Propylene‐1H‐1,2,3‐triazole‐4‐methylene‐tethered Isatin‐coumarin Hybrids: Design,Synthesis, and In Vitro Anti‐tubercular Evaluation

A series of novel propylene‐1H‐1,2,3‐triazole‐4‐methylene‐tethered isatin‐coumarin hybrids 7a–l that were composed of three anti‐tubercular bioactive substances/pharmacophore coumarin, isatin, and I‐A09 were designed, synthesized, and assessed for their in vitro anti‐tubercular activity against Mycobacterium tuberculosis (MTB) H₃₇Rv. In spite of the hybrids were inactive against the tested MTB H₃₇Rv, the structure–activity relationship was enriched, and these hybrids may act as an ideal starting point for developing new isatin‐coumarin anti‐TB candidates with various linkers.     

1H‐1,2,3‐Triazole‐tethered Isatin–coumarin Hybrids: Design,Synthesis and In Vitro Anti‐mycobacterial Evaluation

A series of novel 1H‐1,2,3‐triazole‐tethered isatin–coumarin hybrids 7a – l integrate three anti‐tuberculosis bioactive substances/pharmacophoric units including coumarin, isatin, and I ‐ A09 were designed, synthesized, and tested for their in vitro anti‐mycobacterial activity against Mycobacterium smegmatis and Mycobacterium tuberculosis H37Rv as well as cytotoxicity in VERO cell line. The results showed that all hybrids exhibited weak to moderate activity against the tested two strains with minimum inhibitory concentration ranging from 50 to 200 μg/mL.     

Design,Synthesis, and in vitro Anti‐mycobacterial Evaluation of Propylene‐1H‐1,2,3‐triazole‐4‐methylene‐tethered (Thio)semicarbazone‐isatin‐moxifloxacin Hybrids

A new class of propylene‐1H‐1,2,3‐triazole‐4‐methylene‐tethered (thio)semicarbazone‐isatin‐moxifloxacin hybrids 6a – h was designed, synthesized, and screened for their in vitro anti‐mycobacterial activities against Mycobacterium tuberculosis (MTB) H₃₇Rv and MDR‐TB as well as cytotoxicity in VERO cell line. All the synthesized hybrids (MIC: 0.05–2.0 μg/mL) exhibited excellent activities against M. tuberculosis H₃₇Rv and MDR‐TB; in particular, conjugate 6c (MIC: 0.05 and 0.12 μg/mL) was no inferior to the three references MXFX (MIC: 0.10 and 0.12 μg/mL), RIF (MIC: 0.39 and 32 μg/mL), and INH (MIC: 0.05 and >128 μg/mL) against the tested two strains. All hybrids (CC₅₀: 2–8 μg/mL) were much more cytotoxic than the parent MXFX (CC₅₀: 128 μg/mL) should be further optimized.     

Design,Synthesis, and In Vitro Anti‐mycobacterial Evaluation 1H‐1,2,3‐triazole‐tethered Ciprofloxacin and Isatin Conjugates

Eight novel 1H‐1,2,3‐triazole‐tethered ciprofloxacin (CPFX) isatin conjugates 5a – h with greater lipophilicity compared with CPFX were designed, synthesized, and evaluated for their in vitro anti‐mycobacterial activity against Mycobacterium smegmatis and Mycobacterium tuberculosis (MTB) H₃₇Rv. The preliminary results showed that all hybrids (MIC: 12.5–100 μg/mL) exhibited considerable activity against M. smegmatis , but less active than the parent CPFX (MIC: 6.25 μg/mL) and the reference INH (MIC: 0.78 μg/mL). Against MTB H₃₇Rv, all hybrids displayed excellent inhibitory activity with MICs ranging from 1.56 to 25 μg/mL, particularly, 5h (MIC: 1.56 μg/mL) was twofold more active CPFX (MIC: 3.12 μg/mL), warrant further investigations.     

