18-iso-acetyl-oleanolic acid

Amidoboronic acid-containing peptidomimetics are an important class of scaffolds in chemistry and drug discovery. Despite increasing interest in boron-based enzyme inhibitors, constrained amidoboronic acids have received little attention due to the limited options available for their synthesis. We describe a new methodology to prepare both α- and β-amidoboronic acids that impose restrictions on backbone angles. Lewis acid-promoted Boyer-Schmidt-Aube lactam ring expansions using an azidoalkylboronate enabled generation of constrained α-amidoboronic acid derivatives, whereas assembly of the homologous β-amidoboronic acids was achieved through a novel boronic acid-mediated lactamization process stemming from an α-boryl aldehyde. The results of quantum chemical calculations suggest carboxylate-boron coordination to be rate-limiting for small ring sizes, whereas the tetrahedral intermediate formation is rate limiting in the case of larger rings. As part of this study, an application of β-amidoboronic acid derivatives as novel VIM-2 metallo-β-lactamase inhibitors has been demonstrated.

Compared with the impressive achievements of catalytic carbonyl-olefin metathesis (CCOM) mediated by Lewis acid catalysts, exploration of the CCOM through Brønsted acid-catalyzed approaches remains quite challenging. Herein, we disclose a synthetic protocol for the construction of a valuable polycycle scaffold through the CCOM with the inexpensive, nontoxic phosphomolybdic acid as a catalyst. The current annulations could realize carbonyl-olefin, carbonyl-alcohol, and acetal-alcohol in situ CCOM reactions and feature mild reaction conditions, simple manipulation, and scalability, making this strategy a promising alternative to the Lewis acid-catalyzed COM reaction.

Background: Diet can affect the body's acid-base balance due to its content of acid or base precursors. There is conflicting evidence for the role of metabolic acidosis in the development of cardiometabolic disorders, hypertension (HT), and insulin resistance (IR). Objective: We hypothesized that dietary acid load (DAL) is associated with adverse metabolic risk factors and aimed to investigate this in the elderly. Methods: A total of 114 elderly participants were included in the study. The participants were divided into four groups, such as HT, diabetes (DM), both HT and DM, and healthy controls. Anthropometric, biochemical, and clinical findings were recorded. Potential renal acid load (PRAL) and net endogenous acid production (NEAP) results were obtained for three days, 24-hour dietary records via a nutrient database program (BeBiS software program). Results: The groups were matched for age, gender, and BMI. There was a statistically significant difference between the groups regarding NEAP (p =0.01) and no significant difference for PRAL ( p = 0.086). The lowest NEAP and PRAL levels were seen in the control group while the highest in the HT group. Both NEAP and PRAL were correlated with waist circumference (r = 0,325, p = 0.001; r=0,231, p =0,016, respectively). Conclusion: Our data confirmed that subjects with HT and DM had diets with greater acid-forming potential. High NEAP may be a risk factor for chronic metabolic diseases, particularly HT. PRAL could not be shown as a significantly different marker in all participants. Dietary content has a significant contribution to the reduction of cardiovascular risk factors, such as HT, DM, and obesity.