, 37:48 | Cite as

Age-related variations of protein carbonyls in human saliva and plasma: is saliva protein carbonyls an alternative biomarker of aging?

  • Zhihui Wang
  • Yanyi WangEmail author
  • Hongchen Liu
  • Yuwei Che
  • Yingying Xu
  • Lingling E


Free radical hypothesis which is one of the most acknowledged aging theories was developed into oxidative stress hypothesis. Protein carbonylation is by far one of the most widely used markers of protein oxidation. We studied the role of age and gender in protein carbonyl content of saliva and plasma among 273 Chinese healthy subjects (137 females and 136 males aged between 20 and 79) and discussed the correlation between protein carbonyl content of saliva and plasma. Protein carbonyl content of saliva and plasma were, respectively, 2.391 ± 0.639 and 0.838 ± 0.274 nmol/mg. Variations of saliva and plasma different age groups all reached significant differences in both male and female (all p < 0.05) while both saliva and plasma protein carbonyls were found to be significantly correlated with age (r = 0.6582 and r = 0.5176, all p < 0.001). Gender was discovered to be unrelated to saliva and plasma protein carbonyl levels (all p > 0.05). Saliva and plasma protein carbonyls were positively related (r = 0.4405, p < 0.001). Surprisingly, saliva and plasma protein carbonyls/ferric reducing ability of plasma (FRAP) ratios were proved to be significantly correlated with age (r = 0.7796 and r = 0.6938, all p < 0.001) while saliva protein carbonyls/FRAP ratio and plasma protein carbonyls/FRAP ratio were also correlated (r = 0.5573, p < 0.001). We concluded that saliva protein carbonyls seem to be an alternative biomarker of aging while the mechanisms of protein carbonylation and oxidative stress and the relationship between saliva protein carbonyls and diseases need to be further investigated.


Saliva Plasma Protein carbonylation Free radicals Oxidative stress Aging 


Author contributions

Guarantor: Yanyi Wang had full access to all of the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.

Study concept and design Zhihui Wang, Yanyi Wang, Hongchen Liu.

Acquisition of data Zhihui Wang, Yanyi Wang, Yuwei Che, Yingying Xu, Lingling E.

Analysis and interpretation of data Zhihui Wang, Yanyi Wang, Yuwei Che, Yingying Xu, Lingling E.

Drafting of the manuscript Zhihui Wang, Yanyi Wang.

Critical revision of the manuscript for important intellectual content Zhihui Wang, Yanyi Wang, Hongchen Liu, Yuwei Che, Yingying Xu, Lingling E.

Obtained funding Zhihui Wang, Yanyi Wang.

Conflict of interest

None declared.


This study was funded by three grants from China: National High-tech R&D Program (863 Program) (grant number 2012AA020809), Natural Science Foundation of Hainan Province (grant number 20158317), and Sanya Medical Development and Innovation Program (grant number 2014YW34).

Role of the Sponsor

The sponsor had no role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; and preparation, review, or approval of the manuscript.

Ethical approval

The Medical Ethical Committee of the Chinese People’s Liberation Army General Hospital (grant number s2014-114-01) approved the study in 2014.


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Copyright information

© American Aging Association 2015

Authors and Affiliations

  • Zhihui Wang
    • 1
  • Yanyi Wang
    • 1
    Email author
  • Hongchen Liu
    • 2
  • Yuwei Che
    • 3
  • Yingying Xu
    • 3
  • Lingling E
    • 2
  1. 1.Department of StomatologyHainan Branch of Chinese People’s Liberation Army General HospitalSanyaChina
  2. 2.Institute of StomatologyChinese People’s Liberation Army General HospitalBeijingChina
  3. 3.Department of ProsthodonticsChinese People’s Liberation Army General HospitalBeijingChina

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