Investigation of piperidine derivatives in ex vivo models of pain and platelet aggregation

Piperidine derivatives are known to exhibit analgesic activities and are likely to possess the ability to block the effects of prostaglandins through inhibition of downstream signaling pathways. The present study investigated the activity of five derivatives (PD2-6) of 4-(4??-bromophenyl)-4-piperidinol (PD1), against pain and platelet aggregation mediated by the release of prostaglandins and thromboxane A2, respectively. The results showed that compound PD1 and its two phenacyl derivatives PD3 and PD5 exhibited a highly significant analgesic effect (p < 0.01), whereas PD4 and PD6 also showed significant activity. PD3, the most active analgesic compound when docked to the opioid receptor, had interactions between the oxygen of its nitro group and the amino group of ARG 573, indicating a distance of 1.2563 ?. The antiplatelet data showed that compound PD5 (4-(4??-bromo-phenyl)-4-hydroxy-1-[2-(2??,4??-dimethoxyphenyl)-2-oxo-ethyl]-piperidinium bromide) had an IC₅₀ = 0.06 mM, which was the most active compound, whereas PD3 was the second most active compound against platelet aggregating factor-induced aggregation with an IC₅₀ = 80 mM. Acetyl salicylic acid (IC₅₀ = 150 ??M) was used as a positive control.     

Novel 1,3-diarylpyrazole acrylamides: synthesis, antiplatelet activity screening, and in silico evaluation studies

(E)-3-[3-(pyridin-4-yl)-1-phenyl-1H-pyrazole-4-yl]acryl amides were evaluated for their antiplatelet activities. Compounds 4o and 4r were found as active derivatives showing a potent inhibitory activity on the arachidonic acid-induced aggregation, with IC₅₀ of 20.2 and 30.3 μM, respectively. Compounds 4j, 4k, and 4u presented significant inhibitor effect on collagen-induced platelet aggregation (73.1, 82.5, and 86.7 %, respectively). All synthesized compounds demonstrated good drug-likeness and drug-score values in silico evaluations.     

Antimicrobial and antiurease activities of newly synthesized morpholine derivatives containing an azole nucleus

2-[6-(Morpholin-4-yl)pyridin-3-ylamino]acetohydrazide (4) was obtained starting from 6-morpholin-4-ylpyridin-3-amine (2) via the formation of ester (3) and then converted to the corresponding Schiff bases (5, 6) with the reaction with aromatic aldehydes. The carbothioamide (9), obtained from the reaction of hydrazide with phenylisothiocyanate, was converted to the corresponding 1,2,4-triazole (11) and 1,3,4-thiadiazole (12) derivatives by the treatment with NaOH or H₂SO₄, respectively. The cyclocondenzation of 9 with 4-chlorophenacyl bromide or ethyl bromoacetate produced the corresponding 1,3-thiazole (10) or 1,3-thiazolidine derivatives (13), respectively. Antimicrobial and antiurease activities of newly synthesized compounds were investigated. Some of them were found to be active on M. smegmatis, and they displayed activity toward C. albicans and S. cerevisiae in high concentration. Compound 10 proved to be the most potent showing an enzyme inhibition activity with an IC₅₀ = 2.37 ± 0.19 μM.     

Synthesis and pharmacological activities of some novel 5-chloro-N-(4-(1,5-(disubstituted)-4,5-dihydro-1H-pyrazol-3-yl)phenyl)-2-methoxybenzamide derivatives

A series of substituted pyrazole derivatives were prepared from N1-[4-(cinnamoyl) phenyl]-5-chloro-2-methoxybenzamides 2a–c, which were prepared from N-(4-acetylphenyl)-5-chloro-2-methoxybenzamide as starting material. Treating of compound 2a–c with methylhydrazine or phenylhydrazine afforded the corresponding N-substituted pyrazoline derivatives 3a–c and 4a–c, respectively. The acryloyl derivatives 2a–c were reacted with hydrazine hydrate in dioxane afforded a pyrazoline 5a–c, which was acetylated with acetyl chloride in dioxane to yield the N-acetyl analogue 6a–c. In addition, pyrazoline 5c was reacted with morpholine in the presence of paraformaldehyde to give the corresponding N-substituted pyrazoline derivative 7. The structure assignments of the new compounds are based on chemical and spectroscopic evidence. The pharmacological screening showed that many of these compounds have less toxicity and good anti-inflammatory activities.     