Design,Synthesis and in vitro Antimycobacterial Activities of Isatin‐1,2,3‐triazole‐moxifloxacin Hybrids

A new class of isatin‐1,2,3‐triazole‐moxifloxacin ( MXFX ) hybrids 5a–j was designed, synthesized, and screened for their in vitro antimycobacterial activities against Mycobacterium tuberculosis H₃₇Rv and MDR‐TB. All the synthesized hybrids (MIC: 0.10–0.78 μg/mL) exhibited excellent activities against MTB H₃₇Rv and MDR‐TB, in spite of none of them were more potent than the parent MXFX (MIC: 0.10 and 0.12 μg/mL). Against MTB H₃₇Rv, the most active 5f (MIC: 0.10 μg/mL) was comparable with MXFX and 4 times more potent than RIF (MIC: 0.39 μg/mL). Against MDR‐TB, all hybrids were more active than RIF (MIC: 32 μg/mL) and INH (MIC: >128 μg/mL). In particular, hybrid 5e (MIC: 0.10 μg/mL) was comparable with MXFX and 256 and >1,024 times more potent than RIF and INH . Both conjugates 5e and 5f warrant further investigations.     

1H‐1,2,3‐triazole‐tethered 8‐OMe Ciprofloxacin and Isatin Hybrids: Design,Synthesis and in vitro Anti‐mycobacterial Activities

A new class of 1H ‐1,2,3‐triazole‐tethered 8‐OMe ciprofloxacin (8‐OMe CPFX) isatin hybrids 5a–l was designed, synthesized and screened for their in vitro anti‐mycobacterial activities against Mycobacterium tuberculosis H₃₇Rv and multi‐drug‐resistant tuberculosis (MDR‐TB). All targets (minimum inhibitory concentration (MIC): 0.20–8.0 μg/mL) exhibited promising inhibitory activity against MTB H₃₇Rv and MDR‐TB. Among them, conjugate 5h (MIC: 0.20 μg/mL), was 2–16 times more potent in vitro than the references CPFX (MIC: 3.12 μg/mL), 8‐OMe CPFX (MIC: 1.56 μg/mL) and RIF (MIC: 0.39 μg/mL) against MTB H₃₇Rv. The most potent hybrid 5l (MIC: 0.25 μg/mL) was 8–256 times more active than the three references (MIC: 2.0–64 μg/mL) against MDR‐TB. Both of them warrant further investigations.     

Isatin‐(thio)semicarbazide/oxime‐1H‐1,2,3‐triazole‐coumarin Hybrids: Design,Synthesis, and in vitro Anti‐mycobacterial Evaluation

Isatin and coumarin derivatives with potential anti‐tubercular activity, while (thio)semicarbazide/oxime and 1H‐1,2,3‐triazole moieties exhibited favorable properties such as hydrogen bonding and/or metal chelation capability, so integration of the four pharmacophores into one molecule may provide more effective anti‐tubercular candidates. Based on the consideration earlier, 12 isatin‐(thio)semicarbazide/oxime‐1H‐1,2,3‐triazole‐coumarin hybrids 8a–l were designed, synthesized, and evaluated for their in vitro anti‐mycobacterial activities against M. tuberculosis (MTB) H₃₇Rv and MDR‐TB. The results showed that all the hybrids (MIC: 50–>200 μg/mL) exhibited weak to moderate inhibitory activity against MTB H₃₇Rv and MDR‐TB, which were far less potent than the references isoniazid (MIC: 0.05 μg/mL) and rifampicin (MIC: 0.39 μg/mL) against MTB H₃₇Rv. The most active hybrid 8h (MIC: 50 μg/mL) was comparable with rifampicin (MIC: 32 μg/mL) and more active than isoniazid (MIC: >128 μg/mL) against MDR‐TB, could be act as a lead for further optimization. Moreover, the enriched structure–activity relationship paved the way to the further rational development of this kind of hybrids.     

Design,Synthesis, and In Vitro Anticancer Activities of Diethylene Glycol Tethered Isatin‐1,2,3‐triazole‐coumarin Hybrids

A series of novel diethylene glycol tethered isatin‐1,2,3‐triazole‐coumarin hybrids 9a – l were designed, synthesized, and evaluated for their in vitro anticancer activities against HepG2 (liver carcinoma), Hela (cervical cancer), A549 (lung adenocarcinoma), DU145 (prostatic cancer), SKOV3 (ovarian carcinoma), MCF‐7 (breast cancer), and drug‐resistant MCF‐7/DOX (doxorubicin‐resistant MCF‐7) human cancer cell lines. The results showed that most of the synthesized hybrids exhibited considerable in vitro activities against the tested seven cancer cell lines, and these hybrids can be acted as starting points for further investigation.     

