Implication of Cyclic Nucleotide Phosphodiesterase Inhibition in the Vasorelaxant Activity of the Citrus-Fruits Flavonoid (±)-Naringenin

Abstract

The potential vasorelaxant, antioxidant and cyclic nucleotide phosphodiesterase (PDE) inhibitory effects of the citrus-fruit flavonoids naringin and (±)-naringenin were comparatively studied for the first time in this work. (±)-Naringenin (1 μM - 0.3 mM) did not affect the contractile response induced by okadaic acid (OA, 1 μM). However, (±)-naringenin relaxed, in a concentration-dependent manner, the contractions elicited by phenylephrine (PHE, 1 μM) or by a high extracellular KCl concentration (60 mM) in intact rat aortic rings. Mechanical removal of endothelium and/or pretreatment of aorta rings with glibenclamide (GB, 10 μM) or tetraethylammonium (TEA, 2 mM) did not significantly modify the vasorelaxant effects of this flavanone. (±)-Naringenin (10 μM - 0.1 mM) did not alter the basal uptake of ⁴⁵Ca²⁺ but decreased the influx of ⁴⁵Ca²⁺ induced by PHE and KCl in endothelium-containing and endothelium-denuded rat aorta. (±)-Naringenin (10 μM - 0.1 mM) was ineffective to scavenge superoxide radicals (O₂ ^·-) generated by the hypoxanthine (HX)-xanthine oxidase (XO) system and/or to inhibit XO activity. (±)-Naringenin (0.1 mM) significantly increased the production of cGMP and cAMP decreased by PHE (1 μM) and high KCl (60 mM) in cultured rat aortic myocytes. (±)-Naringenin preferentially inhibited calmodulin (CaM)-activated PDE1, PDE4 and PDE5 isolated from bovine aorta with IC₅₀ values of about 45 μM, 60 μM and 68 μM, respectively. In contrast, the 7-rhamnoglucoside of (±)-naringenin, naringin (1 μM - 0.3 mM), was totally inactive in all experiments. These results indicate that the vasorelaxant effects of (±)-naringenin seem to be basically related to the inhibition of PDE1, PDE4 and PDE5 activities.

Abbreviations

CaM:calmodulin

GB:glibenclamide

HX:hypoxanthine

IBMX:3-isobutyl-1-methylxanthine

MLC:myosin light chain

NBT:nitroblue tetrazolium

O₂ ^·-:superoxide radical

OA:okadaic acid

PBS:phosphate-buffered saline

PDE(s):cyclic nucleotide phosphodiesterase(s)

PHE:phenylephrine

SOD:superoxide dismutase

TEA:tetraethylammonium

XO:xanthine oxidase

(±)-Naringenin - flavanone - cyclic nucleotide phosphodiesterases - ⁴⁵Ca²⁺ uptake - rat aorta - vasorelaxation

