acid content), making them more suitable for fresh consumption by a broader range of consumers, but, at the same time, abundant in phenolic compounds, especially quercetin and isorhamnetin glycosides. We also observed a greater biodiversity among accessions within the A. cepa Aggregatum group in all the analyzed physico-chemical parameters compared to the other shallot groups. The investigated shallot accessions have an excellent in vitro antioxidant capacity, as well as excellent nutritional properties.

From By-Products to Fertilizer: Chemical Characterization Using UPLC-QToF-MS via Suspect and Non-Target Screening Strategies

The increasing demands of agriculture and the food market have resulted in intensive agricultural practices using synthetic fertilizers to maximize production. However, significant efforts have been made to implement more environmentally friendly procedures, such as composting, to overcome the adverse impact of these invasive practices. In the terms of this research, composting was applied to the production of two biofertilizers, using onion and mushroom by-products as raw materials respectively. The main purposes of this work were to identify the compounds that pass from the raw materials to the final products (onion-based and mushroom-based), as well as the characterization of the chemical profile of these final products following suspect and non-target screening workflows via UPLC-qToF-MS. Overall, 14 common compounds were identified in the onion and its final product, while 12 compounds were found in the mushroom and its corresponding product. These compounds belong to fatty acids, organic acids, and flavonoids, which could be beneficial to plant health. The determination of parameters, such as the pH, conductivity, organic matter, nitrogen content, and elemental analysis, were conducted for the overall characterization of the aforementioned products.

The Influence of Plants from the Alliaceae Family on Morphological Parameters of the Intestine in Atherogenic Rats

Bulbs from the Alliaceae family have been well-known and valued spices for thousands of years, not only for their unique flavor and aroma features, but also for their high nutritional and health-promoting values. Long-term or excessive consumption of these vegetables, especially raw garlic, can have side effects in the body (including in the digestive tract), causing a number of pathological changes in the intestinal wall; these changes lead, in turn, to its damage, dysfunction, and disorder development. Therefore, the aim of this study was to investigate the effect of the addition of freeze-dried vegetables from the Alliaceae family, i.e., garlic (Allium sativum L.), white onion, and red onion (Allium cepa L.) on the morphometric parameters (intestinal villi length, crypt depth, thickness of tunica mucosa, and the thickness of tunica muscle) of the jejunum of rats fed a semi-synthetic atherogenic diet (1% dietary cholesterol). In freeze-dried vegetables administered to rats, the contents of selected bioactive ingredients and their antioxidant potentials were determined. The effect of the onion vegetable supplements on growth parameters, serum lipid profile, plasma antioxidant potential, and the intestinal morphological parameters of rats loaded with cholesterol was determined. In an animal experiment, 30 male Wistar rats were divided into 5 diet groups, diet consumption and FER were studied. Supplementation of the atherogenic diet with vegetables improved the blood plasma lipid profiles and atherogenic indices, in a manner that was dependent on the type of supplementation used, with the best hypolipidemic and anti-atherosclerotic effects found in garlic use. The atherogenic diet, as well as the supplementation of this diet with the tested vegetables from the Alliaceae family, influenced the histological changes in the epithelium of the jejunum of rats. The damage to the intestinal mucosa was the greatest in animals fed an atherogenic diet supplemented with garlic. Bearing in mind that the desired beneficial therapeutic or prophylactic effects of onion vegetables (in particular garlic) in the course of various metabolic ailments (including atherosclerosis) are achieved during long-term supplementation, it is important to remember their possible cytotoxic effects (e.g., on the digestive tract) in order to achieve real benefits related to the supplementation with vegetables from the Alliaceae family.

