Pharmacokinetics of cycloalliin, an organosulfur compound found in garlic and onion, in rats

Bioavailability of Organosulfur Compounds after the Ingestion of Black Garlic by Healthy Humans

The consumption of black garlic has been related to a decreased risk of many human diseases due to the presence of phytochemicals such as organosulfur compounds (OSCs). However, information on the metabolization of these compounds in humans is limited. By means of ultra-high-performance liquid chromatography coupled with high-resolution mass spectrometry (UHPLC-HRMS), this study aims to determine the OSCs and their metabolites excreted in urine 24 h after an acute intake of 20 g of black garlic by healthy humans. Thirty-three OSCs were identified and quantified, methiin (17,954 ± 6040 nmol), isoalliin (15,001 ± 9241 nmol), S-(2-carboxypropyl)-L-cysteine (8804 ± 7220 nmol) and S-propyl-L-cysteine (deoxypropiin) (7035 ± 1392 nmol) being the main ones. Also detected were the metabolites N-acetyl-S-allyl-L-cysteine (NASAC), N-acetyl-S-allyl-L-cysteine sulfoxide (NASACS) and N-acetyl-S-(2-carboxypropyl)-L-cysteine (NACPC), derived from S-allyl-L-cysteine (SAC), alliin and S-(2-carboxypropyl)-L-cysteine, respectively. These compounds are potentially N-acetylated in the liver and kidney. The total excretion of OSCs 24 h after the ingestion of black garlic was 64,312 ± 26,584 nmol. A tentative metabolic pathway has been proposed for OSCs in humans.

Hepatoprotective effect of a novel lactic acid-fermented garlic extract functional food product against acute liver injury

Lactic acid-fermented garlic extract (LAFGE) has been shown to have hepatoprotective role in liver diseases. This study was conducted to evaluate the efficacy of a new LAFGE-based hepatoprotective functional food product (named D-18-007) formulated with other additive components, including l-arginine, l-ornithine, and the leaf extract of licorice and artichoke. In a rat model of d-galactosamine(GalN)/LPS-induced liver injury, the survival was significantly higher in animals treated with D-18-007 than in animals treated with LAFGE. The hepatic injury was alleviated by either LAFGE or D-18-007, but the overall effect was more significant in D-18-007, as shown by the necrosis, histology, and serum analyses. Also, the decrease in GalN/LPS-induced lipid peroxidation in the liver tissue was more significant in D-18-007 than LAFGE. The decrease in IL-6 protein in the liver was similar between LAFGE and D-18-007. Moreover, we compared the amount of the bile in normal animals and found that D-18-007 has better choleretic activity than LAFGE. Using this acute liver injury model, our results suggest that D-18-007 has an enhanced hepatoprotective effect in acute liver injury compared with LAFGE alone.

Comprehensive NMR analysis of compositional changes of black garlic during thermal processing

Black garlic is a processed food product obtained by subjecting whole raw garlic to thermal processing that causes chemical reactions, such as the Maillard reaction, which change the composition of the garlic. In this paper, we report a nuclear magnetic resonance (NMR)-based comprehensive analysis of raw garlic and black garlic extracts to determine the compositional changes resulting from thermal processing. (1)H NMR spectra with a detailed signal assignment showed that 38 components were altered by thermal processing of raw garlic. For example, the contents of 11 l-amino acids increased during the first step of thermal processing over 5 days and then decreased. Multivariate data analysis revealed changes in the contents of fructose, glucose, acetic acid, formic acid, pyroglutamic acid, cycloalliin, and 5-(hydroxymethyl)furfural (5-HMF). Our results provide comprehensive information on changes in NMR-detectable components during thermal processing of whole garlic.

Inhibitory effect of aqueous and ethanolic garlic (Allium sativum L., Lilliaceae) extracts on the rat atria

The acute negative inotropic and chronotrophic effects of aqueous and alcoholic garlic extracts (Allium sativum L.) on spontaneous and adrenalin-stimulated contractions of the Wistar rat atria were investigated. The addition of garlic extracts to isolated rat atria evoked negative inotropic and chronotropic effects. Ethanolic garlic extract exerts much stronger negative inotropic (58.33 +/- 14.76%) effects than aqueous extract (43.66 +/- 16.32%). The difference in frequency reduction is especially conspicuous. Aqueous garlic extract very slightly affects the frequency, while ethanolic extract reduces it by more than 40%. In addition to these effects, the positive inotropism and chronotropism induced by the addition of noradrenaline, were much more antagonized by ethanolic garlic extract than by aqueous extract. Moreover, ethanolic garlic extract establishes sinus rhythm in the atria with extrasystoles induced by noradrenaline.

An exploratory NMR nutri-metabonomic investigation reveals dimethyl sulfone as a dietary biomarker for onion intake

The metabolome following intake of onion by-products is evaluated. Thirty-two rats were fed a diet containing an onion by-product or one of the two derived onion by-product fractions: an ethanol extract and the residue. A 24 hour urine sample was analyzed using (1)H NMR spectroscopy in order to investigate the effects of onion intake on the rat metabolism. Application of interval extended canonical variates analysis (ECVA) proved to be able to distinguish between the metabolomic profiles from rats consuming normal feed and rats fed with an onion diet. Two dietary biomarkers for onion intake were identified as dimethyl sulfone and 3-hydroxyphenylacetic acid. The same two dietary biomarkers were subsequently revealed by interval partial least squares regression (PLS) to be perfect quantitative markers for onion intake. The best PLS calibration model yielded a root mean square error of cross-validation (RMSECV) of 0.97% (w/w) with only 1 latent variable and a squared correlation coefficient of 0.94. This indicates that urine from rats on the by-product diet, the extract diet, and the residue diet all contain the same dietary biomarkers and it is concluded that dimethyl sulfone and 3-hydroxyphenylacetic acid are dietary biomarkers for onion intake. Being able to detect specific dietary biomarkers is highly beneficial in the control of nutritionally enhanced functional foods.

Freshly crushed garlic is a superior cardioprotective agent than processed garlic

In this study, we compared the cardioprotective effects of freshly crushed garlic vis-a-vis that of processed garlic. Two groups of rats were gavaged with respective garlic preparations while the control group received vehicle only. After 30 days, all of the rats were sacrificed and isolated the hearts were subjected to 30 min ischemia followed by 2 h of reperfusion. Both of the garlic preparations provided cardioprotection, but superior cardiac performance was noticed for those fed with freshly crushed garlic. Consistent with these results, the freshly crushed garlic group displayed significantly greater phosphorylation of antiapoptotic ERK1/2 proteins, reduced Bax/Bcl-2 ratio, and reduced phosphorylation of proapoptotic p-38MAPK and JNK. Moreover, the survival signaling network consisting of Akt-FoxO1 was increased in the freshly crushed garlic treated hearts. Freshly crushed garlic, but not the processed garlic, showed enhanced redox signaling as evident by increased level of p65 subunit of NFkappaB, Nrf2, and enhanced GLUT 4, PPARalpha, and PPARdelta. The results thus show that although both freshly crushed garlic and processed garlic provide cardioprotection, the former has additional cardioprotective properties presumably due to the presence of H2S.