Identification of two meridianins from the crude extract of the tunicate Aplidium meridianum by tandem mass spectrometry.

As part of the development of an analytical technique for the detection of meridianins and related compounds in biological fluids, a crude extract of the tunicate Aplidium meridianum was analysed using neutral loss tandem mass spectrometry. The 41 u neutral loss-EI(+) mass spectrum showed molecular ions corresponding to two previously undetected alkaloids. We report herein the isolation and structure elucidation of these alkaloids, meridianins F and G. †Dedicated to the memory of Dr Alicia M. Seldes, Founder and Leader of the research group on Marine Natural Products at the Department of Organic Chemistry, FCEN-UBA.