- Synthesis of new steroidal carbamates with plant-growth-promoting activity: Theoretical and experimental evidence
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A priority of modern agriculture is to use novel and environmentally friendly plant-growth promoter compounds to increase crop yields and avoid the indiscriminate use of synthetic fertilizers. Brassinosteroids are directly involved in the growth and development of plants and are considered attractive candidates to solve this problem. Obtaining these metabolites from their natural sources is expensive and cumbersome since they occur in extremely low concentrations in plants. For this reason, much effort has been dedicated in the last decades to synthesize brassino-steroids analogs. In this manuscript, we present the synthesis and characterization of seven steroi-dal carbamates starting from stigmasterol, β-sitosterol, diosgenin and several oxygenated derivatives of it. The synthesis route for functionalization of diosgenin included epoxidation and epoxy opening reactions, reduction of carbonyl groups, selective oxidation of hydroxyl groups, among others. All the obtained compounds were characterized by1H and13C NMR, HRMS, and their melting points are also reported. Rice lamina inclination test performed at different concentrations es-tablished that all reported steroidal carbamates show plant-growth-promoting activity. A molecular docking study evaluated the affinity of the synthesized compounds towards the BRI1-BAK1 receptor from Arabidopsis thaliana and three of the docked compounds displayed a binding energy lower than brassinolide.
- Pacheco, Daylin Fernández,Ceballos, Leonardo González,Castro, Armando Zaldo,Conde González, Marcos R.,de la Torre, Laura González,Rostgaard, Lia Pérez,Espinoza, Luis,Díaz, Katy,Olea, Andrés F.,García, Yamilet Coll
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- In vitro neuroprotective and anti-inflammatory activities of natural and semi-synthetic spirosteroid analogues
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Two spirosteroid analogues were synthesized and evaluated for their in vitro neuroprotective activities in PC12 cells, against glutamate-induced excitotoxicity and mitochondrial damage in glucose deprivation conditions, as well as their anti-inflammatory potential in LPS/IFNγ-stimulated microglia primary cultures. We also evaluated the in vitro anti-excitotoxic and anti-inflammatory activities of natural and endogenous steroids. Our results show that the plant-derived steroid solasodine decreased PC12 glutamate-induced excitotoxicity, but not the cell death induced by mitochondrial damage and glucose deprivation. Among the two synthetic spirosteroid analogues, only the (25R)-5α-spirostan-3,6-one (S15) protected PC12 against ischemia-related in vitro models and inhibited NO production, as well as the release of IL-1β by stimulated primary microglia. These findings provide further insights into the role of specific modifications of the A and B rings of sapogenins for their neuroprotective potential.
- García-Pupo, Laura,Zaldo-Castro, Armando,Exarchou, Vassiliki,Tacoronte-Morales, Juan Enrique,Pieters, Luc,Berghe, Wim Vanden,Nu?ez-Figueredo, Yanier,Delgado-Hernández, René
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- Novel 5β-hydroxyspirostan-6-ones ecdysteroid antagonists: Synthesis and biological testing
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Eight new 5β-hydroxy-spirostan-6-ones bearing hydroxy and amino functions in the A ring, i.e., 3β-OH, 3α-OH, 2β,3β-OH, 2α,3β-OH, 3β-NH2, 2α-NH2-3β-OH, 2β-NH2-3β-OH, and 2β-OH-3β-NH2, were efficiently synthesized, and their antiecdysteroid activities were evaluated on the metamorphosis bioassay of mosquito Aedes aegypti. To our knowledge, these new steroids represent the first 5β-hydroxy-spirostanes which have been tested for antiecdysteroid activity in mosquitoes. The higher antagonistic effect was found for compounds bearing the 3β-hydroxy and 2β,3β-dihydroxy functionality, which show promise as environmental friendly insecticides.
- Rivera, Daniel G.,León, Fredy,Coll, Francisco,Davison, Gema P.
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- The preparation of the spirostanic analogues of brassinolide and castasterone
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Methods for the preparation of the spirostanic analogues of brassinosteroids (25R)-5α-spirostan-6-one-2α,3α-diol and (25R)-B-homo-5α-spirostan-6-oxo-7-oxalactone-2α,3α-diol, starting from diosgenin, were examined. The best preparative route was via diosgenin tosylation, isosteroidal rearrangement with potassium acetate in aqueous acetone, oxidation with Jones reagent, cyclopropyl ring opening with hydrobromic acid, hydrogen bromide elimination with lithium bromide and carbonate, dihydroxylation with osmium tetroxide and N-methylmorpholine N-oxide, producing (25R)-5α-spirostan-6-one-2α,3α-diol in 57.3% overall yield and lactonization with trifluoroperoxyacetic acid producing (25R)-B-homo-5α-spirostan-6-oxo-7-oxalactone-2α,3α-diol in 24.6% overall yield from diosgenin. The shortest route to (25R)-5α-spirostan-6-one-2α,3α-diol results in only 39.4% overall yield.
- Robaina Rodriguez, Caridad M.,Teixeira Zullo, Marco Antonio,Queiroz, Helena Mueller,Martins De Azevedo, Mariangela De Burgos,Becerra, Esther Alonso,Manchado, Francisco Coll
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p. 637 - 646
(2007/10/03)
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