AUTHOR=Wang Pei , Chen Xin , Wang Hao , Huang Shengzhuo , Cai Caihong , Yuan Jingzhe , Zhu Guoliang , Xu Xinglian , Mei Wenli , Dai Haofu 

TITLE=Four New Picrotoxane-Type Sesquiterpenes From Dendrobium nobile Lindl

JOURNAL=Frontiers in Chemistry

VOLUME=7

YEAR=2019

URL=https://www.frontiersin.org/journals/chemistry/articles/10.3389/fchem.2019.00812

DOI=10.3389/fchem.2019.00812

ISSN=2296-2646

ABSTRACT=<p>Four picrotoxane-type sesquiterpenes, dendroterpene A–D (<bold>1</bold>–<bold>4</bold>), together with four known compounds (<bold>5</bold>–<bold>8</bold>), were isolated from the stems of <italic>Dendrobium nobile</italic> Lindl. Their structures were elucidated by spectroscopic analysis, X-ray diffraction analysis, analysis of the ECD data according to the Klyne's lactone sector rule, and quantum ECD calculation. Compounds <bold>1</bold> and <bold>2</bold> are two new picrotoxane-type sesquiterpenes with a new carbon skeleton containing a formamide group, which may be derived from the previously reported dendrobiumane B skeleton by the C(9)-C(11) carbon bond cleavage. Compounds <bold>3</bold>, <bold>5</bold>, <bold>6</bold>, and <bold>8</bold> exhibited inhibitory activity against α-glycosidase. Compounds <bold>5</bold> and <bold>6</bold> were cytotoxic against SGC-7901, K562, A549, BEL-7402, and Hela cell lines.</p>