Design,Synthesis, and In Vitro Anti‐mycobacterial Activities of Propylene‐Tethered Gatifloxacin‐Isatin Hybrids

A series of propylene‐tethered mono‐/bis‐isatin‐gatifloxacin hybrids 3a–f and 4a–f were designed, synthesized, and evaluated for their in vitro anti‐mycobacterial activities against Mycobacterium tuberculosis (MTB) H37Rv and multidrug‐resistant tuberculosis (MDR‐TB) as well as cytotoxicity against VERO cell line. The results indicated that all hybrids exhibited promising anti‐mycobacterial activities against MTB H37Rv and MDR‐TB with MIC ranging from 0.25 to 16 μg/mL. In particular, the mono‐isatin‐gatifloxacin hybrid 3e (MIC: 0.25 and 0.25 μg/mL) was found to be most active against MTB H₃₇Rv and MDR‐TB strains, which was twofold more active than the parent gatifloxacin (MIC: 0.5 μg/mL) and comparable with rifampicin ( RIF ) (MIC: 0.25 μg/mL) against MTB H₃₇Rv, and 4‐ > 512 times more potent than the three references gatifloxacin (MIC: 1.0 μg/mL), RIF (MIC: 64 μg/mL), and isoniazid (>128 μg/mL) against MDR‐TB, could act as a starting point for further optimization.     

Design,Synthesis and In Vitro Anti‐mycobacterial Activities of 8‐OMe Ciprofloxacin‐1H‐1,2,3‐triazole‐isatin‐(thio) Semicarbazide/Oxime Hybrids

A series of novel 8‐OMe ciprofloxacin (8‐OMe CPFX)‐1H‐1,2,3‐triazole‐isatin‐(thio) semicarbazide/oxime hybrids 6a – l with the capacity to form hydrogen bond were designed, synthesized, and evaluated for their in vitro anti‐mycobacterial activities against Mycobacterium tuberculosis (MTB) H₃₇Rv and MDR‐TB as well as cytotoxicity. All the synthesized hybrids (MIC: 0.39–16 μg/mL) exhibited excellent activities against MTB H₃₇Rv and MDR‐TB, and the majority of them were more potent than the parent 8‐OMe CPFX (MIC: 1.56 and 2.0 μg/mL, respectively). In particular, the most active conjugate 6h (MIC: 0.39 and 1.0 μg/mL, respectively) was two to eight times more potent in vitro than the references CPFX (MIC: 3.12 and 4.0 μg/mL, respectively) and 8‐OMe CPFX against the tested strains and was comparable with or 64‐folds more potent than RIF (MIC: 0.39 and 64 μg/mL, respectively) against MTB H₃₇Rv and MDR‐TB, respectively. In addition, all conjugates (CC₅₀: 16–64 μg/mL) showed acceptable cytotoxicity, although most of them were more toxic than the parent (CC₅₀: 64 μg/mL) in VERO cell line.     

Design,Synthesis, and In Vitro Antibacterial Activities of Propylene‐tethered Gatifloxacin‐isatin Hybrids

A series of novel mono‐/bis‐isatin‐gatifloxacin hybrids 3a–f and 4a–f tethered through propylene were designed, synthesized, and evaluated for their in vitro antibacterial activities against representative Gram‐positive and Gram‐negative pathogens. The results indicated that all mono‐isatin‐gatifloxacin hybrids exhibited considerable antibacterial activities with minimum inhibitory concentration ranging from 0.06 to 4 μg/mL against the majority of the tested strains. In particular, the mono‐isatin‐gatifloxacin hybrid 3b was found as potent as the parent gatifloxacin against Gram‐positive organisms and could act as a starting point for further optimization.     