Design, synthesis, and anticonvulsant screening of some substituted piperazine and aniline derivatives of 5-phenyl-oxazolidin-2,4-diones and 5,5-diphenylimidazolidin-2,4 diones

Substituted piperazine and aniline derivatives of oxazolidin-2,4-diones and imidazolidin-2,4-diones were synthesized by N3 alkylation and screened for their anticonvulsant activity by the maximal electroshock (MES) test, and their neurotoxicity was evaluated by the rotarod test. Among all the synthesized derivatives, compounds 4b, 6c, 6d, 10b, 11a, 11b, and 11d were found to exhibit maximum seizure protection in MES test and were devoid of any neurotoxic effects. Furthermore, the functional activity of these compounds were evaluated in vivo for 5-HT_1A receptor affinity by using rectal body temperature and lower lip retraction in rats, while head twitch response in mice was performed for the determination of probable affinity toward 5-HT_2A receptor. The results of these tests demonstrated that compounds 4b, 6c, 6d, 10b, 11a, 11b, and 11d exhibited 5-HT_1A (pre- and postsynaptic) agonist/antagonist features whereas compounds 11a and 11b exhibited antagonist action for 5-HT_2A receptor. From the in vivo studies it was observed that a majority of aniline derivatives (6c, 6d, 11a, 11b, 11d) were found to be more active as compared to their bulky piperazine congeners (4b, 10b). Thus, the overall reduction in the bulkiness of the derivatives without compromising the lipophilicity is well appreciated for providing insights into the structural requirements necessary for development of new effective molecules having anticonvulsant effect.     

Synthesis of new pyridazinone derivatives as platelet aggregation inhibitors

This paper describes the synthesis and the antiplatelet activity of a series of 6-(4-(substituted-amino)phenyl)-4,5-dihydro-3(2H)-pyridazinones. Antiplatelet activity was determined by using the tail transaction bleeding test. All of the newly synthesized pyridazinone derivatives exhibited significant platelet aggregation inhibitory activity. The compounds IIIc and IIIh displayed two times more platelet aggregation inhibitory effect compared with standard drug aspirin.     

Synthesis, pharmacological evaluation and molecular docking studies of indanone derivatives

A new series of isoxazole fused indanones were synthesized form indane-1,3-dione. The newly synthesized derivatives were confirmed by IR, ¹H NMR, and mass spectral data. The synthesized title compounds were evaluated for analgesic, anti-inflammatory, and antimicrobial activities. The modifications carried out in indanone had a positive effect in anti-inflammatory activity when compared to that of other pharmacological activities. The compounds BD ₆ , BD ₇ , BD ₉ , BD ₁₀ , and BD ₁₁ showed good anti-inflammatory activity when compared to that of standard indomethacin. BD ₃ , BD ₄ , and BD ₅ compounds possess moderate anti-inflammatory activity. Some compounds possess moderate analgesic and antimicrobial activity. Docking study reveals that isoxazole nucleus is essential for biological activity. It was concluded that the fusion of isoxazole with indanone nucleus will increase anti-inflammatory activity than analgesic and antimicrobial activity.     

Synthesis and evaluation of antioxidant and antimicrobial properties of thymol containing pyridone moieties

Various derivatives of 1,2-dihydro-6-(4-hydroxy-5-isopropyl-2-methylphenyl)-2-oxo-4-arylpyridine-3-carbonitrile (IVa–m) were synthesized and characterized. Their antioxidant and antimicrobial properties were evaluated by measuring their activity in vitro. Among the newly synthesized derivatives IVg, IVh, IVi, IVj, IVk, IVl, and IVm showed good antioxidant activity. However, all derivatives show better antibacterial and antifungal properties than that of parent thymol. The probable mechanism, particularly for antioxidant properties of these compounds is proposed.     

