SUMMARY
Biological activity of a natural product involved in several certain characteristics will influence its pharmaceutical application. Secondary metabolites, considered as chemical compounds, are now thought to mediate plant defense mechanism by providing chemical barriers against animal and microbial predators. Brine Shrimp Lethality Test (BSLT) method has been used as preliminary test for screening the activity of chemical compounds in n hexane, ethyl acetate, and methanol extracts from mesocarp and seeds of Phaleria macrocarpa, fam. Thymelaeaceae. BSLT method used shrimp larvas of Artemia salina L. to study the mortality effect that was caused by the sample extracts. All of crude extracts showed bioactivity with LC50 values from 0.16 to 11.83 µg/ml (baseline 1000 µg/ml). It means, at the concentration the crude extracts can cause 50% mortality of A. salina L. shrimp larvas, after 24 hours incubation. These results clearly indicate that crude extracts of P. macrocarpa showed high potential biological activity.