Influence of Cooking Methods on Onion Phenolic Compounds Bioaccessibility

The impact of domestic cooking (baking, boiling, frying and grilling) and in vitro digestion on the stability and release of phenolic compounds from yellow-skinned (YSO) and red-skinned onions (RSO) have been evaluated. The mass spectrometry identification pointed out flavonols as the most representative phenolic class, led by quercetin-derivatives. RSO contained almost the double amount of phenolic compounds respect to YSO (50.12 and 27.42 mg/100 g, respectively). Baking, grilling and primarily frying resulted in an increased amount of total phenolic compounds, especially quercetin-derivatives, in both the onion varieties. Some treatments promoted the degradation of quercetin-3-O-hexoside-4′-O-hexoside, the main compound present in both the onion varieties, leading to the occurrence of quercetin-4′-O-hexoside and protocatechuic acid-4-O-hexoside. After in vitro digestion, the bioaccessibility index for total phenolic compounds ranged between 42.6% and 65.5% in grilled and baked YSO, respectively, and between 39.8% and 80.2% in boiled and baked RSO, respectively. Baking contributed to the highest amount of bioaccessible phenolic compounds for both the onion varieties after in vitro digestion. An in-depth design of the cooking process may be of paramount importance in modulating the gastro-intestinal release of onion phenolic compounds.

Barbero G, Palma M. Development of a Rapid UHPLC-PDA Method for the Simultaneous Quantification of Flavonol Contents in Onions (Allium cepa L.)

Onion, one of the most consumed vegetables in the world, is also known to contain high levels of antioxidant compounds, with protective effects against different degenerative pathologies. Specifically, onion is rich in flavonols, mainly quercetin derivatives, which are compounds with high antioxidant and free radical scavenging power. For this reason, it is of the utmost importance to count on optimal analytical methods that allow for the determination and quantification of these compounds of interest. A rapid ultra-high performance liquid chromatography (UHPLC)-photo-diode array (PDA) method for the separation of the major flavonols in onions was developed using a Box–Behnken design in conjunction with multiresponse optimization on the basis of the desirability function. The conditions that provided a successful separation were 9.9% and 53.2% of phase B at the beginning and at the end of the gradient, respectively; 55 °C column working temperature; and 0.6 mL min⁻¹ flow rate. The complete separation was achieved in less than 2.7 min with excellent chromatographic characteristics. The method was validated, and its high precision, low detection and quantification limits, good linearity, and robustness were confirmed. The correct applicability of the method improves the analysis of the raw material, increasing the quality of onions and its subproducts in terms of bioactive compounds and functional characteristics for consumers.

Flavonol Composition and Antioxidant Activity of Onions (Allium cepa L.) Based on the Development of New Analytical Ultrasound-Assisted Extraction Methods

The onion is one of the most cultivated and consumed vegetables, and is a very valuable source of antioxidant substances. Every onion variety is rich in flavonols-mainly quercetin derivatives which makes onions the main dietary source of these compounds. This study intends to develop an ultrasound-assisted extraction method (UAE), an economical, green, and efficient technique, that allows us to determine the quality of onion extracts in terms of flavonol composition and antioxidant activity. For this purpose, an ultrasound-assisted extraction method has been optimized to obtain extracts with a high amount of flavonols, as well as with a high antioxidant activity, not only separately using a Box-Behnken design, but also simultaneously, based on multi-response optimization. Multiple response optimization has not only demonstrated an efficacy level similar to that of the individual ones, but it also represents a considerable reduction in terms of cost, time and work. The optimal conditions for simultaneous extractions were determined as follows: 76.8% methanol as an extraction solvent at pH 2 and 58.5 °C temperature, 85% amplitude, 0.9 s cycle, and 0.2:13 g:mL sample mass/solvent volume ratio. Furthermore, the developed method exhibited a high precision level and great recoveries in a rather short extraction time (2 min). These results, together with the development of a fast and simple UHPLC analysis method, lead us to consider the developed UAE method as a suitable technique for the extraction of bioactive compounds from onion matrices.

