Efficient Synthesis and Biological Evaluation of a Novel Series of 1,5‐Benzodiazepine Derivatives as Potential Antimicrobial Agents

A series of novel 1,5‐benzodiazepine derivatives were rationally designed and synthesized following the principle of the superposition of bioactive substructures by the combination of 1,5‐benzodiazepine, pyridine (phenyl), and an ester group. The structures of the target compounds were determined by ¹H NMR, ¹³C NMR, MS, IR, and elemental analysis. All the synthesized compounds were evaluated for their antimicrobial activities in vitro against the fungi C. neoformans, C. neoformans clinical isolates (ATCC 32264), C. albicans (ATCC 10231), Gram‐negative bacterium E. coli (ATCC 44752), and Gram‐positive bacterium S. aureus (ATCC 25923). The results of the bioactive assay demonstrated that most of the tested compounds exhibited variable inhibitory effects on the growth of the tested microorganisms. All the active compounds showed better antifungal activity than antibacterial activity. Notably, compound 2b displayed the highest activity (MIC = 30 μg/mL) against C. neoformans and (MIC = 31 μg/mL) against C. neoformans clinical isolates. In addition, compound 2a also showed excellent activity against C. neoformans and C. neoformans clinical isolates with minimum inhibitory concentration of 35 and 36 μg/mL, respectively. Compounds 2a and 2b were further studied by evaluating their cytotoxicities, and the results showed that they have relatively low level cytotoxicity for BV2 and 293T cell. Preliminary structure‐activity relationship study on three diverse sets (C‐2, C‐3, and C‐8 positions) of 1,5‐benzodiazepines was performed. The results revealed that the presence of a ‐CH₃ group at the C‐8 position had a positive effect on the inhibitory activity of these compounds. Additionally, the 2‐pyridyl group at the C‐2 position may be a pharmacophore and ‐COOC₂H₅ at C‐3 position is the best substituent for the maintenance of antimicrobial activities.     

Platinum and Palladium‐triazole Complexes as Highly Potential Antitumor Agents

The palladium complexes [(dppe)Pd(L)₂PdCl₂], [(dppe)Pd(L)₂PtCl₂], [(dppp)Pd(L)₂PdCl₂], [(dppm) Pd(L)₂NiCl₂], and [(dppm)Pd(L)₂SnCl₄] 15–19 were prepared. The antiproliferative activity of the newly synthesized complexes as well as their previously prepared analogues 3–14 and 20–26 were screened against a large panel of human cancer cell lines derived from haematological CD4⁺ human T‐cells containing an integrated HTLV‐1 genome (MT‐4). The complex 12a , b exhibited remarkable antiproliferative activity against MT‐4, CD4⁺ human acute T‐lymphoblastic leukemia (CCRF‐CEM), human splenic B‐lymphoblastoid cells (WIL‐2NS), human acute B‐lymphoblastic leukemia (CCRF‐SB), skin melanoma (SK‐MEL‐28), and prostate carcinoma (DU145) cell lines (CC₅₀ = 0.5 μM, 0.4 ± 0.05 μM, 0.6 ± 0.05 μM, 0.4 ± 0.1 μM, and 0.8 ± 0.2 μM, respectively), meanwhile, 9a , b , 14a , b , and 23 showed significant activity against the CCRF‐SB cell lines (CC₅₀ = 0.6 ± 0.06 μM, 0.7 ± 0.05 μM, 0.6 ± 0.05 μM, and 0.8 ± 0.15 μM, respectively). Further, 19 exhibited activity against the CCRF‐CEM cell line (CC₅₀ = 0.4 ± 0.05 μM).     

Synthesis and Biological Evaluation of Novel FtsZ‐targeted 3‐arylalkoxy‐2,6‐difluorobenzamides as Potential Antimicrobial Agents

Novel series of 3‐O‐arylalkylbenzamide and 3‐O‐arylalkyl‐2,6‐difluorobenzamide derivatives were synthesized and evaluated for their on‐target activity and antibacterial activity. The results indicated that the 3‐O‐arylalkyl‐2,6‐difluorobenzamide derivatives possessed much better on‐target activity and antibacterial activity than the 3‐O‐arylalkylbenzamide derivatives. Among them, 3‐O‐chlorobenzyl derivative 36 was the most effective in antibacterial activity (0.5, 4, and 8 μg/mL) against Bacillus subtilis ATCC9372, methicillin‐resistant Staphylococcus aureus ATCC29213, and penicillin‐resistant Staphylococcus aureus PR, while 3‐O‐methylbenzyl derivative 41 only exhibited the most potent activity (2 μg/mL) against Staphylococcus aureus ATCC25923.     

