Possible degradation/biotransformation of lutein in vitro and in vivo: isolation and structural elucidation of lutein metabolites by HPLC and LC-MS (atmospheric pressure chemical ionization).
Metabolites of lutein are highly concentrated in the human macula and are known to provide protection against age-related macular degeneration. The aim of this investigation was to characterize the in vitro oxidation products of lutein obtained through photo-oxidation and to compare them with biologically transformed dietary lutein in intestine, plasma, liver, and eyes of rats. In vivo studies involved feeding rats a diet devoid of lutein for 2 weeks to induce deficiency. Rats were divided into two equal groups (n=6/group) and received either micellar lutein by gavage for 10 days or diet supplemented with fenugreek leaves as a lutein source for 4 weeks. Lutein metabolites/oxidation products obtained from in vivo and in vitro studies were characterized by HPLC and LC-MS (APCI) techniques to elucidate their structure. The characteristic fragmented ions resulting from photo-oxidation of lutein were identified as 523 (M(+)+H(+)-3CH(3)), 476 (M(+)+H(+)-6CH(3)), and 551 (M(+)+H(+)-H(2)O). In the eyes, the fragmented molecules resulting from lutein were 13-Z lutein, 13'-Z lutein, 13-Z zeaxanthin, all-E zeaxanthin, 9-Z lutein, 9'-Z lutein, and 3'-oxolutein. Epoxycarotenoids were identified in liver and plasma, whereas anhydrolutein was identified in intestine. This study emphasizes the essentiality of dietary lutein to maintain its status in the retina.
Lakshminarayana
Rangaswamy
R
Department of Biochemistry and Nutrition, Central Food Technological Research Institute, CSIR, Mysore 570 020, India.
Aruna
Gorusupudi
G
Sangeetha
Ravi Kumar
RK
Bhaskar
Narayan
N
Divakar
Sounder
S
Baskaran
Vallikannan
V
D000284:Administration, Oral; D000818:Animals; D001711:Biotransformation; D002851:Chromatography, High Pressure Liquid; D002853:Chromatography, Liquid; D014975:Lutein / Q000008:administration & dosage / Q000378:metabolism*; D008297:Male; D013058:Mass Spectrometry; D010084:Oxidation-Reduction; D051381:Rats; D017208:Rats, Wistar
D014975:Lutein