Hydrogenation of ecdysteroids

In vitro adjuvant antitumor activity of various classes of semi-synthetic poststerone derivatives

“…The molecule contains a conjugated Δ7-6-keto group in ring B, an important chromophore present in virtually all ecdysteroid molecules. The reductive transformations of this group studied for cholestane type ecdysteroids [22] offer the prospects for the synthesis of brassinosteroid type hybrid molecules, some of which have a natural antitumor potential [23]. Hydrogenation of cholestane and pregnane type ecdysteroids with 10% Pd-C as a catalyst in the presence of sodium nitrite in ethanol was earlier reported [24].…”

Evaluation of ecdysteroid antisera for a competitive enzyme immunoassay and extraction procedures for the measurement of mosquito ecdysteroids

“…We did not find any reference to this interaction in the insect literature at-large, or to any prior studies that compared the efficiency of methanol for extraction of endogenous ecdysteroids from whole insect bodies alone or with known amounts of added ecdysteroids. In contrast, directed reduction of insect steroids has been used to enhance identification (Dinan and Rees, 1978; Savchenko and Odinokov, 2012) while prior studies also provide evidence for reductive cleavage of hydroxyl groups under specific conditions (Horn and Bergamasco, 1985; Harmatha, et al, 2002). Our MS data showed the presence of multiple species rather than a single identifiable reduced form after treatment of 20E with methanol and MgCl 2 (Supplementary Fig.…”

Synthetic Aspects of Brassinosteroids

“…Under the best experimental conditions, the reaction led to a mixture of the ketone (2), overreduction products (3,4), and the starting material (1). Catalytic hydrogenation of ∆ 7 -6-ketones was shown to smoothly proceed but with the formation of unnatural 7,8a-dehydro derivatives [23]. Catalytic hydrogenation of ∆ 7 -6-ketones was shown to smoothly proceed but with the formation of unnatural 7,8a-dehydro derivatives [23].…”