ABSTRACT
Successful vascular healing after percutaneous coronary interventions is related to the inhibition of abnormal vascular smooth muscle cell proliferation and efficient re-endothelialization. In the search for vascular smooth muscle cell anti-proliferative agents from natural sources we identified piperine (1), the main pungent constituent of the fruits from Piper nigrum (black pepper). Piperine inhibited vascular smooth muscle cell proliferation with an IC50 of 21.6 µM, as quantified by a resazurin conversion assay. Investigations of ten piperamides isolated from black pepper fruits and 15 synthesized piperine derivatives resulted in the identification of three potent vascular smooth muscle cell proliferation inhibitors: the natural alkaloid pipertipine (4), and the two synthetic derivatives (2E,4E)-N,N-dibutyl-5-(3,5-dimethoxyphenyl)penta-2,4-dienamide (14) and (E)-N,N-dibutyl-3-(naphtho[2,3-d][1,3]dioxol-5-yl)acrylamide (20). They showed IC50 values of 3.38, 6.00, and 7.85 µM, respectively. Furthermore, the synthetic compound (2E,4E)-5-(4-fluorophenyl)-1-(piperidin-1-yl)penta-2,4-dien-1-one (12) was found to be cell type selective, by inhibiting vascular smooth muscle cell proliferation with an IC50 of 11.8 µM without influencing the growth of human endothelial cells.
Subject(s)
Alkaloids/pharmacology , Benzodioxoles/pharmacology , Cell Proliferation/drug effects , Muscle, Smooth, Vascular/drug effects , Piper nigrum/chemistry , Piperidines/pharmacology , Plant Extracts/pharmacology , Polyunsaturated Alkamides/pharmacology , Alkaloids/chemical synthesis , Alkaloids/chemistry , Alkaloids/isolation & purification , Benzodioxoles/chemical synthesis , Benzodioxoles/chemistry , Benzodioxoles/isolation & purification , Fruit/chemistry , Humans , Inhibitory Concentration 50 , Molecular Structure , Piperidines/chemical synthesis , Piperidines/chemistry , Piperidines/isolation & purification , Plant Extracts/chemistry , Plant Extracts/isolation & purification , Polyunsaturated Alkamides/chemical synthesis , Polyunsaturated Alkamides/chemistry , Polyunsaturated Alkamides/isolation & purificationABSTRACT
SCOPE: Vascular smooth muscle cell (VSMC) proliferation is involved in the pathogenesis of cardiovascular disease, making the identification of new counteracting agents and their mechanisms of action relevant. Ginger and its constituents have been reported to improve cardiovascular health, but no studies exist addressing a potential interference with VSMC proliferation. METHODS AND RESULTS: The dichloromethane extract of ginger inhibited VSMC proliferation when monitored by resazurin metabolic conversion (IC50 = 2.5 µg/mL). The examination of major constituents from ginger yielded [6]-shogaol as the most active compound (IC50 = 2.7 µM). In the tested concentration range [6]-shogaol did not exhibit cytotoxicity toward VSMC and did not interfere with endothelial cell proliferation. [6]-shogaol inhibited DNA synthesis and induced accumulation of the VSMC in the G0 /G1 cell-cycle phase accompanied with activation of the nuclear factor-erythroid 2-related factor 2 (Nrf2)/HO-1 pathway. Since [6]-shogaol lost its antiproliferative activity in the presence of the heme oxygenase-1 (HO-1) inhibitor tin protoporphyrin IX, HO-1 induction appears to contribute to the antiproliferative effect. CONCLUSION: This study demonstrates for the first time inhibitory potential of ginger constituents on VSMC proliferation. The presented data suggest that [6]-shogaol exerts its antiproliferative effect through accumulation of cells in the G0 /G1 cell-cycle phase associated with activation of the Nrf2/HO-1 pathway.