References

• 1 Middleton E J r, Kandaswami C, Theoharides T C. The effects of plant flavonoids on mammalian cells: implications for inflammation, heart disease, and cancer.  Pharmacol Rev. 2000;  52 673-751
• 2 Noguera M A, Ivorra M M, Lugnier C, D’Ocon P. Role of cyclic nucleotide phosphodiesterase isoenzymes in contractile responses of denuded rat aorta related to various Ca²⁺ sources.  Naunyn Schmiedeberg’s Arch Pharmacol. 2001;  363 612-9
• 3 Rybalkin S D, Yan C, Bornfeldt K E, Beavo J A. Cyclic GMP phosphodiesterases and regulation of smooth muscle function.  Circ Res. 2003;  93 280-91
• 4 Hou Y C, Hsiu S L, Yen H, Chen C C, Chao P DL. Effect of honey on naringin absorption from a decoction of the pericarps of Citrus grandis .  Planta Med. 2000;  66 439-43
• 5 Sánchez De Rojas V R, Somoza B, Ortega T, Villar A M. Isolation of vasodilatory active flavonoids from the traditional remedy Satureja obovata .  Planta Med. 1996;  62 272-4
• 6 Herrera M D, Zarzuelo A, Jiménez J, Marhuenda E, Duarte J. Effects of flavonoids on rat aortic smooth muscle contractility: structure-activity relationships.  Gen Pharmacol. 1996;  27 273-7
• 7 Ajay M, Gilani A U, Mustafa M R. Effects of flavonoids on vascular smooth muscle of the isolated rat thoracic aorta.  Life Sci. 2003;  74 603-12
• 8 Orallo F, Álvarez E, Camiña M, Leiro J M, Gómez E, Fernández P. The possible implication of trans-resveratrol in the cardioprotective effects of long-term moderate wine consumption.  Mol Pharmacol. 2002;  61 294-302
• 9 Orallo F. Study of the in vivo and in vitro cardiovascular effects of a hydralazine-like vasodilator agent (HPS-10) in normotensive rats.  Br J Pharmacol. 1997;  121 1627-36
• 10 Vidrio H, Fernández G, Medina M, Álvarez E, Orallo F. Effects of hydrazine derivatives on vascular smooth muscle contractility, blood pressure and cGMP production in rats: comparison with hydralazine.  Vasc Pharmacol. 2003;  40 13-21
• 11 Lugnier C, Schoeffter P, Le Bec A, Strouthou E, Stoclet J C. Selective inhibition of cyclic nucleotide phosphodiesterases of human, bovine and rat aorta.  Biochem Pharmacol. 1986;  35 1743-51
• 12 Kameni Tcheudji J F, Lebeau L, Virmaux N, Maftei C G, Cote R H, Lugnier C, Schultz P. Molecular organisation of bovine rod cGMP-phosphodiesterase 6.  J Mol Biol. 2001;  310 781-91
• 13 Keravis T M, Wells J N, Hardman J G. Cyclic nucleotide phosphodiesterase activities from pig coronary arteries. Lack of interconvertibility of major forms.  Biochim Biophys Acta. 1980;  613 116-29
• 14 Orallo F. Regulation of cytosolic calcium levels in vascular smooth muscle.  Pharmacol Ther. 1996;  69 153-71
• 15 Hussain M B, Marshall Y. Characterization of α₁-adrenoceptor subtypes mediating contractions to phenylephrine in rat thoracic aorta, mesenteric artery and pulmonary artery.  Br J Pharmacol. 1997;  122 849-58
• 16 Borges F, Fernandes E, Roleira F. Progress towards the discovery of xanthine oxidase inhibitors.  Curr Med Chem. 2002;  9 195-217
• 17 Cos P, Ying L, Calomme M, Hu J P, Cimanga K, Van Poel B, Pieters L, Vlietinck A J, Berghe D V. Structure-activity relationship and classification of flavonoids as inhibitors of xanthine oxidase and superoxide scavengers.  J Nat Prod. 1998;  61 71-6
• 18 Wakabayashi I, Sakamoto K, Hatake K. Inhibitory effects of cadmium ion on extracellular Ca²⁺-independent contraction of rat aorta.  Eur J Pharmacol. 1995;  293 133-40
• 19 Karaki H, Ozaki H, Hori M, Mitsui-Saito M, Amano K I, Harada K I. et al . Calcium movements, distribution, and functions in smooth muscle.  Pharmacol Rev. 1997;  49 157-230
• 20 van der Zypp A, Rechtman M, Majewski H. The role of cyclic nucleotides and calcium in the relaxation produced by amrinone in rat aorta.  Gen Pharmacol. 2000;  34 245-53
• 21 Lorenz J N, Bielefeld D R, Sperelakis N. Regulation of calcium channel current in A7r5 vascular smooth muscle cells by cyclic nucleotides.  Am J Physiol. 1994;  266 C1656-63
• 22 Felgines C, Texier O, Morand C, Manach C, Scalbert A, Regerat F, Remesy C. Bioavailability of the flavanone naringenin and its glycosides in rats.  Am J Physiol Gastrointest Liver Physiol. 2000;  279 G1148-54