Characterization of phenolic constituents inhibiting the formation of sulfur-containing volatiles produced during garlic processing

New Ionone Glycosides from the Aerial Parts of Allium sativum and Their Anti-Platelet Aggregation Activity

The bulbs of Allium sativum known as garlic are widely used as food or seasoning. In China they have been used as a traditional Chinese medicine (TCM) since ancient times for the treatment of scabies, tuberculosis, pertussis, diarrhea and dysentery. A. sativum has reportedly shown platelet aggregation inhibition and has been used in the treatment of cardiovascular diseases. However, there are only few studies focussing on the aerial parts, which are normally discarded during harvest. In this study, two new ionone glycosides, dasuanxinosides D and E (1, 2: ), are isolated from the aerial parts together with 13 known compounds including alkanes derivatives and alkyl glycosides (3 - 15: ), which are reported for the first time from this plant. Their structures are identified by extensive NMR and HRMS analyses. The isolated compounds are evaluated for their inhibitory effect on adenosine diphosphate (ADP)-induced platelet aggregation in vitro.

Three new flavonoid glycosides from the aerial parts of Allium sativum L. and their anti-platelet aggregation assessment

Three new flavonoid glycosides, Dasuanxinoside F-H (1-3), were isolated from the aerial parts of Allium sativum, together with eight known compounds which were firstly reported in this plant, including three flavonoid glycosides (4-6) and five phenylethanoid glycosides (7-11). Their structures were identified by UV-vis, IR, 1D and 2D NMR spectra, as well as HR-ESI-MS analyses. The inhibitory effect of the isolated compounds on platelet aggregation induced by adenosine diphosphate (ADP) was evaluated in vitro. The results showed that most compounds displayed different degrees of inhibition. Among them, 2, 5, 8 and 9 exhibited the strongest activity on platelet aggregation.

The nutritional applications of garlic (Allium sativum) as natural feed additives in animals

Garlic (Allium sativum) is an essential vegetable that has been widely utilized as seasoning, flavoring, culinary and in herbal remedies. Garlic contains several characteristic organosulfur compounds, such as diallyl sulfide, allicin (diallyl thiosulphate), γ-glutamylcysteine, and S-allyl cysteine (alliin) and ajoene, which garlic has beneficial effects on inflammation, oxidative stress markers, hypertension, hyperlipidaemia and endothelial function in vitro or in animal model. These bioactive molecules are also playing pivotal role in livestock and fisheries production apart from its application in humans. Supplementation of animal feed with garlic and its related products is consistent with the modern agricultural concept of organic animal husbandry. This review compiles the information describing the effects of feeding garlic and its extracts on selected performance parameters in animals (chicken, rabbits, ruminants, pigs and fish). This review may provide reference for scientists and entrepreneurs to investigate the applications of feeds added with garlic and allicin by-products for the improvement of animal husbandry and aquatic production.

Comprehensive Metabolite Profiling in Genetic Resources of Garlic (Allium sativum L.) Collected from Different Geographical Regions

Garlic (Allium sativum) is the second most important Allium crop that has been used as a vegetable and condiment from ancient times due to its characteristic flavor and taste. Although garlic is a sterile plant that reproduces vegetatively through cloves, garlic shows high biodiversity, as well as phenotypic plasticity and environmental adaptation capacity. To determine the possible mechanism underlying this phenomenon and to provide new genetic materials for the development of a novel garlic cultivar with useful agronomic traits, the metabolic profiles in the leaf tissue of 30 garlic accessions collected from different geographical regions, with a special focus on the Asian region, were investigated using LC/MS. In addition, the total saponin and fructan contents in the roots and cloves of the investigated garlic accessions were also evaluated. Total saponin and fructan contents did not separate the garlic accessions based on their geographical origin, implying that saponin and fructan contents were clone-specific and agroclimatic changes have affected the quantitative and qualitative levels of saponins in garlic over a long history of cultivation. Principal component analysis (PCA) and dendrogram clustering of the LC/MS-based metabolite profiling showed two major clusters. Specifically, many Japanese and Central Asia accessions were grouped in cluster I and showed high accumulations of flavonol glucosides, alliin, and methiin. On the other hand, garlic accessions grouped in cluster II exhibited a high accumulation of anthocyanin glucosides and amino acids. Although most of the accessions were not separated based on country of origin, the Central Asia accessions were clustered in one group, implying that these accessions exhibited distinct metabolic profiles. The present study provides useful information that can be used for germplasm selection and the development of new garlic varieties with beneficial biotic and abiotic stress-adaptive traits.

