New pentacyclic cyclol-type naphthohydroquinone from the roots of Pentas bussei

The novel naphthohydroquinone, methyl 5,10-dihydroxy-7-methoxy-1,1,3a-trimethyl-1a,2,3,3a,10c,10d-hexahydro-1H-4-oxacyclobuta[cd]indeno[5,6-a]naphthalene-9-carboxylate , was isolated from the hexane extract of dried roots of Pentas bussei. Its structure elucidation was done by detailed spectroscopic methods. It is the first cyclol moiety containing naphthohydroquinone to be reported, and a novel natural product from P. bussei.