Isoindole Derivatives: Propitious Anticancer Structural Motifs.

Isoindole derivatives constitute an important class of biologically active heterocyclic compounds and continue to attract considerable attention due to their diverse pharmacological profile such as, antimicrobial, anthelmintic, insecticidal, cyclooxygenase isoenzyme (COX-2) and thrombin inhibition with special emphasis on anticancer activity. This review highlights anticancer properties of isoindole derivatives and its related structures and hoping that it would further help in generation of new concepts towards rational design and development of more potent and less toxic anticancer agents.

Imidazo[1,2-a]pyridine Scaffold as Prospective Therapeutic Agents.

Imidazo[1,2-a]pyridine is one of the most potential bicyclic 5-6 heterocyclic rings that is recognized as a "drug prejudice" scaffold due to its broad range of applications in medicinal chemistry such as anticancer, antimycobacterial, antileishmanial, anticonvulsant, antimicrobial, antiviral, antidiabetic, proton pump inhibitor, insecticidal activities. This scaffold has also been represented in various marketed preparations such as zolimidine, zolpidem, alpidem. Therefore, several attempts were made to carry out the structural modifications of this scaffold to discover and develop novel therapeutic agents. This review provides a valuable insight into the research findings of wide range of derivatives of imidazo[1,2-a]pyridine scaffold leading to promising heterocyclic compounds which could be explored further for the synthesis of new derivatives as well as construction of potential drug-like chemical libraries for biological screening in search of new therapeutic agents.

Soluble curcumin amalgamated chitosan microspheres augmented drug delivery and cytotoxicity in colon cancer cells: In vitro and in vivo study.

In present investigation, initially curcumin was complexed with 2-HP-ß-CD (curcumin-2-HP-ß-CD-complex) in 1:1 ratio and later amalgamated with chitosan microspheres (curcumin-2-HP-ß-CD-CMs) for selective delivery in colon only through oral route of administration. Various analytical, spectral and in-silico docking techniques revealed that the curcumin was deeply inserted in the 2-HP-ß-CD cavity with apparent stability constant of 3.35×10-3M. Furthermore, the mean particle size of 6.8±2.6µm and +39.2±4.1mV surface charge of curcumin-2-HP-ß-CD-complex-CMs in addition to encapsulation efficiency of about 79.8±6.3% exhibited that the tailored microspheres were optimum for colon delivery of curcumin. This was also demonstrated in dissolution testing and standard cell proliferation assay in which curcumin-2-HP-ß-CD-complex-CMs exhibited maximum release in simulated colonic fluid (SCF, pH ∼7.0-8.0, almond emulsion-ß-glucosidase) with improved therapeutic index in HT-29 cells. Consistently, curcumin-2-HP-ß-CD-complex-CMs successively enhanced the colonic bio-distribution of curcumin by ∼8.36 folds as compared to curcumin suspension in preclinical pharmacokinetic studies. In conclusion, curcumin-2-HP-ß-CD-complex-CMs warrant further in vivo tumor regression study to establish its therapeutic efficacy in experimental colon cancer.

Telmisartan complex augments solubility, dissolution and drug delivery in prostate cancer cells.

Telmisartan (TEL) requires superior bioavailability in cancer cell compartments. To meet these challenges, we have synthesized a 2-HP-ß-CD-TEL complex with stability constant (Kc) of 2.39 × 10(-3)mM. The absence in the FTIR spectrum of 2-HP-ß-CD-TEL complex of the characteristic peaks of TEL at 1,699 cm(-1) (carboxylic acid) and 741 and 756 cm(-1) (1,2-disubstituted benzene ring vibrations), is indicative of the encapsulation of TEL in the 2-HP-ß-CD cavity. DSC and PXRD also confirmed the synthesis and amorphous structure of complex. The interaction of TEL with 2-HP-ß-CD was examined by NMR and 2D-ROESY which affirms the encapsulation of TEL in the 2-HP-ß-CD cavity in at least two orientations with equal binding energies. The complex also exhibited its superiority in both in vitro release and cytotoxicity experiments on prostate cancer, PC-3 cells as compared to free drug. These data warrant an in depth in vivo to scale-up the technology for the management of prostate cancer.

Cytotoxic activity of 3-(5-phenyl-3H-[1,2,4]dithiazol-3-yl)chromen-4-ones and 4-oxo-4H-chromene-3-carbothioic acid N-phenylamides.

6/6,7-Substituted-3-formylchromones (8a-g) were reacted with 2 equivalents thiobenzamide (9) in refluxing toluene to furnish substituted-3-(5-phenyl-3H-[1,2,4]dithiazol-3-yl)chromen-4-ones (10a-g) in high yields. Similarly, when substituted-2-anilino-3-formylchromones (8a-d) were reacted with thiobenzamide (9, 2 equivalents) in refluxing xylene, 4-oxo-4H-chromene-3-carbothioic acid N-phenylamides (11a-d) were obtained in high yields. All the compounds (10a-g) and (11a-d) display significant cytotoxic activity against a number of human cancer cell lines. Among these compounds 10e (IC(50) = 10 microM), 10b (IC(50) = 14.6 microM) and 10a (IC(50) = 10.5 microM) showed maximum cytotoxic activity on neuroblastoma. Also, the compound 10c (IC(50) = 10.5 microM) showed maximum cytotoxic activity on ovarian cancer cell line.

Mechanism of unusual formation of 3-(5-phenyl-3H-[1,2,4]dithiazol-3-yl)chromen-4-ones and 4-oxo-4H-chromene-3-carbothioic acid N-phenylamides and their antimicrobial evaluation.

6/6,7-Substituted 3-formylchromones (9a-e) react with 2 equivalents of 2-phenyl-4-dimethylamino-1-thia-3-azabuta-1,3-diene (10) or thiobenzamide (11) in refluxing toluene to furnish novel substituted 3-(5-phenyl-3H-[1,2,4]dithiazol-3-yl)chromen-4-ones (12a-e). However, reactions of substituted 2-anilino-3-formylchromones (15a-d) with thiobenzamide (11, 2 equivalents) in refluxing xylene furnish 4-oxo-4H-chromene-3-carbothioic acid N-phenylamide (17a-d) in high yields. A mechanistic rationalization of the conversion of 2-anilino-3-formylchromones (15a-d) to N-phenylamides (17a-d), and 3-formylchromones (9a-e) to the corresponding thioaldehydes, is proffered. All the compounds (12a-e, 17a-d) display very high antifungal and antibacterial activities against a number of strains. Dithiazole 12d exhibits a very high antifungal activity (MIC 5 microg/ml) against Geotrichum candidum, better than fluconazole (MIC 09 microg/ml) and also possesses good antibacterial activity (MIC 52 microg/ml) against Shigella flexneri.