Copper(ii)-catalyzed synthesis of multisubstituted indoles through sequential Chan-Lam and cross-dehydrogenative coupling reactions.

Starting from arylboronic acids and ester (Z)-3-aminoacrylates, one-pot syntheses of diverse indole-3-carboxylic esters have been described through copper(ii)-catalyzed sequential Chan-Lam N-arylation and cross-dehydrogenative coupling (CDC) reactions. The initial Chan-Lam arylation can proceed in DMF at 100 °C for 24 h to give ester (Z)-3-(arylamino)acrylate intermediates in the presence of Cu(OAc)2/tri-tert-butylphosphine tetrafluoroborate, a catalytic amount of myristic acid as the additive, KMnO4 and KHCO3. Sequentially, these in situ arylated intermediates can undergo an intramolecular oxidative cross-dehydrogenative coupling process in mixed solvents (DMF/DMSO = 2 : 1) at 130 °C to give C3-functionalized multi-substituted indole derivatives.

Tunable synthesis of quinolinone-fused isoquinolines through sequential one-pot nucleophilic addition and palladium-catalyzed intramolecular C-H alkenylation.

An efficient sequential one-pot synthesis of fused heterocycles based on 4-quinolinone and isoquinoline scaffolds of biological interest has been developed. In all cases, the first nucleophilic addition of 2-aryl quinolin-4(1H)-ones to alkynyl bromides in tert-pentyl alcohol can proceed in a chemo-, regio- and stereoselective manner to give (Z)-N-(1-bromo-1-alken-2-yl)quinolin-4-ones at 110 °C. Sequentially, these in situ functionalized adducts can undergo direct intramolecular aromatic C-H alkenylation in the presence of PdCl2 (5 mol%) in mixed solvents (tert-pentyl alcohol/DMF = 1 : 1), affording the novel quinolinone-fused isoquinoline derivatives in good yields.

Synthesis of 4H-Chromen-4-one Derivatives by Intramolecular Palladium-Catalyzed Acylation of Alkenyl Bromides with Aldehydes.

The palladium-catalyzed intramolecular acylation of alkenyl bromides and aldehydes was developed for an efficient synthesis of 4H-chromen-4-ones. With Pd(PPh3)4/Xphos as the catalyst and K2CO3 as the base, this protocol was applied to synthesize a small library of diversely functionalized flavonoids in moderate to good yields in 1,4-dioxane.

[Antioxidant activity of different extracts from Astragalus mongholicus].

OBJECTIVE: To study the antioxidant activities of different extracts from Astragalus mongholicus. METHOD: The antioxidant activities of the total flavanoids (TFA), the total saponins (TSA) and the total polysaccharides (TPA) from A. mongholicus were measured by means of biochemiluminescence. The concentrations of these samples varied from 1.25 x 10(-3) g x L(-1) to 25 x10(-3) g x L(-1). RESULT: All the extracts showed antioxidant activities of scavenging 3 different free radicals with obvious concentration-scavenging capacity relationship. The antioxidant activity of TFA was the strongest among them. The IC50 of scavenging superoxide anion radicals of TFA (55.48% TFA, 0.59% TFA and 0.36% TFA) were 0.654 2, 4.654 4 and 6.055 2 g x L(-1), the IC50 of scavenging hydroxyl anion were 0.060 5, 0.254 4 and 0.493 0 g x L(-1), and the IC50 of scavenging hydrogen peroxide were 0.010 4, 0.156 0 and 0.224 0 g x L(-1), respectively. CONCLUSION: The extracts are more sensitive to hydrogen peroxide and hydroxyl anion than to superoxide anion radicals. TFA of A. mongholicus Bunge is the main component responsible for antioxidant activity, while TSA and TPA have weaker antioxidant activity. The antioxidant activity of TFA increases with the rise of its purity. On the contrary, the antioxidant activity of TSA and TPA decreases with the rise of their purity.

Astragaloside IV improved intracellular calcium handling in hypoxia-reoxygenated cardiomyocytes via the sarcoplasmic reticulum Ca-ATPase.

Although astragaloside IV, a saponin isolated from Astragalus membranaceus, has been shown to protect the myocardium against ischemia/reperfusion injury, its effect on the status of sarcoplasmic reticulum (SR) Ca2+ transport in the injured myocardium remains largely unknown. In this study, we investigated whether in cultured cardiomyocytes subjected to hypoxia and reoxygenation (H/R) administration of astragaloside IV during H/R attenuates the myocardial cell injury and prevents changes in Ca2+ handling activities and gene expression of SR Ca2+ pump. Cultured cardiomyocytes from neonatal rats were exposed to 6 h of hypoxia followed by 3 h of reoxygenation. Myocyte injury was determined by the release of cardiac troponin I in supernatant. Astragaloside IV significantly inhibited cardiac troponin I release after H/R in a dose-dependent manner. The diastolic [Ca2+]i measured with Fura-2/AM was significantly increased after reoxygenation. Astragaloside IV prevented the rise of diastolic [Ca2+]i and the depression of caffeine-induced Ca2+ transients caused by H/R. Furthermore, the observed depressions in SR Ca2+-ATPase activity as well as the mRNA and protein expression of SR Ca2+-ATPase in hypoxic-reoxygenated cardiomyocytes were attenuated by astragaloside IV treatment. These results suggest that the beneficial effect of astragaloside IV in H/R-induced injury may be related to normalization of SR Ca2+ pump expression and, thus, may prevent the depression in SR Ca2+ handling.

