Microwave-enhanced synthesis of 26-amino-22-oxocholestanes and their cytotoxic activity.

The synthesis of a series of 26-amino-22-oxocholestanes derived from diosgenin was accomplished via the substitution of an iodine atom at C-26 by primary and secondary amines. The reactions were conducted in refluxing acetonitrile and through microwave-assisted heating. The latter shows significant improvements in terms of reaction times going from hours to a few minutes or even seconds for completion.

Nematicidal activity of furanoeremophilenes against Meloidogyne incognita and Nacobbus aberrans.

Background: While searching for novel small molecules for new organic pesticide agents against plant-parasitic nematodes, we found that the hexane extract from the roots of Senecio sinuatos and its main secondary metabolite, 3β-angeloyloxy-6β-hydroxyfuranoeremophil-1(10)-ene (1), possess nematicidal activity against the second stage juvenile (J2) of Meloidogyne incognita and Nacobbus aberrans. Both species reduce yield of various vegetable crops. These results encouraged us to synthesize esters 3-9 formed by diol 2, obtained by alkaline hydrolysis of 1 and acetic anhydride, benzoic acid, 2-nitrobenzoic acid, 2-bromobenzoic acid, 4-nitrobenzoic acid, 4-bromobenzoic acid, and 4-methoxybenzoic acid, respectively.

22-Oxocholestane oximes as potential anti-inflammatory drug candidates.

22-Oxocholestanes bearing the oxime functionality in the side chain have been synthesized from diosgenin and evaluated in vivo as anti-inflammatory agents in an acute inflammation mouse ear model, against the commercial glucocorticoid dexamethasone. The final compounds were all regioselectively obtained with an E configuration at the oxime double bond. The title compounds reduced ear-induced inflammation and edema.

Mimicking natural phytohormones. 26-Hydroxycholestan-22-one derivatives as plant growth promoters.

26-Hydroxycholestan-22-one derivatives with oxygenated functions in the rings A and/or B were successfully synthesized from diosgenin. After the modifications of rings A and B, the spiroketal side chain was selectively opened through a Lewis acid mediated acetolysis to afford the cholestane derivatives. These compounds incorporate pharmacophores, which mimic the activity of natural phytohormones and show high growth promoting activity in Mexican rice cultivars using the rice lamina inclination test.

Regioselective Spirostan E-Ring Opening for the Synthesis of Dihydropyran Steroidal Frameworks.

The regioselective opening of the ring E in spirostan sapogenins provides new dihydropyran derivatives. This novel side chain is obtained after a Lewis acid mediated acetolysis followed by an alkaline workup. The reaction mechanism is analyzed via density functional theory computations, and both experimental and computational data support the formation of an oxacarbenium intermediate.

22-Oxocholestanes as plant growth promoters.

The spirostanic steroidal side-chain of diosgenin and hecogenin was modified to produce 22-oxocholestane derivatives. This type of side-chain was obtained in good yields through a straightforward four-step pathway. These compounds show potent brassinosteroid-like growth promoting activity evaluated via the rice lamina joint inclination bioassay.