• These are yellow pigments which occurs in plant kingdome either in the free state or as a glycosides or accociated with tanins

• These are also known as the anthoxanthins

• Flavones (flavus = yellow), are a class of flavonoids based on the backbone of 2-phenylchromen-4-one (2-phenyl-1-benzopyran-4-one)

• Isoflavones comprise a class of organic compounds, often naturally occurring, related to the isoflavonoids.

• Many act as phytoestrogens in mammals.

• Some are termed antioxidants because of their ability to trap singlet oxygen.

• Isoflavones are produced almost exclusively by the members of the Fabaceae

• (i.e., Leguminosae, or bean) family.

Isoflavones are produced via a branch of the general phenylpropanoid pathway that produces flavonoid

compounds in higher plants

•Determination of structure of isoflavone

•(1) Number of –OH gp. and –OCH3 gp. are determined by Zerewitinoff’s and Zeisel’smethod.

• (2) On reaction with KOH it gives following :

(3) On oxidation with alkaline H2O2 , degradation of isoflavon occurs .

•These method provide usefull information of the substituents in the 3-phenyl nucleus.

Synthesis :-

• Spath synthesis

• Baker – ollis synthesis

• Wessley synthesis

• A depside is a type of polyphenolic compound composed of two or more monocyclic aromatic units linked by an esterbond.

• Depsides are most often found in lichens, but have also been isolated from higher plants, including species of the Ericaceae, Lamiaceae, Papaveraceae and Myrtaceae

• Depsides have antibiotic, anti-HIV, antioxidant, and anti-proliferative activity.

• As inhibitors of prostaglandin synthesis and leukotriene B4biosynthesis, depsides are potent non-steroidal anti-inflammatories

• A depsidase is a type of enzyme that cuts depside bonds,Onesuch enzyme is tannase.

• Gyrophoric acid, found in the lichen Cryptothecia rubrocincta, is a depside.

Gyrophoric acid