Novel substituted and fused pyrrolizine derivatives: Synthesis, anti-inflammatory and ulcerogenecity studies

Development of safe and antioxidant COX-2 inhibitors; Synthesis, molecular docking analysis and biological evaluation of novel pyrrolizine 5-carboxamides

In the current study, a series of new pyrrolizine-5-carboxamide derivatives (5-8, 9a-d, 10a-d, 11a,b and 12a,b) were developed, synthesized and evaluated in terms of in vitro COX-2 enzyme inhibition. The in vivo anti-inflammatory evaluation was conducted on the most selective compounds (9a,b,d, 10b,c and 11a,b). For the most active five compounds (9a, 10b,c and 11a,b), ulcerogenic liability, histopathological examinations, physicochemical properties study and antioxidant activity were investigated. Also, nitric oxide donor activity was evaluated for compounds (6, 7, 10a-d and 12a,b), while, compounds (10c,d and 12a,b) showed a high significant result relative to the normal control. According to the findings of this study, 2,3-dihydro-1H-pyrrolizine-5-carboxamide (9a) demonstrated high antioxidant (highest beta-carotene concentration (10.825 µg/ml)) and anti-inflammatory activity (EIP = 63.6 %) with lower ulcerogenicity (ulcer index 13.67), presenting it as a promising candidate for treating inflammatory diseases which are complicated by oxidative tissue damage. Furthermore, MOE software tools docking software was used to carry out the in silico studies. Docking study for the most active compounds showed that all compounds made three to four H-bond interactions in COX-2 active site adopting excellent docking scores.

Pyrrolizine/indolizine-bearing (un)substituted isoindole moiety: design, synthesis, antiproliferative and MDR reversal activities, and in silico studies

Two new series of pyrrolizine/indolizine derivative-bearing (un)substituted isoindole moiety were designed and synthesized. The anticancer potential of the new compounds was evaluated against hepatocellular carcinoma (HepG-2), colorectal carcinoma, colon cancer (HCT-116), and breast cancer (MCF-7) cell lines. Compounds 6d and 6o were the most potent derivatives with IC50 values ranging from 6.02 to 13.87 μM against HePG-2, HCT-116, and MCF-7 cell lines. Moreover, methyl analog of the fluoro-substituted indolizine derivative 6m revealed significant antiproliferative activity against HePG-2, HCT-116, and MCF-7 cancer cell lines with IC50 values of 11.97, 28.37, and 19.87 μM, respectively. The most active anticancer analogs, 6d, 6m, and 6o, were inspected for their putative mechanism of action by estimating their epidermal growth factor receptor (EGFR) and cyclin-dependent kinase (CDK 2) inhibitory activities. Thus, compound 6o displayed the most inhibitory activity against EGFR and CDK 2 with IC50 values of 62 and 118 nM, respectively. Additionally, the quantitative real-time PCR analysis for the P-glycoprotein effect of compounds 6d, 6m, and 6o was performed, in which compound 6o illustrated significant down-regulation of P-gp against the HepG-2 cell line by 0.2732 fold. Mechanistic studies for the most active compounds involving the reversal doxorubicin (DOX) effect of compounds 6d, 6m, and 6o were performed, which illustrated cytotoxic activity with IC50 22.27, 3.88, and 8.79 μM, respectively. Moreover, the apoptotic activity of the most active derivative 6o on HCT-116 cancer cells showed accumulation in the G1 and S phases of the cell cycle.

Novel 1,2,4-triazoles derived from Ibuprofen: synthesis and in vitro evaluation of their mPGES-1 inhibitory and antiproliferative activity

Some novel triazole-bearing ketone and oxime derivatives were synthesized from Ibuprofen. In vitro cytotoxic activities of all synthesized molecules against five cancer lines (human breast cancer MCF-7, human lung cancer A549, human prostate cancer PC-3, human cervix cancer HeLa, and human chronic myelogenous leukemia K562 cell lines) were evaluated by MTT assay. In addition, mouse embryonic fibroblast cells (NIH/3T3) were also evaluated to determine the selectivity. Compounds 18, 36, and 45 were found to be the most cytotoxic, and their IC50 values were in the range of 17.46-68.76 µM, against the tested cancer cells. According to the results, compounds 7 and 13 demonstrated good anti-inflammatory activity against the microsomal enzyme prostaglandin E2 synthase-1 (mPGES-1) enzyme at IC50 values of 13.6 and 4.95 µM. The low cytotoxicity and non-mutagenity of these compounds were found interesting. Also, these compounds significantly prevented tube formation in angiogenesis studies. In conclusion, the anti-inflammatory and angiogenesis inhibitory activities of these compounds without toxicity suggested that they may be promising agents in anti-inflammatory treatment and they may be supportive agents for the cancer treatment.

