A Cyclopeptide and a Tetrahydroisoquinoline Alkaloid from <i>Ophiorrhiza nutans</i>

A new cyclopeptide, ophiorrhisine A (<b>1</b>), a new tetrahydroisoquinoline alkaloid, 7′,10-dide-<i>O</i>-methylcephaeline (<b>2</b>), two known β-carboline alkaloids, and four known tetrahydroisoquinoline alkaloids were isolated from <i>Ophiorrhiza nutans</i> (Rubiaceae). Compound <b>1</b> is a tetrapeptide possessing a 14-membered paracyclophane ring and a novel <i>N,N,N-</i>trimethyltyrosine residue in the side chain. The stereochemistry at the aryl–alkyl ether bond was different from that of other known 14-membered paracyclophanes. The structure of <b>2</b> was established by spectroscopic analysis and semisynthesis