Oxidized Metabolites of 20-Hydroxyecdysone and Their Activity on Skeletal Muscle Cells: Preparation of a Pair of Desmotropes with Opposite Bioactivities

Abstract

Increasing the activation of protein kinase B (Akt) has been suggested as a key signaling step in the nonhormonal anabolic activity of the phytoecdysteroid 20-hydroxyecdysone (20E) in mammals. Base-catalyzed autoxidation of this compound was shown previously to yield interesting B-ring-modified analogues. Herein is reported a thorough study on this reaction, resulting in the preparation and complete NMR spectroscopic assignments of calonysterone (5) and its previously overlooked desmotropic pair (7), along with two new sensitive metabolites of 20E. The two isomers showed considerable stability in solution. Time dependency of the reaction for yield optimization is also presented; by means of analytical HPLC, the two desmotropes can reach a maximum combined yield of >90%. The activity of these compounds on Akt phosphorylation was tested in murine skeletal muscle cells. Compounds 2 and 5 showed more potent activity than 20E in increasing Akt activation, while compound 7 exerted an opposite effect. As such, the present study provides the first direct evidence for a pair of desmotropes exerting significantly different bioactivities.

A Commercial Extract of Cyanotis arachnoidea Roots as a Source of Unusual Ecdysteroid Derivatives with Insect Hormone Receptor Binding Activity

“…The 2,3-dioxolane-substituted compound 19 , 12 9α,20E ( 20 ), and 5α-9α,20E ( 21 ) 42 were available from previous work on semisynthetic derivatives of 20E.…”

Squalenoylated Nanoparticle Pro-Drugs of Adjuvant Antitumor 11α-Hydroxyecdysteroid 2,3-Acetonides Act as Cytoprotective Agents Against Doxorubicin and Paclitaxel

“…It may be of interest in this regard that we recently found 20-hydroxyecdysone (20E; structural isomer of compound 1 , differing in the position of one hydroxyl group) and poststerone (11-deoxy analog of compound 2 ) to act on protein kinase B (Akt) with a bell-shaped dose-response curve ( Issaadi et al., 2019 ). Ecdysteroids can modulate Akt phosphorylation in a Ca 2+ -dependent manner ( Gorelick-Feldman et al., 2010 ), and while this was first observed for 20E as an activation, some ecdysteroids may also act as inhibitors ( Csábi et al., 2015 ). Considering the central role of Akt in cell death and survival ( Song et al., 2019 ), one may hypothesize that it should somehow be involved in the chemoresistance altering activity of ecdysteroids.…”

New ring‐rearranged metabolite of 20‐hydroxyecdysone obtained by base‐catalyzed auto‐oxidation

“…Firstly, as a most likely intermediate, the formation of an X type enolate structure is suggested. Hydroxylation in position C‐9 and subsequent epimerization at C‐5 were recently reported, and also the oxidation of HC(2)‐OH to C = O seems to be straightforward. Our NMR results unambiguously confirmed the cleavage of the C‐3–C‐4 bond in ring A, resulting in a negative charge on C‐3 (intermediate Y ), which may be stabilized by the Δ 2,3 − enolate.…”

“…Synthesis and purification of compound 2 : base‐catalyzed auto‐oxidation was performed as reported previously . Briefly, 120 mg of 1 was stirred for 1 day at room temperature in 10 ml of 10% MeOH (aq) containing 100 mg of NaOH.…”

“…We recently reported a thorough study on the base‐catalyzed auto‐oxidation of 20‐hydroxyecdysone (20E; compound 1 ), including the isolation, structure elucidation, and bioactivity testing of several B‐ring modified ecdysteroid derivatives, as well as the analysis of the reaction's time dependency . The main products of this auto‐oxidation reaction, accounting for nearly 100% of yield at certain reaction times, have been identified, and their activity on the Akt phosphorylation in C2C12 myotubes was assessed, which revealed the first case of a desmotropic pair with significantly different bioactivities …”