Design, synthesis, anti-inflammatory, analgesic screening, and molecular docking of some novel 2-pyridyl (3H)-quinazolin-4-one derivatives

A novel series of 6-bromo-2-(4-pyridyl)-quinazolin-4(3H)-ones were synthesized by reacting 5-bromo anthranilic acid with isonictinoly chloride in the presence of acetic anhydride, which were further reacted with p-amino acetophenone to obtain 3-(4-acetylphenyl)-6-bromo-2-(pyridin-4-yl)quinazolin-4(3H)-one (3). Compound 3 underwent further reactions with different aldehydes to afford chalcone derivatives 4–10, which in turn underwent various cyclization reactions to afford cyclized products 15–18. 2-aminothiazole derivatives 12 obtained by reaction of 3 with bromine then with thiourea. Compound 14 obtained by treatment of 11 with KSCN followed by cyclization. Some of the synthesized compounds 4, 5, 12, 14, 15 and 18 were screened for both analgesic and anti-inflammatory activities. All tested compounds showed good analgesic and anti-inflammatory activity in comparison to the reference standard indomethacin. Compounds 4 and 5 showed the highest anti-inflammatory activity, while compounds 14 and 15 showed the highest analgesic activity among all the tested compounds.     

The cytotoxic effects of diketopiperaizes against Leishmania donovani promastigotes and amastigotes

A series of diketopiperazine derivatives (1–12) were evaluated for their in vitro cytotoxic activity against Leishmania donovani promastigotes and amastigotes. Cytotoxicity study revealed that the number and types of the substituents in the phenyl rings have valuable influence on cytotoxic activity. Compounds 1, 3, 4, 11, and 12 demonstrated appreciable cytotoxic activities with the mean IC₅₀ values 1.4, 1.1, 1.02, 1, 0.7 μg/ml on extra cellular promastigotes and 1.6, 1.8, 0.61, 0.53, 1.1 μg/ml on intracellular amastigotes, respectively. The results suggested that diketopiperazine derivatives 4, 11, and 12 could be envisaged as new entrants in the domain of antileishmanial agents.     

Synthesis of 1-amidoalkyl-2-naphthols and oxazine derivatives with study of their antibacterial and antiviral activities

An efficient and direct protocol for the preparation of 1-amidoalkyl-2-naphthols 1a–f employing a multi-component, one-pot condensation reaction of 2-naphthol, heterocyclic aldehydes, and amides in the presence of anhydrous zinc chloride under solvent-free conditions is described. The thermal solvent-free offer advantages such as shorter reaction times, simple work-up and excellent yield. Ring closure of 1a–f gave the pyrazolyl- and indolyl oxazine derivatives 2a–f. On the other hand, the reaction of 2-naphthol, aldehydes, and ammonia solution gave the dipyrazolyl- and di-indolyl oxazine derivatives 3a,b. Some of the newly synthesized compounds showed promising antibacterial and anti-H₅N₁ activities.     

A facile and single pot strategy for the synthesis of novel naphthyridine derivatives under microwave irradiation conditions using ZnCl2 as catalyst, evaluation of AChE inhibitory activity, and molecular modeling studies

A series of novel naphthyridine derivatives 3 and 4 was prepared from substituted pyridine 2 and ketones using ZnCl₂ as catalyst under microwave irradiation conditions. All the compounds were evaluated for AChE inhibitory activity and promising compounds 3d, 3e, 4b, and 4g was identified. Representative compounds 3d and 3e were found to show insignificant THLE-2 liver cell viability/toxicity. The binding mode between X-ray crystal structure of human AChE and compounds was studied using molecular docking method and fitness scores were found to be in good correlation with the activity data.     

