**Acknowledgements**

*Bioactive Compounds - Biosynthesis, Characterization and Applications*

from aerial parts of *Chenopodium album* [84], amurensin and cosmosiin from *Trigonella foenum graecum* [85], rhamnosides flavonol, kaempferol-3-*O*-rhamnoside and quercetin-3-*O*-rhamnoside from leaves of *Pometia pinnata* [86] and a new flavonol glycoside, sabiapside A from *Sabia parviflora* [87] (**Figure 10**).

*Several different structures of flavonol isolated from parts of plant species.*

Flavonoids are a large class of natural compounds, which isolated from various of plants as seed, root, bark, flower, leaves, fruit etc. and prevent from various diseases. The biosynthesis of flavonoids is highly complicated because a group of enzyme (DHAP synthase, SA kinase, EPSP synthase, PAL, 4CL, CHS, CHI, F3H, DFR) plays a key role in the pathway of flavonoids biosynthesis. These enzymes play a potential role in modification of flavonoids via isomerases, hydroxylases, reductases, and polymerises reaction. The proanthocynidins are interested natural compounds, which formed via polymerization reaction of flavonoids. The flavonoids are synthesized in various plant species via shikimate and phenylpropanoid

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pathway.

**5. Conclusions**

**Figure 10.**

Author thanks to UGC, New Delhi, India for institutional fellowship. The author is also thankful to the Chairman, Department of Chemistry, AMU, Aligarh, for providing research facilities.