Protective effect of astragalosides on myocardial injury by isoproterenol in SD rats.

We have extracted and roughly purified astragalosides (AS) from Astragalus membranaceus, a natural herb used as a traditional Chinese medicine, regarded to have pharmacodynamic benefits of protecting injured myocardium. We hypothesized that the astragalosides might exert beneficial effect in myocardial lesion by preserving both energy metabolism and Ca(2+) homeostasis. Sprague-Dauley (SD) rats were injected with isoproterenol (ISO) subcutaneous (s.c.) at a dose of 5 mg/kg/day consecutively for two days as models and were treated with astragalosides and trimetazidine intraperitoneally (i.p.) respectively, at a dose of 5 mg/kg/day one day prior to isoproterenol for 8 days. The histological changes were alleviated in isoproterenol-injected SD rats treated with astragalosides. Compared with isoproterenol-injected rats, the concentration of myocardial intracellular [Ca(2+)]i was decreased, L-type Ca(2+) current density and sarcoplasmic reticulum (SR) Ca(2+) load were recovered, the concentration of myocardial ATP was increased and phosphocreatine (PCr) was decreased in rats treated with astragalosides. In conclusion, the efficacious treatment of astragalosides for myocardial injury might be through regulating intracellular Ca(2+) homeostasis and energy metabolism.

Simultaneous analysis of seven astragalosides in Radix Astragali and related preparations by liquid chromatography coupled with electrospray ionization time-of-flight mass spectrometry.

A method has been developed for the qualitative and quantitative analysis of pharmacologically active astragalosides isolated from several species of the genus Astragalus by high performance liquid chromatography coupled with electrospray ionization time-of-flight mass spectrometry. Seven astragalosides in Radix Astragali and their commercial pharmaceutical preparations were analyzed using the developed method. The extracted ion current chromatograms were obtained from the total ion current chromatogram using the m/z of [M+Na]+ ions produced by target compounds for peak determination. The limits of detection and limits of quantification were in the range of 0.10-0.22 ng and 0.22-0.52 ng in full scan mode, respectively. All calibration curves showed good linear regression (r2 > or = 0.9965) within the test range. The overall intra- and inter-day precision was less than 2.86% for peak area and the accuracy was higher than 92.9% on using ginsenoside I as internal standard. The assay was successfully utilized to analyze the major biologically active astragalosides in six samples of Astragalus membranaceus (Fisch.) Bge var. mongholicus (Bge.) Hsiao. and eight commercial preparations. The overall results demonstrate that this method is simple, selective, and suitable for the quality control of Chinese medicine and their preparation in the low nanogram range.

Effect of astragalosides on intracellular calcium overload in cultured cardiac myocytes of neonatal rats.

Astragalosides were the main active components from a native Chinese herb Astragalus membranaceus. Recent studies have shown that Astragalosides have a protective effect on myocardial injury in rats. The present study was designed to investigate the effect of Astragalosides on intracellular calcium overload and sarcoplasmic reticulum calcium load (SR Ca2+ load) in cultured cardiac myocytes from neonatal rats. Astragalosides (100 microg/ml) were incubated in the presence of isoproterenol (ISO) (10(-5) M) for 72 hours in cardiomyocytes. Metoprorol (10(-6) M), a beta1-selective antagonist, was cultured in the same condition as Astragalosides. The result showed that intracellular calcium concentration ([Ca2+]i) and SR Ca2+ load increased in ISO-treated cardiac myocytes as compared to control (P < 0.01). Astragalosides prevented ISO-induced increase in [Ca2+]i and SR Ca2+ load. Metoprolol also inhibited those increase. The mRNA expression and activity of sarcoplasmic reticulum Ca2+ ATPase (SERCA) were enhanced following ISO treatment in cardiac myocytes, and these increases were inhibited by Astragalosides or metoprolol (P < 0.05). The decrease of superoxide dismutase (SOD) activity and the elevation of intracellular maleic dialdehyde (MDA) were observed after ISO treatment in cardiac myocytes. Both Astragalosides and metoprolol restored the SOD activity and reduced the level of MDA. We conclude that Astragalosides have the effects on reducing [Ca2+]i and SR Ca2+ load, enhancing free radical removal and decreasing lipid peroxidation in ISO-treated cardiomyocytes, which might account for their protective effect on myocardial injury.