New pyrazoline bearing 4(3H)-quinazolinone inhibitors of monoamine oxidase: synthesis, biological evaluation, and structural determinants of MAO-A and MAO-B selectivity.

A new series of pyrazoline derivatives were prepared starting from a quinazolinone ring and evaluated for antidepressant, anxiogenic and MAO-A and -B inhibitory activities by in vivo and in vitro tests, respectively. Most of the synthesized compounds showed high activity against both the MAO-A (compounds 4a-4h, 4j-4n, and 5g-5l) and the MAO-B (compounds 4i and 5a-5f) isoforms. However, none of the novel compounds showed antidepressant activity except for 4b. The reason for such biological properties was investigated by computational methods using recently published crystallographic models of MAO-A and MAO-B. The differences in the intermolecular hydrophobic and H-bonding of ligands to the active site of each MAO isoform were correlated to their biological data. Compounds 4i, 4k, 5e, 5i, and 5l were chosen for their ability to reversibly inhibit MAO-B and MAO-A and the availability of experimental inhibition data. Observation of the docked positions of these ligands revealed interactions with many residues previously reported to have an effect on the inhibition of the enzyme. Among the pyrazoline derivatives, it appears that the binding interactions for this class of compounds are mostly hydrophobic. All have potential edge-to-face hydrophobic interactions with F343, as well as pi-pi stacking with Y398 and other hydrophobic interactions with L171. Strong hydrophobic and H-bonding interactions in the MAO recognition of 4i could be the reason why this compound shows selectivity toward the MAO-B isoform. The very high MAO-B selectivity for 4i can be also explained in terms of the distance between the FAD and the compound, which was greater in the complex of MAO-A-4i as compared to the corresponding MAO-B complex.

Antitrypanosomal cycloartane glycosides from Astragalus baibutensis.

Baibutoside (5), a new cycloartane-type triterpene glycoside, has been isolated from the roots of Astragalus baibutensis along with four known glycosides, acetylastragaloside I (1), and astragalosides I, II, and IV (2-4, resp.). The structure elucidation of the compounds were achieved by a combination of one- and two-dimensional NMR techniques (DQF-COSY, HSQC, HMBC, and ROESY), and mass spectrometry (ESI-MS), where all the compounds were shown to have cycloastragenol (=(20R,24S)-3beta,6alpha,16beta,25-tetrahydroxy-20,24-epoxy-9,19-cyclolanostane) as aglycone. All compounds were tested for in vitro antiprotozoal activity. Compounds 1-4 displayed notable activity vs. Trypanosoma brucei rhodesiense, with acetylastragaloside I (1) being the most potent (IC50 9.5 microg/ml). Acetylastragaloside I (1) was also lethal to T. cruzi (IC50 5.0 microg/ml), and it is the first cycloartane-type triterpene with remarkable trypanocidal activity against both T. brucei rhodesiense and T. cruzi. However, it exhibits some cytotoxicity on mammalian cells.

In vivo metabolism of 2-[1'-phenyl-3'-(3-chlorophenyl)-2'-propenylyden]hydrazino-3-methyl-4(3H)-quinazolinone in rats.

The aim of this study was to investigate by HPLC the in vivo metabolism of 2-[1'-phenyl-3'-(3-chlorophenyl)-2'-propenylyden]hydrazino-3-methyl-4(3H)-quinazolinone as a substrate, and as a model compound in rats. The substrate was dissolved in DMSO/water (1:4) and administered intraperitoneally at a dose of 100 mg/kg in a volume of approximately 0.1 mL. Blood samples were taken before and 30 min, 1.5, 3, 6, 9, 11, 30 and 48 h after i.p. drug administration. The chromatographic separation of the substrate and its metabolites was performed using a stainless steel Novopak C18 column (150 x 4.6 mm i.d., 5-microm particle size). The optimal composition of the mobile phase was reached by introducing different mixtures of pure acetonitrile and water in a linear gradient system. Following the biotransformation of this compound, 2-hydrazino-3-methyl-4(3H)-quinazolinone (M1) and 3-(3-chlorophenyl)-1-phenylprop-2-en-1-one (M2) derivatives were identified together with substrate by comparing them to reference standards using HPLC-UV/DAD. In addition, the composition of these metabolites and substrate was confirmed by LC-MS in plasma.

Synthesis, anti-inflammatory and analgesic activity of some new 4(3H)-quinazolinone derivatives.

4(3H)-quinazolinone and pyrazole derivatives have been shown to have analgesic and anti-inflammatory properties. In this study, 14 new 3-methyl-4(3H)quinazolinone derivatives bearing 2-[1'-phenyl-3'-(substituted-phenyl)-2'-propenylidene]hydrazino or 2[5'-(substituted phenyl)-3'-phenyl-2'-pyrazolin-1'-yl] groups have been synthesized with the aim of obtaining new analgesic and anti-inflammatory leads. The structures were elucidated by means of UV, IR, 1H-NMR, 13C-NMR, mass spectroscopy, and elemental analysis data. The anti-inflammatory activities of the synthesized compounds were determined by carrageenan-induced hind paw edema test in mice. All the compounds showed statistically significant effects. For analgesic activity assessment, p-benzoquinone-induced writhing test was applied in mice. The results obtained were in accordance with the anti-inflammatory activity tests.