Free Radicals in Biological Materials

Free Radicals: Properties, Sources, Targets, and Their Implication in Various Diseases

“…These two ions can react with NO and form N 2 O and OH . NO can react with a variety of radicals such as H 2 O 2 and HOCl to form N 2 O 3 , NO 2 -and NO 3 - [62].…”

“…Later in 1954, Gershman proposed ''free radical theory of oxygen toxicity'', according to which, the toxicity of oxygen is due to its ability to form free radicals [2]. In the same year, the electron paramagnetic resonance (EPR) studies by Commoner et al 1954 [3] confirmed the presence of free radicals in biological materials. Soon thereafter Denham Harman, in 1956, proposed the ''free radical theory of aging'', which states that free radicals play a central role in the aging process.…”

An appraisal of chloroquine

“…It is possible that the stabilized free radicals serve a detoxifying function for photochemical products (96,97). Melanin is thought to be a dumping ground for unpaired photochemically generated electrons, apparently capable of sequestering electrons in an inactive form (98). As only about 501, of light subserves vision at ordinary illumination, the remainder of the energy entering the eye must be removed in thermal, chemical, and perhaps, electrical forms (98).…”

“…Melanin is thought to be a dumping ground for unpaired photochemically generated electrons, apparently capable of sequestering electrons in an inactive form (98). As only about 501, of light subserves vision at ordinary illumination, the remainder of the energy entering the eye must be removed in thermal, chemical, and perhaps, electrical forms (98). It has been established that in melanin granules chloroquine is concentrated most intensely (54,85).…”

Some EPR Signals in Tumour Tissue

“…THE epr technique has been used to study the differences between normal and malignant tissues using lyophilized (Commoner, Townsend and Pake, 1954;Saprin et al, 1966a, b, c;Driscol et al, 1967;Mulay and Mulay, 1967;Wallace et al, 1970), frozen (Nebert and Mason, 1963;Hodgkinson and Cole, 1965;Slater and Cook, 1969) and wet samples (Mallard and Kent, 1966;Swartz, Lewis and Darin, 1971;Swartz, 1972;Duchesne and Van de Vorst, 1970). However, these differences are difficult to interpret, due primarily to a lack of identifiable paramagnetic species.…”