Novel Heterocyclic Hybrids Based on 2-Pyrazoline: Synthesis and Assessment of Anti-Inflammatory and Analgesic Activities

AIM AND OBJECTIVE

A series of new 2-pyrazoline analogues were synthesized. The structures of the synthesized compounds were elucidated by the analytical and spectroscopic data. Some selected compounds were screened for the anti-inflammatory activity by using animal model of carrageenan-induced paw edema in mice. Additionally, the analgesic and acute toxicity of these compounds were evaluated and exhibited reasonable results. The anti-oxidant and anti-inflammatory effects of these compounds were established by measuring the contents of malondialdehyde (MDA), reduced glutathione (GSH), nitric oxide (NO), and tumor necrosis factor alpha (TNF-α) in the edema paw tissue.

MATERIALS AND METHODS

All chemicals and reagents used in current study were of analytical grade. Melting points were determined using APP. Digital ST 15 melting point apparatus and are uncorrected. FT-IR spectra were recorded on a Pye-Unicam SP3-100 spectrophotometer in KBr pellet. All 1H and 13C NMR spectra were recorded on AVANCE-III (400 MHz) High Performance FT-NMR Spectrometer Brucker (Switzerland) and some 1H NMR spectra were recorded on Varian EM-360L NMR Spectrophotometer (60 MHz) (USA) in CDCl3 or DMSO-d6 as solvent. Chemical shifts are reported in δ units and the coupling constants (J) are reported in hertz. C, H, N and S analyses were performed with a Vario EL C, H, N, S Analyzer. Carrageenan (product number C1013) was obtained from Sigma-Aldrich (USA).

RESULTS

The structures of the compounds were confirmed by IR, 1H NMR, 13C NMR, and elemental analyses. The results of pharmacological activity revealed that compounds 5, 6, 7, and 15 could be recognized as potential multi-potent anti-inflammatory.

CONCLUSION

A simple and suitable method for the synthesis of new pharmacophore was reported. We have designed nineteen heterocycles related to pyrazoline ring, and evaluated eleven of them for their antiinflammatory, analgesic and acute toxicity activities. Compounds 5, 6, 7, and 15 proved to be the interesting compounds, they have high anti-inflammatory activity. However, all the selected compounds show remarkable analgesic activity.

Transition-Metal-Free, Atom- and Step-Economic Synthesis of Aminoketopyrrolizines from Benzylamine, Acylethynylpyrroles, and Acylacetylenes

A concise, atom-economic strategy for the synthesis of pyrrolizines with amino and keto substituents has been developed. It includes the following key steps: (i) the base-catalyzed (K₃PO₄/DMSO) addition of a benzylamine to 2-acylethynylpyrroles and (ii) noncatalyzed addition of enaminones obtained to the triple bond of acylacetylenes followed by intramolecular cyclization of the intermediate pentadiendiones thus formed to the target 1-(benzylamino)-2-acyl-3-methylenoacylpyrrolizines.

Isothiourea-catalysed enantioselective pyrrolizine synthesis: synthetic and computational studies

The catalytic enantioselective synthesis of a range of cis-pyrrolizine carboxylate derivatives with outstanding stereocontrol (14 examples, >95 : 5 dr, >98 : 2 er) through an isothiourea-catalyzed intramolecular Michael addition-lactonisation and ring-opening approach from the corresponding enone acid is reported. An optimised and straightforward three-step synthetic route to the enone acid starting materials from readily available pyrrole-2-carboxaldehydes is delineated, with benzotetramisole (5 mol%) proving the optimal catalyst for the enantioselective process. Ring-opening of the pyrrolizine dihydropyranone products with either MeOH or a range of amines leads to the desired products in excellent yield and enantioselectivity. Computation has been used to probe the factors leading to high stereocontrol, with the formation of the observed cis-steroisomer predicted to be kinetically and thermodynamically favoured.