Docking, synthesis, and pharmacological investigation of novel substituted thiazole derivatives as non-carboxylic, anti-inflammatory, and analgesic agents

A series of substituted thiazole derivatives (6–16) were synthesized to obtain new compounds with potential anti-inflammatory and analgesic activities. At equimolar oral doses, compounds 3-(piperidin-1-yl-methyl)-1, 3, 4-oxadiazol-2-thione (14), 5-amino-4-ethyl ester pyrazole (15), and 5-amino-3-phenylpyrazole derivatives (16) displayed anti-inflammatory and analgesic activities significant to those of diclofenac sodium in the carrageenan-induced paw edema test in rat and acetic acid-induced writhing test in mice,-respectively. The most active members of the series (9, 11, 14, 15, and 16) were selected for ulcerogenic potential study. These compounds exhibited quite less ulcerogenic index in the range of 0.44 to 0.62 whereas diclofenac sodium showed 4.67. The docking study results also indicated that the compound 6, 7, 8, 11, and 14 exhibited the docking score ranging from ?3.951 to ?4.691.     

Anti-HIV-1 and cytotoxicity studies of piperidyl-thienyl chalcones and their 2-pyrazoline derivatives

A series of 12 new pyrazoline derivatives was prepared from piperidyl chalcones, which in turn were synthesized by condensing 4-piperidin-1-ylbenzaldehyde with diverse acetylthiophenes. The target compounds were characterized by spectroscopic techniques (NMR, IR, MS) and elemental analysis. All the compounds were screened for cytotoxic and anti-HIV-1 activities. Compounds 1c, 1g, 1j, 2a, 2c, 2e, 2g, and 2k demonstrated potential anti-HIV activity but were cytotoxic except for 2e and 2k, which displayed no cytotoxicity in primary human cells. Bioassay results show that the type and positions of the substituents seem to be critical for their cytotoxic and anti-HIV-1 activities.     

5-phenyl-1-benzofuran-2-yl derivatives: synthesis, antimicrobial, and antioxidant activity

Previously unknown biphenyl containing 5-phenyl-1-benzofuran-2-yl derivatives; methanones (2a–i), tertiary alcohols (3a–l), and carbinols (4a–f) were synthesized and evaluated for their antimicrobial and antioxidant activities to study the effect of functionalization at the carbonyl carbon and substitution at biphenyl ring on these activities. The introduction of hydroxyl group at carbonyl carbon enhanced the antioxidant property (3a, 3g, 3h, 4a, and 4b), while antimicrobial activity decreased; the carbinol and tertiary alcohols corresponding to methanone 2a and 2b showed no antimicrobial activity. Biphenyl methanones 1, 2a, 2f, and 2g exhibited antimicrobial activity with minimal inhibitory concentration ranging between 0.001 and 0.500 mg/mL, tertiary alcohols 3a, 3g, and 3h and carbinols 4a and 4b exhibited the promising antioxidant property. The mode of action of these active compounds was carried out by docking of receptor GlcN6P synthase with newly synthesized candidate ligands 1, 2a, 2e, 2f, 2g, 2h, 3a, 3g, 3h, 4c, and 4d.     

Synthesis of new oxadiazole derivatives as anti-inflammatory, analgesic, and antimicrobial agents

In search of pharmalogically active molecules in the class of oxadiazoles, the present article deals with the synthesis of 5-(5′-fluoro-2′-methoxybiphenyl-3-yl)-1,3,4-oxadiazol-2(3H)-one 2 from its hydrazide analog 1. The compound 2 was regioselectively N-alkylated with alkyl halides and produced the compounds 3a–f. Compound 3f was further functionalized with substituted benzenesulfonyl chlorides to give compounds 3g–j. The synthesized compounds were characterized by elemental and spectral analysis. Newly synthesized compounds were tested for their in vivo anti-inflammatory, analgesic, and in vitro antimicrobial activities. The compounds 3a–c were found to have promising anti-inflammatory and analgesic activities. Compounds 3b, 3f, and 3g showed significant antibacterial and antifungal activities.     

