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Recent studies have shown that low concentrations of brassinolide induce a rapid generation of nitric oxide in mesophyll cells of maize leaves, which can be easily detected by fluorimetric methods. In this work we describe a series of natural and synthetic brassinosteroids that are able to trigger in vitro NO production in tomato cells that exhibits dose–response behavior. We propose that this effect...
Most sterols, such as cholesterol and ergosterol, become functional only after the removal of the two methyl groups at C-4 from their biosynthetic precursors. Nevertheless, some findings suggest that 4,4-dimethyl sterols might be involved in specific physiological processes. In this paper we present the synthesis of a collection of analogues of 4,4-dimethyl sterols with a diamide side chain and a...
In this paper we report the synthesis of four ring-A difluorinated analogs of brassinosteroids. The bioactivity of these new compounds was evaluated using the rice lamina inclination test. The results show that one of these analogs elicits a bioactivity comparable to that of 28-homocastasterone, a highly active natural brassinosteroid. This finding suggests that both hydroxyls at C-2 and C-3 in active...
In this paper we report the synthesis of a new family of sterol analogues that have two amidic bonds on the side chain. These azasterols were obtained by a straightforward procedure including an Ugi condensation that allows the facile attachment of a polyfunctionalized side chain into the steroidal framework.Some of the new compounds showed an interesting inhibitory effect on the growth of two pathogenic...
In this paper we report the synthesis of four fluorinated analogues of brassinosteroids in which fluorine was introduced stereoselectively at C-2. The bioactivity of these new compounds was evaluated using the rice lamina inclination test. The results show that two of these analogues elicit high bioactivity, suggesting the involvement of hydrogen bond interactions between the active brassinosteroids...
In this paper we report the use of an intramolecular Ugi reaction to synthesize new 4-azacholestanes diversely substituted both at N-4 and C-5.Both the scope and the stereochemical outcome of this approach were studied by varying the nature of the components necessary for this multicomponent reaction.In sight of our results we concluded that this methodology can be applied to obtain 4-azasteroids...
Brassinosteroids are a novel group of steroids that appear to be ubiquitous in plants and are essential for normal plant growth and development. It has been previously reported that brassinosteroid analogues exert an antiviral activity against herpes simplex virus type 1 (HSV-1) and arenaviruses. In the present study, we report the chemical synthesis of compounds (22S,23S)-3β-bromo-5α,22,23-trihydroxystigmastan-6-one...
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