Total synthesis of (+)-lepadin F.

An enantioselective total synthesis of (+)-lepadin F is described. The synthetic sequence features an intermolecular aza-[3 + 3] annulation, homologation of a vinylogous amide via Eschenmoser's episulfide contraction, and a highly stereoselective hydrogenation essential for achieving the 1,3-anti relative stereochemistry at C2 and C8a.

Non peptidic urotensin II antagonists: perspectives for a new class of drugs.

Urotensin II (U-II) is a cyclic peptide isolated from a fish. Subsequently, human U-II and its receptor were identified. In rat thoracic aorta U-II triggers powerful vasoconstrictor activity. However, the constrictor response to U-II appears to be variable and highly dependent on the vascular bed examined. Vasoconstriction is not its only effect; U-II and its receptor have been demonstrated in the central nervous system, where U-II induces a cardiovascular, behavioural, motor and endocrine response and in the kidney, where it seems to influence renal hemodynamics but also salt and water excretion, in rat pancreas where it inhibits insulin secretion, in the heart where it seems to play a role in cardiac hypertrophy and fibrosis. In humans high plasma or urine levels of U-II have been described in some pathologic conditions. Peptidic and non peptidic UT receptor antagonists have been synthesized and their effects have been evaluated particularly in animal models of diabetes and heart failure. After promising results in animal models, palosuran, a non peptidic U-II antagonist has been administered also in diabetic patients to evaluate its potential nephroprotective activity. This review presents the data available on the U-II system and its role in physiological and pathological conditions, together with data regarding palosuran and other non peptidic and peptidic U-II antagonists.

New trends in anti-malarial agents.

Malaria is the major parasitic infection in many tropical and subtropical regions, leading to more than one million deaths (principally young African children) out of 400 million cases each year (WHO world health report 2000). More than half of the world's population live in areas where they remain at risk of malaria infection. During last years, the situation has worsened in many ways, mainly due to malarial parasites becoming increasingly resistant to several antimalarial drugs. Furthermore, the control of malaria is becoming more complicated by the parallel spread of resistance of the mosquito vector to currently available insecticides. Discovering new drugs in this field is therefore a health priority. Several new molecules are under investigation. This review describes the classical treatments of malaria and the latest discoveries in antimalarial agents, especially artemisinin and its recent derivatives as well as the novel peroxidic compounds.

New quinoline alkaloids from the leaves and stems of Orixa japonica, orijanone, isopteleflorine and 3'-O-methylorixine.

Orixajaponica (Rutaceae) is a shrub widely distributed in Japan, and has been found to contain various quinoline alkaloids. We investigated the alkaloidal constituents of O. japonica, and four quinoline alkaloids were isolated and characterized. Three of these alkaloids are new natural products.

Structure-activity relationship studies of antiviral N-quinolin-4-yl-N'-benzylidenehydrazine derivatives by discriminant analysis.

The classification technique of linear discriminant analysis (LDA) is applied for studying the structure-activity relationship among antiviral N-quinolin-4-yl-N'-benzylidenehydrazine (II) derivatives. The total hydrophilicity of substituents in the benzylidene moiety along with 4 indicator variables is found to significantly (p less than 0.001) discriminate 25 inactive congeners of (II) from 28 active congeners with more than 80% posterior classification ratio. The predictive stability of the discriminant functions is established by the leave-one-out procedure. In the light of the posterior probabilities of assignment calculated from these functions it is observed that ethoxy group at position 7 and methoxy group at positions 8 and 6 in the quinoline system favour activity while a methoxy group at ortho or para position in the phenyl ring decreases activity. In view of the finer classification within the active class the three-group analysis is also performed using LDA and the adaptive-least-squares techniques.