Table 2.

Main bands in the infrared spectra of root and lyophilized R. tinctorum extract and of two of its main constituents.

R. tinctorum		Anthraquinone	4-tert-butyl-2-phenylphenol	Assignment
Root Powder	Extract
3334	3335			Bonded O–H stretching (cellulose)
		2964		sp3 C–H
2920	2920	2925		=C–H groups of aromatic rings
		2856		aliphatic C–H asymmetrical stretching
		2724		β–OH, typical of α-hydroxy anthraquinone
1727	1733			C=O from esters
		1704		ester C=O
		1676		C=O in anthraquinones
1639	1620	1633		C=O in anthraquinones
1602	1605	1592	1585	phenyl ring (aromatic skeletal vibration) >C=C< in anthraquinones
1552			1545	carboxylate stretches/C=C aromatic
	1511		1480	methylene C–H bend
		1461	1470	methyl C–H asymmetrical
	1435		1430	=C–H in plane bending
1414	1416		1420	vinyl C–H in plane bending
1370	1406 1370	1377 1366	1385	C–C asymmetrical stretching phenolic hydroxyl groups
			1355	C–O stretching/methylene C–H bending
		1333 1329	1325	C–H in-plane deformation methylene C–H bending
1316	1316	1306		vinylidene C–H in plane bending
1255	1255	1287	1270	C–O stretching/C=C symmetric stretching
		1207	1215	C–O stretching/C–H in plane bending
		1171	1180	–C–O–C– stretching
	1142	1153	1135
	1100	1099
		1087	1080
1020			1025	C–C stretching
	951	969		C–H out-of-plane bending