Page Banner

United States Department of Agriculture

Agricultural Research Service

Survey of Phenolic Compounds Produced in Citrus
Experimental Methods

Nuclear Magnetic Resonance (NMR)

NMR was used to resolve two closely eluting flavonoids in our chromatographic profiles: didymin (isosakuranetin–7–O–rutinoside) and poncerin.

1H NMR (270 MHz, DMSO–d6) Didymin: d=1.15 (R-Me), 2.57 (3 eq) (3 ax is under the H-b2-eO solvent peak, as are many of the sugar H's), 3.77 (4'-OMe) 4.54 (R-1), 5.01 (G-1), 5.45 (2), 6.23 (6,8), 6.98 doublet (3', 5'), 7.42 doublet (2',6'). Poncerin: d=1.15 (R-Me), 2.80 (3 eq), 3.77 (OMe) 4.48 (R-1), 5.10 (G-1), 5.6 (2), 6.12 (6', 8'), 6.98 doublet (3', 5'), 7.43 doublet (2', 6').

13C NMR (270 MHz, DMSO–d6) Didymin: didymin's spectrum is somewhat weak but resembles naringin's (Agrawal and Bensal 1989, Markham and Ternai 1976) except that it lacks a G-6 peak between 56 and 64 mg/L. This is diagnostic of rutinosides (Markham and Ternai 1976). Poncerin: poncerin contains a G-6 peak at 60.5, which is diagnostic of G-6 in neohesperidosides (Markham and Ternai 1976). The 13C NMR spectrum of the phenolic portion of the two compounds resembles that of naringin with the addition of a 4'–methoxy peak at 55.1 mg/L and the following shifted peaks: 113.9 (3', 5') and 128.2 (2', 6').


previous pagenext page 

United States Department of Agriculture
Agricultural Research Service

The material on this page is in the public domain.

Original posting: April 1, 1999.

Last Modified: 8/13/2016
Footer Content Back to Top of Page