Isolation and characterization of components responsible for neuroprotective effects of Allium cepa outer scale extract against ischemia reperfusion induced cerebral injury in mice

The antioxidant-mediated neuroprotective effect of Allium cepa outer scale extract (ACE) in mice with cerebral ischemia-reperfusion (I-R) injury was demonstrated in our earlier work. The current investigation aimed at establishing the bioactive component(s) responsible for this activity. Thus ACE was fractionated into ethyl acetate (EF) and aqueous (AF) fractions. These fractions were evaluated against cerebral I-R injury in mice. I-R injury in mice was induced by bilateral common carotid artery occlusion followed by 24 hr reperfusion. Memory, sensorimotor functions, cerebral infarct size, and oxidative stress were measured to address the neuroprotective mechanism of test substances. EF showed marked improvement of memory and sensorimotor functions by reducing brain oxidative stress and infarct size in mice after I-R injury. The bioactive EF was subjected to chromatographic (HPLC-PDA, HPLC-MS, preparative HPLC) and spectroscopic studies to isolate and identify the neuroprotective compounds. This lead to separation of three components, namely quercetin, quercetin 4'-O-glucoside, and the remaining fraction, from EF. The separated components were biologically evaluated. These components showed improvement in mice with I-R injury. But, EF displayed more marked neuroprotective effects as compared to the isolated components. The distinct neuroprotective outcome of EF may be credited to the synergistic action of compounds present in EF. Further studies such as evaluation of neurotoxic effects and other possible neuroprotective mechanisms are required to develop EF as a neuroprotective drug.

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.

Novel insights on the multi-functional properties of flavonol glucosides from red onion (Allium cepa L) solid waste - In vitro and in silico approach

Flavonol glucosides was extracted from red onion solid waste (ROSW) and multi-functional properties were determined to develop alternative strategy for therapeutic beneficiation and utilisation as functional food. The major flavonol glucosides extracted from ROSW were confirmed as quercetin-3, 4'-O-diglucoside (QDG), quercetin-3-O-glucoside (isoquercetin), quercetin-4'-O-glucoside (spiraeoside), isorhamnetin- 4'-glucoside (IMG), quercetin glycoside (QG), and quercetin (Q) using a combination of chromatographic, spectroscopic and scientific literature data. The ROSW solvent fractions and extracted flavonol glucosides showed significant antioxidant effect with DPPH, ABTS, FRAP, and ORAC radical scavenging assays. The in vitro and in silico study revealed that the QG, QDG, isoquercetin, and spiraeoside from ROSW exhibited potent α-glucosidase, tyrosinase and xanthine oxidase enzyme inhibitory activity. In addition, QG, QDG, isoquercetin, and spiraeoside showed potent anticancer effect on HeLa cancer lines. Considering these results, the utilization of ROSW and their flavonol glucosides might be helpful for developing potential antioxidant, anticancer and enzyme inhibitory agents.

Allium cepa fraction attenuates STZ-induced dementia via cholinesterase inhibition and amelioration of oxidative stress in mice

Background An earlier study demonstrated significant antioxidant and anticholinesterase activities of hydromethanol extract (HME) of Allium cepa. The aim of the study was to investigate the component responsible for these activities followed by an in vivo study. Methods In vitro antioxidant and anticholinesterase activities of standardized ethylacetate fraction (EAF) of HME were assessed. Bioactivity-guided fractionation showed that, as compared with its subfractions, EAF had most significant activity in 2,2-diphenyl-1-picrylhydrazyl and Ellman assays. Thus, EAF was further examined using a streptozotocin (STZ)-induced model of Alzheimer's disease in mice. STZ was injected intracerebroventricularly on days 1 and 3 (3 mg/kg) in mice. EAF was thereafter administered (42, 84, and 168 mg/kg b.w./day p.o.) from days 9 to 22. The Morris water maze test was used to evaluate learning and memory in mice. Acetylcholinesterase (AChE) activity and oxidative stress markers were assessed in the brain homogenates of mice. Additionally, histopathological studies were performed to observe effects in the brain at the cellular level. EAF was standardized based on quercetin and quercetin 4'-O-glucoside content using a validated thin layer chromatography densitometric method. Results STZ produced significant (p < 0.05) memory impairment along with oxidative stress and a cholinergic deficit in mice. EAF treatment ameliorated STZ-induced behavioral deficits and biochemical alterations in mice in a significant and dose-dependent manner. Conclusions Our results show that EAF is efficacious in improving memory and learning via AChE inhibition and antioxidant activity in the mice brain. Thus, AC could be explored further to find out a lead candidate for Alzheimer's disease.

