re-check the content and modify: Nucleic acid extraction is the first step in every molecular biology study, hence it is regarded as an essential precudure (Gupta, 2019). Using DNA isolation technology, pure DNA can be efficiently extracted in sufficient quantity and quality, free of contaminants. The ability to extract DNA is paramount for studying the genetic causes of disease, developing diagnostics and pharmaceuticals. It is also essential in conducting forensic medicine, sequencing genomes, and detecting bacteria and viruses in the environment (Tan and Yiap, 2009).
DNA contains the genetic information about an organism; therefore, it can be obtained from body fluids such as blood, saliva, semen, and urine as well as nail, hair, bone, and teeth. The primary steps involved in DNA extraction involves the cell lysis, precipitation, and purification (El-Ashram, Al Nasr and Suo, 2016). All the different techniques available for DNA isolation revolves around this primary basis. Methods for DNA extraction involve the adsorption methods (i.e., silicone gel technique), organic methods (i.e., phenol-chloroform technique) as well as non- organic methods (i.e., salting out technique) (Dairawan and Shetty, 2020).
Recent advances in the use of saliva as a liquid biopsy have made a variety of applications possible in the fields of medicine, dentistry, microbiology, and forensic research (Sullivan et al., 2020). Saliva is a readily available biofluid or matrix that provides a non-invasive collection procedure, minimising the discomfort and distress related to collecting blood and urine. Laidi et al. (2014) utilised salivary and serum tumour marker CA 15-3 in healthy women and breast cancer patients to demonstrate a substantial positive connection between saliva and serum, indicating it might be utilised as a substitute for blood sample. 
As well as that, the Covid-19 pandemic presented the global community with its most severe challenge and health emergencies since its first outbreak in late 2019 (Shi et al., 2020). Controlling the outbreak in the community and in hospitals required a quick and precise diagnosis. The suggested specimen types for Covid-19 examinations were nasal and oropharyngeal swabs. Close contact between healthcare professionals and patients was necessary for the collection of these specimen types, which increased the risk of viral transmission, causing discomfort, and resulting in bleeding, particularly in individuals with conditions like thrombocytopenia. Since it was self-administered, saliva samples were easily acquired. The collection of saliva was non-invasive and significantly reduced the exposure of the virus to the health workers (Sri Santosh et al., 2020).
Therefore, genomic DNA previously collected from venous blood is increasingly being replaced with DNA obtained from saliva (Abraham et al., 2012). It is accessible to kids, elderly people, and individuals with disabilities, and it may be simply repeated in accordance with the needs of the experiment. Several potential sources for DNA isolation can be found in the oral cavity. Human genomic DNA from buccal cells, mitochondrial DNA, cell free DNA and DNA from the natural oral microbiota can all be isolated from saliva samples (Durdiaková et al., 2012). 
According to the current need for new methods for the increasing applications of molecular studies, it is crucial to use a DNA isolation method that can maximize the yield and purity of DNA. Although there are plenty of commercial kits in the market for this concern, it is an expensive procedure especially in the developing countries, which may not be applicable for large or mass testing. Hence, the purpose of this study is to establish an optimal, quick, and easy method for isolating DNA from saliva samples. Genomic DNA will be isolated from buccal cells as well as cell-free DNA present in saliva, using a modified phenol-chloroform extraction technique to produce a high yield of DNA which can improve the performance of other downstream applications (Cao et al., 2003). The isolated DNA will be further confirmed for its yield and quality by checking for the presence of natural oral bacteria DNA using PCR and gel electrophoresis.