Ch. Pavan Kumar

First stereoselective total synthesis and anticancer activity of new amide alkaloids of roots of pepper.

The first stereoselective total synthesis of new natural amide alkaloids 1-3 have been achieved from commercially available starting materials. Wittig olefination, Sharpless asymmetric dihydroxylation, epoxidation, a trans regioselective opening of 2,3-epoxy alcohol, Horner-Wadsworth-Emmons (HWE) olefination and amide coupling are the key steps. The amide alkaloids 1-3 are evaluated for their anticancer activity against colon (HT-29), breast (MCF-7) and lung (A-549) human cancer cell lines for the first time.

4,4′-Unsymmetrically substituted-2,2′-bipyridines: novel bidentate ligands on ruthenium(II) [3 + 2 + 1] mixed ligand complexes for efficient sensitization of nanocrystalline TiO2 in dye solar cells

A series of five new ruthenium [3 + 2 + 1] complexes coded as MC107–MC111, with novel unsymmetrical bipyridines as ancillary ligands and terpyridine tricarboxylic acid as an anchoring ligand have been successfully synthesized and characterized by 1H NMR, 13C NMR and UV-Visible spectrometry. Improvement in the molar extinction coefficient of all these sensitizers was observed compared with reference standard N749 dye under comparable conditions. Among all the new sensitizers MC108 exhibited a maximum solar to electrical conversion efficiency of 5.573% (Jsc = 16.81 mA cm−2, Voc = 0.50 V. FF = 0.65) under standard global AM 1.5 G solar condition, when compared to the N749 dye with an efficiency of 6.29% (Jsc = 13.74 mA cm−2, Voc = 0.67 V. FF = 0.68) under similar fabrication and evaluation conditions. Density functional theory (DFT) and time-dependent DFT calculations are carried out for MC107–MC111 to understand their structural, electronic and photophysical properties.

Synthesis of costunolide derivatives by Pd-catalyzed Heck arylation and evaluation of their cytotoxic activities

Abstract As part of pharmacological–phytochemical integrated studies of medicinal plants from Indian flora, costunolide (1) was isolated as a major compound from Saussurea lappa, plant traditionally used in different Asian traditional medicine systems. To improve the efficacy of this natural product lead, a series of analogues have been synthesized by the coupling of various aryl iodides using the standard Heck reaction conditions and evaluated for their cytotoxic activities against human cancer cell lines. The results indicated that several of the analogues were effective against the tested cell lines compared to the parent compound costunolide. Among the tested compounds, 2c and 2j demonstrated good activity against Hela cell line while compounds 2d showed potent activity against DU-145 and MCF-7 cell lines, respectively.Graphical AbstractA series of costunolide derivatives have been synthesized by Pd(II)-catalyzed Heck reaction and were studied for their cytotoxic properties against the panel of human cancer cell lines (B-16, DU-145, Hela, A549, MCF-7).

Hetero aromatic donors as effective terminal groups for DPP based organic solar cells

Four new solution-processable donor–acceptor–donor (D–A–D) structured low bandgap small molecules (CSDPP5, CSDPP6, CSDPP7 and CSDPP8) with diketopyrrolopyrrole as central acceptor unit and phenoxazine (POZ) or carbazole (CBZ) as terminal units were designed, synthesized and characterized. The new small molecules have been employed as donors along with the PC71BM as electron acceptor in solution processed BHJ organic solar cells, showed broad absorption bands with suitable electrochemical energy levels. When the BHJ active layer was cast from THF solvent, the optimal power conversion efficiencies obtained with CSDPP5, CSDPP6, CSDPP7 and CSDPP8 are 2.97% 3.06%, 2.42% and 2.43% respectively. The PCE of the devices when processed with DIO/THF solvent, have been further enhanced to 4.69%, 4.14% for CSDPP6:PC71BM and CSDPP8:PC71BM active layers respectively. The enhancement in PCE has been attributed to change in nanoscale morphology and more balanced charge transport resulting from increased hole mobility.

Design, synthesis and anti-proliferative activities of novel 7′-O-substituted schisantherin A derivatives

A series of schisantherin A (1) derivatives were efficiently synthesized utilizing Yamaguchi esterification (2,4,6-trichlorobenzoyl chloride, Et3N, THF, DMAP, toluene) at the C-7′ position of the schisantherin A core. The synthesized derivatives were evaluated for their anti-cancer activities against SIHA, PANC 1, MDA-MB-231, IMR-32, DU-145 and A549 cancer cell lines using sulforhodamine B assay. Within the new series tested, compound 29 displayed the most promising cytotoxic effect against the human cervical cancer cell line (SIHA) with a GI50 value of <0.01 μM, which is comparable to that of the standard drug, doxorubicin. Mechanism of action studies validated that 29 functions as a microtubule inhibitor. Additionally, several of the other analogues exhibited potent activity against the tested cell lines. Based on the results obtained, structure–activity relationships (SARs) were established and a correlation between the activities was also observed and discussed.

“Click” reaction mediated synthesis of costunolide and dehydrocostuslactone derivatives and evaluation of their cytotoxic activity

Abstract As part of pharmacological–phytochemical integrated studies on medicinal plants from Indian flora, costunolide (1) and dehydrocostus lactone (2), were isolated as major phytochemicals from Saussurea lappa, a plant traditionally used in different Asian systems of medicine. A series of 1,4-disubstituted-1,2,3-triazoles conjugates were synthesized through diastereo selective Michael addition followed by regioselective Huisgen 1,3-dipolar cycloaddition reactions. All these triazolyl derivatives (5a–5j) & (7a–7j) were well characterized using modern spectroscopic techniques and evaluated for their anticancer activity against a panel of five human cancerous celllines. The results indicated that all the analogs displayed moderate cytotoxic activity. Graphical abstract

Synthesis, photophysical and anticancer study of D-ring extended estrone analogues

A concise route for the highly substituted ring extended estrone derivatives has been established. This protocol involves very simple, facile and one step ring transformation and cyclization process. The preliminary absorption, emission spectroscopic and biological studies of these compounds revealed the possible use of such prototypes in cancer chemotherapy as fluorescence probes.