Quantification of flavonoids, total phenols and antioxidant properties of onion skin: a comparative study of fifteen Indian cultivars

Onion waste disposal issue could be solved by using onion skin as food ingredient. Therefore, the aim of present study is the estimation of flavonoid concentration, total phenolic content (TPC), total flavonoid content (TFC) and antioxidant activities of onion skin of fifteen Indian cultivars. Flavonoid quantification was achieved by high performance liquid chromatography, which showed highest concentration of quercetin, quercetin 3-β-D-glucoside, luteolin and kaempferol in cv. 'NHRDF Red' (11,885.025 mg/kg), 'Hissar-2' (1432.875 mg/kg), 'Pusa Riddhi' (1669.925 mg/kg) and 'Bhima Shakti' (709.975 mg/kg), respectively in dry weight. Highest TPC and TFC were found in cv. 'NHRDF Red' while lowest were measured in cv. 'Bhima Shubhra'. DPPH assay (%), ABTS assay (%) and FRAP assay (µmol gallic acid/g) were showed maximum antioxidant capacity for cv. 'NHRDF Red' whereas least obtained for cv. 'Bhima Shubhra'. Skin of cv. 'Hissar-2' and 'NHRDF Red' are the best source of flavonoids and natural antioxidants.

UPLC-ESI-MS/MS based identification and antioxidant, antibacterial, cytotoxic activities of aqueous extracts from storey onion (Allium cepa L. var. proliferum Regel)

Storey onion (Allium cepa L. var. proliferum Regel) is a variety of onion commonly grown in northern China that has not been researched in detail. This study aimed to identify the chemical compositions of storey onion aqueous extracts by UPLC-ESI-MS/MS, as well as characterize the antioxidant, antibacterial and cytotoxic activities, compared with welsh onion and onion. A total of 42 compounds were identified, among which the contents of organosulfur compounds (962.20 ± 34.55 μg/g), polyphenols (100.40 ± 12.55 μg/g) and organic acids (54.04 ± 2.69 μg/g) in storey onion were higher than those in welsh onion and onion. Additionally, the contents of cycloalliin (551.74 ± 8.12 μg/g), ajoene (159.31 ± 5.30 μg/g) and (E)-1-propene-1-sulfenic acid (72.12 ± 2.98 μg/g) in storey onion were the highest. Storey onion had pronounced DPPH• (IC₅₀ = 1.24 ± 0.52 mg/mL) and OH• scavenging activities (IC₅₀ = 14.45 ± 1.29 mg/mL) as well as ferric ion reducing power (absorbance from 0.32 to 2.21). Onion had the highest ABTS•⁺ scavenging activity (IC₅₀ = 1.64 ± 0.64 mg/mL), while welsh onion had the lowest antioxidant activity. Storey onion had the strongest inhibitory effect on all the tested strains (MIC 31.3-125 mg/mL), and cell viability assays against human liver (HepG2) cancer cell lines also illustrated that aqueous extracts from storey onion significantly inhibited cell proliferation (when incubated for 24 h, IC₅₀ = 33.21 ± 1.12 mg/mL) and induced cell apoptosis. Welsh onion and onion also had weaker antibacterial and anticancer activites, with those of onion being the weakest. The results showed that storey onion with excellent biological activity may benefit to human health and can be developed into functional foods.

