Effect of dehydration and pulsed light treatment on decontamination of minced onions: Microbial safety and physicochemical properties.

Microbial contamination of dehydrated onion products is a challenge to the industry. The study focused on opting for a suitable drying condition for minced onion and exploring the decontamination efficacy of pulsed light (PL) treatment conditions for the dehydrated product. The minced onions were hot air dried at 55-75°C for 280 min. The drying condition selected was 195 min at 75°C with a final water activity of 0.5 and moisture content of 7% (wet basis [w.b.]). The weight losses, browning indexes (BI), shrinkage volumes (%), and thiosulfinate content were considered. The dehydrated product was exposed to PL treatment corresponding to an effective fluence range of 0.007-0.731 J/cm2. A fluence of 0.444 J/cm2 (1.8 kV for 150 s) achieved 5.00, 3.14, 2.96, and 2.98 log reduction in total plate count, yeast and mold count, Bacillus cereus 10876, and Escherichia coli ATCC 43888, respectively. The PL-treated sample (0.444 J/cm2) produced a microbially safe product with no significant difference in the moisture contents (%w.b.) and water activity (aw) from the untreated dehydrated sample. Further, a 30.9% increase in the BI and a 4.25% depletion in thiosulfinate content were observed after PL treatment. An optimum drying combination (75°C for 195 min) of minced onion followed by decontamination using pulsed light treatment at 0.444 J/cm2 fluence satisfies the microbial safety and quality. PRACTICAL APPLICATION: Dehydrated minced onion can be used for dishes requiring low water content and short cooking time. It is helpful during shortages, high price fluctuations, and famines.

Organosulfur Compounds of Allium Subgenus Nectaroscordum Species.

Organosulfur compounds formed upon comminuting the bulbs of two Allium subgenus Nectaroscordum species (Allium siculum and Allium tripedale) were analyzed by HPLC-PDA-MS/MS. The major organosulfur components were isolated and structurally characterized (MS, NMR), including several previously unknown compounds. It was found that the organosulfur chemistry occurring when these plants are cut is very similar to that observed in onion (Allium cepa). In all cases, however, the organosulfur compounds found in Nectaroscordum species were higher homologues of those observed in onion, being formed by various combinations of C1 and C4 building blocks derived from methiin and homoisoalliin/butiin, respectively. Thiosulfinates, bis-sulfine, cepaenes, and several cepaene-like compounds were identified among the major organosulfur components present in the homogenized bulbs. Several groups of 3,4-diethylthiolane-based compounds, structurally homologous with onionin A, cepathiolane A, allithiolanes A-H, and cepadithiolactone A, found in onion, were also detected.

Black Garlic and Thiosulfinate-Enriched Extracts as Adjuvants to Ceftriaxone Treatment in a Rat Peritonitis Model of Sepsis.

To date, there have been no new drugs or adjuvants able to decrease both morbidity and mortality in the context of sepsis and septic shock. Our objective was to evaluate the use of thiosulfinate-enriched Allium sativum and black garlic extracts as adjuvants in the management of sepsis. An experimental in vivo study was carried out with male Sprague-Dawley® rats. Animals were randomized in four treatment groups: antibiotic (ceftriaxone) treatment (group I), ceftriaxone plus thiosulfinate-enriched extract (TASE, group II), ceftriaxone plus thiosulfinate-enriched extract and black garlic extracts (TASE + BGE, group III), and ceftriaxone plus black garlic extract (BGE, group IV). All animals were housed and inoculated with 1 × 1010 CFU/15 mL of intraperitoneal Escherichia coli ATCC 25922. Subsequently, they received a daily treatment according to each group for 7 days. Clinical, analytical, microbiological, and histopathological parameters were evaluated. Statistically significant clinical improvement was observed in rats receiving garlic extracts in weight (groups II and III), ocular secretions, and piloerection (group IV). Moreover, less liver edema, vacuolization, and inflammation were observed in groups receiving adjuvant support (groups II, III, and IV). When comparing interleukins 24 h after bacteria inoculum, we found statistically significant differences in TNF-alpha levels in groups receiving BGE (groups III and IV, p ≤ 0.05). Blood and peritoneal liquid cultures were also analyzed, and we detected a certain level of Enterococcus faecalis in peritoneal cultures from all treatment groups and less bacteria presence in blood cultures in rats receiving garlic extracts (groups II, III, and IV). In conclusion, TASE and BGE could be promising nutraceutical or medicinal agents as coadjuvants in the treatment of sepsis because of its effects in modulating the inflammatory response.

Acute and subchronic 90-days toxicity assessment of propyl-propane-thiosulfinate (PTS) in rats.

