Stereoselective total synthesis of (+)-brevipolide H from D-galactal

The efficient and concise synthesis of cytotoxic 5, 6-dihydro-α-pyrone (+)-brevipolide H has been accomplished in 12 long linear steps with 8.65% overall yield from readily available chiral synthons, D-galactal and L-ethyl lactate. The features of this synthesis are highly diastereoselective Simmons-Smith cyclopropanation and carbohydrate-based chiron approach to rapid access to key 5, 6-dihydro-α-pyrone skeleton.

Compatible organic and natural solvent mixture of synthesising biodegradable polymeric nanoparticles

The Flory-Huggins model interaction explained the compatibility and extent of polymer dissolution in selected solvent mixtures via Hansen Solubility Parameters (HSP). Metastable zone where nucleation of NPs would start was determined by the solvent mixture – polymer – water interaction. Simulation results explained that the combination of acetone-chloroform (0.20:0.80) was better than acetone-ethyl lactate (0.40:0.60) for PCL solvation while ethyl lactate-dimethyl sulfoxide (0.60:0.40) was better for PLA solvation as compared to ethyl lactate-acetone (0.80:0.20). Nanoprecipitation with aqueous to organic volume ratio of 10 was used to prepare the biodegradable PCL nanoparticles for experimental validation. The organic phase was 1 g L−1 PCL in solvents or solvent mixtures and the antisolvent was deionized (DI) water. Scanning Electron Microscope (SEM) and Atomic Force Microscope (AFM) were used to examine the morphology and size of nanoparticles formed. Results showed that the acetone-chloroform with volume fraction of 0.20 to 0.80 was the best solvent mixture for PCL in producing NPs with the mean size less than 100 nm. Solvent mixture proved by numerical simulation and experimental validation, able to enhance the affinity of polymer (PCL or PLA) for water to produce nanoparticles with much smaller size.

A GREEN AND FACILE APPROACH FOR ANTIDIABETIC AND ANTI-INFLAMMATORY POTENCY FOR FICUS SUBINCISA FRUIT

Ficus subincisa belongs to the Moraceae family comprising approximately 850 species. Many Ficus species have been used ethnopharmacologically for the treatment of many health-promoting effects. With increasing economical and ecological concerns for several chemical processes, green chemistry is providing various kinds of “green” solvents that can be a recruit for the extraction and isolation of numerous alleviative and important phytoconstituents from plants. The present study was undertaken to prepare crude extracts of F. subincisa fruits with different polarities of green solvents (d-limonene, isopropyl alcohol, ethyl lactate, and hydroalcohol) by using a modified magnetic stirrer extraction method and assessing in vitro anti-diabetic, anti-inflammatory activities by the spectrophotometric method. Among all, ethyl lactate and hydroalcohol fraction of F. subincisa have shown the highest α-amylase and α-glucosidase enzyme inhibitory activity with an IC50 value of 166.91±2.73 and 118.73±0.67 µg/mL, respectively, which were comparable with that of acarbose. At a concentration of 1000 µg/mL, the hydroalcohol and ethyl lactate of fruit produced 134.53±1.23 and 114.67±4.23 µg/mL inhibition of HRBC hemolysis and bovine serum albumin, respectively, as compared with standard drug aspirin and sodium diclofenac. However, there has been no report on the anti-inflammatory and antidiabetic activity of F. subincisa fruit. Therefore this study was aimed to evaluate the anti-inflammatory and antidiabetic activity of F. subincisa fruit extracts of different green solvents. Our study validated the traditional claim with pharmacological data of the Ficus genus. Taken together, these findings imply that the F. subincisa could be useful therapeutic agents to attenuate muscle insulin resistance due to diet-induced obesity and its associated inflammation.

Ethyl lactate production by reactive distillation – optimization of reaction kinetics and energy efficiency

Background: Ethyl lactate is an environmentally benign solvent, which could substitute petrol-based volatile organic compounds (VOCs) in many applications if production costs are reduced. It is usually produced by the esterification of lactic acid with ethanol – two important chemical building blocks of biorefineries that are available at industrial scale. Reactive distillation is a promising alternative production process, which utilises process intensification to increase energy efficiency and space-time yield by enhancing the reaction kinetics. Methods: In this work, process intensification of ethyl lactate production by means of distillation was analysed with special focus on the efficient separation of water. Different setups were evaluated. The feedstock requirements were studied and the process was optimized regarding reaction kinetics in experiments on laboratory level. The preparation of anhydrous starting mixtures for ethyl lactate formation was tested in batch experiments and applied to reactive distillation. The simultaneous distillation was optimized and assessed for its energy efficiency. For this purpose, integrated reactive distillation was compared to a simple setup for distillation enhanced esterification. Results: It was found that an optimized serial setup of reactors and distillation steps can offer similar process intensification at a lower distillate rate compared to simultaneous reactive distillation and is therefore more energy efficient. Moreover, the serial setup is more flexible and straight-forward to regulate and scale-up. Conclusions: Based on the experimental results, the optimal setup and parameters of a continuous process for ethyl lactate production by distillation enhanced esterification was presented.

Comparison of Synthetic and Natural Zeolite Catalysts’ Behavior in the Production of Lactic Acid and Ethyl Lactate from Biomass-Derived Dihydroxyacetone

This article presents the results of the conversion of dihydroxyacetone (DHA) to lactic acid (LA) with the use of zeolite catalysts. For this purpose, synthetic zeolite beta (BEA) and natural clinoptilolite (CLI) were used as a matrix. The zeolites were modified with various metals (Sn, Fe, Cu and Zn) during ion exchange under hydrothermal conditions. The DHA conversion process with the participation of metal-functionalized zeolites allowed us to obtain intermediates, i.e., pyruvic aldehyde (PAL), which during the further reaction was transformed into a mixture of products such as ethyl lactate (EL), pyruvic aldehyde (PA), lactic acid and ethyl acetate (EA). The best selectivity towards lactic acid was achieved using Sn-CLI (100%) > Na-BEA (98.7%) > Sn-BEA (95.9%) > Cu-BEA (92.9%), ethyl lactate using Cu-CLI, and pyruvic aldehyde using the Zn-BEA catalyst. In the case of a natural zeolite, modification with Sn is promising for obtaining a pure lactic acid with a relatively good carbon balance.