Hyperattenins L and M, two new polyprenylated acylphloroglucinols with adamantyl and homoadamantyl core structures from Hypericum attenuatum

Abstract Hyperattenins L ( 1 ) and M ( 2 ), two new benzoylated polyprenylated phloroglucinol derivatives possessing unusual adamantyl and homoadamantyl core structures, were isolated from the aerial parts of Hypericum attenuatum . Their structures were determined by extensive NMR spectroscopic methods. Compound 1 possesses an unusual tetracyclo[6.3.1.1 1,10 .0 1,5 ]tridecane skeleton, representing the second report of natural product with this carbon skeleton. Compound 2 features an unexpected 2,3,13-trioxapentacyclo[7.5.3.1 7,11 .0 5,16 .0 12,16 ]octodecane ring system formed by the fusion of 2,3,8-trioxabicyclo[4.3.1]decane moiety to the tricycle[4.3.1.1 3,8 ]undecane core. Both compounds were evaluated for their cytotoxic activities against five human cancer cell lines and compound 1 showed excellent inhibitory activities against HL-60, A-549, and MCF-7 cell lines with IC 50 values of 3.86, 4.34, and 5.78 μM, respectively.