Novel quinolyl-thienyl chalcones and their 2-pyrazoline derivatives with diverse substitution pattern as antileishmanial agents against Leishmania major

A series of twenty-two new pyrazoline derivatives was prepared from quinoline-based chalcones which in turn were synthesized by condensing formylquinolines with diverse acetylthiophenes. The titled compounds were characterized by spectroscopic techniques (NMR, IR and MS) and elemental analysis. All the compounds were screened for antileishmanial activities. Compounds 1e, 1f, 2a, 2c, 2d, 2g, 2k, and 4a were found potentially active antileishmanial agents. Bioassay results show that the type and positions of the substituents seem to be critical for their antileishmanial activities.     

Synthesis, antimicrobial, analgesic activity, and molecular docking studies of novel 1-(5,7-dichloro-1,3-benzoxazol-2-yl)-3-phenyl-1H-pyrazole-4-carbaldehyde derivatives

Condensation of 5,7-dichloro-2-hydrazino-1,3-benzoxazole 3 with different aromatic acetophenones in methanol using catalytic amount of glacial acetic acid afforded the corresponding 1-phenylethanone(5,7-dichloro-1,3-benzoxazol-2-yl)hydrazones 5a–e in good yield. The compounds 5a–e, when subjected to Vilsmeier–Haack reaction with POCl₃ in DMF yielded (5,7-dichloro-1,3-benzoxazol-2-yl)-3-phenyl-1H-pyrazole-4-carbaldehyde derivatives 6a–e. The structural assignments of the compounds 6a–e are based on their spectral data and elemental analysis. The obtained compounds were tested for antimicrobial and analgesic activities, and subjected to molecular docking studies with respect to antimicrobial activity. The compound 6b showed pronounced antimicrobial and analgesic activity and exhibited an interesting binding profile with very high receptor affinity.     

Dimeric 2-(2-chlorophenyl)-quinazolin-4-ones as potential antimicrobial agents

3-(Aryl)-2-(2-chlorophenyl)-6-{2-[2-(2-chlorophenyl)-4-oxo(3-hydroquinazolin-3yl)]ethyl}-3-hydroquinazolin-4-ones had been selected as target bio-active molecules. Several quinazoline derivatives were prepared by using anthranilic acid, acid chloride, 2-amino-ethanol, and different amines. Newly synthesized compounds were screened for their antibacterial and antifungal activities on Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, Staphylococcus pyogenes, Candida albicans, Aspergillus niger, and Aspergillus clavatus. The compounds 5e, 5g, and 5h are shown to have excellent activity, while 5c, 5d, 5i, 5k, 5l are shown to have very good activity against several strains of bacteria. The structures of the synthesized compounds were firmly established by well-defined spectral analysis techniques like IR, ¹H-NMR, ¹³C-NMR, and Mass spectra.     

Synthesis and antitumor evaluation of α-methylene-γ-butyrolactone-linked to 5-Substituted uracil nucleic acid bases

Six, heretofore undescribed, 5′-Methyl-5′-(5-Substituted uracil-1-ylmethyl)-2′-oxo-3′-methylenetetrahydrofurans (F, Cl, Br, I, CH₃, H) (6a-f) were synthesized and evaluated against three cell lines (FM-3A, P-388 and U-937). For the preparation of α-methylene-γ-butyrolactone bearing 5-substituted uracils (6a-f), the efficient Reformatsky type reaction was employed which involves the treatment of ethyl α-(bromomethyl) acrylate and zinc with the respective 5-substituted uracil-1-ylacetones (5a-f). The acetone derivatives (5a-f) were directly obtained by the respective alkylation reaction of 5-substituted uracils with chloroacetone in the presence of K₂CO₃ (or NaH). These lactone compounds6a-f exhibited moderate to significant activity in all of the three cell lines, and6b, 6c and6e showed significant antitumor activities (inhibitory concentrations (IC₅₀) ranged from 1.3–3.8 μg/ml).