Vasorelaxant effect of curcubisabolanin A isolated from Curcuma longa through the PI3K/Akt/eNOS signaling pathway.

ETHNOPHARMACOLOGICAL RELEVANCE: Curcuma longa L. (Zingiberaceae) is a known blood-activating and stasis-removing traditional Chinese medicine and has relevant pharmacological properties. The rhizomes of C. longa have been used for the treatment of cardiovascular disease (CVD) in China. Previous studies have shown that sesquiterpenoids from C. longa have significant vasorelaxant effects, which are closely associated with the prevention and treatment of CVD. AIM OF THE STUDY: To explore the sesquiterpenoids with vasorelaxant effects from C. longa and investigate the underlying mechanisms. MATERIALS AND METHODS: The compound was isolated from C. longa by multiple chromatography technologies. Its structure was determined by extensive spectroscopic analyses, nuclear magnetic resonance (NMR) data calculations, electronic circular dichroism (ECD) data calculations, and optical rotation (OR) data calculations. The vasorelaxant effect of the isolated compound was evaluated by KCl- or phenylephrine (PHE)-inducing contraction of the rat thoracic aortic rings. Endothelial removal and L-NAME pretreatment experiments were used to verify the endothelium-dependent vasorelaxant effect of the isolated compound in rat thoracic aortic rings. NO production was monitored in human umbilical vein endothelial cells (HUVECs). Western blot was carried out in HUVECs to elucidate the potential mechanisms. RESULTS: A new bisabolane-type sesquiterpenoid, curcubisabolanin A [(+)-(1S,7S,9E)-bisabola-2(3),4(15),9(10)-trien-11-ol], was isolated from the rhizomes of C. longa. curcubisabolanin A exhibited endothelium-dependent relaxation on rat thoracic aortic rings, while pre-treatment of intact aortic rings with an eNOS inhibitor (L-NAME) attenuated the vasorelaxant response of curcubisabolanin A. In addition, curcubisabolanin A induced intracellular NO production and significantly increased the levels of phosphorylated PI3K (p-PI3K), phosphorylated Akt (p-Akt), and phosphorylated eNOS (p-eNOS) in HUVECs. LY294002 (a blocker of PI3K) and MK-2206 (a highly selective inhibitor of Akt) significantly decreased these effects of curcubisabolanin A. CONCLUSIONS: These findings demonstrated that the vasorelaxant effect of curcubisabolanin A was partially endothelium-dependent and was related to regulation of NO production in vascular endothelial cells through the PI3K/Akt/eNOS signaling pathway.

New lignans from the fruits of Leonurus japonicus and their hepatoprotective activities.

Twelve tetrahydrofuran lignans (1-12), including six new compounds (1-6), were isolated from the 70% EtOH extract of the fruits of Leonurus japonicus. Spectroscopic analyses and ECD and OR calculations were used to determine their structures. Compounds 5 and 6 were unusual alkaloidal lignans with a butyrolactam unit. Based on the beneficial effects of the fruits of L. japonicus (Chongweizi in Chinese) on the liver in traditional Chinese medicine (TCM), the hepatocyte protective activities of the isolates were studied by MTT, Hoechst 33,342 staining, and western blotting. The MTT results revealed that compounds 1, 2, 7, and 8 significantly increased the survival rates of HL-7702 cells injured by acetaminophen, with EC50 values of 10.41 ± 0.90 µM, 19.86 ± 3.13 µM, 9.68 ± 1.93 µM, and 21.35 ± 3.58 µM, respectively. In the Hoechst 33,342 fluorescence staining, compounds 1 and 7 suppressed the apoptosis of the injured HL-7702 cells. Furthermore, the western blot analysis showed that compounds 1 and 7 increased the Bcl-2/Bax protein expression ratio and procaspase-3 protein expression, indicating that compounds 1 and 7 may exert hepatoprotective activity by regulating the mitochondrial apoptotic pathway.