The organosulfur compounds (OSC) extracted from Allium spp. exhibit antibacterial, antifungal, and antioxidant properties. The agri-food industry is taking advantage of these properties by using them as natural feed and food additives. In the present work, an acute and a subchronic 90-days toxicity studies have been conducted for the first time to assess the safety of the OSC propyl-propane-thiosulfinate (PTS). Both studies were carried out following the Organization for Economic Co-operation and Development test guidelines (425 and 408, respectively). The acute study provided a maximum tolerated dose (MTD) of 175 mg/kg and the subchronic study established the Non Observed Adverse Effect Level (NOAEL) ≥ 55 mg/kg body weight (b.w.)/day in both sexes. In addition, the subchronic study performed on rats exposed to 14, 28 and 55 mg/kg b.w./day PTS, revealed no changes in any of the hematological parameters measured as well as no differences in body weight and water/food consumption. However, biochemical parameters were altered in some groups, although they were not biologically significant (Ca2+ in female rats, and the thyroids hormones T3 and T4 in rat males). Furthermore, the histopathological assessment evidenced no abnormality on the gastrointestinal, respiratory, lymphoid, urinary, circulatory, nervous, musculoskeletal, and reproductive systems.

Thiosulfinate Tolerance Is a Virulence Strategy of an Atypical Bacterial Pathogen of Onion.

Unlike most characterized bacterial plant pathogens, the broad-host-range plant pathogen Pantoea ananatis lacks both the virulence-associated type III and type II secretion systems. In the absence of these typical pathogenicity factors, P. ananatis induces necrotic symptoms and extensive cell death in onion tissue dependent on the HiVir proposed secondary metabolite synthesis gene cluster. Onion (Allium. cepa L), garlic (A. sativum L.), and other members of the Allium genus produce volatile antimicrobial thiosulfinates upon cellular damage. However, the roles of endogenous thiosulfinate production in host-bacterial pathogen interactions have not been described. We found a strong correlation between the genetic requirements for P. ananatis to colonize necrotized onion tissue and its capacity for tolerance to the thiosulfinate "allicin" based on the presence of an eleven-gene, plasmid-borne, virulence cluster of sulfur redox genes. We have designated them "alt" genes for allicin tolerance. We show that allicin and onion thiosulfinates restrict bacterial growth with similar kinetics. The alt gene cluster is sufficient to confer allicin tolerance and protects the glutathione pool during allicin treatment. Independent alt genes make partial phenotypic contributions indicating that they function as a collective cohort to manage thiol stress. Our work implicates endogenous onion thiosulfinates produced during cellular damage as major mediators of interactions with bacteria. The P. ananatis-onion pathosystem can be modeled as a chemical arms race of pathogen attack, host chemical counterattack, and pathogen defense.

Topical Applications of Thiosulfinate-Enriched Allium sativum Extract Accelerates Acute Cutaneous Wound Healing in Murine Model.

OBJECTIVE: To determine whether topical applications of thiosulfinate-enriched Allium sativum extract (TASE) can accelerate acute cutaneous wound healing (WH) in a murine model. METHODS: Keratinocyte viability and in vitro wound closure were assessed in keratinocyte cultures. Effects of topical TASE (0.5 µg/mL of allicin in 97% ethanol) on acute cutaneous WH were determined in a murine model of acute cutaneous wound. Twelve mice were alternately assigned to the vehicle- and TASE-treated groups (n=6 per group). Expression levels of mRNA for keratinocyte differentiation marker-related proteins (filaggrin, loricrin and involucrin) and lipid synthetic enzymes (elongation of very long chain fatty acids protein 4 (ELOVL4), fatty acid synthase (FA2H), 3-hydroxy- 3-methyl-glutaryl-coenzyme A reductase (HMGCoA), and serine palmitoyltransferase (SPT)) were assessed using real-time quantitative polymerase chain reaction on day 3 and 8 after wounding, while transepidermal water loss (TEWL) rates were measured in wounded areas. RESULTS: TASE accelerated WH both in vivo (40% vs. 22% reduction in wound area, P<0.01) and in vitro (90% vs. 65% reduction in wound area, P<0.01). Moreover, topical applications of TASE upregulated the expression levels of epidermal mRNA for ELOVL4, HMGCoA, SPT, filaggrin, loricrin and involucrin (P<0.05 vs. vehicle-treated controls) on day 3 after wounding. Likewise, TASE significantly lowered TEWL rates in comparison with vehicle alone on day 8 (33.06±2.09 g/(m2·h) vs. 24.60±2.04 g/(m2·h), P<0.01). CONCLUSIONS: Topical applications of TASE stimulated keratinocyte proliferation and formation of epidermal permeability barrier function, leading to acceleration of acute cutaneous WH. Topical products containing TASE could be used to manage acute cutaneous WH.

