Two crystal polymorphs of a flavonoid from Melicope ellyrana

The crystal structure determinations of two crystalline components of the h exane extract of the fruit of the indigenous Australian tree Melicope ellyr ana have shown them to be polymorphs of the same compound, namely the flavo noid 4',5-dihydroxy-3,3',8-trimethoxy-7-(3-methylbut-2-enyloxy)flavone [sys tematic name: 5-hydroxy-2-(4-hydroxy-3-methoxyphenyl)-3,8-dimethoxy-7-(3-me thylbut-2-enyloxy)-4H-1-benzopyran-4-one], C23H24O8. The two polymorphs, on e monoclinic (polymorph A) and the other triclinic (polymorph B), show sign ificant conformational differences, particularly in the enyloxy side chain, while only one (polymorph A) shows intermolecular hydrogen bonding.