Validated HPLC method and temperature stabilities for oil-soluble organosulfur compounds in garlic macerated oil

Organosulfur in food samples: Recent updates on sampling, pretreatment and determination technologies

Organosulfur compounds (OSCs), mainly found in garlic, are the main biologically active substances for their pharmacological effects, including lowering of blood pressure and cholesterol, anti-cancer effect, liver protection, and anti-inflammatory. Efficient and sensitive pretreatment and determination methods of OSCs in different food matrices are of great significance. This review provides a comprehensive summary about the pretreatment and determination methods for OSCs in different food samples since 2010. Commonly used pretreatment methods, such as liquid-liquid extraction, microwave-assisted extraction, pressurized liquid extraction, liquid-liquid microextraction, solid phase extraction, dispersive solid phase extraction, solid-phase microextraction, and so on, have been summarized and overviewed in this paper. In particular, we discussed and compared various analysis methods including high performance liquid chromatography coupled with different detectors, gas chromatography-based methods, and few other methods. Finally, we tried to highlight the applicability, advantages and disadvantages of different pretreatment and analysis methods, and identified future prospects in this field.

Garlic (Allium sativum L.) in diabetes and its complications: Recent advances in mechanisms of action

Diabetes mellitus (DM) is a metabolic disease characterized by chronic hyperglycemia and impaired islet secretion that places a heavy burden on the global health care system due to its high incidence rate, long disease course and many complications. Fortunately, garlic (Allium sativum L.), a well-known medicinal plant and functional food without the toxicity and side effects of conventional drugs, has shown positive effects in the treatment of diabetes and its complications. With interdisciplinary development and in-depth exploration, we offer a clear and comprehensive summary of the research from the past ten years, focusing on the mechanisms and development processes of garlic in the treatment of diabetes and its complications, aiming to provide a new perspective for the treatment of diabetes and promote the efficient development of this field.

Stabilities of Three Key Biological Trisulfides with Implications for Their Roles in the Release of Hydrogen Sulfide and Bioaccumulation of Sulfane Sulfur

Trisulfides and higher polysulfides are important in the body due to their function as key reservoirs of sulfane sulfur and their rapid reactions to release persulfides. Recent work has shown that persulfides act as powerful antioxidants and release hydrogen sulfide, an emerging gasotransmitter with numerous therapeutic effects. Despite the important role of polysulfides, there is a lack of understanding of their stabilities in aqueous systems. To investigate the reactivity of trisulfides and polysulfides, three key biologically important trisulfides were synthesized from cysteine, glutathione, and N-acetylcysteine, and the tetrasulfide of N-acetylcysteine was synthesized as a representative polysulfide. The stabilities of sulfides were monitored in buffered D₂O using ¹H NMR spectroscopy under a range of conditions including high temperatures and acidic and alkaline environments. The tri- and tetrasulfides degraded rapidly in the presence of primary and tertiary amines to the corresponding disulfide and elemental sulfur. The half-lives of N-acetylcysteine tri- and tetrasulfides in the presence of butylamine were 53 and 1.5 min, respectively. These results were important because they suggest that tri- and tetrasulfide linkages are short-lived species in vivo due to the abundance of amines in the body. Under basic conditions, cysteine and glutathione trisulfides were unstable due to the deprotonation of the ammonium group, exposing an amine; however, N-acetylcysteine trisulfide was stable at all pH values tested. Hydrogen sulfide release of each polysulfide in the presence of cysteine was quantified using a hydrogen sulfide-sensitive electrode and ¹H NMR spectroscopy.

Use of citric acid and garlic extract to inhibit Salmonella enterica and Listeria monocytogenes in hummus

Recently, the consumption of hummus has become popular in the United States, European countries, and Canada, and unfortunately, several foodborne outbreaks and recalls have been reported due to its contamination with Listeria monocytogenes and Salmonella enterica. The current study aimed to investigate the inhibitory activity of 0.5, 1.0, and 1.5% citric acid (CA) and 1.0, 2.0 and 3.0% garlic extract (GE) toward S. enterica and L. monocytogenes in hummus stored at 4, 10 and 24 °C. L. monocytogenes grew well in untreated (control) hummus samples at all tested temperatures, whereas S. enterica grew only at 10 and 24 °C. CA at 0.5 to 1.5% reduced L. monocytogenes numbers by 3.0-3.3 log CFU/g at 4 °C, 1.7-3.9 log CFU/g at 10 °C, and 0.9-1.4 log CFU/g at 24 °C. Numbers of S. enterica were reduced by 0.6-1.7, 4.1-4.9 and <1.5 log CFU/g, at 4, 10 and 24 °C, respectively, compared to the control during 10 d storage. GE at 1.0-3.0% also reduced numbers of L. monocytogenes at 10 d by 0.7-3.0, and 1.3-3.6 log CFU/g at 4 and 10 °C, respectively, and numbers of S. enterica by 0.7-1.2, 1.8-2.6 and 0.5-1.6 log CFU/g, at 4, 10 and 24 °C, respectively, compared to the control. Chromatographic analysis of GE revealed the presence of four organosulfur compounds including diallyl disulfide, diallyl trisulfide, 2-vinyl-(4H)-1,3-dithiin and 3-vinyl-(4H)-1,2-dithiin where the latter was the predominant compound with a level of 22.9 mg/g which significantly contributed to the inhibitory effect of GE. CA and GE are adequate natural antimicrobials in hummus to reduce L. monocytogenes and S. enterica numbers and enhance product safety.

