TY - JOUR
T1 - Mechanism of melatonin protection against copper-ascorbate-induced oxidative damage in vitro through isothermal titration calorimetry
AU - Ghosh, Arnab K.
AU - Naaz, Shamreen
AU - Bhattacharjee, Bharati
AU - Ghosal, Nirajan
AU - Chattopadhyay, Aindrila
AU - Roy, Souvik
AU - Reiter, Russel J.
AU - Bandyopadhyay, Debasish
N1 - Funding Information:
Dr. AKG acknowledges the receipt of a Research Associate (RA) award from CSIR, Govt. of India, New Delhi. SN and NG are supported by the funds from the “Teacher's Research Grant” available to Prof. DB from BI-92 of Department of Physiology University of Calcutta. BB acknowledges the receipt of a DST-Inspire fellowship from the Department of Science and Technology (DST), Govt. of India. Dr. AC is supported from the grants available to her from a UGC Minor Research Project. Prof. RJR is supported from funds available to him from University of Texas Health Science Center at San Antonio, TX, USA. This work is also partially supported from the funds available to Prof. DB from a UGC Major Research Project under CPEPA Scheme of UGC awarded to University of Calcutta (Grant No: 8-2/2008(NS/PE) DATED 14.12.2011) as well as UPE–II Scheme of UGC, Govt. of India awarded to University of Calcutta. Prof. DB further gratefully acknowledges the support that he received from DST PURSE Grant awarded to Calcutta University.
Publisher Copyright:
© 2017 Elsevier Inc.
PY - 2017/7/1
Y1 - 2017/7/1
N2 - Aims Involvement of oxidative stress in cardiovascular diseases is well established. Melatonin's role as an antioxidant and free radical scavenger via its receptor dependent and receptor independent pathways is well known. The aim of this study is to identify and elaborate upon a third mechanism by which melatonin is able to abrogate oxidative stress. Main methods Oxidative stress was induced in vitro, by copper (0.2 mM)-ascorbate (1 mM) in isolated goat heart mitochondria, cytosol and peroxisomes and they were co-incubated with graded doses of melatonin. Similar experiments in a cell-free chemical system involving two pure antioxidant enzymes, Cu-Zn superoxide dismutase and catalase was also carried out. Biochemical changes in activity of these antioxidant enzymes were analysed. Isothermal titration calorimetric studies with pure Cu-Zn superoxide dismutase and catalase were also carried out. Key findings Incubation with copper-ascorbate led to alteration in activity of Cu-Zn superoxide dismutase and catalase which were found to be protected upon co-incubation with melatonin (80 μM for catalase and 1 μM for others). Results of isothermal titration calorimetric studies with pure Cu-Zn superoxide dismutase and catalase along with different combinations of copper chloride, ascorbic acid and melatonin suggest that when melatonin is present in the reaction medium along with copper-ascorbate, it restrains the copper-ascorbate molecules by binding with them physically along with scavenging the free radicals generated by them. Significance The present study suggests that possibly, binding of melatonin with antioxidant enzymes masks the vulnerable sites of these antioxidant enzymes, thus preventing oxidative damage by copper-ascorbate molecules.
AB - Aims Involvement of oxidative stress in cardiovascular diseases is well established. Melatonin's role as an antioxidant and free radical scavenger via its receptor dependent and receptor independent pathways is well known. The aim of this study is to identify and elaborate upon a third mechanism by which melatonin is able to abrogate oxidative stress. Main methods Oxidative stress was induced in vitro, by copper (0.2 mM)-ascorbate (1 mM) in isolated goat heart mitochondria, cytosol and peroxisomes and they were co-incubated with graded doses of melatonin. Similar experiments in a cell-free chemical system involving two pure antioxidant enzymes, Cu-Zn superoxide dismutase and catalase was also carried out. Biochemical changes in activity of these antioxidant enzymes were analysed. Isothermal titration calorimetric studies with pure Cu-Zn superoxide dismutase and catalase were also carried out. Key findings Incubation with copper-ascorbate led to alteration in activity of Cu-Zn superoxide dismutase and catalase which were found to be protected upon co-incubation with melatonin (80 μM for catalase and 1 μM for others). Results of isothermal titration calorimetric studies with pure Cu-Zn superoxide dismutase and catalase along with different combinations of copper chloride, ascorbic acid and melatonin suggest that when melatonin is present in the reaction medium along with copper-ascorbate, it restrains the copper-ascorbate molecules by binding with them physically along with scavenging the free radicals generated by them. Significance The present study suggests that possibly, binding of melatonin with antioxidant enzymes masks the vulnerable sites of these antioxidant enzymes, thus preventing oxidative damage by copper-ascorbate molecules.
KW - Antioxidant enzymes
KW - Isothermal titration calorimetry
KW - Melatonin
KW - Oxidative stress
KW - Reactive oxygen species
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U2 - 10.1016/j.lfs.2017.05.022
DO - 10.1016/j.lfs.2017.05.022
M3 - Article
C2 - 28528861
AN - SCOPUS:85019851087
VL - 180
SP - 123
EP - 136
JO - Life Sciences
JF - Life Sciences
SN - 0024-3205
ER -