Marine Natural Products. XXX. Two New 3-Keto-4-methylene Steroids, Theonellasterone and Conicasterone, and a Diels-Alder Type Dimeric Steroid Bistheonellasterone, from the Okinawan Marine Sponge Theonella swinhoei.
Preliminary Structure-Activity Relationship on Theonellasterol, a New Chemotype of FXR Antagonist, from the Marine Sponge Theonella swinhoei
摘要:
Using theonellasterol as a novel FXR antagonist hit, we prepared a series of semi-synthetic derivatives in order to gain insight into the structural requirements for exhibiting antagonistic activity. These derivatives are characterized by modification at the exocyclic carbon-carbon double bond at C-4 and at the hydroxyl group at C-3 and were prepared from theonellasterol using simple reactions. Pharmacological investigation showed that the introduction of a hydroxyl group at C-4 as well as the oxidation at C-3 with or without concomitant modification at the exomethylene functionality preserve the ability of theonellasterol to inhibit FXR transactivation caused by CDCA. Docking analysis showed that the placement of these molecules in the FXR-LBD is well stabilized when on ring A functional groups, able to form hydrogen bonds and π interactions, are present.
Peroxiredoxin-1, a key enzyme in the cellular detoxification pathway, has been identified through a chemoproteomicapproach as the main partner of theonellasterone, a marine bioactive metabolite. A combination of chemical and biochemical assays disclosed its mechanism of action at the molecular level.
Marine Natural Products. XXX. Two New 3-Keto-4-methylene Steroids, Theonellasterone and Conicasterone, and a Diels-Alder Type Dimeric Steroid Bistheonellasterone, from the Okinawan Marine Sponge Theonella swinhoei.
Two new 3-keto-4-methylene steroids, theonellasterone (3) and conicasterone (4), and a Diels-Alder type dimeric steroid, bistheonellasterone (5), were isolated together with two known 4-methylene sterols, theonellasterol (1) and conicasterol (2), from the Okinawan marine sponge Theonella swinhoei. The structures of these steroids have been elucidated on the basis of chemical and physicochemical evidence. Bistheonellasterone (5) is considered to be biosynthesized through a Diels-Alder cycloaddition of theonellasterone (3) and its Δ4-isomer. Very interestingly, theonellasterone (3) and conicasterone (4) were seen under an optical microscope as crystals deposited in the tissue of fresh marine sponge.
Using theonellasterol as a novel FXR antagonist hit, we prepared a series of semi-synthetic derivatives in order to gain insight into the structural requirements for exhibiting antagonistic activity. These derivatives are characterized by modification at the exocyclic carbon-carbon double bond at C-4 and at the hydroxyl group at C-3 and were prepared from theonellasterol using simple reactions. Pharmacological investigation showed that the introduction of a hydroxyl group at C-4 as well as the oxidation at C-3 with or without concomitant modification at the exomethylene functionality preserve the ability of theonellasterol to inhibit FXR transactivation caused by CDCA. Docking analysis showed that the placement of these molecules in the FXR-LBD is well stabilized when on ring A functional groups, able to form hydrogen bonds and π interactions, are present.