PHOTOPEROXIDATION OF CHOLESTEROL IN HOMOGENEOUS SOLUTION, ISOLATED MEMBRANES, AND CELLS: COMPARISON OF THE 5α‐ AND 6β‐HYDROPEROXIDES AS INDICATORS OF SINGLET OXYGEN INTERMEDIACY

Korytowski, Witold; Bachowski, Gary J.; Girotti, Albert W.

doi:10.1111/j.1751-1097.1992.tb09594.x

Cited by 91 publications

(58 citation statements)

References 24 publications

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“…The percentage of sterol photooxidation was estimated using Eq. (3) (Christodoulou et al, 2009), based on the ratio 4 -6α/β-hydroperoxides/ 6 -5α-hydroperoxides found in biological membranes (0.30) (Korytowski et al, 1992):…”

Section: -Sterolsmentioning

confidence: 99%

Seasonal survey of the composition and degradation state of particulate organic matter in the Rhône River using lipid tracers

et al. 2015

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Abstract. Lipid tracers including fatty acids, hydroxyacids, n-alkanols, sterols and triterpenoids were used to determine the origin and fate of suspended particulate organic matter (POM) collected in the Rhône River (France). This seasonal survey (April 2011 to May 2013) revealed a yearround strong terrestrial higher-plant contribution to the particulate organic matter (POM), with significant algal inputs observed in March and attributed to phytoplanktonic blooms likely dominated by diatoms. Major terrigenous contributors to our samples are gymnosperms, and more precisely their roots and stems, as evidenced by the presence of high proportions of ω-hydroxydocosanoic acid (a suberin biomarker). The high amounts of coprostanol detected clearly show that the Rhône River is significantly affected by sewage waters.Specific sterol degradation products were quantified and used to assess the part of biotic and abiotic degradation of POM within the river. Higher-plant-derived organic matter appears to be mainly affected by photo-oxidation and autoxidation (free radical oxidation), while organic matter of mammal or human origin, evidenced by the presence of coprostanol, is clearly more prone to bacterial degradation. Despite the involvement of an intense autoxidation-inducing homolytic cleavage of peroxy bonds, a significant proportion of hydroperoxides is still intact in higher plant debris. These compounds could affect the degradation of terrestrial material by inducing an intense autoxidation upon its arrival at sea.

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Section: -Sterolsmentioning

confidence: 99%

Seasonal survey of the composition and degradation state of particulate organic matter in the Rhône River using lipid tracers

et al. 2015

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“…D 4 -6a/6b-Hydroperoxides were selected as tracers of photooxidation of D 5 -sterols because of their high specificity and relative stability (Christodoulou et al 2009;Rontani et al 2009). These compounds were quantified after NaBH 4 reduction to the corresponding diols and the sterol photooxidation percentage was estimated with the following equation (Christodoulou et al 2009;Rontani et al 2009): Sterol photooxidation % 5 (D 4 -3b,6a/b-dihydroxysterol %) 3 (1 + 0.3)/ 0.3, on the basis of the ratio D 4 -6a/6b-hydroperoxides/D 6 -5a-hydroperoxides measured in biological membranes (0.30, Korytowski et al 1992).…”

Section: -Cismentioning

confidence: 99%

Degradation of particulate organic matter in the equatorial Pacific Ocean: Biotic or abiotic?

