Cynaroside

Abstract: In our ongoing search for bioactive compounds originating from the endemic species in Korea, we found that the hexane and EtOAc fractions of the MeOH extract from the root of Dystaenia takeshimana (Nakai) Kitagawa (Umbelliferae) showed cyclooxygenase-2 (COX-2) and 5-lipoxygenase (5-LOX) dual inhibitory activity by assessing their effects on the production of prostaglandin D2 (PGD2) and leukotriene C4 (LTC4) in mouse bone marrow-derived mast cells. By activity-guided fractionation, five coumarins, viz. psoralen (2), xanthotoxin (3), scopoletin (4), umbelliferone (5), and (+)-marmesin (6), together with beta-sitosterol (1), were isolated from the hexane fraction, and two phenethyl alcohol derivatives, viz. 2-methoxy-2-(4'-hydroxyphenyl)ethanol (7) and 2-hydroxy-2-(4'-hydroxyphenyl)ethanol (8), three flavonoids, viz. apigenin (9), luteolin (10), and cynaroside (11), as well as daucosterol (12) were isolated from the EtOAc fraction using silica gel column chromatography. In addition, D-mannitol (13) was isolated from the BuOH fraction by recrystallization. Two of the coumarins, scopoletin (4) and (+)-marmesin (6), the two phenethyl alcohol derivatives (7, 8) and the three flavonoids (9-11) were isolated for the first time from this plant. Among the compounds isolated from this plant, the five coumarins as well as the three flavonoids showed COX-2/5-LOX dual inhibitory activity. These results suggest that the anti-inflammatory activity of D. takeshimana might in part occur via the inhibition of the generation of eicosanoids.

Abstract: Objectives The aim of this study was to investigate the flavonoid composition of Scutellaria immaculata and S. ramosissima (Lamiaceae) and the in-vitro biological activity of their extracts and flavonoids. Methods The flavonoid composition of S. immaculata (Si) and S. ramosissima (Sr) were analysed using LC-MS. Antimicrobial activity was studied in vitro against a range of bacteria and fungi using diffusion and microdilution methods. Anti-trypanosomal and cell proliferation inhibitory activity of the extracts and flavonoids was assessed using MTT. The antioxidant activity of the flavonoids and extracts were evaluated using DPPH* test. Key findings LC-MS investigation of Si and Sr plants allowed the identification, for the first time, of an additional 9 and 16 flavonoids, respectively. The methanol, chloroform and water extracts from these plants and six flavonoids (scutellarin, chrysin, apigenin, apigenin-7-O-glucoside, cynaroside and pinocembrine) exhibited significant inhibition of cell growth against HeLa, HepG-2 and MCF-7 cells. The chloroform extract of Sr showed potent cytotoxic effects with IC50 (drug concentration which resulted in a 50% reduction in cell viability) values of 9.25 ± 1.07 µg/ml, 12.83 ± 1.49 µg/ml and 17.29 ± 1.27 µg/ml, respectively. The highest anti-trypanosomal effect against T. b. brucei was shown by the chloroform extract of Sr with an IC50 (drug concentration which resulted in a 50% inhibition of the biological activity) of 61 µg/ml. The pure flavonoids showed an IC50 range between 3 and 29 µm, with cynaroside as the most active compound with an IC50 value of 3.961 ± 0.133 µm. The chloroform extract of Sr has potent antimicrobial activity against Streptococcus pyogenes (minimum inhibitory concentration, MIC = 0.03 mg/ml). Pinocembrine exhibited a strong activity against the all bacteria except Escherichia coli and yeasts. Water extracts of Sr and Si exhibited potent antioxidant activity with IC50 values of 5.62 ± 0.51 µg/ml and 3.48 ± 0.02 µg/ml, respectively. Scutellarin exerted stronger antioxidant activity than other flavonoids. Conclusions This is the first study reporting an in-vitro biological investigation for Si and Sr. Especially the chloroform extract of Sr showed potent anticancer and antimicrobial activity. Cynaroside had a highly selective and strong cytotoxicity against T. b. brucei while showing only mild effects against cancer cells.

Abstract: Flavonoids with potent anti-oxidative effects are the major effective components in traditional herbal medicine used in treating cardiovascular diseases. Cynaroside is a flavonoid compound that exhibits anti-oxidative capabilities. However, little is known about its effect on oxidative injury to cardiac myocytes and the underlying mechanisms. This study was designed to investigate the protective effects of cynaroside against H2O2-induced apoptosis in H9c2 cardiomyoblasts. H9c2 cells were pretreated with cynaroside for 4 h before exposure to 150 µM H2O2 for 6 h. H2O2 treatment caused severe injury to the H9c2 cells, which was accompanied by apoptosis, as revealed by analysis of cell nuclear morphology, through Annexin V FITC/PI staining and caspase proteases activation. Cynaroside pretreatment significantly reduced the apoptotic rate by enhancing the endogenous anti-oxidative activity of superoxide dismutase, glutathione peroxidase, and catalase, thereby inhibiting intracellular reactive oxygen species (ROS) generation. Moreover, cynaroside moderated H2O2-induced disruption of mitochondrial membrane potential, increased the expression of anti-apoptotic protein Bcl-2 while decreased the expression of pro-apoptotic protein Bax, and thereby inhibited the release of apoptogenic factors (cytochrome c and smac/Diablo) from mitochondria in H9c2 cells. Our data also demonstrated that cynaroside pretreatment showed an inhibitory effect on the H2O2-induced increase in c-Jun N-terminal kinase (JNK) and P53 protein expression. These results suggest that cynaroside prevents H2O2-induced apoptosis in H9c2 cell by reducing the endogenous production of ROS, maintaining mitochondrial function, and modulating the JNK and P53 pathways. J. Cell. Biochem. 112: 2019–2029, 2011. © 2011 Wiley-Liss, Inc.

Abstract: High-dose aqueous extracts from artichoke leaves were found to inhibit cholesterol biosynthesis from (14)C-acetate rather moderately in HepG2 cells in contrast to primary cultured rat hepatocytes in which the inhibition was stronger. Preincubation of the extracts with several glycohydrolases revealed that pretreatment with beta-glucosidase considerably reinforced the inhibition. A significant reduction of acetate incorporation was found above extract concentrations of 0.01 mg/mL and at 0.2 mg/mL almost 60% inhibition was observed. Cytotoxic effects detected by the MTT-assay were restricted to higher concentrations of the extracts with and without beta-glucosidase pretreatment. Since cynaroside represents a major glucoside in artichoke extracts, both cynaroside and its aglycone luteolin were tested. It could be demonstrated that cynaroside is indeed one of the targets of beta-glucosidase and that the liberated luteolin is responsible for the inhibitory effect. Direct measurements of beta-glucosidase activity in rat hepatocytes and HepG2 cells revealed that endogenous enzyme activity in hepatocytes may be sufficient to convert cynaroside to its aglycone, while in HepG2 cells this may not be the case. These findings emphasize the importance of beta-glucosidase-dependent liberation of luteolin for the ability of artichoke extracts to inhibit hepatic cholesterol biosynthesis.