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Nonribosomal depsipeptides are natural products composed of amino and hydroxy acid residues. The hydroxy acid residues often derive from α-keto acids, reduced by ketoreductase domains in the depsipeptide synthetases. Biochemistry and structures reveal the mechanism of discrimination for α-keto acids and a remarkable architecture: flanking intact adenylation and ketoreductase domains are sequences separated by >1,100 residues that form a split 'pseudoAsub' domain, structurally important for the depsipeptide module's synthetic cycle.

We report a short synthetic strategy for direct preparation of (2-ketulosonyl)onate donors. These donors feature a cyclic thionocarbonate group at the C2 and C3 positions, which plays a multitude of chemical roles. It protects the C2 and C3 hydroxyls during building block preparation. In glycosylation, the thionocarbonate can be activated by a sulfenylating promoter and serves as a leaving group. Because of its β-configuration, it also plays the role of a stereo-directing group during the formation of the α-glycosidic bond. In addition, the thionocarbonate donors can couple with thioglycoside acceptors. This orthogonal property was used for the development of the first one-pot glycosylation method for 2-keto acid sugars.

Background: The effects of keto acid (KA) supplements on Chinese patients receiving maintenance hemodialysis (MHD) are unclear. This study aimed to evaluate the effects of KA supplementation on nutritional status, inflammatory markers, and bioelectric impedance analysis (BIA) parameters in a cohort of Chinese patients with MHD without malnutrition. Methods: This was a prospective, randomized, controlled, single-center clinical study conducted in 2011 till 2014. Twenty-nine patients with MHD were randomly assigned to a control (n = 14) or a KA (n = 15) group. The control group maintained a dietary protein intake of 0.9 g/kg/day. The KA group received additional KA supplement (0.1 g/kg/day). BIA was used to determine the lean tissue mass, adipose tissue mass, and body cell mass. The patients’ nutritional status, dialysis adequacy, and biochemical parameters were assessed at the ends of the third and sixth months with t test or Wilcoxon rank-sum test. Results: The daily total energy intake for both groups was about 28 kcal/kg/day. After 6 months, the Kt/V (where K is the dialyzer clearance of urea, t is the dialysis time, and V is the volume of the distribution of urea) was 1.33 ± 0.25 in KA group, and 1.34 ± 0.25 in the control group. The median triceps skin-fold thickness in KA group was 12.00 and 9.00 mm in the control group. In addition, the median hand-grip strength in KA group was 21.10 and 25.65 kg in the control group. There were no significant differences between the groups with respect to the anthropometry parameters, dialysis adequacy, serum calcium and phosphorus levels, inflammatory markers, and amino-acid profiles, or in relation to the parameters determined by BIA. Both groups achieved dialysis adequacy and maintained nutritional status during the study. Conclusions: In this cohort of Chinese patients with MHD, the patients in the control group whose dietary protein intake was 0.9 g/kg/day and total energy intake was 28 kcal/kg/day, maintained well nutritional status during study period. The KA supplement(0.1 g/kg/day) did not improve the essential amino acid/non-essential amino acid ratio, nor did it change the patients’ mineral metabolism, inflammatory parameters, or body compositions. Key words: Chinese; Hemodialysis; Keto acid; Nutrition

Six optically active macroheterocycles bearing ester and dihydrazide moieties were synthesized from available natural (-)-α-pinene through the intermediate keto acid, (31R,33R)- 1-hydroxy-32,32-dimethyl-1,4-dioxopentaphane, using the [2+1] reaction of this keto acid with di- or triethylene glycols and the [1+1] condensation of the resulting α,ω-diketo diesters with dicarboxylic acid dihydrazides in the key steps.

The stability of refined, bleached, and deodorized palm olein (RBDPO) was studied under controlled heating conditions. RBDPO was heated continuously for 24 h at 160, 170, and 180 &deg, C, with oil sampled at four hour intervals. Thermo-oxidative alterations were measured through various parameters, such as monomeric oxidized triacylglycerols (oxTAG), total polar compounds (TPC), polymerized triacylglycerols (PTG), oxidative stability, and fatty acid composition. After 24 h of heating, the TPC and triacylglycerol oligomers showed a linear increase with heating time at all heating temperatures. At the end of the heating study, more epoxy acids were formed than keto and hydroxy acids. Moreover, caprylic acid, which was not present in fresh oil, was formed in significant amounts. The increase in oxTAG was strongly correlated with the increase in the p-anisidine value and total oxidation value. The decreases in diacylglycerol and free fatty acids were strongly correlated with an increase in PTG.

