Synthesis, characterization and evaluation of antioxidant activities of some novel chalcones analogues.

BACKGROUND: Chalcone, an important intermediate of flavonoid synthetic pathway, has been shown to exhibit diverse biological and pharmacological activities such as anti- cancer, antioxidant, anti-inflammatory, etc. RESULTS: In this study, a novel series of chalcones fatty acid esters 5b-e and 6b-e have been synthesized via the reaction of the respective chalcones with either palmitic or stearic acid. Another related class of compounds comprising 2,3-disubstituted chalcones 7b-d and 8b(b')-d as well as 2-amino-6-(substituted-phenyl)-4-substitutedphenyl-nicotinonitrile derivatives 9a,c,e have been also prepared by both electrophilic and Michael addition reactions, respectively, with the corresponding chalcones. The structures of all compounds are confirmed via a wide range of spectroscopic techniques including IR, (1)H and (13)C NMR, and mass spectra. Significantly, all synthesized compounds have been tested for their promising antioxidant activities via utilization of 1,1-biphenyl-2-picrylhydrazyl as a free radical scavenging reagent. Surprisingly, the results demonstrated that compound 5e (68.58% at C = 2 µg/ml) was more effective as an antioxidant agent than the ascorbic acid, a commonly used antioxidant. Furthermore, the role and contribution of different functional groups on the antioxidant activity of the synthesized chalcone derivatives are also probed and rationalized in terms of their electronic and structural effect. CONCLUSION: Good activity was noted for chalcone fatty acid esters, with some members recorded higher antioxidant activity than ascorbic acid.

Synthesis, antimicrobial, and anti-inflammatory activity, of novel S-substituted and N-substituted 5-(1-adamantyl)-1,2,4-triazole-3-thiols.

The reaction of 5-(1-adamantyl)-4-phenyl-1,2,4-triazoline-3-thione (compound 5) with formaldehyde and 1-substituted piperazines yielded the corresponding N-Mannich bases 6a-f. The reaction of 5-(1-adamantyl)-4-methyl-1,2,4-triazoline-3-thione 8 with various 2-aminoethyl chloride yielded separable mixtures of the S-(2-aminoethyl) 9a-d and the N-(2-aminoethyl) 10a-d derivatives. The reaction of compound 5 with 1-bromo-2-methoxyethane, various aryl methyl halides, and ethyl bromoacetate solely yielded the S-substituted products 11, 12a-d, and 13. The new compounds were tested for activity against a panel of Gram-positive and Gram-negative bacteria and the pathogenic fungus Candida albicans. Compounds 6b, 6c, 6d, 6e, 6f, 10b, 10c, 10d, 12c, 12d, 12e, 13, and 14 displayed potent antibacterial activity. Meanwhile, compounds 13 and 14 produced good dose-dependent anti-inflammatory activity against carrageenan-induced paw edema in rats.

Microwave- and ultrasound-assisted synthesis of some acyclonucleobases based on a uracil moiety using dmap as base.

In this study, 1-(bromoalkanoyl)-1H-pyrimidine-2,4-diones, (2,4-dioxo-pyrimidin-1-yl)-oxo-alkanoic acids, and bis(2,4-dioxo-3,4-dihydro-2H-pyrimidin-1-yl)-alkanones were successfully prepared via electrophilic substitution of uracil and its derivatives. High yields and pure products were obtained when microwave and ultrasound methodologies were used for undertaking the reactions. Importantly, the use of 4-dimethylaminopyridine in the present investigation gave rise to higher conversions of the starting material and afforded facile access to regioselective N-1 products.

2-{[5-(Adamantan-1-yl)-4-methyl-4H-1,2,4-triazol-3-yl]sulfan-yl}-N,N-dimethyl-ethanamine.

In the title compound, C(17)H(28)N(4)S, the 1,2,4-triazole ring is nearly planar [maximum deviation = 0.005 (2) Å]. There are no significant hydrogen bonds observed in the crystal structure. The crystal studied was a non-merohedral twin, the refined ratio of twin components being 0.281 (3):0.719 (3).

3-(1-Adamant-yl)-4-amino-1-(2-benzoyl-1-phenyl-eth-yl)-1H-1,2,4-triazol-5(4H)-thione.

In the title compound, C(27)H(30)N(4)OS, the 3-(adamantan-1-yl)-4-amino-1H-1,2,4-triazole-5(4H)-thione unit and the O atom are each disordered over two sets of sites with refined site-occupancies of 0.7630 (13) and 0.2370 (13). The 1,2,4-triazole ring of the major component forms dihedral angles of 62.61 (17) and 61.93 (16)° with the benzene rings, while that of the minor component makes corresponding angles of 86.3 (4) and 79.1 (4)°. The dihedral angle between the benzene rings is 39.21 (16)°. The mol-ecular structure is stabilized by an intra-molecular C-H⋯N hydrogen bond, which generates an S(6) ring motif. In the crystal, mol-ecules are linked into inversion dimers by pairs of N-H⋯S hydrogen bonds.

N'-[(1E)-(4-Fluoro-phen-yl)methyl-idene]thio-phene-2-carbohydrazide.

In the title compound, C(12)H(9)FN(2)OS, the thienyl ring is disordered over two positions, with the S atom of the major component [occupancy = 87.08 (16)°] oriented towards the ortho-H atom of the benzene ring. The mol-ecule is nearly planar, the dihedral angle between the thio-phene and benzene rings being 13.0 (2)° in the major component. The azomethine C=N double bond in the mol-ecule is of an E configuration. In the crystal, mol-ecules are linked by pairs of N-H⋯O hydrogen bonds, forming inversion dimers.