(-)-Praeruptorin A

(+/-)-3'-O, 4'-O-dicynnamoyl-cis-khellactone, a derivative of (+/-)-praeruptorin A, reverses P-glycoprotein mediated multidrug resistance in cancer cells.[Pubmed:16875827]

Bioorg Med Chem. 2006 Nov 1;14(21):7138-45.

P-glycoprotein (Pgp) is an ATP-driven membrane exporter for a broad spectrum of hydrophobic xenobiotics. Pgp-overexpression is a common cause of multidrug resistance (MDR) in cancer cells and could lead to chemotherapeutic failure. Through an extensive herbal drug screening program we previously showed that (+/-)-praeruptorin A (PA), a naturally existing pyranocumarin isolated from the dried root of Peucedanum praeruptorum Dunn., re-sensitizes Pgp-mediated MDR (Pgp-MDR) cancer cells to cancer drugs. A number of PA derivatives were synthesized and one of these, (+/-)-3'-O, 4'-O-dicynnamoyl-cis-khellactone (DCK), was more potent than PA or verapamil in the reversal of Pgp-MDR. In Pgp-MDR cells DCK increased cellular accumulation of doxorubicin without affecting the expression level of Pgp. In Pgp-enriched membrane fractions DCK moderately stimulated basal Pgp-ATPase activity, suggesting some transport substrate-like function. However, DCK also inhibited Pgp-ATPase activity stimulated by the standard substrates verapamil or progesterone with decreased V(max)s but K(m)s were relatively unchanged, suggesting a primarily non-competitive mode of inhibition. While the binding of substrates to active Pgp would increase the reactivity of the Pgp-specific antibody UIC2, DCK decreased UIC2 reactivity. These results suggest that DCK could bind simultaneously with substrates to Pgp but perhaps at an allosteric site and thus affect Pgp-substrate interactions.

(+/-)-Praeruptorin A enantiomers exert distinct relaxant effects on isolated rat aorta rings dependent on endothelium and nitric oxide synthesis.[Pubmed:20433815]

Chem Biol Interact. 2010 Jul 30;186(2):239-46.

Praeruptorin A is a coumarin compound naturally occurring in the roots of Peucedanum praeruptorum Dunn., a commonly used traditional Chinese medicine for the treatment of certain respiratory diseases and hypertension. Although previous studies indicated the relaxant effects of (+/-)-praeruptorin A on tracheal and arterial preparations, little is known about the functional characteristics of the enantiomers. In the present study, the two enantiomers were successfully isolated and identified by using a preparative Daicel Chiralpak AD-H column, and their relaxant effects on aorta rings were observed and compared. (+)-Praeruptorin A showed more potent relaxation than (-)-Praeruptorin A against KCl- and phenylephrine-induced contraction of rat isolated aortic rings with intact endothelium. Removal of the endothelium remarkably reduced the relaxant effect of (+)-praeruptorin A but not that of (-)-Praeruptorin A. Pretreatment of aortic rings with N(omega)-nitro-L-arginine methyl ester (L-NAME, an inhibitor of nitric oxide synthase) or methylene blue (MB, a soluble guanylyl cyclase inhibitor) resulted in similar changes of the relaxant effects of the two enantiomers to endothelium removal. Molecular docking studies also demonstrated that (+)-praeruptorin A was in more agreement to nitric oxide synthase pharmacophores than (-)-Praeruptorin A. On the other hand, the two enantiomers of praeruptorin A could slightly attenuate the contraction of rat aortic rings induced by internal Ca(2+) release from sarcoplasmic reticulum (SR). These findings indicated that (+)-praeruptorin A and (-)-Praeruptorin A exerted distinct relaxant effects on isolated rat aorta rings, which might be mainly attributed to nitric oxide synthesis catalyzed by endothelial nitric oxide synthase.

The effects of (+/-)-Praeruptorin A on airway inflammation, remodeling and transforming growth factor-beta1/Smad signaling pathway in a murine model of allergic asthma.[Pubmed:22974581]

Int Immunopharmacol. 2012 Dec;14(4):392-400.

(+/-)-Praeruptorin A (PA) is a pair of coumarin enantiomers isolated from the root of Peucedanum praeruptorum Dunn (PPD), a common Chinese herbal medicine for the treatment of asthma. Considering its anti-inflammatory, anti-contractile and anti-hyperplasia activities, the effects of PA on airway inflammation and airway remodeling were investigated using a murine model of chronic asthma. Ovalbumin-sensitized BALB/c mice were challenged with ovalbumin to induce asthma every other day on eight successive weeks. PA was administered intragastrically before every ovalbumin challenge. Airway responsiveness was evaluated by a lung function analysis system 48 h after the last ovalbumin challenge. The total and differential leukocytes in bronchoalveolar lavage fluid (BALF) were counted using a hemocytometer and Diff-Quick-stained smears. Lung tissue samples were used for hematoxylin and eosin, periodic acid Schiff, Masson's trichrome and alpha-SMA immunohistochemistry staining. Levels of cytokines in BALF, immunoglobulin (Ig) E in serum as well as expression of TGF-beta1 and Smad proteins in lung tissue were measured by enzyme-linked immunosorbent assay, immunohistochemistry or western blot analysis. Compared with the model group, PA suppressed airway inflammation, airway hyperresponsive and remodeling, reduced levels of IL-4 and IL-13 in BALF, and IgE in serum, inhibited expression of TGF-beta1 and pSmad2/3, up-regulated the expression of Smad7 in lung tissue, and also increased the levels of INF-gamma in BALF. These results suggested that PA significantly suppressed airway inflammation and airway remodeling induced by ovalbumin challenge, and is a potential candidate for the treatment of asthma.