Compounds useful as chemotherapeutic, chemopreventive, and antiangiogenic agents are provided. The compounds are flavanoids, including flavanones, flavanols, and chalcones. The compounds have the structure of formula (I) ##STR00001## wherein R.sup.1 through R.sup.3 and R.sup.5 through R.sup.11 are defined herein, and .alpha., .beta., and .gamma. are optional bonds, providing that when .alpha. is absent, .beta. is present, and when .beta. is absent, .alpha. is present. When .alpha. is present, preferred R.sup.4 moieties are selected from O, S, NH and CH.sub.2, and when .alpha. is absent, preferred R.sup.4 groups are selected from OH, SH, NH.sub.2 and CH.sub.3. When .gamma. is present, the preferred R.sup.5 substituent is O, while when .gamma. is absent, the preferred R.sup.5 substituent is OH. Pharmaceutical compositions are provided as well, as are methods of synthesis and use.