Rontani

Zabeti

Wakeham

2011

Limnology & Oceanography

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The behavior of organic matter (OM) in suspended and sinking particles in the equatorial Pacific Ocean was monitored by measuring lipid degradation products that are specific for biodegradation, photooxidation, and autoxidation. Photodegradation and autoxidation were significant for lipids associated with both suspended and sinking particles. Abiotically degraded terrestrial material strongly contributed to suspended particles and to sinking material in the deep ocean, probably as the result of incorporation of terrestrial particles into sinking aggregates. Analyses of degradation products of 24-methylcholesta-5,22-dien-3b-ol, 24-ethylcholest-5-en-3b-ol, and cholest-5-en-3b-ol gave diagnostic information concerning the differential behavior of phytoplanktonic, terrestrial, and zooplanktonic OM, respectively. Planktonic lipids were more susceptible to biodegradation than terrestrial lipids and biodegradation was more intense in sinking particulate organic matter (POM) than suspended POM, which we attribute to efficient transfer of singlet oxygen from suspended and senescent phytoplankton cells to associated bacteria and subsequent inhibition of heterotrophic degradation. There is a direct link between the photooxidation state of lipids of senescent phytoplankton cells in suspended particles and the apparent resistance of lipids toward biotic degradation. Terrigenous vascular plant OM, which is strongly autoxidized on land or in the atmosphere as it is transported to the remote ocean, is only weakly biodegraded during sedimentation in this open ocean setting. A significant increase in alkenone-based U K9 37 values (+0.07 equivalent to an inferred temperature change of +2uC) was observed in sinking particles with depth and the detection of epoxyalkenones further confirming the potential detrimental effect of aerobic bacterial degradation processes on the U K9 37 paleotemperature proxy.

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“…Colour deterioration and lipid oxidation may be linked, although the precise mechanisms are still unclear 16 . Furthermore, the oxidation of PUFA would induce cholesterol oxidation [17][18] . It is known that cholesterol oxidation products (COP) are clearly involved in the development of cardiovascular diseases 19 , and are also associated with the development of some biological effects like cytotoxicity, mutagenesis and carcinogenesis [20][21][22] .…”

Section: Introductionmentioning

confidence: 99%

Functional dry fermented sausages manufactured with high levels of n‐3 fatty acids: nutritional benefits and evaluation of oxidation

2004

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Dry fermented sausages were manufactured adding fish oil extracts rich in n-3 fatty acids in order to obtain functional products and their nutritional advantages and intensity of oxidation process compared with traditional ones. Modified products were manufactured with 0.53% (batch A) and 1.07% (batch B) of fish oil extract. The amounts of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) per 100g of dry fermented sausages were 0.15g and 0.13g in batch A, 0.33g and 0.26g in batch B, respectively, in contrast with the control products which only showed 0.01g EPA and 0.03g DHA. No significant differences were found in the rest of fatty acids. A decrease in the n-6/n-3 ratios from 16.14 in the control to 7.78 in batch A and 5.32 in batch B was achieved. TBA values were similar in control (0.31ppm) and in batch A products (0.34ppm) but increase significantly in batch B products (1.22ppm). No statistical differences were observed among batches for the content of cholesterol oxidation products (2.36 to 2.43 μg/g fat) leading to similar percentages of oxidation. 7-Ketocholesterol, considered as an indicator of oxidation was not present in any sample.Values obtained for L* and Hue (arctg b*/a*) were comparable to that of meat products. Although no effect was observed in COP formation and instrumental measurements of colour the high level of n-3 fatty acid seems to accelerate significantly the oxidation process. RUNNING TITLEFunctional n-3 fatty acid containing dry fermented sausages

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PHOTOPEROXIDATION OF CHOLESTEROL IN HOMOGENEOUS SOLUTION, ISOLATED MEMBRANES, AND CELLS: COMPARISON OF THE 5α‐ AND 6β‐HYDROPEROXIDES AS INDICATORS OF SINGLET OXYGEN INTERMEDIACY

Cited by 91 publications

References 24 publications

Seasonal survey of the composition and degradation state of particulate organic matter in the Rhône River using lipid tracers

Seasonal survey of the composition and degradation state of particulate organic matter in the Rhône River using lipid tracers

Degradation of particulate organic matter in the equatorial Pacific Ocean: Biotic or abiotic?

Functional dry fermented sausages manufactured with high levels of n‐3 fatty acids: nutritional benefits and evaluation of oxidation

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