Synthesis of 2-Prenylated Alkoxylated Benzopyrans by Horner-Wadsworth-Emmons Olefination with PPARα/γ Agonist Activity

We have synthesized series of 2-prenylated benzopyrans as analogues of the natural polycerasoidol, a dual PPARα/γ agonist with anti-inflammatory effects. The prenylated side chain consists of five or nine carbons with an α-alkoxy-α,β-unsaturated ester moiety. Prenylation was introduced via the Grignard reaction, followed by Johnson-Claisen rearrangement, and the α-alkoxy-α,β-unsaturated ester moiety was introduced by the Horner-Wadsworth-Emmons reaction. Synthetic derivatives showed high efficacy to activate both hPPARα and hPPARγ as dual PPARα/γ agonists. These prenylated benzopyrans emerge as lead compounds potentially useful for preventing cardiometabolic diseases.

Synthesis of benzopyran derivatives as PPARα and/or PPARγ activators

We describe the synthesis of 26 compounds, small polycerasoidol analogs, that are Lipinski's rule-of-five compliant. In order to confirm key structural features to activate PPARα and/or PPARγ, we have adopted structural modifications in the following parts: (i) the benzopyran core (hydrophobic nucleus) by benzopyran-4-one, dihydrobenzopyran or benzopyran-4-ol; (ii) the side chain at 2-position by shortening to C3, C4 and C5-carbons versus C-9-carbons of polycerasoidol; (iii) the carboxylic group (polar head) by oxygenated groups (hydroxyl, acetoxy, epoxide, ester, aldehyde) or non-oxygenated motifs (allyl and alkyl). Benzopyran-4-ones 6, 12, 13 and 17 as well as dihydrobenzopyrans 22, 24 and 25 were able to activate hPPARα, whereas benzopyran-4-one (7) with C5-carbons in the side chain exhibited hPPARγ agonism. According to our previous docking studies, SAR confirm that the hydrophobic nucleus (benzopyran-4-one or dihydrobenzopyran) is essential to activate PPARα and/or PPARγ, and the flexible linker (side alkyl chain) should containg at least C5-carbon atoms to activate PPARγ. By contrast, the polar head ("carboxylic group") tolerated several oxygenated groups but also non-oxygenated motifs. Taking into account these key structural features, small polycerasoidol analogs might provide potential active molecules useful in the treatment of dyslipidemia and/or type 2 diabetes.

Polycerasoidol, a Natural Prenylated Benzopyran with a Dual PPARα/PPARγ Agonist Activity and Anti-inflammatory Effect

Dual peroxisome proliferator-activated receptor-α/γ (PPARα/γ) agonists regulate both lipid and glucose homeostasis under different metabolic conditions and can exert anti-inflammatory activity. We investigated the potential dual PPARα/γ agonism of prenylated benzopyrans polycerasoidol (1) and polycerasoidin (2) and their derivatives for novel drug development. Nine semisynthetic derivatives were prepared from the natural polycerasoidol (1) and polycerasoidin (2), which were evaluated for PPARα, -γ, -δ and retinoid X receptor-α activity in transactivation assays. Polycerasoidol (1) exhibited potent dual PPARα/γ agonism and low cytotoxicity. Structure-activity relationship studies revealed that a free phenol group at C-6 and a carboxylic acid at C-9' were key features for dual PPARα/γ agonism activity. Molecular modeling indicated the relevance of these groups for optimal ligand binding to the PPARα and PPARγ domains. In addition, polycerasoidol (1) exhibited a potent anti-inflammatory effect by inhibiting mononuclear leukocyte adhesion to the dysfunctional endothelium in a concentration-dependent manner via RXRα/PPARγ interactions. Therefore, polycerasoidol (1) can be considered a hit-to-lead molecule for the further development of novel dual PPARα/γ agonists capable of preventing cardiovascular events associated with metabolic disorders.

Linchpin dienes: key building-blocks in the synthesis of polyenic frameworks

This review focuses on the preparation of dienic linchpin reagents and on their use in the synthesis of polyenic frameworks.