Amino Acid Derivatives,Part 4: Synthesis and Anti‐HIV Activity of New Naphthalene Derivatives

A new series of 2‐(naphthalen‐2‐yloxy)‐N‐[(aryl‐5‐thioxo‐4,5‐dihydro‐1H‐1,2,4‐triazol‐3‐yl)methyl] acetamides 5a–f was synthesized from naphthalene‐derived glycine derivative 2 via the hydrazinoacetamide analogs 4a–f . Alternatively, treatment of 4a with H₂SO₄ afforded 2‐(naphthalen‐2‐yloxy)‐N‐((5‐(phenylamino)‐1,3,4‐thiadiazol‐2‐yl)methyl) acetamide 6a . Alkylation or sulphonylation of 5a afforded the S‐alkylated derivatives 7 and 8 , respectively. Interestingly, treatment of 3 with methoxide ion gave the triazine derivative 9 . The synthesized compounds have been screened for their inhibitory activity against HIV‐1 and HIV‐2 in MT‐4 cells. However, 7 was found to be the potent inhibitor in vitro for the replication of HIV‐1 (EC₅₀ = 0.20 μg/mL), suggesting a new lead in the development of an antiviral agent.     

Discovery of Novel 2‐(piperidin‐4‐yl)‐1H‐benzo[d]imidazole Derivatives as Potential Anti‐Inflammatory Agents

A novel 2‐(piperidin‐4‐yl)‐1H‐benzo[d]imidazole derivative 5 with good anti‐inflammatory activity was identified from our in‐house library. Based on hit compound 5 , two series of 2‐(piperidin‐4‐yl)‐1H‐benzo[d]imidazole derivative 6a – g and 7a – h were designed and synthesized as novel anti‐inflammatory agents. Most of synthesized compounds exhibited good inhibitory activity on NO and TNF‐α production in LPS‐stimulated RAW 264.7 macrophages, in which the compound 6e showed most potent inhibitory activity on NO (IC₅₀ = 0.86 μm ) and TNF‐α (IC₅₀ = 1.87 μm ) production. Further evaluation revealed that compound 6e displayed more potent in vivo anti‐inflammatory activity than ibuprofen did on xylene‐induced ear oedema in mice. Additionally, Western blot analysis revealed that compound 6e could restore phosphorylation level of IκBα and protein expression of p65 NF‐κB in LPS‐stimulated RAW 264.7 macrophages.     

Design and Synthesis of 2‐Phenoxynicotinic Acid Hydrazides as Anti‐inflammatory and Analgesic Agents

A series of 2‐phenoxynicotinic acid hydrazides were synthesized and evaluated for their analgesic and anti‐inflammatory activities. Several compounds having an unsubstituted phenyl/4‐pyridyl or C‐4 methoxy substituent on the terminal phenyl ring showed moderate to high analgesic or anti‐inflammatory activity in comparison to mefenamic acid as the reference drug. The compounds with highest anti‐inflammatory activity were subjected to in vitro COX‐1/COX‐2 inhibition assays and showed moderate to good COX‐1 and weak COX‐2 inhibition activities.     

Synthesis and Biological Evaluation of 4‐Arylphthalazones Bearing Benzenesulfonamide as Anti‐Inflammatory and Anti‐Cancer Agents

Nine 4‐arylphthalazones bearing benzenesulfonamide (2a – i ) were synthesized by the condensation of the appropriate 2‐aroylbenzoic acid ( 1a – i ) and 4‐hydrazinobenzenesulfonamide in ethanol. The structures of these compounds were elucidated by elemental analysis, IR, ¹H NMR, ¹³C NMR, and MS spectroscopy. Two compounds, 2b and 2i , showed significant anti‐inflammatory activity comparable to that of the standard drug celecoxib in the carrageenan‐induced rat paw edema model. These compounds ( 2b and 2i ) had selective inhibitory activity towards the COX‐2 enzyme. Compound 2b had a better selectivity ratio (COX‐1/COX‐2) compared to that of celecoxib and can be used as a novel template for the design of selective COX‐2 inhibitors. Compounds 2d and 2i were screened for their antiproliferative activity toward 60 human cancer cell lines by the National Cancer Institute (USA). The compounds 2d and 2i displayed mild activity toward the renal cancer cell line UO‐31.     

