Extended Abstract
1. Introduction
uman serum albumin (HSA) is one of the most abundant proteins in the blood circulation, which regulates the transportation of numerous chemical compounds and molecules. Many investigations have indicated that the presence of the remnants of pesticides in soil, water and agricultural products can intoxicate humans and upon the entrance  to the bloodstream, they easily bind to circulating serum proteins.The purpose of this systematic review is to evaluate the biological effects of three groups of pesticides, namely insecticides, herbicides, and fungicides, on the molecular structure of the HSA protein. 
Materials and Methods: 
This systematic review assessed 35 studies published in the field of biophysics in which the impact of 39 pesticides was examined on the HSA protein. These pesticides were further divided into 11 insecticides, 11 fungicides and 17 herbicides (Table 2). The collected publications were selected from comprehensive databases, such as PubMed, Science Direct, Web of Science, and Google Scholar, between 1980 and 2019. 
Results
The results indicated that 21 out of 35 articles selected from databases used the UV-Vis spectroscopy method. The UV-Vis spectroscopy analysis assessed the decrease/increase of the absorbance of the HSA protein in parallel with the increase in the concentration the presence of pesticides. The most studies have employed different fluorescence methods to analyze the effect of pesticides on the structure of the HSA protein. The obtained extinction coefficient, along with a decrease in the fluorescence intensity of HSA, indicates that pesticides are bound to tryptophan or one of the residues located at the proximity of this amino acid. The biological effects of Diazinon, methyl Thiophonate, Glycophosphate, Permethrin, Diuron, and 2, 4 D were evaluated by the Fourier-transform infrared spectroscopy (FTIR) method, while 26 out of 35 articles applied the circular dichroism (CD) method for analyzing the secondary structures of the HSA protein. Upon the interaction of Thiophanate Methyl and Atrazine with HSA, the percentages of the β-turn structure were decreased by 4.3% (from 30.9 to 26.6) and 1.9% (from 28.2 to 26.3), respectively. On the other hand, the interaction of Tebuconazole and Pyrazosulfuron Ethyl with HSA increased the percentages of the α-helix structure by 5% (from 55 to 60) and 5.89% (from 45.38 to 51.27), respectively. In the rest interactions of pesticides with HSA caused a marked reduction in the structure of α-helices, as well as a substantial increase in the number of other secondary structures, including β-sheet, β-anti, β-turn, and random coils. The binding constants of these interactions were at a range of 10 3 to 10 6 M-1(Table 1). According to previous reports, it has been demonstrated that pesticides interact with HSA by hydrophobic, electrostatic, and hydrogen bonding interactions. 25 out of 32 studies that assessed the binding of pesticides to the HSA protein showed that the site of interaction by pesticides is located at the subdomain IIA (Based on references 12 to 46). 
Discussion
The changes in the absorption and emission of the HSA protein denote the occurrence of structural changes as a result of the presence of pesticides, exposing the tryptophan residue to the hydrophobic/hydrophilic milieu or changing the charge of the protein, leading to the improper conformational changes and protein instability (66). Generally, a vast majority of the interactions of compounds with HSA occur at the subdomain IIA because it has a big hydrophobic cavity enabling this pocket to hold multiple compounds simultaneously (5). Therefore the alteration at the vicinity of Trp-214 is capable of inducing conformational changes at the subdomain IIA and causing loss of function that can lead to a decrease in the concentration of free HSA and interruption of the transport of the essential compounds in the systemic circulation, such as drugs and hormones. Our data indicated that the concentration of free HSA would be declined when exposed to pesticides, due to partial changes in the structure of HSA. These conformational alterations affect the secondary and tertiary structure of the HSA protein, and they are proportional to the time of the presence of pesticides in the human body. HSA is one of the crucial proteins having myriad biological functions, implying that the detrimental role of pesticides in the functional impairment of this protein should not be underestimated. 
The authors had writing standards based on the recommendations of the International Committee of Medical Journal Publishers.
Ethical Considerations
Compliance with ethical guidelines
 In this study, all principles of the research ethics were considered.

 






 

Funding
the paper not extracted from a thesis and it have not any financial supporters
Authors' contributions
Software and Validation:
(Mohammad Taghizadeh)
Analysis, Investigation, Resources, Data Curation and Writing:
(Shahrzad Hadichegeni)
Review & Editing and Supervision:
(Bahram Goliaei)
Conflicts of interest
The authors declare no conflict of interest.
Acknowledgements
We would like to thank from the efforts of all the researchers who have been able to add this systematic review to our country’s scientific literature by using their scientific research article.