Simultaneous determination of Allium compounds (Propyl propane thiosulfonate and thiosulfinate) in animal feed using UPLC-MS/MS

Propyl-propane-thiosulfonate (PTSO) and Propyl-propane-thiosulfinate (PTS) are organosulfur compounds used to supplement the diet of livestock because of their beneficial effects on feed palatability, their antibacterial, anti-inflammatory, and antimethanogenic activities. Besides, antibiotic residues in the environment can be reduced by using these natural bioactive compounds. The objective of this study was to optimize the extraction parameters for the analysis of PTSO and PTS in feed matrices by performing a solid-liquid extraction and quantification by Ultra performance liquid chromatography coupled to tandem mass spectrometry (UPLC-MS/MS). Optimization was performed using the Response Surface Methodology on a Box-Behnken experimental design, optimizing the following parameters: solvent:sample ratios and evaporation temperature set for the rotary evaporator. The method was validated for 3 concentration levels for both PTSO (100, 500, 1000 ng g^-1) and PTS (500, 1150, 2300 ng g^-1). The highest recoveries of PTSO and PTS were obtained using 12.5 mL of 100% acetonitrile, stirring for 15 min, and an evaporation temperature of 20 °C. The validated method was further applied to detect and quantify these compounds in different feed matrices. In conclusion, this is the first study to simultaneously analyze PTSO and PTS at low concentrations, employing a sensitive technique such as UPLC-MS/MS.

Hyaluronic Acid-Based Nanocapsules as Efficient Delivery Systems of Garlic Oil Active Components with Anticancer Activity

Diallyl disulfide (DADS) and diallyl trisulfide (DATS) are garlic oil compounds exhibiting beneficial healthy properties including anticancer action. However, these compounds are sparingly water-soluble with a limited stability that may imply damage to blood vessels or cells after administration. Thus, their encapsulation in the oil-core nanocapsules based on a derivative of hyaluronic acid was investigated here as a way of protecting against oxidation and undesired interactions with blood and digestive track components. The nuclear magnetic resonance (¹H NMR) technique was used to follow the oxidation processes. It was proved that the shell of the capsule acts as a barrier limiting the sulfur oxidation, enhancing the stability of C=C bonds in DADS and DATS. Moreover, it was shown that the encapsulation inhibited the lysis of the red blood cell membrane (mainly for DADS) and interactions with serum or digestive track components. Importantly, the biological functions and anticancer activity of DADS and DATS were preserved after encapsulation. Additionally, the nanocapsule formulations affected the migration of neoplastic cells—a desirable preliminary observation concerning the inhibition of migration. The proposed route of administration of these garlic extract components would enable reaching their higher concentrations in blood, longer circulation in a bloodstream, and thus, imply a better therapeutic effect.

Effect of dietary coated granules containing garlic oil diallyl disulphide and diallyl trisulphide on performance, in vitro digestibility and gastrointestinal functionality in laying hens

This experiment was conducted to investigate the effects of dietary supplementation with coated granules (CG) on performance, in vitro digestibility and the gastrointestinal functionality in laying hens. A total of 40 Hisex Brown laying hens (36 weeks of age) were randomly divided into five equal groups; one served as a control and the other four were actual experimental groups supplemented with 0.75, 1.5, 3 or 6 g CG per day. All the hens were fed restrictively with target feed intake of 100 g basal diet/hen per day. There were no differences in egg production or egg weight among the groups, but feed conversion ratio was significantly improved (linearly, p < 0.05) with the dose level of CG in diet. Dietary CG increased the jejunal weight (linear and quadratic terms, p < 0.05) but decreased the ileal weight (linearly, p < 0.05). There was mostly statistical interaction between dietary CG and specific activity of intestinal digestive enzymes with similar patterns for dietary CG treatments (p < 0.05). A positive linear correlation was observed with in vitro protein digestibility by using the crude enzyme extract from dietary CG supplementation. Dietary CG decreased the caecal Escherichia coli population while the Lactobacillus spp.: E. coli ratio increased (quadratic fit, p < 0.05). CG supplementation, on the other hand, significantly altered intestinal morphology by increasing the height of duodenal and ileal villi (linearly, p < 0.05). Also, duodenal antioxidant capacity observed via remaining reducing power improved linearly (p < 0.05). This suggests that CG, unlike garlic oils without encapsulation, may be a good candidate for feed supplementation in commercial egg production. It could be included up to 6 g CG per day without any adverse effects on performance, which may relate to improving nutrient digestibility and better utilization of limited feed intake when using a low amount of diet or other observations in this study.

