Combined Experimental and Theoretical Study of the Synthesis of 5,7-Dihydroxy-4-methylcoumarin via a Pechmann Condensation in the Presence of UiO-66-SO3H Catalysts.

An efficient synthesis of 5,7-dihydroxy-4-methylcoumarin from phloroglucinol with ethyl acetoacetate in the UiO-66-SO3H metal-organic framework is reported. The potential of UiO-66-SO3H as a solid catalyst was determined through optimized-condition experiments and quantum molecular calculations. The optimal conditions for the synthesis of 5,7-dihydroxy-4-methylcoumarin with UiO-66-SO3H were as follows: phloroglucinol/ethyl acetoacetate molar ratio = 1:1.6, reaction time = 4 h, and temperature = 140 °C, for which the reaction yield reached 66.0%. The reusability of UiO-66-SO3H catalysts for Pechmann condensation was examined. The activation energy of the reaction occurring on a sulfonic group of the UiO-66-SO3H catalyst was 12.6 kcal/mol, which was significantly lower than 22.6 kcal/mol of the same reaction on the UiO-66 catalyst. To comprehend the reaction mechanism, density functional theory with the ONIOM approach was applied for the synthesis of coumarin on the UiO-66-SO3H and UiO-66 clusters. A possible reaction mechanism was proposed involving three steps: a trans-esterification step, an intramolecular hydroxyalkylation step, and a dehydration step. The rate-determining step was suggested to be the first step which acquired an activation energy of 15.7 and 29.5 kcal/mol, respectively. Information from this study can be used as guidelines to develop more efficient catalytic metal-organic frameworks for various organic syntheses.

Cardiac protection of germinated brown rice extract in rabbit model of chronic myocardial infarction.

Ischemic heart disease is a leading cause of mortality in the world. This study aimed to investigate the cardioprotective effects of germinated brown rice (GBR) on a rabbit model of chronic myocardial infarction. Eighteen New Zealand white rabbits were randomly divided into three groups receiving: 1) regular rabbit food; 2) regular rabbit food plus vehicle; and 3) regular rabbit food plus GBR for 120 d. The left circumflex coronary artery was ligated to induce myocardial ischemia 60 d after starting the experiment (baseline). Heart functions were monitored by electrocardiography and echocardiography at 0, 30, and 60 d after coronary artery ligation. The incidences of heart rate (HR) and ventricular arrhythmias have been compared between groups. GBR showed the effects to prevent life-threatening ventricular tachycardia and electrocardiographic signs of myocardial ischemia in a model of arrhythmias. GBR consumption group exhibited significantly improved cardiac function and reduced the HR, along with reduced mean arterial pressure and plasma glucose level. The results demonstrated that GBR exerts cardioprotective effects against chronic myocardial injury in rabbits. These biological actions of GBR may explain the benefits gained from the use of GBR products as a possible prophylactic lifestyle intervention.

Cardio-Protective Effects of Germinated Brown Rice Extract Against Myocardial Ischemia Reperfusion Injury.

INTRODUCTION: Ischemic heart disease is closely associated with many risk factors. Germinated brown rice extract (GBR) has potent antioxidant activities for alleviating the factors for developing heart failure such as hypertension and diabetes mellitus. AIM: The objective of the present study was to determine the cardio-protective effects of GBR and to elucidate the mechanisms underlying these effects in a model of simulated myocardial ischemic/ reperfusion injury (sI/R). METHODS: An in vitro study was performed on cultured rat cardiomyoblasts (H9c2) exposed to sI/R. The expression of apoptosis and signaling proteins was assessed using Western blot analyses. Eighteen New Zealand White rabbits were divided into 3 groups and the left circumflex coronary artery was ligated to induce myocardial ischemia. Heart functions were monitored by electrocardiography and echocardiography 0, 30, and 60 days after coronary artery ligation. RESULTS: GBR consumption group showed significantly improved cardiac function and reduced the heart rate, along with reduced mean arterial pressure and plasma glucose level. Also, GBR showed good scavenging activity, pretreatment with GBR inhibited I/R induced apoptosis by suppressing the production of caspase 3 and p38 MAPK. CONCLUSIONS: These results suggest that intake of germinated brown rice may effectively to protect cell proliferation and apoptosis and may provide important nutrients to prevent heart failure due to myocardial ischemia.

Serratene triterpenoids and their biological activities from Lycopodiaceae plants.

The plants of Lycopodiaceae family, distributed across China, India and also Southeast Asia, have been used as folk medicines. The phytochemical constitutent studies of this family was widely reported. Serratene trierpenoids is one of phytochemical constitutent type, which have been mainly isolated from this plant family. To date, more than 100 serratene-type triterpenoids have been reported and several of them have been shown promising biological activities, especially cytotoxicity and chemopreventive activity. This review covers the structural classification, biological activities and hypotheses about biosynthetic pathways of serratene-type triterpenes.