cytellin and hentriacontane

An ethyl acetate extract of Oryza sativa (rice) hulls yielded seven compounds: hentriacontane, 1-tetratriacontanol, beta-sitosterol, momilactone A, momilactone B, tricin (a flavonoid), and beta-sitosterol-3-O-beta-D-glucoside. The structures of these compounds were elucidated with 500 MHz nuclear magnetic resonance (NMR), using 1D and 2D spectral methods, aided by electron ionization mass spectrometry (EI-MS), fast atom bombardment mass spectrometry (FAB-MS), infrared (IR), and ultraviolet (UV) spectrophotometry. The complete 1H NMR assignments for momilactone A and B and 13C NMR assignments for tricin are discussed. To the best of our knowledge, hentriacontane, 1-tetratriacontanol, and beta-sitosterol-3-O-beta-D-glucoside were identified for the first time in rice hulls. In biological activity tests using these identified compounds, momilactone A and B showed potent inhibitory activity against duckweed (Lemna paucicostata). 1-Tetratriacontanol and beta-sitosterol-3-O-beta-D-glucoside also showed about 13-20% inhibitory activity based on chlorophyll reduction. Hentriacontane and beta-sitosterol did not show any herbicidal activity. In a germination assay of three weed species (Leptochloa chinenesis L., Amaranthus retroflexus L., and Cyperus difformis L.) in culture tubes both momilactones A and B had high inhibitory effects. Momilactone B completely inhibited germination of all three weed species at 20 ppm. Germination of L. chinensis L. was completely inhibited by a 4 ppm solution of momilactone B.

Topics: Amaranthus; Cyperus; Diterpenes; Fatty Alcohols; Flavonoids; Germination; Herbicides; Hydrocarbons; Lactones; Oryza; Plant Development; Plants; Sitosterols; Spectrum Analysis

The chemical constituents of Rosa bracteata Wendl. var. bracteata were studied for the first time. Six compounds were isolated from the fruits of the plant, and four of them have been identified as 5-hydroxymethyl furfural, 5-acetoxymethyl furfural, beta-sitosterol, oleanolic acid. 5-hydroxymethy furfural and 5-acetoxymethyl furfural were obtained from genus Rosa L. for the first time. Otherwise, a white wax was obtained by silica gel column chromatography, from which four main constituents were identified as nonadecene, n-docosane, hentriacontane and hexatriacontane by GC-MS.

Topics: Chromatography, Gas; Fruit; Furaldehyde; Gas Chromatography-Mass Spectrometry; Hydrocarbons; Oleanolic Acid; Plants, Medicinal; Rosa; Sitosterols