Improved microvascular reactivity after aged garlic extract intake is not mediated by hydrogen sulfide in older adults at risk for cardiovascular disease: a randomized clinical trial.

PURPOSE: This study aimed to investigate the effects of AGE on microvascular reactivity, systolic blood pressure (SBP), and diastolic blood pressure (DBP) in older individuals at high risk for cardiovascular disease (CVD). Urinary thiosulfate was also investigated as an indirect marker of endogenous hydrogen sulfide (H2S) synthesis. The study was conducted in a randomized, double-blind, crossover, and placebo-controlled way. METHODS: Twenty-eight participants (14 male), 67 ± 6 years old with CVD risk factors, ingested 2.4 g of AGE or placebo (PLA). Near-infrared spectroscopy evaluated tissue oxygen saturation (StO2) during a vascular occlusion test (30 s baseline, 5 min occlusion, and 2 min reperfusion). The upslope of StO2 signal after cuff release was calculated to measure microvascular reactivity. Urinary thiosulfate levels were measured using a high-performance liquid chromatography system. RESULTS: The upslope of StO2 was significantly faster after AGE (1.01 ± 0.37% s-1) intake compared to PLA (0.83 ± 0.35% s-1; P < 0.001; d = 0.50). Relative changes in Δ% SBP from pre- to post-AGE intake (- 5.17 ± 5.77%) was significantly different compared to Δ% PLA (0.32 ± 5.99%; P = 0.001; d = 0.93). No significant changes in urinary thiosulfate concentrations were observed between interventions. Moreover, no significant gender effect in any parameter assessed was found. CONCLUSION: This study demonstrated that a single dose of AGE improved microvascular reactivity in older adults at risk of CVD despite such an effect was not linked with urinary thiosulfate levels. This trial was registered at clinicaltrials.gov as NCT04008693 (May 19, 2020).

A versatile and efficient approach for the synthesis of chiral 1,3-nitroamines and 1,3-diamines via conjugate addition to new (S,E)-γ-aminated nitroalkenes derived from L-α-amino acids.

New chiral (S,E)-γ-N,N-dibenzylated nitroalkenes 2a-c were synthesized from natural L-(α)-amino acids in five steps with overall yields of 68-88%. The conjugate addition of hydride, methoxide, nitronate and azide nucleophiles to 2a-c led to the corresponding chiral 1,3-nitroamines in 74-90% yield. The conjugate addition of cyanide anion to 2a,b was followed by HNO2 elimination affording chiral aminated acrylonitriles (73-98%). On the other hand, the azide anion reacted with 2a, in acetonitrile, via a [3 + 2]-cycloaddition in which HNO2 was lost, providing the corresponding 1,2,3-triazole derivative. Direct reduction of 1,3-nitroamine derivatives 9a,b produced the corresponding 1,3-diamines in good yields.

Diastereoselective synthesis of nitroso acetals from (S,E)-γ-aminated nitroalkenes via multicomponent [4 + 2]/[3 + 2] cycloadditions promoted by LiCl or LiClO4.

Chiral nonracemic aminated nitroso acetals were synthesized via diastereoselective multicomponent [4 + 2]/[3 + 2] cycloadditions employing new (S,E)-γ-nitrogenated nitroalkenes 5a-c as heterodienes, ethyl vinyl ether (EVE) as a dienophile, and selected electron-deficient alkenes as 1,3-dipolarophiles. The employment of different organic solutions of LiClO4 or LiCl as promoter systems provided the respective nitroso acetals with yields from 34-72% and good levels of diastereoselectivity. In addition, the nitroso acetal 9c was transformed to the pyrrolizidin-3-one derivative 14c, proving the usefulness of the route in the synthesis of an interesting chiral compound. The elucidation of the stereostructures was based on 2D COSY, NOESY and HSQC NMR experiments as well as an X-ray diffraction experiment.