Functional Application of Sulfur-Containing Spice Compounds

Sulfur-containing spice compounds possess diverse biological functions and play an important role in food, chemicals, pharmaceuticals, and agriculture. The development of functional spices has become increasingly popular, especially for medicinal functions for dietary health. Thus, this review focuses on the properties and functions of sulfur-containing spice compounds, including antioxidant, anti-inflammatory, antiobesity, anticancer, antibacterial, and insecticidal functions, among others. Developments over the last five years concerning the properties of sulfur-containing spice compounds are summarized and discussed.

Short Total Synthesis of Ajoene, (E,Z)-4,5,9-Trithiadodeca-1,6,11-triene 9-oxide, in Batch and (E,Z)-4,5,9-Trithiadodeca-1,7,11-triene in Continuous Flow

A short total synthesis of ajoene, (E,Z)-4,5,9-trithiadodeca-1,6,11-triene 9-oxide, has been achieved over six steps. In addition, a continuous flow synthesis under mild reaction conditions to (E,Z)-4,5,9-trithiadodeca-1,7,11-triene is described starting from simple and easily accessible starting materials. Over four steps including propargylation, radical addition of thioacetate, deprotection, and disulfide formation/ allylation, the target product can be obtained at a rate of 0.26 g h-1 in an overall yield of 12 %.

A new methodology for sensory quality assessment of garlic based on metabolomics and an artificial neural network

This study has established a new method for the sensory quality determination of garlic and garlic products on the basis of metabolomics and an artificial neural network. A total of 89 quality indicators were obtained, mainly through the metabolomics analysis using gas chromatography/mass spectrometry (GC/MS) and high performance liquid chromatography coupled with tandem mass spectrometry (HPLC-MS/MS). The quality indicator data were standardized and fused at a low level, and then seven representative indicators including the a* (redness) value, and the contents of S-methyl-l-cysteine, 3-vinyl-1,2-dithiacyclohex-5-ene, glutamic acid, l-tyrosine, d-fructose and propene were screened by partial least squares discriminant analysis (PLS-DA), analysis of variance (ANOVA) and correlation analysis (CA). Subsequently, the seven representative indicators were employed as the input data, while the sensory scores for the garlic obtained by a traditional sensory evaluation were regarded as the output data. A back propagation artificial neural network (BPANN) model was constructed for predicting the sensory quality of garlic from four different areas in China. The R² value of the linear regression equation between the predicted scores and the traditional sensory scores for the garlic was 0.9866, with a mean square error of 0.0034, indicating that the fitting degree was high and that the BPANN model built in this study could predict the sensory quality of garlic accurately. In general, the method developed in this study for the sensory quality determination of garlic and garlic products is rapid, simple and efficient, and can be considered as a potential method for application in quality control in the food industry.

This study has established a new method for the sensory quality determination of garlic and garlic products on the basis of metabolomics and an artificial neural network.

Application of Direct Analysis in Real Time-High Resolution Mass Spectrometry to Investigations of Induced Plant Chemical Defense Mechanisms-Revelation of Negative Feedback Inhibition of an Alliinase

Several plants of agricultural and medicinal importance utilize defense chemistry that involves deployment of highly labile, reactive, and lachrymatory organosulfur molecules. However, this chemistry is difficult to investigate because the compounds are often short-lived and prone to degradation under the conditions required for analysis by common analytical techniques. This issue has complicated efforts to study the defense chemistry of plants that exploit the use of sulfur in their defense arsenals. This work illustrates how direct analysis in real time-high resolution mass spectrometry (DART-HRMS) can be used to track organosulfur defense compound chemistry under mild conditions. Petiveria alliacea was used as a model plant that exploits the enzyme alliinase to generate induced organosulfur compounds in response to herbivory. Tracking of the organosulfur compounds it produces and quantifying them by DART-HRMS using isotopically labeled analogues revealed a feedback inhibition loop through which the activities of the alliinase are stymied shortly after their activation. The results show that the downstream thiosulfinate products petivericin (100 μM) and pyruvate (8.4 mM) inhibit alliinase activity by 60% and 29%, respectively, after 1 h, and a mixture of the two inhibited alliinase activity by 65%. By 2 h, alliinase activity in the presence of these alliinase-derived products had ceased completely. Because thiosulfinate, pyruvate, and lachrymatory sulfine compounds are produced via the same alliinase-derived sulfenic acid intermediate, the inhibition of alliinase activity by increasing concentrations of downstream products shows how production of these defense compounds is modulated in real time in response to a tissue breach. These findings provide a framework within which heretofore unexplained phenomena observed in the defense chemistry of P. alliacea, onion, garlic, and other plants can be explained, as well as an approach by which to track labile compounds and enzymatic activity by DART-HRMS.