Arsenic Removal from Water by Green Synthesized Magnetic Nanoparticles

Magnetite nanoparticles were synthesized by a simple and ecofriendly method using onion peel (MNp-OP) and corn silk extract (MNp-CS), in order to develop new low-cost adsorbents for arsenic removal from groundwater. As a point of comparison, magnetite nanoparticles were also synthesized with a conventional chemical process (MNp-CO). The antioxidant potential of onion peel and corn silk extracts was determined using ferric reducing antioxidant power (FRAP) and free radical (DPPH) scavenging assays, including the total phenolics, flavonoids and tannins contents. The synthesized magnetite nanoparticles were characterised using different techniques (Scanning electron microscope/Energy dispersive spectroscopy (SEM/EDS), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR) and Brunauer-Emmett-Teller (BET) surface area analyzer). The adsorption capacity of MNp-OP and MNp-CS and the arsenic removal mechanism of these novel adsorbents was investigated through kinetic and equilibrium experiments and their corresponding mathematical models. Characterisation of MNp-OP and MNp-CS shows high BET specific surface areas of 243 m2/g and 261 m2/g, respectively. XRD and FTIR analysis confirmed the formation and presence of magnetite nanoparticles. The arsenic adsorption mechanism on MNp-OP, MNp-CS and MNp-CO involves chemisorption, intraparticle and external diffusion. Maximal adsorption capacities of MNp-OP, MNp-CS and MNp-CO were 1.86, 2.79, and 1.30 mg/g respectively. The green synthesis applied using onion peel and corn silk extracts was cost effective and environmentally friendly, and results in adsorbents with a high capacity for arsenic and magnetic properties, making them a very promising alternative approach in the treatment of arsenic contaminated groundwater.

Comprehensive analysis of an uninvestigated wild edible medicinal garlic species from Turkey: Allium macrochaetum Boiss. & Hausskn

The study was aimed to investigate the phenolic compounds of Allium macrochaetum by LC-MS/MS, as well as the antioxidant, antialzheimer, and antimicrobial activities of the extracts, and determination of the essential oil and fatty acid compositions by GC-MS. The results indicate that malic acid and t-caffeic acid are the major compounds in the bulbs. The main components of fatty acids were found to be linolenic (40.72%), oleic (19.79%), and palmitic (18.45%) acids. The allyl disulfide (66.97%) was found as major compound in the essential oil. The ethanol extract of the bulbs exhibited stronger ABTS cation (IC₅₀ : 55.90 ± 1.08 µg/ml) and DPPH free (IC₅₀ : 204.43 ± 2.17 µg/ml) radical scavenging activities than the other extracts. The extract also showed moderate cupric reducing activity with 1.52 absorbance at 100 µg/ml concentration. Only the ethanol extract of the bulbs showed weak inhibition (23.34 ± 0.11%) against butrylcholinesterase enzyme at 200 µg/ml. PRACTICAL APPLICATIONS: Allium macrochaetum is a wild and edible garlic species which grown in Turkey, Iran, Iraqi, and Syria. A. macrochaetum has been used by local people in Turkish folk medicine as an antibiotic, and for the treatment of alopecia. The health benefits and nutritional values of A. macrochaetum were clarified in the first time. Phenolic compounds of A. macrochaetum were detected by LC-MS/MS. The essential oil and fatty acid compositions of A. macrochaetum were identified by GC-MS. Antioxidant, antialzheimer, and antimicrobial activities potential of A. macrochaetum were determined.

Simultaneous identification of low-molecular weight phenolic and nitrogen compounds in craft beers by HPLC-ESI-MS/MS

Phenolic and nitrogenous compounds from different styles craft beers were identified by high performance liquid chromatography and mass spectrometry in order to stratify beer samples according to their style. For this, an exploratory assessment relying on Linear Discriminant Analysis was performed. Fifty-seven phenolic compounds were reported and twelve of them were found for the first time in beer: benzoic acids, 2,4-dihydroxybenzoic acid, 2,3-dihydroxybenzoic acid, dimethoxybenzoic acid; phenolic acid conjugates, 3-p-coumaroylquinic acid, 4-p-coumaroylquinic acid, 3-feruloylquinic acid, 4-feruloylquinic acid, 5-feruloylquinic acid; flavonoids, taxifolin hexoside, quercetin dihexoside, apigenin-6,8-dipentoside, and isofraxidin hexoside. Additionally, 11 nitrogenous compounds belonging to the phenolamide class were found. Two discriminant functions were generated and allowed a satisfactory separation among all beer styles. 3-Caffeoylquinic acid, 3-p-coumaroylquinic acid, 4-p-coumaroylquinic acid, 5-caffeoylquinic acid, coumaric acid, kaempferol-3-O-rutinoside, proanthocyanidin B dimer III and proanthocyanidin B dimer V were the compounds that showed the highest capacity of discriminate the beer styles (IPA, Lager and Weiss).

