Chemistry and biological activity of natural and semi-synthetic chromone alkaloids

Chromone alkaloids consist of a flavonoid or a noreugenin chromone component linked with a ring containing one or more nitrogen atoms. These alkaloids have been found in only a few species so far and have a scattered distribution within the plant kingdom. The structures of some of the piperidine-noreugenin compounds have had to be revised from those originally reported in the light of more detailed NMR studies and there have been some reports on analytical procedures. No studies have been carried out on the biogenesis of flavonoid and chromone alkaloids but there has been some success in the synthesis of some of the compounds included in this category. Although there is little relevant ethnobotanical data on the medicinal use of these plants, the results of screening procedures have given rise to considerable interest in the biological activity of this group of compounds. The flavonoidal alkaloids and their derivatives, notably flavopiridol, have kinase-inhibition properties which could be applied to cancer chemotherapy whilst the piperidone-noreugenin alkaloids display antiviral activity, particularly against HIV and Herpes Simplex Virus. Patents have been taken out on both of these groups and advanced studies are being carried out on flavopiridol.