PubMed · 13876513
The source did not provide an abstract. Follow the original record for more information.
Explore connections, maps & timelines
C CARDINI, C VENEZIANI, A CALO. 1961. [Analytic research on 4,2',4'-trimethoxychalcone].. https://pubmed.ncbi.nlm.nih.gov/13876513/
Cite the original work for its findings. Save a collection to share your selection of sources.
KEEP EXPLORING
Infrared nuCO (cm(-1)) of s-cis and s-trans frequencies and nuclear magnetic resonance chemical shifts delta(1)H (ppm) of H-alpha and H-beta, delta(13)C (ppm) of C-alpha and C-beta data were assigned from their respective spectra of a series of various substituted styryl 4-bromo-1-naphthyl chalcones. These values are correlated with various Hammett substituent constants. From the results of statistical analysis, the effect of substituents can be explained.
A systematic investigation of two well-known and popular commercial suncreams reveals significant degradation when exposed to simulated UV sunlight at an irradiance corresponding to natural sunlight. We have examined the photochemistry of two widely used sunscreen active agents in pure solvents separately and together (in solution), and in neat form, as well as their photochemistry when present in the actual suncream emulsion (as thin films on a glass substrate) since their combination typically produces suncreams with high sun protection factors (SPF): (1a) octyl methoxycinnamate (OMC; octinoxate) and (2a) 4-tert-butyl-4'-methoxydibenzoylmethane (also known as avobenzone and Parsol 1789), present in the two suncream formulations in combination with others (one also contained TiO2). Intermediates and/or photoproducts were identified by UV/visible spectroscopy, HPLC and liquid chromatographic/mass spectral methods, and by both 1H and 13C-NMR techniques. Structural assignments of the substrates produced were aided by examining model systems {viz. ethyl cinnamate (1b) and dibenzoylmethane (2b)} of the two sunscreen active agents. Irradiation of the cinnamates and the diketones together led to a [2 + 2] photocycloaddition process yielding cinnamate dimers and cyclobutylketone photoadducts that subsequently fragmented into substituted oxopentanoates and oxobutanoates. Similar findings were observed when the two active agents were simultaneously present in the same suncream emulsion.
The homoisoflavanone 5,7-dihydroxy-6-methoxy-3-(9-hydroxy-phenylmethyl)-chroman-4-one (1) and its structurally related 2',4',6'-trihydroxy-3'-methoxy-alpha-hydroxymethyl-beta-hydroxy-dihydrochalcone (2) along with the known pashanone (3), flavokawin B (4) and cardamonin or alpinetin chalcone (5) pinostrobin (6) and 5,8-dimethoxy-7-hydroxychroman-4-one (7) were isolated from dry leaves of Polygonum ferrugineum (Polygonaceae). To our knowledge, this is the first report of the isolation of a homoisoflavanone from the Polygonum genus and the Polygonaceae family, and could be an important chemotaxonomic finding. In addition, the pattern of substitution of this homoisoflavanone is different from others previously reported.