Morphological and Biochemical Diversity of Shallot Landraces Preserved Along the Croatian Coast

Shallots are a valuable minor Allium crop, and are propagated vegetatively and maintained in home gardens across generations along the Croatian coast and island areas. Shallot landraces growing along the Croatian coast fall into three genotypes: Allium cepa Aggregatum group (2n = 2x = 16), A. × proliferum (Moench) Schard. (2n = 2x = 16), and A. × cornutum Clementi ex Vis. (2n = 3x = 24), among which A. × cornutum is the most widespread. The aim of this study was to differentiate shallot accessions collected from local farmers using morphological markers. Also, the chemical composition including phenolic content, phenolic profile, total antioxidant capacity, and mineral composition, of shallot accessions was compared with that of the local landraces of common onion, and with market available shallot and common onion cultivars. Based on morphological observations and using multivariate classification, shallot landraces were classified into three distinct groups. Properties, based on which A. × cornutum can be differentiated from A. cepa Aggregatum and A. × proliferum, are stamen morphology, stamen length, leaf and scape vegetative properties, number of bulbs in cluster, cluster mass, and bulb diameter. Flower diameter and flower pedicel length differentiate A. × cornutum and A. × proliferum from A. cepa Aggregatum. Significant variability was observed in the biochemical profiles across tested accessions. Compared with the commercial common onion cultivars, local shallot accessions have higher bulb N, P, and K content. The major phenolic compounds identified in shallots were quercetin-4'-glucoside and quercetin-3,4'-diglucoside. Additionally, several other minor phenolic compounds were also identified. Morphological and biochemical profiles were evaluated using Partial Least Square (PLS) analysis. Specific morphological traits and biochemical markers for possible species identification are proposed.

Optimization of Polyphenol Extraction from Allium ampeloprasum var. porrum through Response Surface Methodology

Allium ampeloprasum var. porrum has been recognized as a rich source of secondary metabolites, including phenolic acids, flavonoids and flavonoid polymers (proanthocyanidins or condensed tannins), with related health benefits. Both parts of Allium ampeloprasum var. porrum (white bulb and pseudostem) are traditionally consumed either as a vegetable or as a condiment in many Mediterranean countries. The aim of the present study was to optimize the extraction conditions of polyphenols from white leek stem and green leek leaf by implementing a Box-Behnken design (BBD). The optimization considered basic factors affecting extraction efficiency, including extraction time, solvent to plant material ratio and solvent mixture composition. Maximum polyphenol yield was achieved at an extraction time of 80 and 100 min for white leek stem and green leek leaf extracts respectively, solvent to plant material ratio of 5:1 (v/w) and methanol to water ratio of 40:60 (v/v), for both leek extracts. Interestingly, higher total phenolic content was found in green leek leaf extracts compared to white leek stem extracts, due to a possible relationship between polyphenol production and sunlight radiation. High correlation values were also observed between total phenolic content and antioxidant-antiradical activity of optimized leek extracts.

Antioxidant and antiplatelet potential of different methanol fractions and flavonols extracted from onion (Allium cepa L.)

In this study, we reported the potential of various methanol fractions of onion (MFO) and its components quercetin and quercetin glucosides on platelet aggregation and antioxidant activity. The onion extracts were separated into several fractions using methanol and water. Further, these extracts were analyzed using simple high-performance liquid chromatography-diode array detector method to separate quercetin (Q), quercetin-4'-O-monoglucoside and quercetin-3, 4'-O-diglucoside from onion sample. It was observed that the bioactive compounds were accumulated in the non-polar portions rather than in the polar one. MFO and flavonol glucosides inhibited collagen-induced platelet aggregation, and the anti-aggregatory effects were comparatively studied using rat PRP (platelet-rich plasma). Among the extracted compounds, quercetin was found as a potent inhibitor of platelet aggregation compared to quercetin glucosides, whereas quercetin glucosides showed high antioxidant activities. These results suggest that MFO, quercetin and quercetin glucosides have powerful antiplatelet and antioxidant activities. These studies provide possible information leading to the intake of onions rich in these flavonols as a dietary supplement and functional food ingredient to prevent thrombosis and cardiovascular and oxidative stress-related diseases and might be utilized as a real source of valuable phytochemicals for the pharmaceutical and food industries for the development of antioxidant, anticoagulant and antiplatelet agents.

