Iron mediated reductive cyclization/oxidation for the generation of chemically diverse scaffolds: An approach in drug discovery.

Chemically diverse scaffolds represent a main source of biologically important starting points in drug discovery. Herein, we report the development of such diverse scaffolds from nitroarene/ nitro(hetero)arenes using a key synthetic strategy. In a pilot-scale study, the synthesis of 10 diverse scaffolds was achieved. The 1,7-phenanthroline, thiazolo[5,4-f]quinoline, 2,3-dihydro-1H-pyrrolo[2,3-g]quinoline, pyrrolo[3,2-f]quinoline, 1H-[1,4]oxazino[3,2-g]quinolin-2(3H)-one, [1,2,5]oxadiazolo[3,4-h]quinoline, 7H-pyrido[2,3-c]carbazole, 3H-pyrazolo[4,3-f]quinoline, pyrido[3,2-f]quinoxaline were obtained from nitro hetero arenes in ethanol using iron-acetic acid treatment followed by reaction under oxygen atmosphere. This diverse library is compliant with the rule of five for drug-likeness. The mapping of chemical space represented by these scaffolds revealed a significant contribution to the underrepresented chemical diversity. Crucial to the development of this approach was the mapping of biological space covered by these scaffolds which revealed neurotropic and prophylactic anti-inflammatory activities. In vitro, neuro-biological assays revealed that compounds 14a and 15a showed excellent neurotropic potential and neurite growth compared to controls. Further, anti-inflammatory assays (in vitro and in vivo models) exhibited that Compound 16 showed significant anti-inflammatory activity by attenuating the LPS-induced TNF-α and CD68 levels by modulating the NFkB pathway. In addition, treatment with compound 16 significantly ameliorated the LPS-induced sepsis conditions, and pathological abnormalities (in lung and liver tissues) and improved the survival of the rats compared to LPS control. Owing to their chemical diversity along with bioactivities, it is envisaged that new quality pre-clinical candidates will be generated in the above therapeutic areas using identified leads.

Synthesis of novel trifluoromethyl substituted furo[2,3-b]pyridine and pyrido[3',2':4,5]furo[3,2-d]pyrimidine derivatives as potential anticancer agents.

A series of novel trifluoromethyl substituted furo[2,3-b]pyridine and pyrido[3',2':4,5]furo[3,2-d] pyrimidine derivatives 3a-b, 6a-k, 9, 10a-b, 11a-c and 12a-c were prepared from 2-carbethoxy-3-amino-6-trifluoromethyl furo[2,3-b]pyridine 1 under different set of conditions. Compounds functionalized with oxadiazole 11a-c were also prepared from 2-carbohydrazide-3-amino-6-trifluoromethyl furo[2,3-b]pyridine 4. All the final products were screened for anticancer activity against four human cancer cell lines such as Neuro-2a, Hela, A549 and COLO 205 as well as normal human lung cell line, IMR-90. All the compounds showed promising anticancer activity against all the tested cell lines at <25 µM concentration except 5b, 6d, 6e and 6k. The selectivity index (SI) values have also been calculated for all the tested compounds in comparison to the normal cell line. Compounds 6g, 10a, 10b, and 11a were considered as potential leads which showed cytotoxicity with IC50 values of 10, 10.7, 11.0 and 10.5 µM, respectively. Compounds 7 and 12a were considered as highly potent exhibiting promising cytotoxicity with IC50 value of 5.8 and 3.6 µM, respectively.

Synthesis of novel lipoamino acid conjugates of sapienic acid and evaluation of their cytotoxicity activities.

Novel lipoamino acids were prepared with the coupling of sapienic acid [(Z)-6-hexadecenoic acid] with α - amino group of amino acids and the resulting N-sapienoyl amino acids were tested for their cytotoxicity activities against four cancer based cell lines. Initially, sapienic acid was synthesized by the Wittig coupling of triphenylphosphonium bromide salt of 6-bromohexanoic acid and decanal with a Z specific reagent. The prepared sapienic acid was subsequently converted to its acid chloride which was further coupled with amino acids by the Schotten-Baumann reaction to form N-sapienoyl amino acid conjugates. Structural characterization of the prepared N-sapienoyl amino acid derivatives was done by spectral data (IR, mass spectra and NMR). These lipoamino acid derivatives were screened for in vitro cytotoxicity evaluation. Cytotoxicity evaluation against four cancer cell lines showed that N-sapienoyl isoleucine was active against three cell lines whereas other derivatives either showed activity against only one or two cell lines with very moderate activity and two derivatives were observed to be inactive against the tested cell lines.