Synthesis and biological activities of thio-avarol derivatives. 
Eleven new thio-avarol derivatives (3-13) were synthesized.  Their antimicrobial, brine shrimp lethality, and free-radical scavenging activities and acetylcholinesterase inhibition, together with 12 already reported semisynthetic thio-avarol derivatives (14-25), were evaluated.  Structure-activity relationships among these thio derivatives were determined.