Majapolene A, a cytotoxic peroxide, and related sesquiterpenes from the red alga Laurencia majuscula

Seven new sesquiterpenes, majapolenes A [1] and B [2], majapolone [3], and majapols A [4], B [5], C [6], and D [7], were isolated from a Philippine collection of Laurencia majuscula. With the exception of majapolene B [2], all compounds mere isolated as inseparable diastereomeric mixtures. Structure elucidation was achieved by spectroscopic methods. Majapolene A [1], a dioxabicyclo[2.2.2]-alkene, displayed modest activity in the NCI 60-cell line cytotoxicity screen. Majapolene A was also found as a major component of a Philippine collection of Laurencia caraibica.