Synthesis and Biological Evaluation of Oxygen‐containing Heterocyclic Ring‐fused 23‐Hydroxybetulinic Acid Derivatives as Antitumor Agents

A collection of isoxazole and oxadiazole substituted 23‐hydroxybetulinic acid (HBA) derivatives were designed, synthesized and evaluated for their antitumor activity. Most of the newly synthesized compounds exhibited more potent antiproliferative activity than patent compound 23‐hydroxybetulinic acid, especially 13e and 14a were about four‐ to sevenfold more potent against all tested cancer cell lines than 23‐hydroxybetulinic acid. Furthermore, the in vivo antitumor activity of 13e and 14a was validated in H22 liver cancer and B16 melanoma xenograft mouse models. The structure–activity relationships of these 23‐hydroxybetulinic acid derivatives were also discussed based on the present investigation.     

Synthesis and Biological Evaluation of 7‐Azaisoindigo Derivatives

A series of novel 7‐azaisoindigo derivatives 3–14 were designed, synthesized, and structurally characterized by IR, ¹H‐NMR, ¹³C‐NMR, mass spectra, and elemental analyses. Their antiproliferative activities were evaluated in a hormone‐independent prostate cancer cell line DU145. Among them, compounds 8 , 9 , 14 showed the highest activities. Our study also showed that compounds 7 , 11 , 12 exhibited higher inhibitory activities on CDK2/cyclin A than that of the positive control meisoindigo. Western blot analysis on DU145 cells treated with compounds 7 and 9 demonstrated that 7‐azaisoindigo derivatives could decrease the level of CDK2 activity (phosphorylation) and the expression of cyclin D1, and increase the expression of endogenous cyclin‐dependent inhibitor p27.     

Synthesis and Biological Evaluation of Some 1,2‐Disubstituted Benzimidazole Derivatives as New Potential Anticancer Agents

The synthesis of some new 1‐(2‐aryl‐2‐oxoethyl)‐2‐[(morpholine‐4‐yl)thioxomethyl]benzimidazole derivatives and investigation of their anticancer activities were the aims of this work. 2‐(Chloromethyl)benzimidazole compound was reacted with sulfur and morpholine via Willgerodt–Kindler reaction to give 2‐[(morpholine‐4‐yl)thioxomethyl]benzimidazole. Then, the obtained compound was reacted with appropriate α‐bromoacetophenone derivatives in the presence of potassium carbonate to give the final products. Structure elucidation of the final compounds was achieved by FT‐IR, ¹H NMR spectroscopy and MS spectrometry. The anticancer activities of the final compounds were evaluated by MTT assay, BrdU method, and flow cytometric analysis on C6, MCF‐7, and A549 tumor cells. Most of the synthesized compounds exhibited considerable selectivity against the MCF‐7 and C6 cell lines.     

Discovery and Potency Optimization of 2‐Amino‐5‐arylmethyl‐1,3‐thiazole Derivatives as Potential Therapeutic Agents for Prostate Cancer

A new chemical series was identified via high‐throughput screening as having antiproliferative activity on DU‐145 human prostate carcinoma cell line (hit compound potency – 2.9 μM). Medicinal chemistry optimization of two peripheral diversity vectors of the hit molecule, independently, led to SAR generalizations and identification of the ‘best’ moieties. The latter were merged in a single compound that exhibited an over 100‐fold better potency than the hit compound. For the most potent compounds it was confirmed that the observed antiproliferative potency was not associated with the compounds' non‐specific cytotoxicity.     

Fluorinated 1,2,4‐Triazolo[1,5‐a]pyrimidine‐6‐carboxylic Acid Derivatives as Antimycobacterial Agents

A series of fluorinated 1,2,4‐triazolo[1,5‐a]pyrimidine‐6‐carboxylic acid derivatives was designed and synthesized as fluoroquinolone analogues. The synthesized compounds were screened against Mycobacterium tuberculosis H₃₇R_v strain at 6.25 μg/mL concentration. Compound 4 , the 7‐oxo‐2‐(trifluoromethyl)‐4,7‐dihydro‐1,2,4‐triazolo[5,1‐a]pyrimidine‐6‐carboxylic acid was found to be a very potent inhibitor, being able to inhibit 92% growth of M. tuberculosis H₃₇R_v at 6.25 μg/mL concentration. At the same time, it proofed to be nontoxic to mammalian cells (IC₅₀ > 62.5 μg/mL in VERO cells).     

Synthesis and Biological Activities of 2,4‐Diaminopteridine Derivatives

Substituted 2,4‐diaminopteridine derivatives 10a – 10l were prepared in moderate to good yield. Their structures were confirmed by ¹H‐NMR and MS spectroscopy, as well as by elemental analysis. Their inhibitory properties against inducible nitric oxide synthase (iNOS) were evaluated in vitro. Biological tests indicated that compound 10a , 10d , 10e , 10h , 10i , and 10l showed potent inhibitory activities similar to that of methotrexate (MTX), while the activities of compound 10b , 10c , 10f , 10g , 10j , and 10k are stronger than MTX. Two compounds, i. e., 10b (IC₅₀ = 18.85 μM) and 10i (IC₅₀ = 24.08 μM) were further studied for their effect on septic shock in rats and immunologically liver injured mice (in vivo). The results demonstrated that 10b and 10i had the capacity to increase the blood pressure in septic shock and showed notable protective activities on immunological hepatic injury.