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Effects of vitamin E and pinoline on retinal lipid peroxidation
Benny B Tam1, Andrew W Siu, Andy F Lam
1Laboratory of Experimental Optometry, Department of Optometry and Radiography, The Hong Kong Polytechnic University, Kowloon, Hong Kong, China.
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.
Discussion:
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.
