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Discovery of bioactive natural compounds from Traditional Chinese Medicines (TCMs) used against Cardiovascular Disease (CVD)

Final Report Summary - TCM-VASC (Discovery of bioactive natural compounds from Traditional Chinese Medicines (TCMs) used against Cardiovascular Disease (CVD).)

Cardiovascular Disease (CVD) is currently the main cause of mortality and morbidity in the world. To address this major health burden, currently there is an increasing interest in the discovery of novel classes of chemical compounds or dietary supplements that might be effective in the treatment or prevention of CVD. Many medicinal plants are successfully used for centuries in Traditional Chinese Medicine (TCM) for the treatment of CVD, but their mechanisms of action and the responsible bioactive compounds are largely unknown. Therefore, major objective of TCM-VASC is the discovery and characterization of bioactive natural compounds from TCM herbal drugs used against CVD. The project aims to achieve this objective by combining the expertise of the IIF Fellow (Dr. Rongxia Liu) in TCM research and phytochemistry with the know-how available at the Host Lab (Prof. Verena M. Dirsch, Dr. Atanas G. Atanasov) in CVD-relevant functional cell models.

At the beginning of the project medicinal plants traditionally used in China for the treatment of cardiovascular disease were selected and several solvent systems with different polarity were used to prepare crude extracts from the investigated herbal drugs. Main selection criteria applied were traditional use against disease symptoms associated with CVD, as well as limited knowledge regarding the bioactivity of chemical constituents in the respective TCM herbal drugs. The prepared different plant extracts were next tested for effectiveness in functional cell based assays relevant for vascular disease pathogenesis. Most interesting activity was observed with TCM extracts inhibiting the proliferation of vascular smooth muscle cells (VSMC). Within CVD-associated atherosclerotic plaque VSMC are changing their phenotype from a differentiated/contractile into a less differentiated/proliferative. The latter phenotype is responsible for the abnormal growth of the intimal layer of the affected vessel (known as intimal hyperplasia), which is finally resulting in the narrowing of the vessel lumen and decreased blood-flow (ischemia). Accelerated VSMC proliferation also counteracts the therapeutic effectiveness of different surgical interventions like percutaneous transluminal coronary angioplasty (PTCA) or bypass surgery, by contributing to the pathological re-narrowing (restenosis) of the blood vessels. Consequently, discovery and characterization of novel effective compounds and novel molecular targets able to suppress VSMC proliferation is highly relevant. Focusing on the characterization of the bioactive constituents from the TCM herbal extracts that suppressed VSMC proliferation, we have identified a range of interesting pure compounds with inhibitory action. Some of the identified compounds were very potent (with IC50 in the nanomolar range) and among the examined structures there were chemical scaffolds, which were not reported until know to have VSMC proliferation inhibitory potential. Furthermore, some of the compounds inhibited both the serum-induced and platelet-derived growth factor (PDGF)-induced VSMC proliferation. This was a very interesting observation, since we have also tested in parallel a range of compounds known from the literature to inhibit PDGF-induced vascular smooth muscle cell proliferation, and most of them failed to display an inhibitory effect in the presence of serum. Studies addressing the mechanism of action were initiated with some of the most interesting compounds that we have identified. While the mechanistic studies with most of the investigated compounds are still ongoing, for one compound we obtained conclusive evidence that the mechanism of their anti-proliferative action involves activation of the nuclear factor (erythroid-derived 2)-like 2 (also known as NFE2L2 or Nrf2) and its target-gene heme oxygenase-1 (HO-1).

The characterization of bioactive compounds from TCM herbal drugs traditionally used against CVD yields an increase in basic knowledge and has potential impact on patients and consumers. The gained knowledge for TCM chemical constituents and their in vitro mechanisms of action might help to achieve better TCM standardization, with subsequent improved efficacy and safety. This will be beneficial for patients or consumers using TCM as alternative medications or dietary supplements. Furthermore, the identified novel bioactive natural compounds have the potential to be further developed in novel medications or used as supplements for the development of novel functional foods with health-promoting or disease-preventing properties.
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