Isolation of a Non-steroidal Contragestative Agent from Sri Lankan Marine Red Alga, Gelidiella Acerosa

This study reports the isolation of a non-steroidal contragestative agent from the Sri Lankan marine red alga, Gelidiella acerosa. One-hundred grams of MeOH-CH2Cl2 (1:1) crude extract of G. acerosa was initially partitioned into hexane, CH2Cl2 and EtOAc, respectively, using the modified Kupchan scheme. At each separation step, all the resulting fractions were tested for contragestative effects in pregnant rats. The fertility was assessed in terms of the number of viable implants following oral administration of fractions (co-precipitated with polyvinylpyrrolidone), on day 1 through day 7 of pregnancy. The hexane fraction with highest activity was subjected to gel filtration through Sephadex LH-20, vacuum liquid chromatography over TLC-grade silica, two open-column chromatography runs over silica gel (60-120 mesh), and HPLC to isolate the active component. Nuclear magnetic resonance and infrared spectroscopic analysis revealed that the contragestative agent of G. acerosa is a sphingosine derivative.