Ciprofloxacin/Gatifloxacin‐1,2,3‐triazole‐isatin Hybrids and Their In Vitro Anticancer Activity

Eleven novel ciprofloxacin/gatifloxacin‐1,2,3‐triazole‐isatin hybrids ( 8a – k ) were designed, synthesized, and screened for their in vitro anticancer activity in this paper. A significant part of the synthesized hybrids was active against A549, HepG2, and SF‐268 cancer cell lines, whereas the parent drugs ciprofloxacin and gatifloxacin were devoid of activity. Among them, hybrid 8i (IC₅₀: 78.1–90.7 μM) was found to be the most active against A549, HepG2, and SF‐268 cancer cell lines, and it was comparable with or better than Vorinostat (IC₅₀: 71.1 to >100 μM). Thus, these kind hybrids have potentiality for discovery of new anticancer candidates for clinical deployment in the control and eradication of cancers.     

Isatin‐1,2,3‐triazole‐isatin Scaffolds and Their Antibacterial Activity

Twelve novel isatin‐1,2,3‐triazole‐isatin scaffolds 5a – l were designed, synthesized, and assessed for their in vitro antibacterial activity in this paper. The preliminary results showed that all dimers only endowed with weak antibacterial activity, which was less active than the reference ciprofloxacin. However, the structure–activity relationship was enriched, which may be useful for the further development of more efficient candidates.     

Design,Synthesis, and in vitro Anti‐mycobacterial Activities of Propylene‐tethered Heteronuclear Bis‐isatin Derivatives

A series of novel propylene‐tethered heteronuclear bis‐isatin derivatives were designed, synthesized, and assessed for their in vitro and anti‐mycobacterial activities. All hybrids exhibited considerable antibacterial and anti‐mycobacterial activities against Mycobacterium tuberculosis H37Rv and multi‐drug‐resistant tuberculosis (MDR‐TB) with minimum inhibitory concentration (MIC) ranging from 16 to 256 μg/mL. In particular, the heteronuclear bis‐isatin 4i (MIC: 25 and 16 μg/mL) was most active against M. tuberculosis H₃₇Rv and MDR‐TB strains, which was fourfold and greater than eightfold more potent than the first‐line anti‐tubercular agents rifampicin (MIC: 64 μg/mL) and isoniazid (MIC: >128 μg/mL) against MDR‐TB, could act as a lead for further optimization.     

Design,Synthesis, and In Vitro Anti‐mycobacterial Activities of Propylene Tethered Benzofuran–Isatin Hybrids

A series of novel propylene tethered benzofuran–isatin hybrids 5a–j were designed, synthesized, and assessed for their in vitro anti‐mycobacterial activity against Mycobacterium tuberculosis (MTB) H₃₇Rv and multidrug‐resistant (MDR)‐MTB strains. All hybrids exhibited promising anti‐mycobacterial activities against the tested two pathogens with minimum inhibitory concentration (MIC) ranging from 2 to 32 μg/mL, and the resistance index for a significant part of the hybrids was ≤1, indicating their potential for the treatment of drug‐resistant tuberculosis. Hybrid 5g (MIC: 2 and 4 μg/mL) was found to be the most active against MTB H₃₇Rv and MDR‐MTB, which was eightfold and >32‐fold more active than the first‐line anti‐tuberculosis drugs rifampicin (MIC: 32 μg/mL) and isoniazid (MIC: >128 μg/mL) against MDR‐MTB, and it could act as a starting point for further optimization.     

Moxifloxacin/Gatifloxacin‐1,2,3‐triazole‐isatin Hybrids with Hydrogen‐Bond Donor and Their In Vitro Anticancer Activity

A series of novel moxifloxacin/gatifloxacin‐1,2,3‐triazole‐isatin hybrids ( 8a – i ) were designed, synthesized, and screened for their in vitro anticancer activity in this paper. All of the synthesized hybrids were active against A549 and HepG2 cancer cell lines, whereas the parent drugs moxifloxacin and gatifloxacin were devoid of activity. Among them, hybrid 8i (IC₅₀: 41.1–98.3 μM) showed considerable activity against A549, HepG2, and MCF‐7 cancer cell lines, and it was no inferior to Vorinostat (IC₅₀: 64.32 to >100 μM) against the three cancer cell lines. Thus, this kind of hybrids has potentiality for discovery of new anticancer candidates for clinical deployment in the control and eradication of cancers.     

