K. Hara Kishore

Antimicrobial constituents from the rhizomes of Rheum emodi.

The bioassay-guided chemical examination of the rhizomes of R. emodi resulted in the isolation of two new oxanthrone esters, revandchinone-1, revandchinone-2, a new anthraquinone ether revandchinone-3 and a new oxanthrone ether, revandchinone-4. Their structures were established based on spectroscopic and degradative evidence. Occurrence of oxanthrone ether is reported for the first time. The anti bacterial and anti fungal activity of the isolates is studied.

Design, synthesis, structure-activity relationship and antibacterial activity series of novel imidazo fused quinolone carboxamides.

A series of novel 7,8 and 1,8 imidazo fused quinolone carboxamides are synthesized and evaluated against antibacterial activity. 1,8 Imidazo fused quinolones exhibit moderate antibacterial activity. Molecular modeling studies were carried out to optimize the pharmacophore.

Biotransformation of ferulic acid to acetovanillone using Rhizopus oryzae

Microbial transformation of ferulic acid to acetovanillone was studied using growing cells of Rhizopus oryzae. Ferulic acid was added to the growing medium (0.5 g L−1) and incubated for 12 days. The progress of formation of metabolites was monitored by GC and GC-MS after extraction with ethyl acetate. The major metabolite was acetovanillone with minor metabolites formed, such as dihydroferulic acid, coniferyl alcohol and dihydroconiferyl alcohol. Traces of metabolites (≤1–3%), such as vanillin, vanillyl alcohol, vanillic acid and phenyl ethyl alcohol, were also produced. Formation of 4-vinyl guaiacol increased from day 1 (12.4%), reaching a maximum on day 4 (31.7%), and reducing to a minimum on day 12 (3.1%). The formation of acetovanillone increased only from day 2 onward, and reached a maximum (49.2%) on day 12. The optimum concentration of ferulic acid to be added into the medium was found to be only 0.5 g L−1, as any increase in concentration (0.75 and 1.0 g L−1) precipitated the precursor, resulting in no further degradation.

MICROWAVE ASSISTED SYNTHESIS AND ΑΝΤΙMICROBIAL ACTIVITY OF 2,2-DIMETHYL CHROMENES

2,2-Dimethyl chromenes (lb-9b) were prepared from corresponding propargyl ethers (la-9a) under microwave conditions in high yields and anti microbial activity of compounds (6b & 7b) is reported.

Clerodendrone, a novel hydroquinone diterpenoid from Clerodendrum indicum

Chemical investigation of Clerodendrum indicum has resulted in the isolation of clerodendrone, a new member of hydroquinone diterpenoids (which are rare in the investigated family, Verbenaceae). The compound was characterised from its spectral (1D and 2D NMR) data and chemical reactions and was found to contain an uncommon structural pattern with beta-methyl dihydrofuran moiety.

Antimicrobial efficacy of secondary metabolites from Glomerella cingulata

Fungi are known to produce a vast array of secondary metabolites that are gaining importance for their biotechnological applications. Early reports suggest that G. cingulata has the capability to transform many compounds by various enzymatic actions. Therefore, the focus of this study was to determine the antibacterial and antifungal activity of crude ethyl acetate extract of G. cingulata using agar cup bioassay method. Crude extract of G. cingulata exhibited remarkable antifungal activity against Rhizopus oryzae, Chrysoporium tropicum and Beauveria bassiana but no antifungal activity was found against Alternaria tenuissima and Aspergillus niger at any concentrations. The crude extract presented no antibacterial activity against Gram positive and Gram negative bacteria at any concentration.

Chemical transformation of ∆9(15)-africanene and their antibacterial activity

Abstract∆9(15) Africanene, a medicinally important natural sesquiterpenoid has been subjected to chemical transformations to prepare aromatic, hetero aromatic, and aliphatic esters. The synthesized compounds were characterized using IR, mass, and NMR spectrometric analysis. The compounds were evaluated for their antibacterial activities.Graphical Abstract