Cost Effective Use of a Thiosulfinate-Enriched Allium sativum Extract in Combination with Chemotherapy in Colon Cancer.

In this work, we sought to investigate the effects of a thiosulfinate-enriched garlic extract, co-administered with 5-fluorouracil (5-FU) or oxaliplatin chemotherapy, on the viability of colon cancer cells (Caco-2 and HT-29). We also addressed the economic feasibility of a new combined treatment of this thiosulfinate-enriched garlic extract, with oxaliplatin that could reduce the dosage and costs of a monotherapy. The thiosulfinate-enriched garlic extract not only enhanced the impact of 5-FU and oxaliplatin (500 µM) in decreasing Caco-2 and HT-29 viability, but also showed a higher effect than standard 5-FU and oxaliplatin chemotherapy as anti-cancer agents. These results provided evidences for the combination of lyophilized garlic extract and 5-FU or oxaliplatin as a novel chemotherapy regimen in colon cancer cells that may also reduce the clinical therapy costs.

The role of diallyl thiosulfinate associated with nuciferine and diosgenin in the treatment of premature ejaculation: A pilot study.

OBJECTIVE: To assess the efficacy and safety of an association of diallyl thiosulfinate with nuciferine and diosgenin in the treatment of a group of patients suffering from premature ejaculation (PE), primary or secondary to erectile dysfunction (ED). MATERIALS AND METHODS: From July 2015 to October 2016, 143 patients (mean age 25.3; range 18-39) affected by PE completed the study and were finally analyzed in this phase I study. All patients, after clinical assessment and laboratory evaluation were asked to take an association of diallyl thiosulfinate with nuciferine and diosgenin as oral tablet, once a day, on alternate days, for three months. At the baseline and after three months of treatment, each patient was asked to complete the following questionnaires: International Index of Erectile Function (IIEF-5), Premature Ejaculation Diagnostic Tool (PEDT), Male Sexual Health Questionnaire (MSHQ). RESULTS: A statistical significant improvement in terms of erectile function, comparing the IIEF-5 value at baseline and follow- up visit was found (respectively IIEF-5: 8.7 vs 14.01; p < 0.001). Moreover, at follow-up visit, 97/143 men (67.8%) referred a subjective improvement of the erection quality and a better control of the ejaculation (PROs). The IELT improved too between the baseline evaluation and the follow-up visit (p < 0.001). CONCLUSION: In conclusion, our study, even if supported by preliminary results, showed how Diallyl Thiosulfinate, Nuciferine and Diosgenin is able to improve the control of ejaculation in patients suffering from PE, primary or secondary to ED without any significant adverse effects.

An Optimized Facile Procedure to Synthesize and Purify Allicin.

Allicin is a reactive sulfur species (RSS) and defence substance from garlic (Allium sativum L.). The compound is a broad-spectrum antibiotic that is also effective against multiple drug resistant (MDR) strains. A detailed protocol for allicin synthesis based on diallyl-disulfide (DADS) oxidation by H2O2 using acetic acid as a catalyst was published in 2001 by Lawson and Wang. Here we report on improvements to this basic method, clarify the mechanism of the reaction and show that it is zero-order with respect to DADS and first-order with respect to the concentration of H2O2. The progress of allicin synthesis and the reaction mechanism were analyzsd by high-performance liquid chromatography (HPLC) and the identity and purity of the products was verified with LC-MS and ¹H-NMR. We were able to obtain allicin of high purity (>98%) and >91% yield, with standard equipment available in any reasonable biological laboratory. This protocol will enable researchers to prepare and work with easily and cheaply prepared allicin of high quality.

In vitro toxicological assessment of an organosulfur compound from Allium extract: Cytotoxicity, mutagenicity and genotoxicity studies.

Garlic (Allium sativum) and onion (Allium cepa) are being used in the food industry as flavoring but also for their antimicrobial activities. These activities are mainly derived from the organosulfur compounds (OSCs). Propyl propane thiosulfinate (PTS) is an OSC with potential use in the active packaging, but its safety should be guaranteed before being commercialized. The aim of this work was to investigate for the first time the cytotoxicity of PTS as well as its in vitro mutagenic/genotoxic potential using the following battery of genotoxicity tests:(1)the bacterial reverse-mutation assay in S. typhimurium (Ames test, OECD 471, 1997); (2) the micronucleus test (MN, OECD 487, 2016); (3) the mouse lymphoma thymidine-kinase assay (MLA, OECD 476, 2015), and (4) the comet assay (standard and modified with restriction enzymes). The results revealed that PTS was not mutagenic neither in the Ames test nor in MLA. However, genotoxic effects were recorded in the MN test on mammalian cells (L5178YTk+/-cells) after PTS exposure at the highest concentration tested (17.25 µM) without S9, and also its metabolites (+S9, from 20 µM). Moreover, in the comet assay, PTS induced DNA breaks damage in Caco-2 cells at the highest concentration tested (280 µM) but it did not induce oxidative DNA damage.