Design, Synthesis, and Biological Evaluation of Some Novel Pyrrolizine Derivatives as COX Inhibitors with Anti-Inflammatory/Analgesic Activities and Low Ulcerogenic Liability

Non-steroidal anti-inflammatory drugs (NSAIDs) are the most commonly prescribed anti-inflammatory and pain relief medications. However, their use is associated with many drawbacks, including mainly serious gastric and renal complications. In an attempt to circumvent these risks, a set of N-(4-bromophenyl)-7-cyano-6-substituted-H-pyrrolizine-5-carboxamide derivatives were designed, synthesized and evaluated as dual COX/5-LOX inhibitors. The structural elucidation, in vivo anti-inflammatory and analgesic activities using a carrageenan-induced rat paw edema model and hot plate assay, were performed, respectively. From the results obtained, it was found that the newly synthesized pyrrolizines exhibited IC₅₀ values in the range of 2.45–5.69 µM and 0.85–3.44 µM for COX-1 and COX-2, respectively. Interestingly, compounds 12, 13, 16 and 17 showed higher anti-inflammatory and analgesic activities compared to ibuprofen. Among these derivatives, compounds 16 and 19 displayed better safety profile than ibuprofen in acute ulcerogenicity and histopathological studies. Furthermore, the docking studies revealed that compound 17 fits nicely into COX-1 and COX-2 binding sites with the highest binding affinity, while compound 16 exerted the highest binding affinity for 5-LOX. In light of these findings, these novel pyrrolizine-5-carboxamide derivatives represent a promising scaffold for further development into potential dual COX/5-LOX inhibitors with safer gastric profile.

An integrated overview on pyrrolizines as potential anti-inflammatory, analgesic and antipyretic agents

Despite the existence of huge number of NSAIDs, the quest for safer drugs is still in the focus of several drug discovery programs. Pyrrolizine heterocyclic system is among the privileged scaffolds utilized in this regard. At least one of these pyrrolizines, ketorolac, has reached the market. The current review represents a collective effort to highlight the reported pyrrolizines with anti-inflammatory and analgesic potential and categorize them into eight different classes. Furthermore, the various synthetic approaches, structure-activity relationship as well as metabolic pathways have been discussed. Taken together, this review sets a base for researchers to design and synthesize novel pyrrolizine-based libraries for further development into safer and efficient anti-inflammatory and analgesic agents.

10-(4-Chloro-phen-yl)-14a-hy-droxy-12-methyl-8,9,9a,10,12,13,14,14a-octa-hydro-5H-10a,14-methano-indeno-[2',1':4,5]azepino[3,4-b]pyrrolizine-5,15(7H,11H)-dione

The asymmetric unit of the title compound, C26H25ClN2O3, contains two independent mol-ecules (A and B). The conformation of the two mol-ecules differs essentially in the dihedral angle involving the two benzene rings. They are inclined to one another by 52.47 (10) in A and by 31.75 (11)° in B. In both mol-ecules, the six-membered piperidin-3-one rings have chair conformations. In mol-ecule A, all four five-membered rings have twist conformations. In mol-ecule B, only three of the four five-membered rings have twist conformations. The fourth, of the inden-1-one moiety, has an envelope conformation with the spiro C atom, bonded to the N atom of the pyrrolidine ring, as the flap. A weak intra-molecular O-H⋯N hydrogen bond occurs in each independent mol-ecule while a C-H⋯O inter-action is also observed in mol-ecule A. In the crystal, pairs of O-H⋯O hydrogen bonds link the mol-ecules, forming inversion dimers with graph-set motif R 2 (2)(12). These dimers are further inter-connected by C-H⋯O and C-H⋯π inter-actions, forming a three-dimensional network.

Synthesis of isoindoles and related iso-condensed heteroaromatic pyrroles

Over the past few years, isoindoles have found wide application in materials science. Isoindole containing BODIPY dyes are highly fluorescent materials and have been extensively used in various fields of science. Phthalocyanines, metal containing cyclic tetramers of isoindole, form coordination complexes with most elements of the periodic table. These complexes are intensely coloured and are used as pigments and dyes. However, isoindoles are relatively unstable 10π-heteroaromatic systems and few synthetic methods provide these compounds in good yields. This tutorial review will give an overview of the reported synthetic methods towards isoindoles and related heteroaromatic systems over a time span of approximately 10 years (2000 to current), including the applications where they have been reported. The importance of the field will be illustrated and factors influencing product stability will be discussed.

Methyl 4-phenyl-1,2,3,3a,4,4a,5,12c-octa-hydronaphtho[1',2':3,2]furo[5,4-b]pyrrolizine-4a-carboxyl-ate

In the title compound, C₂₆H₂₅NO₃, both pyrrolidine rings adopt envelope conformations, whereas the dihydro­pyran ring adopts a half-chair conformation. The phenyl ring is oriented at an angle of 27.9 (1)° with respect to the naphthalene ring system. An intra­molecular C—H⋯O hydrogen bond is observed. The crystal packing is stabilized by weak inter­molecular C—H⋯π inter­actions.