Novel easily accessible glucosidase inhibitors: 4-hydroxy-5-alkoxy-1,2-cyclohexanedicarboxylic acids

Unusual Rearrangements in Cyclohex-3-ene-1-carboxamide Derivatives: Pathway to Bicyclic Lactones

The synthesis of new bicyclic lactone derivatives was carried out starting from 2-methyl/phenyl-3a,4,7,7a-tetrahydro-1H-isoindole-1,3(2H)-dione. 6-(Hydroxymethyl)-N-methyl/phenylcyclohex-3-ene-1-carboxamide derivatives were obtained from the reduction of tetrahydro-1H-isoindole-1,3(2H)-diones with NaBH4. Bromination and epoxidation reactions of both compounds were examined, and the structures of the resulting products were determined by spectroscopic methods. Substituted bicyclic lactone compounds, which are interesting rearrangement products in both bromination and epoxidation reactions, were obtained. In particular, hydroxymethyl (-CH2OH) and amide (-CONHR) groups attached to the cyclohexene ring in the bromination and epoxidation reactions were found to be effective in product formation. As a result, a new and applicable method was developed for the synthesis of bicyclic lactone derivatives.

Rh(i)-Catalyzed enantioselective and scalable [4 + 2] cycloaddition of 1,3-dienes with dialkyl acetylenedicarboxylates

An asymmetric intermolecular [4 + 2] cycloaddition of 1,3-dienes with dialkyl acetylenedicarboxylates, which was catalyzed by a rhodium(i)-chiral phosphoramidite complex, was developed. This protocol provided a highly enantioselective access to prepare carbonyl substituted cyclohexa-1,4-dienes with up to 96% yield and >99% ee. Notably, a cycloaddition on the 10 g scale gave the product in 92% yield and with 99% ee, which showed great potential for the scale-up synthesis of carbonyl substituted cyclohexa-1,4-dienes. In addition, oxidative aromatizations and hydrolysis of the products were also investigated.

Synthesis and α-glucosidase inhibitory activity evaluation of N-substituted aminomethyl-β-d-glucopyranosides

A series of N-substituted 1-aminomethyl-β-d-glucopyranoside derivatives was prepared. These novel synthetic compounds were assessed in vitro for inhibitory activity against yeast α-glucosidase and both rat intestinal α-glucosidases maltase and sucrase. Most of the compounds displayed α-glucosidase inhibitory activity, with IC50 values covering the wide range from 2.3μM to 2.0mM. Compounds 19a (IC50=2.3μM) and 19b (IC50=5.6μM) were identified as the most potent inhibitors for yeast α-glucosidase, while compounds 16 (IC50=7.7 and 15.6μM) and 19e (IC50=5.1 and 10.4μM) were the strongest inhibitors of rat intestinal maltase and sucrase. Analysis of the kinetics of enzyme inhibition indicated that 19e inhibited maltase and sucrase in a competitive manner. The results suggest that the aminomethyl-β-d-glucopyranoside moiety can mimic the substrates of α-glucosidase in the enzyme catalytic site, leading to competitive enzyme inhibition. Moreover, the nature of the N-substituent has considerable influence on inhibitory potency.

Fliposomes: pH-controlled Release from Liposomes Containing New trans-2-Morpholinocyclohexanol-based Amphiphiles that Perform a Conformational Flip and Trigger an Instant Cargo Release upon Acidification

A new type of pH-sensitive liposome (fliposomes) was designed based on the amphiphiles that are able to perform a pH-triggered conformational flip (flipids). This flip disrupts the liposome membrane and causes rapid release of the liposome cargo, specifically in the areas of increased acidity. The flipids (1-3) are equipped with a trans-2-morpholinocyclohexanol conformational switch. pH-Sensitive fliposomes containing one of these flipids, POPC and PEG-ceramide (molar ratio 50/45/5) were constructed and characterized. These compositions were stable at 4oC and pH 7.4 for several months. Fliposomes loaded with ANTS/DPX demonstrated an unusually quick content release (in a few seconds) at pH below 5.5, which was more efficient in the case of flipid 1 with the shorter linear C12-tails. The pH-titration curve for the fliposome leakage paralleled the curve for the acid-induced conformational flip of 1-3 studied by 1H NMR. A plausible mechanism of the pH-sensitivity starts with an acid-triggered conformational flip of 1, 2 or 3, which changes the molecular size and shape, shortens the lipid tails, and perturbs the liposome membrane resulting in the content leakage.

Synthesis and antidiabetic performance of β-amino ketone containing nabumetone moiety

We wish to report the further design and improved synthesis that resulted in two series of target molecules, TM-1 and TM-2, with remarkably simplified structures containing β-amino ketone of discrete nabumetone moiety. These were obtained via a 'one-pot, two-step, three-component' protocol of Mannich reaction with yield up to 97%. A total of 28 out of 31 new compounds were characterized using (1)H NMR, (13)C NMR, ESI MS and HRMS techniques. Studies on their antidiabetic activities, screened in vitro at 10 μg mL(-1) level, indicate that TM-2 possesses peroxisome proliferator-activated receptor activation and α-glucosidase inhibition activity significantly stronger than that of TM-1, and also that of the series B compounds that were previously synthesized by the group. Analysis of the structure-activity relationship points to the sulfanilamide unit as the most probable potent group of β-amino ketone and, on the basis of which, a tangible strategy is presented for the development of new antidiabetic drugs.

Shikimic acid: review of its analytical, isolation, and purification techniques from plant and microbial sources

Shikimic acid properties and its available analytical techniques are discussed. Plants having the highest content of shikimic acid are shown. The existing isolation methods are analyzed and the most optimal approaches to extracting this acid from natural sources (plants and microorganisms) are considered.

Fliposomes: pH-Sensitive Liposomes Containing a trans-2-morpholinocyclohexanol-Based Lipid That Performs a Conformational Flip and Triggers an Instant Cargo Release in Acidic Medium

Incorporation of a pH-sensitive conformational switch into a lipid structure enables a drastic conformational flip upon protonation that disrupts the liposome membrane and causes rapid release of cargo specifically in areas of increased acidity. pH-sensitive liposomes containing the amphiphile (1) with trans-2-morpholinocyclohexanol conformational switch, a phospholipid, and a PEG-lipid conjugate were constructed and characterized. The optimized composition—1/POPC/PEG-ceramide (50/4/5)—could be stored at 4 °C and pH 7.4 for up to 1.5 years, and was stable in blood serum in vitro after 48 h at 37 °C. Liposomes loaded with ANTS/DPX or methotrexate demonstrated an unusually quick content release (in a few seconds) at pH below 5.5, which was independent of inter-liposome contact. The pH-titration curve for the liposome leakage paralleled the curve for the acid-induced conformational flip of 1 studied by ¹H-NMR. Freeze-fracture electron microscopy images showed budding and division of the bilayer at pH 5.5. A plausible mechanism of pH-sensitivity involves an acid-triggered conformational flip of 1, shortening of lipid tails, and membrane perturbations, which cause the content leakage. The methotrexate-loaded liposomes demonstrated much higher cytotoxicity in HeLa cells than the free drug indicating that they can serve as viable drug delivery systems.