Microwave mediated synthesis of spiro-(indoline-isoxazolidines): mechanistic study and biological activity evaluation

Regioisomeric spiro-(indoline-isoxazolidines) have been synthesized in moderate yields by the cycloaddition reaction between ethyl (3-indolylidene)acetate and various substituted α,N-diphenylnitrones, using environmentally benign microwave technology. A novel concerted reaction mechanism is described that explains the preferential formation of the regioisomeric spiro-(indoline-isoxazolidine) analogs 6 over 5. These compounds were screened for anti-mycobacterial and anti-invasive activities against tumor cells.     

Synthesis and in vivo biological activity of large-ringed calixarenes against Mycobacterium tuberculosis

A series of large-ringed calix[6,7,8]arene analogues have been synthesised and their affect against Mycobacterium tuberculosis in vivo established. In general, when p-phenylcalixarenes and tert-butylcalixarenes were not functionalised at the lower rim, low biological activities were observed. However on going from partially to fully lower rim pegylated calixarenes the anti-mycobacterial properties improved. The addition of cyanopropoxy groups at the lower rim gave rise to low activities, whereas the addition of acetate moieties interestingly had pro-TB effects. Two upper rim sulfonated calixarenes showed promising properties. In the course of this work, a high yielding procedure to synthesise p-phenylcalix[7]arene was also established.     

Antimycobacterial and anticancer activity of newly designed cinnamic acid hydrazides with favorable toxicity profile

A series of twelve novel hybrids of cinnamic acid and thiocarbohydrazones were designed, synthesized in high yield using a simple coupling strategy via acid chlorides, and evaluated for their impact against Mycobacterium tuberculosis (Mtb) and cancer cells survival. Among them, compound 3 demonstrated strong anti-Mtb activity by reducing bacilli survival for>90 % in all three treated Mtb isolates, whereas isoniazid and rifampicin did not. Moreover, compound 3 didn’t affect vitality of HepG-2 cells, implying on advantageous hepatotoxicity profile compared to current therapeutic options for tuberculosis. Compounds 2a and 3b displayed as strong inducers of apoptosis in A549 cells, both activating intrinsic caspase pathway and cell cycle arrest at the G0/G1 phase. Subsequent analyses disclosed differences in their activities, where 3b has ability to induce production of mitochondrial superoxide anions, while 2a significantly inhibited cellular mobility. More importantly, 3b considerably affected viability of HepG-2 and HaCaT cells, whereas 2a had moderate impact only on the later. Molecular modeling studies indicated high permeability and good absorption through the human intestine, and moderate aqueous solubility with poor blood–brain barrier permeability. In summary, our results reveal that novel compounds 3 and 2a represent promising agents for tuberculosis and cancer treatment, respectively, indicating that further investigation needs to be performed to clarify the mechanisms of their anti-Mtb and anticancer activity.     

Benzofuran-isatin-hydroxylimine/thiosemicarbazide hybrids: Design,synthesis and in vitro anti-mycobacterial activity evaluation

A series of novel benzofuran-isatin-hydroxylimine/-thiosemicarbazide hybrids were designed, synthesized and evaluated for their in vitro anti-TB activities against drug-sensitive MTB H₃₇Rv and MDR-TB isolates as well as cytotoxicity. All benzofuran-isatin-hydroxylimine/-thiosemicarbazide hybrids exhibited considerable in vitro anti-mycobacterial activities against the tested three MTB strains, and all of them also showed acceptable cytotoxicity. The most active hybrid 7f was >4.8 and >51 folds more potent than the first line anti-TB agents RIF and INH against both drug-sensitive MTB H₃₇Rv and MDR-TB isolates, respectively. The results demonstrated the potential utility of benzofuran-isatin-hydroxylimine/-thiosemicarbazide hybrids as anti-TB agents.     

A two step facile synthesis of new steroidal linear and angular pyranones having anti-mycobacterial activity

Title compounds 2′,2′-dimethylcholesta-2,4-dien[3,2-b]-pyran-4′-one(3),2′,2′-dimethyl-3β-substituted cholesta-4,6-dien[7,6- b]-pyran-4′-one(6a,b)and(6c)were prepared by the cyclization of 2-acetylcholesta-2,4-dien-3-ol(2),6-acetyl-3β-substituted- cholesta-4,6-dien-7-ol(5a,b)and(5c)respectively,with pyrrolidine,dry benzene and dry acetone using Dean Stark separator through conventional heating.Furthermore,compounds were also found to be active against Mycobacterium tuberculosis.