Enhanced HPLC-DAD Method for Fast Determination of Quercetin-3-O-β-d-Glucoside in Extracts and Polyherbal Formulations Containing Azadirachta indica-Optimization and Validation

Azadirachta indica has been used for its medicinal properties since time immemorial. Herbal medicines which are prepared using this medicinal tree are utilized to treat various diseases and disorders. No reports are available for marker-based standardization of these herbal medicines prepared from leaves of A. indica. Also existing HPLC methods for determination quercetin-3-O-β-d-glucoside are time consuming. There is an obvious need for development of new HPLC method for quantification of quercetin-3-O-β-d-glucoside which is fast enough to carry out analysis in stipulated time period. This article deals with the development, optimization and validation of fast HPLC-DAD method for the determination of quercetin-3-O-β-d-glucoside in extracts containing A. indica for its successive application for marker-based standardization of herbal formulations containing A. indica. The retention time of quercetin-3-O-β-d-glucoside was 11.213 min. The method was found to be linear in the range of 4.0-60 µg mL-1. Limit of detection and limit of quantitation of the proposed method were found to be 1.33 and 4.0 µg mL-1, respectively. The mean recoveries were found to be within 93.53-103.75%. The method can be used as quality control tool for routine analysis of herbal extracts and formulations containing A. indicia.

Chemical Composition and Biological Activity of Allium cepa L. and Allium × cornutum (Clementi ex Visiani 1842) Methanolic Extracts

Here, we report a comparative study of the phytochemical profile and the biological activity of two onion extracts, namely Allium cepa L. and Allium × cornutum (Clementi ex Visiani 1842), members of the family Amaryllidaceae. The identification of flavonoids and anthocyanins, and their individual quantities, was determined by high-performance liquid chromatography (HPLC). The potency of both extracts to scavenge free radicals was determined by the DPPH (2,2'-diphenyl-1-picrylhydrazyl) radical-scavenging activity and oxygen radical absorbance capacity (ORAC) methods. The DNA protective role was further tested by the single-cell gel electrophoresis (COMET) assay and by Fenton's reagent causing double-strand breaks on the closed circular high copy pUC19 plasmid isolated from Escherichia coli. In the presence of both extracts, a significant decrease in DNA damage was observed, which indicates a protective role of Allium cepa and Allium × cornutum on DNA strand breaks. Additionally, cytotoxicity was tested on glioblastoma and breast cancer cell lines. The results showed that both extracts had antiproliferative effects, but the most prominent decrease in cellular growth was observed in glioblastoma cells.

Characterization of phenolic and other polar compounds in peel and flesh of pink guava (Psidium guajava L. cv. 'Criolla') by ultra-high performance liquid chromatography with diode array and mass spectrometric detection

Pink guava (Psidium guajava L.) is a highly consumed fruit in tropical countries. Despite of interesting research on health effects of this fruit, investigations into the profile of secondary plant metabolites are scarce. In this study, the phenolic compounds in the peel and flesh of pink guava were characterized by ultra-high performance liquid chromatography with diode array and mass spectrometric detection. Sixty phenolic compounds were characterized by MS² and classified as ellagitannins, flavones, flavonols, flavanols, proanthocyanidins, dihydrochalcones, and anthocyanidins, and non-flavonoids such as phenolic acid derivatives, stilbenes, acetophenones, and benzophenones. Forty-two polyphenols are reported for the first time in both peel and flesh, and twenty-four compounds were detected for the first time in P. guajava, e.g., phlorizin, nothofagin, astringin, chrysin-C-glucoside, valoneic acid bilactone, cinnamoyl-glucoside, and two dimethoxycinnamoyl-hexosides.

