Quercetin is the aglycone form of a number of other flavonoid glycosides, such as rutin and quercitrin.

1. Structural Elucidation Of Quercetin
Presented By:
•Gandham Malasree
•M Pharmacy
•Regd no: 620209502002
•Dept of Pharmaceutical Chemistry
AU College Of Pharmaceutical Sciences,

2. INTRODUCTION:
 Quercetin is the aglycone form of a number of other flavonoid glycosides, such
as rutin and quercitrin.
 Quercetin is one of the most widely distributed natural pigment and most abundant dietary
flavonoid.
 It occurs as the glycosidic quercetin in the barks of Quercus tinctoria.
 It is naturally occurring polar auxin transport inhibitor.
Sources: Citrus fruit
Buck wheat
Red onions
Red roses
Apples
Honey
Tomatoes
Oak bark

3. STRUCTURE OF QUERCETIN:
Molecular formula: C15
H10O7
Molecular weight: 302gm

4. CONSTITUTION:
• When quercetrin is hydrolysed with HCl it gives quercetin and L - Rhamnose
1. Presence of 5 –OH groups :
• Quercetin forms penta acetyl & penta methyl derivatives, thus the presence of 5 –OH groups are
indicated.
SOLUBILITY
• It is soluble in sodium hydroxide,

5. 2)
3:3’:4’:5:7 – penta hydroxy flavanol
KOH
boiling
6 – hydroxy , ω:2:4- trimethoxy acetophenone

6. 3) Synthesis Of Quercetin
1. Kostaneckis synthesis
1 2
4 3
5
Trimethoxy
phenol
Dimethoxy
benzaldehyde

7. 2. Robinsons method:
Tri hydroxy
acetophenone
1
2
Anhydride

8. Structural relationship between flavanols (quercetin), anthocyanins(cyanidine
chloride) and catechins :
1. They produce same degradation product when fused with KOH

9. 2.

10. • Bauer & his associates in 1954, converted penta acetate of quercetin into cyanidine chloride by
means of LiAlH4
.
3.

11. Spectral Values Of Quercetin
UV spectrum: λmax = 425 nm
IR spectrum: Group Absorption range Strectching/ Bending
2º OH 3282 cm-1 Stretching
C=O 1743 cm-1 Stretching
C=O 1666 cm-1 Stretching
C=C 1610 cm-1 Stretching
-OH 1517 cm-1 Bending
-OH 1430 cm-1 Bending
-OH 1358 cm-1 Bending
C – O 1210 cm-1 Stretching
C – O 1094 cm-1 Stretching
C – O 1001 cm-1 Stretching
C=C 929 cm-1 Bending
C=C 882 cm-1 Bending
C – H 808 cm-1 Bending

12. NMR SPECTRUM
δ - ppm

14. MASS SPECTRUM

15.  Presence of 5,7,3’4’ tetrahydroxy flavonol aglycones were confirmed by the UV spectra.
 The presence of hydroxyl, carbonyl, aromatic and ether group were confirmed by the ir spectra.
 The presence of two meta coupled aromatic protons at h-6,h-8, position confirms the 5,7 di-
substituted ring a were confirmed by H1 NMR.
 The presence carbon atoms were confirmed by C13NMR spectrum .
 Quercetin was confirmed by the all spectral analysis.
CONCLUSION