Haemoglobin Oxidation: A possible mechanism of crude oil toxicity in fish
By: B. A. Ezeawgula , H. A. Onwubiko
Key Words: Crude oil contamination, Freshwater fish, Haemoglobin oxidation, UV-visible spectrophotometer.
Int. J. Biosci. 9(1), 25-33, July 2016.
Haemoglobin oxidation occurs in erythrocytes. It involves the loss of an electron from the ferrous (Fe2+) ion to the ferric (Fe3+) state in the presence of an oxidant. Crude oil, which contains polycyclic aromatic hydrocarbons (PAHs), has the capacity of serving as oxidants to fish haemoglobin to yield the methaemoglobin (Fe3+) species which has lost the capacity to bind oxygen. This study reveals that various quantities (20, 60, 100 and 200 µl) of crude oil used to contaminate and incubate fish haemoglobin at 25 ºC increased the methaemoglobin absorbance at 630 nm wavelength due to methaemoglobin (Fe3+) while there was a decrease at 540 nm and 577 nm. Since polycyclic aromatic hydrocarbons (with alkylated side chains) are the only component in crude oil that is absorbed by fish, it is suggestive that these compounds may be responsible for haemoglobin oxidation in fish.