A new bibenzyl and 9,10-dihydrophenanthrene derivative from aerial parts of crowberry (Empetrum nigrum L.)

Two new natural products - 1 and 2, together with four known compounds (3-6) were isolated from aerial parts of crowberry (Empetrum nigrum L.). All structures were elucidated by extensive 1D and 2D NMR experiments and HR-ESIMS data along with comparison of their spectroscopic data with those reported in the literature. Compound 1 (1-(3,5-dihydroxy-4-methoxyphenyl)-2-phenylethane) is a bibenzyl (dihydrostilbene) derivative. Compound 2 was found to be 6-hydroxy-2,3,4-trimethoxy-9,10-dihydrophenantrene. Compounds 3 and 4 were established as 4,7-dihydroxy-2,3-dimethoxy-9,10-dihydrophenantrene (ephemeranthol-A) and 1-(3-hydroxyphenyl)-2-(3-hydroxy-4,5-dimethoxyphenyl)ethane, respectively. Compounds 5 and 6 were identified as 4?hydroxy-2?-methoxydihydrochalcone and 2?,4?-dihydroxychalcone, respectively.