Synthesis and Evaluation of Novel 2‐Substituted‐quinazolin‐4(3H)‐ones as Potent Analgesic and Anti‐inflammatory Agents

A novel series of 2‐substituted‐quinazolin‐4(3H)‐ones were synthesized by reacting 3,5‐disubstituted‐anthranilic acid with acetic anhydride/benzoyl chloride, which were further reacted with different primary amines to obtain 2,6,8‐substituted‐quinazolin‐4(3H)‐ones 6a–f , 7 , 8 . All the synthesized compounds were characterized and screened for analgesic and anti‐inflammatory activities. Compounds 6,8‐dibromo‐2‐phenyl‐3‐(4′‐carboxyl phenyl)quinazolin‐4(3H)‐one 7 and 6,8‐dibromo‐2‐phenyl‐3‐(2′‐phenylethanoic acid)quinazolin‐4(3H)‐one 8 displayed good analgesic and anti‐inflammatory activity in comparison to the reference standards acetyl salicylic acid and indomethacin, respectively.     

Synthesis and Evaluation of 2‐Alkylthio‐4‐(N‐substituted sulfonamide)pyrimidine Hydroxamic Acids as Anti‐myeloma Agents

A series of pyrimidine hydroxamic acids with a sulfide substituent at the second position and a sulfonamide substituent at the fourth position have been synthesized and evaluated for their activity against human myeloma cell line RPMI 8226. Several compounds exhibited significant anti‐cancer potency. It was found that representative compound 6a selectively killed cancerous but not normal cells. Moreover, compound 6a was effective in causing apoptosis in RPMI 8226 cells and exhibited promising HDAC‐inhibitory activities.     

Synthesis of New N‐Substituted 5‐Arylidene‐2,4‐thiazolidinediones as Anti‐Inflammatory and Antimicrobial Agents

A novel series of 5‐arylidene ‐ 2,4‐thiazolidinediones (TZDs) 2a – p was synthesized from the condensation of 3‐((2‐phenylthiazol‐4‐yl)methyl)thiazolidine‐2,4‐dione with different benzaldehyde derivatives. All the structures were confirmed by their spectral (IR, ¹H NMR, ¹³C NMR and mass) and elemental analytical data. The new molecules were evaluated in vivo as anti‐inflammatory agents in an acute experimental inflammation, evaluating the acute phase bone marrow response and phagocyte activity. All compounds, excepting one, reduced the absolute leukocytes count due to the lower neutrophil percentage. Phagocytary index was decreased by the same molecules, while only half of them reduced the phagocytary activity. The effect was superior to meloxicam, the reference anti‐inflammatory drug, for the majority of the TZD derivatives. The new molecules were also investigated for their antimicrobial properties on Gram‐positive and Gram‐negative bacteria and one fungal strain. Two compounds ( 2e and 2n ) manifested growth inhibition capacity on all the tested strains.     

3‐(3‐Ethylphenyl)‐2‐substituted hydrazino‐3H‐quinazolin‐4‐one Derivatives: New Class of Analgesic and Anti‐Inflammatory Agents

A new series of 3‐(3‐ethylphenyl)‐2‐substituted hydrazino‐3H‐quinazolin‐4‐ones were synthesized by reacting the amino group of 2‐hydrazino‐3‐(3‐ethylphenyl)‐3H‐quinazolin‐4‐one with a variety of aldehydes and ketones. The title compounds were investigated for analgesic, anti‐inflammatory and ulcerogenic index behavior. The compound 2‐(N′‐3‐pentylidene‐hydrazino)‐3‐(3‐ethylphenyl)‐3H‐quinazolin‐4‐one ( AS2 ) emerged as the most active compound in exhibiting analgesic activity and the compound 2‐(N′‐2‐pentylidene‐hydrazino)‐3‐(3‐ethylphenyl)‐3H‐quinazolin‐4‐one ( AS3 ) emerged as the most active compound in exhibiting anti‐inflammatory activity; and these compounds are moderately potent when compared with the reference standard diclofenac sodium. Interestingly, the test compounds showed only mild ulcerogenic potential when compared with aspirin.     

Synthesis and Evaluation of Novel 4‐Substituted Styryl Quinazolines as Potential Antimicrobial Agents

In an attempt to afford possible antibacterial and anti‐human immunodeficiency virus (HIV) agents, a series of 22 novel styryl quinazoline‐based heterocyclic entities were designed and synthesized. Various substituted aryl urea and thiourea cores were incorporated at position 4 of quinazoline, followed by styrylation of position 2, aiming at an augmented biological potential. The synthesized compounds were well characterized through IR, ¹H NMR, ¹³C NMR and elemental analyses. All compounds were screened for their in vitro anti‐HIV activity against the HIV‐1 (IIIB) and HIV‐2 (ROD) strains. The antibacterial activity was also evaluated against various pathogenic Gram‐positive and Gram‐negative bacterial strains.