Application of MootralTM Reduces Methane Production by Altering the Archaea Community in the Rumen Simulation Technique

The reduction of methane emissions by ruminants is a highly desirable goal to mitigate greenhouse gas emissions. Various feed additives have already been tested for their ability to decrease methane production; however, practical use is often limited due to negative effects on rumen fermentation or high costs. Organosulphur compounds from garlic (Allium sativum) and flavonoids have been identified as promising plant-derived compounds which are able to reduce methane production. Here, we evaluated the effects of a combination of garlic powder and bitter orange (Citrus aurantium) extracts, Mootral, on ruminal methane production, ruminal fermentation and the community of methanogenic Archaea by using the rumen simulation technique as ex vivo model. The experiment consisted of an equilibration period of 7 days, an experimental period of 8 days and a withdrawal period of 4 days. During the experimental period three fermenters each were either treated as controls (CON), received a low dose of Mootral (LD), a high dose of Mootral (HD), or monensin (MON) as positive control. Application of Mootral strongly reduced the proportion of methane in the fermentation gas and the production rate of methane. Moreover, the experimental mixture induced a dose-dependent increase in the production rate of short chain fatty acids and in the molar proportion of butyrate. Some effects persisted during the withdrawal period. Both, single strand conformation polymorphism and Illumina MiSeq 16S rRNA amplicon sequencing indicated an archaeal community distinct from CON and MON samples in the LD and HD samples. Among archaeal families the percentage of Methanobacteriaceae was reduced during application of both doses of Mootral. Moreover, several significant differences were observed on OTU level among treatment groups and after withdrawal of the additives for LD and HD group. At day 14, 4 OTUs were positively correlated with methane production. In conclusion this mixture of garlic and citrus compounds appears to effectively reduce methane production by alteration of the archaeal community without exhibiting negative side effects on rumen fermentation.

Allium sativum Constituents Exhibit Anti-tubercular Activity In vitro and in RAW 264.7 Mouse Macrophage Cells Infected with Mycobacterium tuberculosis H37Rv

Background:

Long duration of treatment, side-effects of currently used anti-tubercular drugs and emergence of drug-resistant forms of Mycobacterium tuberculosis (MTB) warrants the need to develop new drugs to tackle the scourge of tuberculosis (TB). Garlic is an edible plant reported to have anti-tubercular activity. However, previous researches on anti-tubercular effect of garlic were focused mostly on preliminary in vitro screening.

Objective:

To identify constituents responsible for anti-tubercular activity of thiosulfinate-derivative rich extract of garlic (GE) and to evaluate activity of the most active constituent in RAW 264.7 mouse macrophage cells infected with M. tuberculosis H37Rv (MTBH).

Materials and Methods:

In the present study, we have isolated eight compounds from GE by flash chromatography. The isolated compounds were characterized by ¹H nuclear magnetic resonance spectroscopy, liquid chromatography-mass spectrometry and Fourier transform infrared spectroscopy. Individual isolates and GE were screened for activity against MTBH by Resazurin Microtitre Plate Assay (REMA).

Results:

Anti-tubercular activity of GE was superior to that of isolates when evaluated by REMA, possibly due to synergism amongst the constituents of GE. Cytotoxicity of GE was evaluated in RAW 264.7 mouse macrophage cells and it was observed that GE had a favorable selectivity index (>10). Therefore, anti-tubercular activity of GE was further evaluated by intracellular macrophage infection model. GE demonstrated concentration-dependent activity in macrophages infected with MTBH.

Conclusion:

This is the first report on intracellular anti-tubercular activity of any extract of garlic or its components. Appreciable intracellular anti-tubercular activity of GE in macrophages combined with low cytotoxicity makes it a suitable candidate for further development as an anti-tubercular agent.

SUMMARY

Thiosulfinate-derivative rich extract of Allium sativum showed better activity than its isolated constituents against Mycobacterium tuberculosis H37Rv.(MTBH) when evaluated by Resazurin Microtitre Plate Assay

The extract showed least cytotoxic potential against RAW 264.7 mouse macrophage cells as compared to rifampicin, isoniazid and ethambutol when evaluated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. The extract had an appreciable selectivity index

Extract showed appreciable activity in RAW 264.7 mouse macrophage cells infected with MTBH, indicating its potential to be developed further as an anti-tubercular agent that can be administered as an adjunct to the existing anti-tubercular drug regimen.

Abbreviations used: TB: Tuberculosis, MTB: Mycobacterium tuberculosis, MTBH: Mycobacterium tuberculosis H37Rv, GE: Thiosulfinate-derivative rich extract of garlic, REMA: Resazurin Microtitre Plate Assay, VD: Vinyldithiin, CFU: Colony forming unit, ¹H NMR: ¹H nuclear magnetic resonance spectroscopy, FT-IR: Fourier transform-infrared spectroscopy, LC-MS: Liquid chromatography-mass spectrometry, IC₅₀: Concentration required to inhibit the cells by 50%, ANOVA: Analysis of variance.