Frangulin B, an Antagonist of Collagen-Induced Platelet Aggregation and Adhesion, Isolated from Rhamnus formosana

Emodin - A natural anthraquinone derivative with diverse pharmacological activities

Emodin (1,3,8-trihydroxy-6-methyl-anthraquinone) is a natural anthraquinone derivative that is present in numerous globally renowned herbal medicines. It is recognised as a protein tyrosine kinase inhibitor and as an anticancer drug, active against various tumour cells, including lung, breast, liver, and ovarian cancer cells. Recently, its role in combination chemotherapy with various allopathic medicines, to minimize their toxicity and to enhance their efficacy, has been studied. The use of emodin in these therapies is gaining popularity, due to fewer associated side effects compared with standard anticancer drugs. Emodin has a broad therapeutic window, and in addition to its antineoplastic activity, it displays anti-ulcer, anti-inflammatory, hepatoprotective, neuroprotective, antimicrobial, muscle relaxant, immunosuppressive and antifibrotic activities, in both in vitro and in vivo models. Although reviews on the anticancer activity of emodin have been published, none coherently unite all the pharmacological properties of emodin, particularly the anti-oxidant, antimicrobial, antidiabetic, immunosuppressive and hepatoprotective activities of the compound. Hence, in this review, all of the available data regarding the pharmacological properties of emodin are explored, with particular emphasis on the modes of action of the molecule. In addition, the manuscript details the occurrence, biosynthesis and chemical synthesis of the compound, as well as its toxic effects on biotic systems.

In Silico Screening for Anti-inflammatory Bioactive Molecules from Ayurvedic Decoction, Balaguluchyadi kashayam

BACKGROUND

Balaguluchyadi kashayam, a polyherbal Ayurvedic decoction prepared from Sidacordifolia L., Tinospora cordifolia (Willd.) Miers, and Cedrusdeodara (Roxb. ex D.Don) G.Don, is used in Ayurveda for the treatment of chronic inflammatory conditions. Although this herbal decoction has been used for a long period for treating chronic inflammatory conditions, the mechanism of action of the decoction in reducing inflammatory conditions associated with chronic inflammation has not been clearly understood. Mass spectroscopy-based identification of bioactive molecules present in the decoction and its interaction with enzymes/proteins involved in the pathogenesis of chronic inflammation has been carried and reported in this study.

INTRODUCTION

Polyherbalism is one of the major principles of Ayurveda. Various phytoconstituents with different activities in the polyherbal decoction act on multi targets of a wide range of diseases. Balaguluchyadi kashayam is a polyherbal decoction prescribed for chronic inflammatory etiologies and the present study aims to evaluate the binding potential of the compounds, identified from Balaguluchyadi kashayam to enzymes/proteins involved in the development and progression of chronic inflammation.

METHODS

The bioactive compounds present in the Balaguluchyadi Kashayam fractions were extracted by preparative HPLC and identified using UPLC MS Q-TOF. The physicochemical characteristics and ADMET properties of the compounds were calculated using Mol soft, Swiss ADME and OSIRIS data warrior software. Then the binding interactions between the molecules and the proinflammatory mediators such as 5 Lipoxygenase, Cyclooxygenase 2, Tumor necrosis factoralpha convertase enzyme (TACE) and Caspase 1 were determined using molecular docking software Auto Dock 4.0 (http://autodock.scripps.edu/downloads).

RESULTS

The identified bioactive molecules in the decoction showed a good binding affinity towards the enzymes/proteins involved in the development and progression of chronic inflammation compared to the binding affinity of known inhibitors/drugs to the respective enzymes/proteins.

CONCLUSION

The bioactive molecules identified in Balaguluchyadi Kashayam could be developed as potential therapeutic molecules against enzymes/proteins involved in the development and progression of chronic inflammation.

Calcium signalling in platelets and other cells

Reviewed are new concepts and models of Ca(2+) signalling originating from work with various animal cells, as well as the applicability of these models to the signalling systems used by blood platelets. The following processes and mechanisms are discussed: Ca(2+) oscillations and waves; Ca(2+) -induced Ca(2+) release; involvement of InsP(3)-receptors and quanta1 release of Ca(2+); different pathways of phospholipase C activation; heterogeneity in the intracellular Ca(2+) stores; store-and receptor-regulated Ca(2+) entry. Additionally, some typical aspects of Ca(2+) signalling in platelets are reviewed: involvement of protein serine/threonine and tyrosine kinases in the regulation of signal transduction; possible functions of platelet glycoproteins; and the importance of Ca(2+) for the exocytotic and procoagulant responses.

