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...

Drought is a major abiotic stress that negatively impacts plant growth and crop production. Among various techniques used to alleviate drought stress in plants, nanoparticle application is considered to be effective and promising. In this study, the responses of plants treated with iron, copper, cobalt, and zinc oxide nanoparticles (NPs) were analyzed in soybean under drought-induced conditions. The obtained results indicated that these metal-based NPs supported the drought tolerance of NP-treated plants. The desired physiological traits, viz., relative water content, drought tolerance index, and biomass reduction rate, were significantly improved, especially in iron NP-treated plants. At the molecular level, quantitative PCR analysis of several drought-responsive genes revealed a gene-, tissue-, and NP-dependent upregulation of gene expression. Iron NP treatment promoted the expression of all tested genes in roots; additionally, the expression of three drought-responsive genes increased in leaves of all NP-treated plants, while the expression of GmERD1 (Early Responsive to Dehydration 1) was induced in both roots and shoots under the four NP treatments tested. Our findings suggest that NP application can improve drought tolerance of soybean plants by triggering drought-associated gene expression.

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A new dibenzocyclooctadiene lignan, acetylepigomisin R ( 1), and a new 3,4-seco-lanostane-type triterpene, seco-coccinic acid F ( 2), along with three known dibenzocyclooctadiene lignans, isovaleroylbinankadsurin A ( 3), kadsuralignan J ( 4), and binankadsurin A ( 5), and one lanostane-type triterpene, 20( R),24( E)-3-oxo-9 beta-lanosta-7,24-dien-26-oic acid ( 6), were isolated from the methanol extract of the Kadsura coccinea roots. Their structures were elucidated on the basis of spectroscopic evidence including ESI-MS, HR-EI-MS, 1D and 2D NMR. The protective effects of these compounds were evaluated in primary cultured rat hepatocytes intoxicated with 1.2 mM T-butyl hydroperoxide. Compounds 1, 3, and 5 showed protective effects with ED (50) values of 135.7, 26.1, and 79.3 microM, respectively.

Eight compounds (1-8) were isolated from a methanol extract of Cibotium barometz rhizomes including two new furan derivatives, cibotiumbarosides A (1) and B (2), and a new glycoglycerolipid, cibotiglycerol (4). Their structures were elucidated by chemical and spectroscopic methods. Compounds 2-5 each showed inhibition of osteoclast formation with no affect on BMM cell viability.

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Four new cucurbitane- type triterpene glycosides, charantosides D-G (1–4) were isolated from a methanol extract of Momordica charantia fruits. The structures of these compounds were determined by chemical and spectroscopic methods to be (19 R)-5 β,19-epoxy-25-methoxycucurbita-6,23-diene-3 β,19-diol 3- O-β-D-glucopyranoside, (19 R)-5 β,19-epoxy-25-methoxycucurbita-6,23-diene-3 β,19-diol 3- O-β-D-allopyranoside, 7 β-methoxycucurbita-5,23 E,25-triene-3 β-ol 3- O-β-D-allopyranoside, and 3 β,7 β-dihydroxycucurbita-5,23 E,25-triene-19-al 3- O-β-D-allopyranoside.

Grey mangrove (Avicennia marina) is a traditional medicine used for the treatment of various diseases, including rheumatism and ulcers; however, the compounds responsible for its curative effects remain largely unknown. Triterpenoids are a diverse group of plant-specialized metabolites derived from a common precursor, 2,3-oxidosqualene. Triterpenoids are potentially responsible for the beneficial effects of A. marina; however, the chemical profiles of triterpenoids in A. marina and their biosynthetic genes have not been identified. Cytochrome P450 monooxygenases (P450s) have key roles in the structural diversification of plant triterpenoids by catalyzing site-specific oxidation of triterpene scaffolds. Recent studies have revealed that the CYP716 family represents the most common clade of P450s involved in triterpenoid biosynthesis. In this study, we performed triterpenoid profiling and RNA sequencing of A. marina leaves. Mining of CYP716 family genes and enzymatic activity assays of encoded proteins revealed that CYP716A259 catalyzed oxidation at the C-28 position of the pentacyclic triterpene skeletons of β-amyrin, α-amyrin, and lupeol to produce oleanolic acid, ursolic acid, and betulinic acid, respectively. The other functionally defined P450, CYP716C53, catalyzed the C-2α hydroxylation of oleanolic acid and ursolic acid to produce maslinic acid and corosolic acid, respectively. The possible involvement of CYP716A259 and CYP716C53 in the biosynthesis of these health-benefiting compounds in A. marina leaves, and the possible contribution of the resulting compounds to the reported bioactivities of A. marina leaf extract, are discussed.