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Oxygenation of anaerobically isolated brain and liver homogenates is associated with chemiluminescence and formation of lipid hydroperoxides, the latter determined by the thiobarbituric acid assay. Light emission and formation of malonaldehyde are 20-fold higher in the brain than in liver; chemiluminescence of both decays when accumulation of malonaldehyde ceases. Exogenous organic peroxides, such as t-butyl hydroperoxide, inhibit the light-emission response to oxygenation by brain homogenate, whereas they enhance that of liver homogenate. t-Butyl hydroperoxide-induced photoemission of liver homogenate shows a polyphasic kinetic pattern that is O2-dependent. The spectral analysis of chemiluminescence arising from brain and liver homogenates on oxygenation shows a spectrum with five emission bands at 420-450, 475-485, 510-540, 560-580 and 625-640 nm. These bands are subjected to intensity changes or shifts of the wavelength whenever t-butyl hydroperoxide is present, either inhibiting or stimulating light emission. The blue-band chemiluminescence, around 435 nm, is possibly due to the weak light emission arising from excited carbonyl compounds [Lloyd (1965) J. Chem. Soc. Faraday Trans. 61, 2182-2193; Vassil'ev (1965) Opt. Spectrosc. (USSR) 18, 131-135], whereas the presence of other bands suggests generation of singlet molecular oxygen either in the process triggered on oxygenation (lipid oxygenation) or after supplementation with organic hydroperoxides. We offer several explanations for the spectral analysis presented here.

Abstract— The spontaneous light emission of soybean seeds is enhanced 4–8 times during the first minute after water imbibition. Other solvents are also effective. The temperature dependence of soybean chemiluminescence identifies two reactions with activation energies of 20 and 68 kJ/mol corresponding to the lipoxygenase reaction and to the autoxidation of unsaturated fatty acids, respectively. Free radical scavengers and lipoxygenase inhibitors decrease soybean photoemission. The singlet oxygen probe 1,4‐diazabicyclo‐[2,2,2]‐octane (DABCO) increases soybean photoemission. The emission spectra of soybean seeds under a variety of conditions show bands between 450 and 720 nm with 50–70% of the emission over 600 nm. The experimental evidence is consistent with singlet oxygen being one of the emitting species, however, due to the complexity of the system it is likely that other chemiluminescent species are also formed.

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