Oncocalyxone A inhibits human platelet aggregation by increasing cGMP and by binding to GP Ibalpha glycoprotein

BACKGROUND AND PURPOSE

Oncocalyxone A (OncoA) has a concentration-dependent anti-platelet activity. The present study aimed to further understand the mechanisms related to this effect.

EXPERIMENTAL APPROACH

Human platelet aggregation was measured by means of a turbidimetric method. OncoA (32-256 microM) was tested against several platelet-aggregating agents, such as adenosine diphosphate (ADP), collagen, arachidonic acid (AA), ristocetin and thrombin.

KEY RESULTS

OncoA completely inhibited platelet aggregation with a calculated mean inhibitory concentration (IC50-microM) of 122 for ADP, 161 for collagen, 159 for AA, 169 for ristocetin and 85 for thrombin. The anti-aggregatory activity of OncoA was not inhibited by 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ). OncoA, at a concentration that caused no significant anti-aggregatory activity, potentiated sodium nitroprusside (SNP) anti-aggregatory activity (18.8+/-2.9%-SNP vs 85.0+/-8.2%-SNP+OncoA). The levels of nitric oxide (NO) or cAMP were not altered by OncoA while cGMP levels were increased more than 10-fold by OncoA in resting or ADP-activated platelets. Flow cytometry revealed that OncoA does not interact with receptors for fibrinogen, collagen or P-selectin. Nevertheless, OncoA decreased the binding of antibodies to GP Ibalpha, a glycoprotein that is related both to von Willebrand factor and to thrombin-induced platelet aggregation.

CONCLUSION AND IMPLICATIONS

OncoA showed anti-aggregatory activity in platelets that was associated with increased cGMP levels, not dependent on NO and with blocking GP Ibalpha glycoprotein. This new mechanism has the prospect of leading to new anti-thrombotic drugs.

Atrovirinone inhibits pro-inflammatory mediator release from murine macrophages and human whole blood

Many plant-derived natural compounds have been reported previously to inhibit the production of important pro-inflammatory mediators such as nitric oxide, prostaglandin E2, TNF-alpha and reactive oxygen species by suppressing inducible enzyme expression via inhibition of the mitogen-activated protein kinase pathway and nuclear translocation of critical transcription factors. This study evaluates the effects of atrovirinone [2-(1-methoxycarbonyl-4,6-dihydroxyphenoxy)-3-methoxy-5,6-di-(3-methyl-2-butenyl)-1,4-benzoquinone)], a benzoquinone that we have previously isolated from Garcinia atroviridis, on two cellular systems that are repeatedly used in the analysis of anti-inflammatory bioactive compounds, namely, RAW 264.7 macrophage cells and whole blood. Atrovirinone inhibited the production of both nitric oxide and prostaglandin E2 from LPS-induced and IFN-gamma-induced RAW 264.7 cells and whole blood, with inhibitory concentration (IC)50 values of 4.62 +/- 0.65 and 9.33 +/- 1.47 micromol/L, respectively. Analysis of thromboxane B2 (TXB2) secretion from whole blood stimulated by either the cyclooxygenase (COX)-1 or the COX-2 pathway showed that atrovirinone inhibits the generation of TXB2 by both pathways, with IC50 values of 7.41 +/- 0.92 and 2.10 +/- 0.48 micromol/L, respectively. Analysis of IC50 ratios showed that atrovirinone was more COX-2 selective in its inhibition of TXB2, with a ratio of 0.32. Atrovirinone also inhibited the generation of intracellular reactive oxygen species and the secretion of TNF-alpha from RAW 264.7 cells in a dose-responsive manner, with IC50 values of 5.99 +/- 0.62 and 11.56 +/- 0.04 micromol/L, respectively. Lipoxygenase activity was also moderately inhibited by atrovirinone. Our results suggest that atrovirinone acts on important pro-inflammatory mediators possibly by the inhibition of the nuclear factor-kappaB pathway and also by the inhibition of the COX/lipoxygenase enzyme activity.

