Five new N-acetyldopamine dimers from Periostracum Cicadae

Periostracum Cicadae, the cast-off shell of the cicada Cryptotympana pustulata Fabricius, is used in traditional Chinese medicine for its diaphoretic, anticonvulsive, sedative, antipyretic, and antiallergic effects. Five new N-acetyldopamine dimers were isolated from Periostracum Cicadae, and their structures were elucidated as (2R,3S)-2-(3′,4′-dihydroxyphenyl)-3-acetylamino-7-(N-acetyl-2′′-aminoethyl)-1,4-benzodioxane 3′-O-β-d-glucopyranoside (1), (2S,3R)-2-(3′,4′-dihydroxyphenyl)-3-acetylamino-7-(N-acetyl-2′′-amino-1′′-hydroxylethyl)-1,4-benzodioxane (2), (2R,3S)-2-(3′,4′-dihydroxyphenyl)-3-acetylamino-6-(N-acetyl-2′′-amino-1′′-hydroxylethyl)-1,4-benzodioxane (3), (2S,3S)-2-(3′,4′-dihydroxyphenyl)-3-acetylamino-6-(N-acetyl-2′′-aminoethyl)-1,4-benzodioxane (4), and (2S,3S)-2-(3′,4′-dihydroxyphenyl)-3-acetylamino-7-(N-acetyl-2′′-aminoethylene)-1,4-benzodioxane (5) by analysis of one-dimensional NMR, two-dimensional NMR, mass spectrometry, CD spectroscopy, and chemical evidence. We showed that treatment with 2, 4, or 5 at a concentration of 400 μM significantly inhibited LPS-induced increases in NO content in RAW264.7 cells. Our results suggest that newly isolated compounds 2, 4, and 5 might mediate the biological effects of Periostracum Cicadae, and future in vivo studies will determine their therapeutic potential.