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The plant Momordica charantia L. (Cucurbitaceae) is widely cultivated in Asian countries, and the fruit of this plant has been used as a bitter stomachic, a laxative, an antidiabetic, and an anthelmintic agent for children in traditional Chinese, Indian, Vietnamese, and Indonesian medicines. The alcoholic extract of M. charantia fruits has been reported to inhibit the increase of serum glucose levels in glucose-loaded rats.1) In addition, many cucurbitane-type triterpenes and their glycosides were isolated from the roots, 2) fruits, [3][4][5][6][7][8][9][10][11][12][13] seeds, 14,15) leaves, and vines [16][17][18][19] of this plant.a-Glucosidase inhibitors are oral anti-diabetic drugs used for diabetes mellitus type 2 that work by preventing the digestion of carbohydrates. Carbohydrates are normally converted into simple sugars, which can be absorbed through the intestine. Hence, inhibition of a-glucosidase enzyme can significantly decrease the postprandial increase in blood glucose levels after a mixed carbohydrate diet and could be a key strategy in the control of diabetes mellitus. In fact, a potent a-glucosidase inhibitor, acarbose, has been shown to effectively reduce the intestinal absorption of sugars in humans. 20)The main drawback of acarbose is its side effects, such as abdominal distention, flatulence, meteorism, and possibly diarrhea.21) Therefore, natural inhibitors from dietary plants that have minimal side effects and have been shown to have stronger inhibitory activity against a-glucosidase may be useful as effective therapies for postprandial hyperglycemia.22) Interestingly, in our search for bioactive metabolites, we have examined the constituents of the methanol extract of M. charantia fruits, and led to the isolation of fourteen cucurbitane-type triterpene glycosides, including three new compounds named charantosides A-C (1, 5, 6). For these reasons, the a-glucosidase inhibitory activity of all these compounds was tested. Herein, we report the isolation, structure elucidation, and biological activities of compounds 1-14 (Fig. 1). Results and DiscussionThe methanol extract of M. charantia fruits yielded three new compounds (1, 5, 6). Compound 1 was obtained as a white powder. The absorption bands at 3407 cm Ϫ1 and 1728 cm Ϫ1 in the IR spectrum indicated hydroxyl and carbonyl functionalities, respectively. A [MϩH] ϩ pseudomolecular ion peak observed at m/z: 649.4337 (Calcd for C 37 H 61 O 9 : 649.4316) in positive HR-electrospray ionization (ESI)-MS, and the 13 C-NMR spectroscopic data indicated a molecular formula of C 37 H 60 O 9 . The 13 C-NMR spectrum of 1 showed 37 carbon signals, of which were attributed to a methoxy group, a sugar moiety, and a triterpene moiety. The distortionless enhancement by polarization transfer (DEPT) experiment permitted differentiation of the 37 carbon signals including eight methyl, eight methylene, fifteen methine, and six quaternary carbons. The 1 H-and 13 C-NMR data assign- Fourteen cucurbitane-type triterpene glycosides (1-14) were isolated from a methano...

Korean ginseng (Panax ginseng C.A. Meyer) has been extensively used as a functional food for thousands of years. This study with the aim to evaluate the potential of P. ginseng flower components as a functional food with medicinal properties resulted in the identification of three new dammarane-type saponins, named floralginsenosides Ka-Kc (1-3), along with seventeen known ones (4-20). Their structures were elucidated on the basis of chemical and spectroscopic methods, and their antioxidant activities were evaluated by the intracellular ROS radical scavenging DCF-DA assay. Among them, floralginsenoside Ka (1) displayed potent scavenging activity with the inhibition value of 64% at 10 microM; and ginsenoside Rb(1) (13), floralginsenoside Kc (3), floralginsenoside Kb (2), vinaginsenoside R(9) (11), majoroside F(1) (12), ginsenoside I (17), and ginsenoside II (18) showed moderate scavenging capacity with the inhibition rate of 28, 33, 35, 35, 35, 38, and 38% at 10 microM, respectively. These results warrant further studies concerning the potential of saponin extracts of P. ginseng flowers for functional foods.

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Four new asterosaponins, astrosteriosides A-D (1-3 and 5), and two known compounds, psilasteroside (4) and marthasteroside B (6), were isolated from the MeOH extract of the edible Vietnamese starfish Astropecten monacanthus. Their structures were elucidated by chemical and spectroscopic methods including FTICRMS and 1D and 2D NMR experiments. The effects of the extracts and isolated compounds on pro-inflammatory cytokines were evaluated by measuring the production of IL-12 p40, IL-6, and TNF-α in LPS-stimulated bone marrow-derived dendritic cells. Compounds 1, 5, and 6 exhibited potent anti-inflammatory activity comparable to that of the positive control. Further studies are required to confirm efficacy in vivo and the mechanism of effects. Such potent anti-inflammatory activities render compounds 1, 5, and 6 important materials for further applications including complementary inflammation remedies and/or functional foods and nutraceuticals.

The renin angiotensin system (RAS) is a hormone system that regulates blood pressure and water balance. Excessive activation of this system is considered to be the main cause of hypertension.1) Angiotensin I-converting enzyme (ACE) is the most important regulatory site of RAS. ACE catalyses the conversion of angiotensin I, an inactive decapeptide, into angiotensin II, an octapeptide with potent vasoconstrictive activity. In fact, a number of synthetic ACE inhibitors have been widely used in patients with cardiac failure and renal disease. Moreover, ACE inhibitors have been identified and isolated from a wide range of plant and animal sources. 2-4)Myrica esculenta BUCH-HAM. ex. D. DON. (Myricaceae) is abundant found in India, South China, Japan, Malaysia, and Vietnam. In Vietnam, the plant is widely distributed in mountainous areas at altitudes ranging from 1000 to 2200 m above sea level. The barks are used in Vietnamese folk medicine to treat catarrhal fever, cough, sore throat, and skin disease.5) Several studies on the chemical constituents of M. esculenta have reported the presence of triterpenoids 6) and tannins. 7) We have been studying the effects of components of Myrica species on cardiovascular diseases. Here we report the isolation of a new monoterpenoid glycoside and eleven known compounds from M. esculenta, and discuss their ACE inhibitory activity. Results and DiscussionDried leaves of M. esculenta were extracted with MeOH and fractionated with chloroform (CHCl 3 ), ethyl acetate (EtOAc) and water. From these extracts and subsequently separation, one new and eleven known compounds were isolated and their structures were elucidated using physicochemical and spectroscopic methods. (Fig. 1 One new monoterpenoid glycoside, myresculoside (1), and eleven known compounds, were isolated from methanol extract of Myrica esculenta leaves by repeated column chromatography. The effects of these compounds on angiotensin I-converting enzyme (ACE) inhibition were investigated. Compounds 3 and 4 showed the most potent ACE inhibition with rates of 29.97% and 25.63% at concentration of 100 mM, respectively. Compounds 5, 6, and 11 showed weak activity with inhibitory rates of 0.07-1.41% at concentration of 100 mM.

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By various chromatographic methods, two new phenylpropanoid esters of sucrose named hidropiperosides A (1) and B (2), and three known compounds as vanicosides A (3), B (4), and E (5) were isolated from the methanolic extract of the whole plant of Polygonum hydropiper L. (Polygonaceae). Their structures were elucidated by extensive spectroscopic methods including 1D-and 2D-NMR experiments, as well as ESI-MS analysis. All the isolated compounds were tested for their antioxidant activity in the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging assay system. Among them, compounds 2 and 3 showed significant antioxidant activity with their SC(50) values of 23.4 and 26.7 microg/mL, respectively.