The interplay of hydrophobic and electrostatic effects in the surfactant-induced aggregation/deaggregation of chlorin p6

The aggregation/deaggregation of chlorin p6 with the surfactants CTAB, SDS, and TX 100 have been studied by using absorption, fluorescence, and light scattering techniques. The ionic surfactants are found to cause aggregation of fluorophore at submicellar concentrations. The aggregates dissolve at higher surfactant concentrations to yield micellized monomers. This is rationalized by the interplay of electrostatic and hydrophobic effects. A prominent pH effect is observed in the ionic surfactant induced aggregation process as the charge on the fluorophore is controlled by the pH of the medium. Interestingly, the neutral TX-100 also induces aggregation of chlorin p6 at low concentrations, indicating that hydrophobic effects by themselves can cause aggregation unless there is a hindrance by repulsive electrostatic effects.     

Total synthesis of the alkaloid (−)-codonopsinine from l-xylose

The enantiopure total synthesis of (−)-codonopsinine is described from commercially available l-xylose in 20% overall yield. The key steps included Julia trans olefination and cascade epoxidation-cyclisation strategies.     

Underpotential deposition studies of copper on glassy carbon

Studies on the deposition and dissolution of copper from 0·5 M sulphuric acid solutions onto glassy carbon (GC) using potential sweep techniques indicated that an additional peak occurs at higher positive potentials than the bulk stripping peak. This peak is identified as due to the stripping of underpotential deposited (UPD) copper. Results of investigations on the effect of sweep rate, deposition potential and time of deposition on the peak characteristics of UPD and bulk deposited copper are also reported.     

Synthesis and computational studies of potent antimicrobial and anticancer indolone scaffolds with spiro cyclopropyl moiety as a novel design element

The indolones nucleus is the central core to develop new effective anticancer agents and its substitution at the 3-position can affect antitumor activity, 3-spirocyclopropyl-2-oxindoles have attracted the scientist's community to design and develop expedition's strategies towards their construction and explore the potential of this useful scaffold with their newer derivatives in medicinal world. The present paper describes the synthesis of 3-spirocyclopropyl-2-indolone derivatives in three steps via synthesis of ylide leading to methylene-indolinones followed by the formation of the final product spirocyclopropyl oxindole derivatives with improved yields. In this milieu we considered motivating to advance exploration the biological potencies and computational studies of our newly synthesized molecules. The aimed target molecules were screened for antimicrobial and anticancer activities where they exhibited substantial effective antimicrobial activities. Amongst them, potent compound, bromospirocyclopropyl indolone, 6d displayed encouraging MIC ranging from 0.007 to 0.49 μg/mL for gram positive microbes and also substantial anticancer activity with an IC₅₀ of 11.5 μg/mL. Finally, the computational modelling studies were performed to explore structure-activity relationship analysis. Active site of receptor protein shows docking scores of these molecules as - 5.78 kcal/mol and ?5.097 kcal/mol for the docked target proteins. The binding energy of the best score is found to be ?41.67 kcal/mol to ?44.67 kcal/mol. Thus, the present paper efficaciously validated spirocyclopropyl indolone framework for drug candidates as potent anticancer as well as antimicrobial compounds.     

Synthesis,characterization and biological evaluation of purine nucleoside analogues

We present a convenient route for the synthesis of C6-amino-C5′-N-cyclopropyl carboxamido-C2-alkynylated purine nucleoside analogues 11a–g via Sonogashira coupling reaction. The nine step synthesis is easy to perform, employing commercially available reagents. Compound 9 is used as key intermediate for the synthesis of analogues 11a–g. Synthetic intermediates and final products are appropriately characterized by IR, ¹H NMR, ¹³C NMR and Mass. The modified nucleoside analogues 11a–g is evaluated for in vitro anticancer activity against MDA-MB-231 and Caco-2 cell lines. Screening data reveals that compounds 11b and 11e displayed potent IC₅₀ value of 7.9, 6.8 µg/mL respectively against MDA-MB-231 and of 7.5, 8.3 µg/mL respectively against Caco-2 than the standard drug doxorubicin, thus establishing the potential anti-cancer properties of these newer derivatives.     

Synthesis of spiroindene-1,3-dione isothiazolines via a cascade michael/1,3-dipolar cycloaddition reaction of 1,3,4-oxathiazol-2-one and 2-arylidene-1,3-indandiones

The reaction of 1,3,4-oxathiazol-2-one derivative with 2-arylidene-1,3-indandione to furnish novel spiroindene-1,3-dione isothiazoline derivatives by Michael/1,3-dipolar [3+2]-cycloaddition reaction was investigated. The key 1,3-dipolar cycloaddition reaction step was examined in toluene solvent at reflux temperature to obtain mixture of two regioisomers (6a and 6b – 14a and 14b) and single isomers (15–20). The scope of this new reaction was demonstrated with many examples with high reactivity and yields.     

Species Diversity and Secondary Metabolites of Sarcophyton-Associated Marine Fungi

Soft corals are widely distributed across the globe, especially in the Indo-Pacific region, with Sarcophyton being one of the most abundant genera. To date, there have been 50 species of identified Sarcophyton. These soft corals host a diverse range of marine fungi, which produce chemically diverse, bioactive secondary metabolites as part of their symbiotic nature with the soft coral hosts. The most prolific groups of compounds are terpenoids and indole alkaloids. Annually, there are more bio-active compounds being isolated and characterised. Thus, the importance of the metabolite compilation is very much important for future reference. This paper compiles the diversity of Sarcophyton species and metabolites produced by their associated marine fungi, as well as the bioactivity of these identified compounds. A total of 88 metabolites of structural diversity are highlighted, indicating the huge potential these symbiotic relationships hold for future research.     

Greener approach toward synthesis of biologically active s-Triazine (TCT) derivatives: A recent update

The greener methodology to synthesize s-triazine derivatives (also known as TCT) is described, including synthesis through microwave, ultrasound, and solvent-free conditions. This review mainly focuses on reactions of TCT (2,4,6-trichloro-1,3,5-triazine) with various substituents having amine and hydroxy functionalities to give corresponding triazine derivatives under a greener approach. The results of reactions indicate that, unlike classical methods, green methods result in better yields of the product, through a rapid reaction, under mild reaction conditions, and by easy workup procedures.     

Chern–Simons classes for a superconnection

In this note we define the Chern–Simons classes of a flat superconnection, D+L$D+L$, on a complex Z/2Z$\mathbb{Z}/2\mathbb{Z}$-graded vector bundle E$E$ on a manifold such that D$D$ preserves the grading and L$L$ is an odd endomorphism of E$E$. As an application, we obtain a definition of Chern–Simons classes of a (not necessarily flat) morphism between flat vector bundles on a smooth manifold. An application of Reznikov's theorem shows the triviality of these classes when the manifold is a compact Kähler manifold or a smooth complex quasi-projective variety in degrees >1$>1$.