Ecdysteroid analogs based on halogenated derivatives of steroidal sapogenins

Ecdysteroids regulate vital metabolic processes, such as metamorphosis (ecdysis) and reproduction in invertebrates, and act as phytoprotectants in plants and modulatory agents in mammals. This study describes the use of diosgenin as a strategic molecular precursor for the synthesis of brominated intermediates with potential anti-ecdysteroid and insecticidal activity against Blatella germanica.

Two synthetic routes were developed. In the first, a tribrominated derivative was obtained through initial acetylation of diosgenin, followed by epoxidation, oxidative ring opening to generate a ketol, and final selective bromination. The second route yielded a dibrominated derivative from diosgenin tosylate. This route involved the formation of an i-steroid, followed by Jones oxidation, isomerization to the C2-C3/C6-keto alkene, and hydroxylation under Prevost-Woodward conditions to yield a C2, C3/C6-keto diacetate. Bromination of the diacetate yielded the dibrominated compound in 62.5% yield.

Structural characterization by FTIR confirmed the integrity of the spirocetal system (signals at 1350–850 cm⁻¹), while ¹H and ¹³C NMR allowed the identification of key chemical shifts at positions C-2, C-3, C-6, C-7, and C-23 of the spirostane core, confirming the equatorial substitution of the bromine atoms and verifying the derivatives obtained.

Preliminary biological studies revealed that the brominated derivatives exhibit insecticidal activity against Blattella germanica. The compounds delayed adult emergence and induced morphogenetic effects, possibly due to the blocking of specific receptors by the presence of bromine functional groups. This proposed synthetic strategy is technically feasible and considers diosgenin as a viable raw material for the development of ecdysis modulators useful in pest control.