Dual-acting agents that possess free radical scavenging and antithrombotic activities: design, synthesis, and evaluation of phenolic tetrahydro-beta-carboline RGD peptide conjugates

Structure-activity relationship studies for multitarget antithrombotic drugs

Thrombosis is a complex process involving multiple pathways. Currently, therapy relies on the combination of two or more antithrombotic drugs, showing that inhibiting more than one target provides benefits in the prevention and treatment of thrombosis. This review focuses on structure-activity relationship studies of molecules possessing multiple actions against thrombosis, namely, dual inhibitors of coagulation, dual inhibitors of coagulation and platelet aggregation, and also dual inhibitors of platelet aggregation. EP217609 has just entered clinical trials, which raise the expectations on the multitarget strategy to prevent or treat thrombosis.

Pharmacological protection of mitochondrial function mitigates acute limb ischemia/reperfusion injury

We describe several novel curcumin analogues that possess both anti-inflammatory antioxidant properties and thrombolytic activities. The therapeutic efficacy of these curcumin analogues was verified in a mouse ear edema model, a rat arterial thrombosis assay, a free radical scavenging assay performed in PC12 cells, and in both in vitro and in vivo ischemia/reperfusion models. Our findings suggest that their protective effects partially reside in maintenance of optimal mitochondrial function.

Pharmacological importance of optically active tetrahydro-β-carbolines and synthetic approaches to create the C1 stereocenter

1,2,3,4-Tetrahydro-β-carbolines (THβCs) are a pharmacologically important group of compounds belonging to the indole alkaloids. C1-Substituted optically active THβCs have been the target of extensive synthetic efforts due to the presence of the scaffold in numerous natural products and synthetic targets. This review briefly summarizes the methods to obtain the C1 stereocenter and concentrates on evaluating the pharmacological importance of optically active C1-substituted THβCs, including their PDE5-inhibitory, antimalarial, antiviral and antitumor activities.

Novel antitumor indolizino[6,7-b]indoles with multiple modes of action: DNA cross-linking and topoisomerase I and II inhibition

A series of bis(hydroxymethyl)indolizino[6,7-b]indoles and their bis(alkylcarbamates) were synthesized for antitumor studies. These agents were designed as hybrid molecules of β-carboline (topoisomerase inhibition moiety) and bis(hydroxymethyl)pyrrole (DNA cross-linking moiety). The preliminary antitumor studies indicated that these agents exhibited significant cytotoxicity against a variety of human tumor cells in vitro. Treatment of human breast carcinoma MX-1 xenograft-bearing nude mice with compounds 18b and 28c achieved more than 99% tumor remission. We also observed that 18a displayed potent therapeutic efficacy against human lung adenocarcinoma A549 and colon cancer HT-29 xenografts. These results revealed that compound 18a was more potent than irinotecan against HT-29 cells and was as potent as irinotecan against A549 cells in xenograft models. Furthermore, we demonstrated that these derivatives possess multiple modes of action, such as induction of DNA cross-linking, inhibition of topoisomerase I and II, and cell-cycle arrest at the S-phase.

Design, synthesis, and biological evaluation of callophycin A and analogues as potential chemopreventive and anticancer agents

Callophycin A was originally isolated from the red algae Callophycus oppositifolius and shown to mediate anticancer and cytotoxic effects. In our collaborative effort to identify potential chemopreventive and anticancer agents with enhanced potency and selectivity, we employed a tetrahydro-β-carboline-based template inspired by callophycin A for production of a chemical library. Utilizing a parallel synthetic approach, 50 various functionalized tetrahydro-β-carboline derivatives were prepared and assessed for activities related to cancer chemoprevention and cancer treatment: induction of quinone reductase 1 (QR1) and inhibition of aromatase, nitric oxide (NO) production, tumor necrosis factor (TNF)-α-induced NFκB activity, and MCF7 breast cancer cell proliferation. Biological results showed that the n-pentyl urea S-isomer 6a was the strongest inducer of QR1 with an induction ratio (IR) value of 4.9 at 50 μM [the concentration to double the activity (CD)=3.8 μM] and its corresponding R-isomer 6f had an IR value of 4.3 (CD=0.2 μM). The isobutyl carbamate derivative 3d with R stereochemistry demonstrated the most potent inhibitory activity of NFκB, with the half maximal inhibitory concentration (IC(50)) value of 4.8 μM, and also showed over 60% inhibition at 50 μM of NO production (IC(50)=2.8 μM). The R-isomer urea derivative 6j, having an appended adamantyl group, exhibited the most potent MCF7 cell proliferation inhibitory activity (IC(50)=14.7 μM). The S-isomer 12a of callophycin A showed the most potent activity in aromatase inhibition (IC(50)=10.5 μM).

Design, synthesis and cardioprotective effect of a new class of dual-acting agents: Phenolic tetrahydro-β-carboline RGD peptidomimetic conjugates

In this study, a new class of phenolic tetrahydro-beta-carboline RGD peptidomimetic conjugates was designed and synthesized. The radical scavenging activities of these newly synthesized compounds 12a-c were evaluated in PC12 cell survival assays. The NO scavenging activities of these compounds were confirmed in the acetylcholine-induced vasorelaxation assay. Compounds 12a-c were efficacious in a rat arterial thrombosis model, and were active in ADP- or PAF-induced in vitro platelet aggregation assays, which suggests these compounds also possess anti-thrombotic activity. The beneficial effects of dual-acting agent 12c were demonstrated on the ischemia-reperfusion induced cardiac infarct size and oxidative change in an in vivo rat model.