By microbial transformation of tylosin (I), the following eight new acyl derivatives were obtained: 3-acetyltylosin (II), 3-propionyltylosin (III), 4"-butyryltylosin (IV), 4"-isovaleryltylosin (V), 3-acetyl-4"-butyryltylosin (VI), 3-acetyl-4"-isovaleryltylosin (VII), 3-propionyl-4"-butyryltylosin (VIII) and 3-propionyl-4"-isovaleryltylosin (IX).

The structure of physiologically active substances, actinopyrones A, B and C, produced by Streptomyces pactum S12538 were determined on the basis of their spectral and chemical character. These substances were structurally related to piericidin A1.

Direct compression is the preferred method for the preparation of tablets. Co-processing is the one of the most widely explored and commercially utilized method for the preparation of directly compressible vehicles. The objective of the present study is to prepare and characterize pregelatinized starch-poly vinyl pyrrolidone (PGS-PVP) co-processed excipient and to evaluate its application as di...

Selenium-containing heterocyclic compounds have been well recognized, not only because of their remarkable reactivities and chemical properties, but also because of their diverse pharmaceutical applications. In this context, isoselenocyanates have been emerged as a powerful tool for the synthesis of selenium-containing heterocycles, since they are easy to prepare and store and are safe to handl...

For many decades, ecologists have asked what prevents herbivores from consuming most of the plant biomass in terrestrial ecosystems, or "Why is the world green?" Here I ask the analogous question for detritivores: what prevents them from degrading most of the organic material in soils, or "Why is the ground brown?" For fresh plant detritus, constraints on decomposition closely parallel constrai...

The advancement of microbial processes for the production of renewable liquid fuels has increased with concerns about the current fuel economy. The development of advanced biofuels in particular has risen to address some of the shortcomings of ethanol. These advanced fuels have chemical properties similar to petroleum-based liquid fuels, thus removing the need for engine modification or infrast...

Fluorescence fluctuation methods have become invaluable research tools for characterizing the molecular-level physical and chemical properties of complex systems, such as molecular concentrations, dynamics, and the stoichiometry of molecular interactions. However, information recovery via curve fitting analysis of fluctuation data is complicated by limited resolution and challenges associated w...

The structure of diheteropeptin (1), a TGF-beta-like active substance from Diheterospora chlamydosporia Q58044, was determined to be a new cyclotetrapeptide, cyclo[2aminoisobutyryl-(S)-phenylalanyl-(R)-prolyl-(2S,8R,9R)-2-am ino-8,9-dihydroxydecanoyl-] by NMR, mass spectrometric and chemical studies.

A novel adaptive-gain twisting controller that is robust to the bounded disturbances with the unknown boundaries is proposed. The control algorithm is derived using the Lyapunov function technique. It is shown that an ideal or real second order sliding mode is established, and the adaptation algorithm does not overestimate the control gain. The efficacy of the proposed adaptive twisting control...