Synthesis and antimycobacterial activity of alkyl 1‐heteroaryl‐1H‐1,2,3‐triazole‐4‐carboxylates

A series of alkyl l‐heteroaryl‐1H‐1,2,3‐triazole‐4‐carboxylates 6a‐u were synthesised in four steps from methyl (Z)‐2‐benzyloxycarbonylarmino‐3‐(dimethylamino)prop‐2‐enoate ( 1 ) and heterocyclic amines 2a‐s. Triazoles 6a‐o were tested against antimycobacterial activity. For the most active compound, n‐pentyl 1‐(6‐phenylpyridazin‐3‐yl)‐1H‐1,2,3‐triazole‐4‐carboxylate ( 6n ), minimum inhibitory concentration 3.13 μg/ml was determined.     

Ciprofloxacin‐isatin‐1H‐1,2,3‐triazole Hybrids: Design,Synthesis, and in vitro Anti‐tubercular Activity against M. tuberculosis

A new set of ciprofloxacin (CPFX)‐isatin‐1H‐1,2,3‐triazole hybrids 6a – l with greater lipophilicity compared with the parent CPFX was designed, synthesized, and assessed for their in vitro anti‐mycobacterial activity against Mycobacterium tuberculosis (MTB) H₃₇Rv as well as cytotoxicity in VERO cell line. The preliminary results showed that all hybrids (MIC: 0.39–50 μg/mL) exhibited promising activities against MTB H₃₇Rv, and six of them (MIC: 0.39–1.56 μg/mL) were more active than the parent CPFX (MIC: 3.12 μg/mL). In particular, the most active conjugate 6h (MIC: 0.39 μg/mL) was comparable with RIF (MIC: 0.39 μg/mL), and eight times more potent than CPFX. All conjugates (CC₅₀: 4–64 μg/mL) were more toxic than the parent (CC₅₀: 128 μg/mL) in VERO cell lines, and the most active hybrids, which also displayed the highest cytotoxicity, should be further optimized.     

Design,Synthesis and In Vitro Antitubercular Evaluation of Isatin‐ciprofloxacin Hybrids with Hydrogen Bonding Capacity

A series of novel isatin‐ciprofloxacin hybrids inhaling oxime, semicarbazone, and thiosemicarbazone groups with hydrogen bonding capacity were designed, synthesized, and evaluated for their in vitro antitubercular activities against Mycobacterium tuberculosis (MTB) H37Rv and multidrug‐resistant‐TB (MDR‐TB). All hybrids endowed with potential activities against the tested MTB H37Rv and MDR‐TB strains with minimum inhibitory concentration (MIC) in a range of 0.20 to 128 μg/mL. In particular, the most active hybrid 5e (MIC: 0.20 and 0.5 μg/mL) was four and two times more active than the parent ciprofloxacin (MIC: 0.78 μg/mL) and rifampicin (MIC: 0.39 μg/mL) against MTB H37Rv, and 4–>256 times more potent than the three references ciprofloxacin (MIC: 2.0 μg/mL), rifampicin (MIC: 32 μg/mL), and isoniazid (>128 μg/mL) against MDR‐TB. Thus, this kind of hybrids holds great promise as future anti‐TB agents against both drug‐sensitive and drug‐resistant MTB strains infection.     

Synthesis and In Vitro Anticancer Activity of Novel 1,3,4‐Oxadiazole‐Linked 1,2,3‐Triazole/Isoxazole Hybrids

A series of new 1,3,4‐oxadiazole‐linked 1,2,3‐triazole/isoxazole derivatives were designed and synthesized. All the synthesized compounds were screened for in vitro anticancer activity against four human cancer cells: HeLa (cervical), MDA‐MB‐231 (breast), DU‐145 (prostate), and HEPG2 (liver). Among 17 compounds tested, 7a , 7c , and 7d showed potent activity toward four cell lines.