1,721,156 research outputs found
Studies on the constituents of Cyclanthera pedata fruits: Isolation and structure elucidation of new triterpenoid saponins
No full textThe isolation of nine triterpenoid saponins (1-9), among them six new natural compounds (1-6), from the MeOH extract of the fruits of Cyclanthera pedata is reported. All of the structures were elucidated by spectroscopic methods, including the concerted application of one-dimensional H-1-H-1 total correlation spectroscopy, H-1-H-1 nuclear Overhauser effect spectroscopy), and C-13-C-13; DEPT-NMR and two-dimensional NMR techniques (double-quantum filtered correlated spectroscopy, rotating-frame Overhauser enhancement spectroscopy, heteronuclear single quantum coherence, and heteronuclear multiple bond correlation). A comparative study of seeds and fruits has been also carried out
A new nor-kaurane-gamma-lactone from Parinari sprucei
No full textThe title tetracyclic diterpenoid, 10,13,16,17-tetrahydroxy-9-methyl-15-oxo-20-norkaurane-18,10-carbolactone hemihydrate, C20H28O6.0.5H(2)O, is a plant metabolite from Parinari sprucei, part of the Venezuelan Amazon flora. The asymmetric unit consists of two nearly identical molecules of the diterpenoid and one molecule of water. Some of the geometric parameters reflect steric strain in the molecule. The extended structure is characterized by hydrogen bonds and weaker hydrogen-mediated interactions, which involve all of the hydroxy groups and propagate in sheets that coincide with the (002) family of planes. The water molecule acts as a double hydrogen-bond donor and single acceptor and thus plays a critical role in the pattern of intermolecular interactions
Constituents of Cupuliferae. XVII. Triterpene saponins and flavonoids from Quercus laurifolia Michx
No full textAntioxidant chalcone glycosides and flavanones from Maclura (Chlorophora) tinctoria
No full textFour chalcone glycosides (1-4), including three new natural products, and three flavanones (5-7) were isolated from the methanol extract of stem bark of Maclura tinctoria. The new compounds have been characterized as 4'-O-beta-D-(2"-p-coumaroyl)glucopyranosyl-4,2',3'-trihydroxychalcone (1), 4'-O-beta-D-(2"-pcoumaroyl-6"-acetyl)glucopyranosyl-4,2',3'-trihydroxychalcone (2), and 3'-(3-methyl-2-butenyl)-4'-O-beta-D-glucopyranosyl-4,2'-dihydroxychalcone (3); the known derivatives were elucidated as 4'-O-beta-D-(2"-acetyl6"-cinnamoyl)glucopyranosyl-4,2',3'-trihydroxychalcone (4), eriodictyol 7-O-beta-D-glucopyranoside (5), naringenin (6), and naringenin 4'-O-D-beta-glucopyranoside (7). Their structures were determined by 1D and 2D NMR and ESIMS. The antioxidant activity of all the isolated compounds was determined by measuring free-radical-scavenging effects using two different assays, namely, the Trolox Equivalent Antioxidant Capacity (TEAC) assay and the coupled oxidation of beta-carotene and linoleic acid (autoxidation assay). The results showed that compound 3 was the most active in both antioxidant assays
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