TLC determination of flavonoids from different cultivars of Allium cepa and Allium ascalonicum

This study comprises the optimization and validation of a new TLC method for determination of flavonols in the bulbs of seven cultivars of onions and shallots. Separation was performed on RP-18 plates with the solvent mixture tetrahydrofuran/water/formic acid (40+60+6, V/V/V) as a mobile phase. The method was evaluated for precision, linearity, LOD, LOQ, accuracy and robustness. Chromatographic analysis of the extracts revealed the presence of three main flavonols, quercetin, quercetin-4'-O-glucoside and quercetin-3,4'-O-diglucoside in the majority of analyzed cultivars. The content of flavonols in the analyzed extracts of onion bulbs varied from 123 ('Exihibition') to 1079 mg kg-1 fresh mass (fm) ('Hybing') in edible parts, and from 1727 ('Hyline') to 28949 mg kg-1 fm ('Red Baron') in outer scales. The bulbs of two shallot cultivars contained 209 ('Ambition') and 523 mg kg-1 fm ('Matador') of flavonols in edible parts and 5426 and 8916 mg kg-1 fm in outer scales, respectively.

Assessment of Various Pretreatment and Extraction Methods for the Extraction of Bioactive Compounds from Orthosiphon stamineus Leaf via Microstructures Analysis

The impacts of various methods such as mechanical grinding, ultrasonic-assisted extraction (UAE), microwave-assisted extraction (MAE), and also sample pretreatments using acid and alkali on the microstructure of plant sample were studied for the extraction of bioactive compounds from Orthosiphon stamineus leaf. From scanning electron microscopy (SEM) analysis of the extracted sample, UAE and MAE induced significant disruption on glandular trichomes structure, which is the main site for biosynthesis of plant secondary metabolites. This improves the diffusion of bioactive compound and resulted in approximately 86–95 % of the total extraction yield quantified by conventional Soxhlet extraction. Chemical pretreatments generally imparted weaker microstructures disruption thus slight improvement on the extraction yields was observed. In this case, acid reagent is more suitable for the pretreatment as the presence of alkali decomposes the bioactive compounds. In a nutshell, the performance of an extraction strongly depends on its degree of disruption on the plant sample microstructure.

Economical and environmentally-friendly approaches for usage of onion (Allium cepa L.) waste

General anatomy and different layers in onion.

Flavonol Glycosides from the Leaves of Allium Macrostemon

Twelve flavonoids were isolated from Allium macrostemon leaves. Five compounds were identified as kaempferol 3,7-di -O-glucoside (1), kaempferol 3,4′-di- O-glucoside (2), quercetin 3- O-glucoside (3), kaempferol 3- O-glucoside (4) and isorhamnetin 3- O-glucoside (5) by UV spectra, LC-MS, acid hydrolysis and HPLC comparisons with authentic standards. Other flavonoids were characterized as kaempferol glycosides (6–8, 10 and 11) and quercetin glycosides (9 and 12). Other compounds, such as steroidal saponins, have been already found from the bulbs of A. macrostemon. However, flavonoids were reported for the first time from the leaves.

Quantitative metabolite profiling of edible onion species by NMR and HPLC-MS

Allium genus is a treasure trove of valuable bioactive compounds with potentially therapeutically important properties. This work utilises HPLC-MS and a constrained total-line-shape (CTLS) approach applied to (1)H NMR spectra to quantify metabolites present in onion species to reveal important inter-species differences. Extensive differences were detected between the sugar concentrations in onion species. Yellow onion contained the highest and red onion the lowest amounts of amino acids. The main flavonol-glucosides were quercetin 3,4'-diglucoside and quercetin 4'-glucoside. In general, the levels of flavonols were, higher in yellow onions than in red onions, and garlic and leek contained a lower amount of flavonols than the other Allium species. Our results highlight how (1)H NMR together with HPLC-MS can be useful in the quantification and the identification of the most abundant metabolites, representing an efficient means to pinpoint important functional food ingredients from Allium species.