Background:
Smokeless tobacco (SLT) products are consumed by millions of people in over 130 countries around the world. SLT products have a large impact on the health of individuals since the products cause several diseases including cancer. Though the smokeless tobacco products have been found to be associated with a large number of health effects and diseases, the understanding of the functions of chemical compounds of the products and their toxicity is very limited. There is a complete lack of extensive analysis of the targets of the chemical compounds and their associated biological mechanisms remain unknown.

Methods:
One hundred and one chemical compounds of SLT products were studied and similarity search algorithms were used to identify similar compounds along with their protein targets using ChEMBL. The protein targets were functionally annotated using PANTHER classification system and Kyoto Encyclopedia of Genes and Genomes (KEGG) to identify the associated Gene Ontologies and diseases respectively and the interaction network was studied. In addition, pharmacological and toxicological profiling ADMET (Absorption, Distribution, Metabolism, Excretion and Toxicity) of chemicals were also studied.

Results:
The study shows that the chemical compounds from SLT products target more than 350 human proteins involved in a plethora of human biological processes and affect around 100 pathways. The study has identified associations of diseases such as neurodegenerative, immune and cardiac diseases which were not known previously along with already established diseases such as cancer.

Conclusions:
We provide the first comprehensive report and systematic analyses of 101 chemical compounds from different SLT products used worldwide. The finding indicates far-reaching impact of SLT products on human health than already known and this finding needs further validations using epidemiological, in-vitro and in-vivo methodologies.