Synthesis and multimodal activity of 3a,6-epoxyisoindole-2(3H)-(carbox/thio/seleno)amides in models of glycation, oxidative stress, and inflammation: Toward the development of agents targeting the triggering mechanisms of fibrogenesis

The aim. Within a series of 3a,6-epoxyisoindole-2(3H)-(carbox/thio/seleno)amides, we sought to identify a multimodal scaffold suitable for the further development of agents to prevent and treat fibrotic diseases by assessing of compound's ability to mitigate glycation and oxidative stress, key triggers of fibrogenesis; to select a non-cytotoxic lead with a balanced combination of these two activities, and to preliminarily evaluate its anti-inflammatory potential. Materials and methods. Target 3a,6-epoxyisoindole-2(3H)-(carbox/thio/seleno)amides were synthesised using the IMDAF approach. Antiglycation activity was evaluated in a bovine serum albumin-glucose model by registering advanced glycation end-product (AGE) fluorescence. Antioxidant properties were determined using the ABTS assay. Cytotoxicity and anti-inflammatory effects were studied in peritoneal macrophages from adult wild-type white mice (n = 4; body mass 30-35 g). Cytotoxicity was assessed by the MTT assay and lactate dehydrogenase (LDH) release, while anti-inflammatory effects were evaluated in a model of LPS-induced nitric oxide (NO) production. Results. The study delineates promising directions for modifying the epoxyisoindole scaffold for drug discovery and proposes a screening framework for agents targeting pathologies dependent on non-enzymatic damaging mechanisms (glycation, oxidation), including fibrotic diseases. Active molecules were identified among derivatives of hydrogenated 3a,6-epoxyisoindole. Compound 2.10 - 7a-chloro-N-(4-chlorophenyl)-1,6,7,7a-tetrahydro-3a,6-epoxyisoindole-2(3H)-carbothioamide - exhibited an optimal balance of antiglycation (at 100 mu M, inhibition of glycation 40.1 +/- 1.7%) and antioxidant activity (at 111 mu M, reduction in ABTS center dot+ colour intensity 57.1 +/- 1.1%) with low cytotoxicity (apparent from >= 250 mu M). By contrast, compounds 2.16-2.19 (bearing an aroyl fragment) showed exceptionally high antioxidant activity (95.0-96.5% reduction in ABTS center dot+ colour intensity) without concordant antiglycation effects (inhibition not exceeding 15%). In the model used, anti-inflammatory activity of 2.10 was not detected. Conclusion. Compound 2.10 is a promising starting point for further structural optimisation toward agents acting on early pathogenetic events driven by non-enzymatic damaging triggers, including the prevention and treatment of fibrotic remodelling.