The inhibition effect of garlic-derived compounds on human immunodeficiency virus type 1 and saquinavir

Garlic has been used as a traditional medicine to treat various diseases. Garlic reduces the risk of some diseases. This protective effect is due to the organosulfur compounds of garlic. The aim of this study was to investigate the inhibition effects of garlic-derived compounds on human immunodeficiency virus type 1 (HIV-1) and as the most important anti-HIV-1 medicine. The activation of saquinavir is believed to be the principal mechanism behind the protective effects of HIV-1. Our theoretical calculations are performed for blood phase by using the density functional theory for the main compounds of garlic. The chemical activity and solubility of ajoene and the mainly derived compounds of garlic as theoretical calculations are important for the medical research comparing with the other compounds of the garlic. The theoretical calculations have helped us to determine which active ingredient of the garlic having inhibition effects on HIV-1 and saquinavir.

Investigation of the dynamic changes in the chemical constituents of Chinese “Laba” garlic during traditional processing

In this study, the whole chemical constituents influencing colour, flavor and physiological function of “Laba” garlic during traditional processing have been investigated.

C-geranylated flavanones from YingDe black tea and their antioxidant and α-glucosidase inhibition activities

YingDe black tea is produced from crude tea prepared from leaves of Camellia sinensis var. assamica. In this work, we isolated and identified five novel flavanones, namely, amelliaone A-E (1-5), along with seven known compounds 6-12 from the ethanol extract of YingDe black tea. The structures of these five novel phenolic compounds were determined using extensive 1D and 2D nuclear magnetic resonance spectroscopy experiments. The compounds were further evaluated for antioxidant, α-glucosidase inhibitory, and cytotoxic activities. Compound 1 exhibited higher α-glucosidase inhibitory activity with a half-maximum inhibitory concentration value (IC₅₀) of 10.2µM compared with acarbose (18.2µM).

Two new flavonoids from the bark of Allium chrysanthum

The isolation and structure elucidation of two new flavonoids, chrysanthumones A and B from the extracts of Allium chrysanthum were reported. Seven known phenolic constituents were also isolated. Their structures were determined on the basis of NMR and MS techniques.

Effect of garlic on plasma lipoprotein(a) concentrations: A systematic review and meta-analysis of randomized controlled clinical trials

OBJECTIVES

Garlic can play an essential role in the prevention of atherosclerosis, but the research addressing the effect of garlic on the concentration of lipoprotein(a) [Lp(a)] has not been fully demonstrated. The aim of this study was to assess the effect of garlic on plasma Lp(a) concentrations through systematic review of literature and meta-analysis of available randomized controlled trials.

METHODS

The literature search included SCOPUS, PubMed-Medline, ISI Web of Science, and Google Scholar databases up to March 10, 2015 to identify randomized controlled trials investigating the effect of garlic on plasma Lp(a) concentrations. Two independent reviewers extracted data on study characteristics, methods, and outcomes. Overall, the effect of garlic on plasma Lp(a) levels was reported in six trials.

RESULTS

Meta-analysis did not suggest a significant alteration in plasma Lp(a) levels after garlic consumption (weighted mean difference [WMD] = 16.86%; 95% confidence interval, -4.59 to 38.31; P = 0.124). This result was robust in the leave-one-out sensitivity analysis. When the studies were categorized according to the duration of supplementation, there was no effect in the subgroup of trials lasting ≤12 wk (WMD = 2.01%; 95% CI, -14.67 to 18.68; P = 0.813) but a significant elevation of plasma Lp(a) concentrations was found in trials lasting >12 wk (WMD = 54.59%; 95% CI, 30.47-78.71; P < 0.001). Random-effects meta-regression suggested an inverse association between the changes in plasma concentrations of Lp(a) and duration of supplementation (slope 1.71; 95% CI, 0.46-2.97; P = 0.007).

CONCLUSIONS

The present meta-analysis did not suggest a significant effect of garlic supplementation on the reduction of Lp(a) levels.