UV absorbent, marmesin, from the bark of Thanakha,Hesperethusa crenulata L.
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We used solvent extractions, SiO2 column chromatographies, and HPLC to isolate from the bark of Thanakha (Hesperethusa crenulata L) an active crystalline compound for absorbing UV-A radiation (320 to 380 nm). Analyses of low-and high-resolution FAB-MS revealed a compound, named marmesin, with a formula of C14H14O4 and a molecular mass of 246. To determine its chemical structure, we conducted 300 MMz NMR analyses using various probes,1H,13C, and DEPT13C. Our NMR data showed a structure of 2,3-dihydro-2(1 -hydroxy-1 -methylethyl)-furanocoumarin. This active compound contains UV-absorbing chromophores, an aromatic ring, a double bond at C3-C4, and a carbonyl at C2. Its λmax is 335 nm, indicating that marmesin could be commercially useful as a natural UV-A-filtering product
Keywordsmarmesin Thanakha (Hesperethusa crenulata L) UV-A-absorbent
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