Evaluation of reduction kinetics of 2,2-diphenyl-1-picrylhydrazyl radical by flavonoid glycoside Rutin in mixed solvent based micellar media

Spectroscopic studies on a natural biomarker for the identification of origin and quality of tea extracts for the development of a portable and field deployable prototype

Even in the era of smart technologies and IoT enabled devices, tea testing technique continues to be a person specific subjective task. In this study, we have employed optical spectroscopy-based detection technique for the quantitative validation of tea quality. In this regard, we have employed the external quantum yield of quercetin at 450 nm (λ_ex = 360 nm), which is an enzymatic product generated by the activity of β-glucosidase on rutin, a naturally occurring metabolite responsible for tea-flavour (quality). We have found that a specific point in a graph representing Optical Density and external Quantum Yield as independent and dependent variables respectively of an aqueous tea extract objectively indicates a specific variety of the tea. A variety of tea samples from various geographical origin have been analysed with the developed technique and found to be useful for the tea quality assessment. The principal component analysis distinctly showed the tea samples originated from Nepal and Darjeeling having similar external quantum yield, while the tea samples from Assam region had a lower external quantum yield. Furthermore, we have employed experimental and computational biology techniques for the detection of adulteration and health benefit of the tea extracts. In order to assure the portability/field use, we have also developed a prototype which confirms the results obtained in the laboratory. We are of the opinion that the simple user interface and almost zero maintenance cost of the device will make it useful and attractive with minimally trained manpower at low resource setting.

A DPPH· Kinetic Approach on the Antioxidant Activity of Various Parts and Ripening Levels of Papaya (Carica papaya L.) Ethanolic Extracts

Papaya fruits (Carica papaya L.) are valuable both as food, including concentrates and mixed beverages and in traditional medicine. The goal of the study was to evaluate the antioxidant activity of various parts of unripe and ripe papaya fruit from the DPPH· kinetics point of view. Peel, pulp, seed, and seed-pulp of unripe and ripe papaya fruits (¼ and >¾ level of ripening) were extracted with ethanol and monitored at 517 nm in the presence of DPPH·. The radical scavenging capacity (RSC) at various time ranges and DPPH· reaction rates for specific time intervals were determined. The highest RSC values were obtained for papaya pulp extracts, consistently higher for the ripe samples in comparison with the unripe ones (86.4% and 41.3%). The DPPH· rates significantly differ for the unripe and ripe papaya extracts, especially for the first time range. They are more than double for the ripe papaya. These values were 2.70, 4.00, 3.25, 2.75 μM/s for the peel, pulp, seed, seed-pulp extracts from the ripe papaya and only 1.00, 1.65, 1.40, 1.80 μM/s for the unripe samples. DPPH· kinetic approach can be useful for a fast and simple evaluation of the overall antioxidant properties of fruit extracts.

Transforming micelles into mixed micelles: a promising approach to tune the catalytic performance of imidazolium-based surface active ionic liquids toward degradation of rhodamine B

Herein, we demonstrate that the catalytic performance of imidazolium-based surface-active ionic liquid (SAIL) micelles can be significantly enhanced through the addition of an appropriate type and amount of intelligently conceived amphiphile to form mixed micelles. Specifically, we show that the catalytic performance of 1-dodecyl-3-methyl imidazolium chloride (DDMIMCl) micelles toward the reductive degradation of rhodamine B (RhB), a carcinogenic dye extensively used in multiple industrial applications, can be appreciably boosted through addition of Brij56, a nonionic surfactant. Detailed kinetic investigations on the catalytic performance of pre- and post-micellar concentrations of DDMIMCl and its mixed micelles with Brij56 over various mole fractions, toward the reductive degradation of RhB, are presented. The data analyzed in light of Berezin's kinetic model suggest that the addition of Brij56 to DDMIMCl micelles significantly enhances their catalytic performance. The catalytic activity exhibited by the DDMIMCl-Brij56 (X_Brij56 = 0.2) mixed micellar system is better than that reported for many state-of-the-art nanoparticle/homogenous catalysts. The results explained in light of Berezin's kinetic model are well supported by physico-chemical studies like conductometry, fluorimetry and dynamic light scattering. The presented results anticipate stimulation of extensive research activity for exploiting the mixed micellization approach as a novel avenue for modulating the catalytic performance of SAILs.

Self-assembled nanocontainer mediated oxidation of Fe(ii) by Cu(ii)–neocuproine complex: a model system to emulate electron transfer proteins

Catalysis of coordination inspired Fe(ii) oxidation by Cu(ii)–neocuproine complex.

Free radical nano scavenger based on amphiphilic novolacs

Synthetic amphiphilic novolacs via click chemistry are capable of forming micelles, and interestingly, can act as highly efficient nano-scavengers for hydroxyl free radicals.