Natural products embedded crown ethers as potent insulin secretory agents.

Natural products embedded crown ethers were prepared by utilizing bioactive natural products including chrysin, tetrahydroisoquinoline (THIQ), and biochanin-A. The prepared crown ether scaffolds were evaluated and compared with their natural product precursors for insulin secretory activity on isolated mice islets and for their fluorescent properties. All the crown adducts were found more active as compared to their natural product precursors. Bischrysin 32-crown-10 (6d), THIQ 15-Crown-5 (6a) and chrysin 16-crown-5 (6c) showed mild, moderate and strong insulin secretory activity, respectively when compared with the standard drug tolbutamide (TB). Particularly crown derivative 6c showed strong activity (31.10 ng/islet/h) that is almost two (02) fold higher than that of standard drug TB (16.82 ng/islet/h). To the best of our knowledge crown ethers based antidiabetic study is being reported for the first time in literature through this work. Furthermore, fluorescence study showed the significant increase in absorption and emission maximum (hypsochromic effect) in crown structures when compared with their natural product precursors. Present optimistic results obtained from this study may be a guided template for developing new effective insulin secretory agents.

Shifted Legendre Collocation Method for the Solution of Unsteady Viscous-Ohmic Dissipative Hybrid Ferrofluid Flow over a Cylinder.

A numerical treatment for the unsteady viscous-Ohmic dissipative flow of hybrid ferrofluid over a contracting cylinder is provided in this study. The hybrid ferrofluid was prepared by mixing a 50% water (H2O) + 50% ethylene glycol (EG) base fluid with a hybrid combination of magnetite (Fe3O4) and cobalt ferrite (CoFe2O4) ferroparticles. Suitable parameters were considered for the conversion of partial differential equations (PDEs) into ordinary differential equations (ODEs). The numerical solutions were established by expanding the unknowns and employing the truncated series of shifted Legendre polynomials. We begin by collocating the transformed ODEs by setting the collocation points. These collocated equations yield a system of algebraic equations containing shifted Legendre coefficients, which can be obtained by solving this system of equations. The effect of the various influencing parameters on the velocity and temperature flow profiles were plotted graphically and discussed in detail. The effects of the parameters on the skin friction coefficient and heat transfer rates were further presented. From the discussion, we come to the understanding that Eckert number considerably decreases both the skin friction coefficient and the heat transfer rate.

Numerical study of heat generating γ Al 2 O 3 - H 2 O nanofluid inside a square cavity with multiple obstacles of different shapes.

A numerical research on uniformly heat generating γ Al 2 O 3 -H 2 O nanofluid filled square cavity with multiple obstacles of different shapes is carried out. The cavity is assumed to be heated at bottom and cooled by vertical walls with linearly varying temperature. An adiabatic condition is assumed at the top of the cavity. Circular, square and triangular shaped obstacles are considered. The mathematical model has been solved using Galerkin finite element method. Results are presented for streamlines, isotherms, local and mean Nusselt numbers. Multiple rotating cells are observed in the streamlines. It is found that the local and mean Nusselt numbers increase with nanoparticle volume fraction and higher heat transfer is achieved in the cavity with triangular obstacles.

New series of 3,5-disubstituted tetrahydro-2H-1,3,5-thiadiazine thione (THTT) derivatives: Synthesis and potent antileishmanial activity.

Four series of heterocyclic compounds, namely, tetrahydro-2H-1,3,5-thiadiazine thione derivatives were synthesized in good to excellent yields and were screened for their in vitro antileishmanial activities against Leishmania major (promastigotes). Most of the compounds showed significant antileishmanial activity within the range of IC50 = 15.48-39.36 µM when compared with standard pentamidine (IC50 = 14.95 µM). The structure-activity relationship showed that N-3 and N-5 substituents have a key role against leishmanicidal activity. The ester analogues (series B) were found to have a 1.5 to 5-fold reduced activity compared to their acidic counterparts. Cytotoxicity against mammalian mouse fibroblast 3 T3 cells was also evaluated and compared between the acid and its ester analogue. The reduction of antileishmanial activity and loss of toxicity in the newly developed THTT ester derivative indicates that these compounds can be used as a template study for the production of effective antileishmanial ester prodrugs.