Effects of vitamin E and pinoline on retinal lipid peroxidation.
BACKGROUND
Pinoline is a pineal indoleamine naturally found in the retina. This study compared the effects of pinoline and vitamin E on the copper (I)-induced retinal lipid peroxidation (LPO).


METHODS
Porcine retinal homogenates were mixed with 120 micro M copper (I) solution. The mixtures were co-incubated with various concentrations of pinoline or trolox (water-soluble vitamin E analogue) at 37 degrees Centigrade for 60 minutes. The amounts of malondialdehyde (MDA) and protein were assayed to quantify the LPO.


RESULTS
Copper (I) ions significantly increased the MDA concentration in the retinal homogenates (p < 0.0007). Both pinoline and trolox significantly suppressed MDA in a dose-dependent manner (p < 0.0001) and their effects were significantly different (p = 0.004). The concentrations that inhibited 50 per cent of LPO were 0.24 mM and 0.68 mM for pinoline and trolox, respectively.


CONCLUSIONS
Pinoline suppressed the LPO at a potency of 2.8 times compared with trolox. The results support an anti-oxidative role for pinoline in the retina. Further study is required to characterise the pharmacological potency of pinoline in vivo.
Tam
Benny B
BB
Laboratory of Experimental Optometry, Department of Optometry and Radiography, The Hong Kong Polytechnic University, Kowloon, Hong Kong, China.
Siu
Andrew W
AW
Lam
Andy F
AF
Lee
Elsa Y
EY
D000818:Animals; D000975:Antioxidants / Q000494:pharmacology*; D002243:Carbolines / Q000494:pharmacology*; D003300:Copper / Q000633:toxicity; D004305:Dose-Response Relationship, Drug; D007454:Iodides / Q000633:toxicity; D015227:Lipid Peroxidation / Q000187:drug effects*; D008315:Malondialdehyde / Q000037:antagonists & inhibitors / Q000378:metabolism; D012160:Retina / Q000187:drug effects* / Q000378:metabolism; D013552:Swine; D014810:Vitamin E / Q000494:pharmacology*
D000975:Antioxidants; D002243:Carbolines; D007454:Iodides; D014810:Vitamin E; C002272:6-methoxytryptoline; D008315:Malondialdehyde; D003300:Copper; C073870:cuprous iodide