Endothelium-independent vasorelaxant effect of a Berberis orthobotrys root extract via inhibition of phosphodiesterases in the porcine coronary artery.

BACKGROUND: Berberis orthobotrys Bien ex Aitch. (Berberidaceae) is a plant indigenous of Pakistan that is locally used for the treatment of hypertension. HYPOTHESIS: This study evaluated the vasoactive properties of a Berberis orthobotrys root extract and its fractions, and investigated the role of the endothelium and the underlying mechanism. STUDY DESIGN: An aqueous methanolic extract of Berberis orthobotrys roots was prepared and submitted to a multi-step liquid-liquid fractionation with solvents of increasing polarity. Vascular reactivity of the different fractions was assessed using porcine coronary artery rings either with or without endothelium, and in the presence or absence of specific pharmacological tools. The ability of Berberis orthobotrys extracts to affect phosphodiesterase (PDE) activity was evaluated using a radioenzymatic method and purified phosphodiesterases. RESULTS: The aqueous methanol extract induced similar relaxations in coronary artery rings with and without endothelium, and, amongst the three derived preparations, the butanol fraction (BFBO) was slightly but significantly more effective than the ethyl acetate fraction and the aqueous residue in rings without endothelium. Analysis of the butanol fraction (BFBO) by LC-ELSD-MS indicated the presence of four major isoquinoline alkaloids including berberine. BFBO significantly potentiated the relaxations induced by cyclic GMP- and cyclic AMP-dependent relaxing agonists, and inhibited contractions to KCl, CaCl2, and U46619 in endothelium denuded rings. In contrast, BFBO did not affect relaxations to endothelium-dependent vasodilators. BFBO concentration-dependently inhibited the cyclic GMP-hydrolyzing activity of basal PDE1, calmodulin-activated PDE1 and PDE5, and of cyclic AMP-hydrolyzing activity of PDE3 and PDE4 with IC50 values ranging from 40 to 130µg/ml. CONCLUSION: The butanol fraction of the aqueous methanol extract of Berberis orthobotrys roots induced pronounced endothelium-independent relaxations and inhibited contractile responses by acting directly at the vascular smooth muscle in the coronary artery. Moreover, BFBO potentiated relaxations induced by both cyclic GMP- and cyclic AMP-dependent vasodilators most likely due to its ability to inhibit several vascular PDEs, and in particular PDE4 and PDE5.

Anti-allergic and anti-inflammatory triterpenes from the herb of Prunella vulgaris.

The activity-guided fractionation of the extract of the herb of Prunella vulgaris (Labiatae) led to the isolation of four triterpenes, i.e., betulinic acid, ursolic acid, 2 alpha,3 alpha-dihydroxyurs-12-en-28-oic acid, and 2 alpha-hydroxyursolic acid. One of these compounds, 2 alpha,3 alpha-dihydroxyursolic acid, demonstrated significant inhibition on the release of beta-hexosaminidase from the cultured RBL-2H3 cells in a dose-dependent manner; the IC50 value was calculated to be 57 microM. When the isolated compounds were tested for their effects on the production of nitric oxide from cultured murine macrophages, RAW 264.7 cells, ursolic acid and 2 alpha-hydroxyursolic acid exhibited strong inhibitory activities (IC50 values, 17 and 27 microM, respectively).

Yomogin inhibits the degranulation of mast cells and the production of the nitric oxide in activated RAW 264.7 cells.

Yomogin (1), an eudesmane sesquiterpene isolated from Artemisia princeps, was tested for the effects on the degranulation process of cultured mast cells and on the nitric oxide production in LPS-activated murine macrophages. It demonstrated a significant inhibition on the release of beta-hexosaminidase from the cultured RBL-2H3 cells in a dose-dependent manner (IC50 value, 50 microM) and also exhibited a potent inhibition on the nitric oxide production from the activated RAW264.7 cells (IC50 value, 3 microM).

Inhibition of mast cell degranulation by tanshinones from the roots of Salvia miltiorrhiza.

The activity-guided fractionation of the extract of the root of Salvia miltiorrhiza B. (Labiatae, Tanshen), led to the isolation of four active components responsible for the anti-allergic activity in vitro. Among them, 15,16-dihydrotanshinone-I and cryptotanshinone demonstrated significant inhibition of the release of beta-hexosaminidase from cultured RBL-2H3 cells in a dose-dependent manner; the IC50 values were calculated as 16 and 36 microM, respectively.