Electrochemical bromination of organosulfur containing species for the determination of the strength of garlic (A. sativum).

The extraction by ethyl acetate and subsequent electrochemical detection of organosulfur containing molecules from garlic is demonstrated. The electrochemical results first evidence the high sensitivity of the process towards the model compound propyl disulfide. Through the in situ formation of bromine at a platinum electrode the propyl disulfide can be readily detected at concentrations as low as 12.5 µM. Second, the work focuses on the detection of organosulfur from fresh garlic samples. Extraction of the organosulfur 'flavour' molecules is achieved with ethyl acetate. Addition of this extract to the electrochemical cell results in an analytically useful signal allowing the voltammetric peak height to be successfully correlated with the garlic strength, as measured using an organoleptic tasting panel.

Allium Discoloration: Color Compounds Formed during Pinking of Onion and Leek.

Structures and formation pathways of compounds responsible for pink discoloration of onion and leek were studied. A procedure was developed for the isolation and purification of the color compounds from various model systems and their identification by HPLC-DAD-MS/MS. In total, structures of 15 major color compounds were tentatively determined. It was found that the pigment is a complex mixture of highly conjugated species composed of two N-substituted 3,4-dimethylpyrrole-derived rings linked by either a methine or a propenylidine bridge. These two-ring units are further modified by various C1- and C3-side chains. Experiments with isotope-labeled thiosulfinates revealed that the methine bridge and C1-side chains originate from the methyl group of methiin, whereas the C3 units are derived from the propenyl group of isoalliin.

Acute toxicological studies of the main organosulfur compound derived from Allium sp. intended to be used in active food packaging.

Some plant extracts have been proposed as potential alternative to the use of synthetic preservatives in the food industry. Among those, extracts from Allium species exhibit interesting antimicrobial and antioxidant properties for the food packaging industry. The present work aims to assess the usefulness and potential safety of the major organosulfur compound present in a commercial Allium sp. extract (PROALLIUM AP®), namely propyl thiosulfinate oxide (PTSO). For this purpose, its antimicrobial activity was studied in a wide range of microorganisms. Moreover, cytotoxicity and ultrastructural cellular damages caused by PTSO were studied in two human cell lines, Caco-2 and HepG2, being the colonic cells more sensitive to this compound. Finally, the protective role of PTSO against an induced oxidative situation was evaluated in the human intestinal Caco-2 cells. The results revealed damage at high concentration, although no significant adverse effects were recorded for the concentration to be used in food packaging. Moreover, the in vivo study also revealed the potential safety use at the established concentrations. In addition, the antimicrobial properties and the antioxidant role of PTSO were confirmed. Therefore, this compound could be considered as a good natural alternative to synthetic preservatives used in the food packaging industry.

Allicin enhances chemotherapeutic response and ameliorates tamoxifen-induced liver injury in experimental animals.

CONTEXT: Tamoxifen (TAM) is widely used for treatment of hormone-dependent breast cancer; however, it may be accompanied with hepatic injury. Allicin is the most abundant thiosulfinate molecule from garlic with the potential to provide beneficial effects on various diseases. OBJECTIVE: To elucidate the effect of commercially available allicin on both antitumor activity and liver injury of TAM. MATERIALS AND METHODS: The cytotoxicity of TAM and/or allicin was evaluated in vitro using cultured Ehrlich ascites carcinoma (EAC) cells and in vivo against murine tumor (solid) model of EAC. TAM induced liver injury in rats by intraperitoneally (i.p.) injection at a dose of 45 mg/kg, for 7 successive days. RESULTS: TAM at a dose of 3 µM (IC50) significantly decreased percent survival of EAC to 52%. TAM combination with allicin (5 or 10 µM) showed a significant cytotoxic effect compared with the TAM-treated group as manifested by a decrease in percent survival of EAC to 35% and 29%, respectively. Allicin (10 mg/kg, orally) enhanced the efficacy of TAM (1 mg/kg, i.p.) in mice as manifested by a significant increase in solid tumor growth inhibition by 82% compared with 70% in the TAM group. In rats, TAM intoxication resulted in a significant decline in SOD, GSH, and total protein with significant elevation in TBARS, ALT and AST, ALP, LDH, total bilirubin, γGT, and TNF-α levels. These changes are abrogated by allicin treatment. DISCUSSION AND CONCLUSION: The results suggest the beneficial role of allicin as an adjuvant to TAM in cancer treatment by alleviating liver injury.