Objective: To analyze the effect of adjuvant α-keto acid therapy on serum renal function indexes and nutritional status in patients with early diabetic nephropathy. Methods: A total of 86 patients with early diabetic nephropathy were divided into observation group and control group, control group received conventional therapy, observation group received conventional therapy + adjuvant α-keto acid therapy, and then differences in serum renal function indexes, nutrition index, vascular endothelial function indexes, micro-inflammation indexes and so on were compared between two groups of patients after 2 months of treatment. Results: Serum renal function indexes UAER level as well as BUN, SCr, CysC and β2-MG content of observation group was lower than those of control group while GFR level was higher than that of control group; nutrition indexes ALB, PA and Hb content were higher than those of control group while nPCR level was lower than that of control group; vascular endothelial function indexes NO and CGRP content were higher than those of control group while ET-1, MCP-1 and resistin content were lower than those of control group; micro-inflammation indexes hsCRP, IL-1β, IL-17, IL-22, TGF-β1 and SAA content were lower than those of control group. Conclusions: Adjuvant α-keto acid therapy helps to improve the renal function and nutritional status of patients with early diabetic nephropathy, and has positive significance in optimizing the overall treatment effect.

The analysis of the products of direct carboxylation of 2-methylbutyn-3-ol-2 with carbon dioxide on Ag- and Cu-containing catalysts by 1Н and 13С NMR and FTIR spectroscopy showed that the desired 4-hydroxy-4-methylpent-2-ynoic acid did not form under the given conditions; instead, the triple bond of the substrate decomposed, and two polyfunctional acids formed: 4-hydroxy-4-methyl-3-oxopentanoic and 3,4-dihydroxy-4-methylpent-2-enic (the latter is the result of the keto-enol rearrangement of the former keto acid).

Objective: To analyze the degree of oxidative stress injury, RAS activity and podocyte loss after patients with diabetic nephropathy received keto acid combined with low protein diet. Methods: A total of 106 cases of patients with diabetic nephropathy who received hospital treatment in our hospital from September 2012 to July 2015 were selected as research subjects and randomly divided into observation group and control group according to different treatment, each group with 53 cases. Control group received low protein diet treatment alone, observation group received keto acid combined with low protein diet treatment, and then the degree of oxidative stress injury, RAS activity and podocyte loss of two groups were compared. Results: Serum MDA and AOPP levels of observation group after treatment were lower than those of control group, and levels of SOD and T-AOC were higher than those of control group; PRA, Ang栻 and Aldosterone levels of observation group after treatment were lower than those of control group; mRNA expression levels of podocin and synaptopodin in urine sediment of observation group after treatment were lower than those of control group. Conclusion: Keto acid combined with low protein diet treatment for patients with diabetic nephropathy can reduce the degree of oxidative stress injury and RAS activity, decrease podocyte loss and optimize patients’ condition.

Bile acids (BAs) are endogenous steroids involved in the transport of lipids in bile, acting also as molecular signaling hormones. Primary BAs synthesized in the liver undergo several metabolic pathways in the intestine by gut microbiota to produce secondary BAs. Together with secondary BAs, other metabolites have been recovered from human faeces, including many oxo-BA analogues produced in the colon through oxidation of BA hydroxy groups. However, the complete oxo-BA characterization in biospecimens (particularly intestinal content and faeces) has not been reported yet, hampering the assessment of their potential physiological role. Herein, we have developed and validated a new RP-HPLC-ESI-MS/MS method in negative ionization mode for the simultaneous analysis of 21 oxo-BAs and their 7 metabolic BAs precursors in human faeces. The elution was performed in gradient mode and 28 compounds, including primary, secondary BAs, and their oxo-derivatives, were separated within 50 min at 40 °C column temperature. The method is accurate (bias%

γ-Keto acids and esters are highly useful compounds in organic synthesis, because a number of five-membered carbocycles and various other heterocycles can be readily obtained from them. A number of γ-keto acids derivatives have been synthesized with high yield by Heck coupling reaction with different alkenes using Pd(OAc)2 as catalyst in dioxane solvent. The obtained products were characterized by elemental analysis, IR, proton NMR, and mass spectral studies.