Analgesic and anti-inflammatory activities of a fraction rich in oncocalyxone A isolated from Auxemma oncocalyx

In the present work we studied the antinociceptive and antiedematogenic effects of a quinone fraction (QF) isolated from the heartwood of Auxemma oncocalyx Taub. The major constituent of QF, which represented around 80% of this fraction, was a terpenoid quinone named oncocalyxone A (1). Results show that QF (10 and 30 mg/kg body wt., i.p.) significantly inhibited paw edema induced by carrageenan at the second, third, and fourth hours. The effect was dose-dependent and long lasting, and QF was less effective orally. An antiedematogenic effect was also demonstrated in the dextran-induced paw edema. In this model, however, QF was somewhat less potent. QF (1 and 5 mg/kg body wt., i.p.) inhibited acetic acid-induced abdominal contractions in mice in a dose-dependent manner. In addition, QF (5 and 10 mg/kg body wt., i.p.) inhibited only the second phase (inflammatory) in the formalin test, and showed no effect in the hot-plate test in mice. The antinociceptive activity of QF was predominantly peripheral and independent of the opioid system. The observed effects of QF are, at least in part, probably due to the presence of oncocalyxone A (1).

Myocardial protection by protykin, a novel extract of trans-resveratrol and emodin

Protykin is an all-natural, high potency standardized extract of trans-resveratrol (20%) and emodin (10%) derived from the dried rhizome of Polygonum cuspidatum. Previous studies have demonstrated free radical scavenging and anti-inflammatory activities of resveratrol. Since free radicals play a crucial role in the pathogenesis of myocardial ischemia/reperfusion injury, we examined whether Protykin could preserve the heart during ischemic arrest. Sprague-Dawley rats were divided into two groups: experimental group was gavaged Protykin (100 mg/kg body wt) dissolved in corn oil for three weeks, while the control group was gavaged corn oil alone. After three weeks, rats were sacrificed, isolated hearts perfused via working mode, were made globally ischemic for 30 min followed by 2 h of reperfusion. Left ventricular functions were continuously monitored and malonaldehyde (MDA) (presumptive marker for oxidative stress) formation were estimated. At the end of each experiment, myocardial infarct size was measured by TTC staining method. Peroxyl radical scavenging activity of Protykin was determined by examining its ability to remove peroxyl radical generated by 2,2'-azobis (2-amidinopropane) dihydrochloride, while hydroxy radical scavenging activity was tested with its ability to reduce 7-OH*-coumarin-3-carboxylic acid. The results of our study demonstrated that the Protykin group provided cardioprotection as evidenced by improved post-ischemic left ventricular functions (dp, dp/dt(max)) and aortic flow as compared to control group. This was further supported by the reduced infarct size in the Protykin group. Formation of MDA was also reduced by Protykin treatment. In vitro studies demonstrated that Protykin possessed potent peroxyl and hydroxyl radical scavenging activities. The results of this study indicate that Protykin can provide cardioprotection, presumably by virtue of its potent free radical scavenging activity.

A tumor cell growth inhibitor from Polygonum hypoleucum Ohwi

Polygonum hypoleucum Ohwi (P. hypoleucum Ohwi) has been used as a Chinese medicine for a long time. In the present study, four anthraquinones, emodin, emodin 1-O-beta-D-glucoside (49A), physcion (62A), and physcion 1-O-beta-D-glucoside (50A) were identified from P. hypoleucum Ohwi and their inhibitory effects on various tumor cells proliferation were investigated. On a percentage basis, emodin had the highest suppressing activity on the various tumor cells proliferation. At 10 microg/ml, the percentage inhibition on K562 cells proliferation for emodin, 49A, 62A, and 50A were 97+/-3.4%, 18+7.3%, 24+/-3.6%, and 31+/-8.9%, respectively. However, inhibitory activities of 10 microg/ml of emodin, 49A, 62A, or 50A on Raji cells proliferation were 98+/-5.0%, 25+/-5.0%, 22+/-3.2%, and 28+/-4.3%, respectively. It was also found that the both C1 and C3 positions of emodin were important for antitumor action. The IC50s of emodin, 49A, 62A, and 50A on various tumor cells were also calculated. The IC50 of emodin on K562 cells was significantly lower than on Raji, HeLa, Calu-1, Wish, and Vero cells (1.5+/-0.2 vs. 2.8+/-0.4 microg/ml, P < 0.01 ;1.5+/-0.2 vs. 8.4+/-1.6 microg/ml; 1.5+/-0.2 vs. 8.9+/-1.0 microg/ml; 1.5+/-0.2 vs. 8.7+/-0.5 microg/ml; 1.5/-0.2 vs. 3.5+/-0.12 microg/ml; P < 0.001). The results indicated that K562 and Raji cells were more sensitive to emodin treatment. Cell viability test indicated that inhibitory effect of emodin on various tumor cell lines was not through direct cytotoxicity. It suggested P. hypoleucum Ohwi included a tumor cell growth inhibitor.