Therapeutic approach to targeting cancer via interaction of small molecules with G-quadruplex structure

Abstract

1.1 Nucleic acid Nucleic acid provides structural support to the genetic material of an organism and plays an important role in different cellular functions. Nucleotides are the basic structural unit of nucleic acid. There are three main building blocks of nucleotide(Figure. 1.1). 1. Phosphoric acid 2. Monosaccharide 3. Organic bases 1.1.1 Phosphoric Acid It is also known as orthophosphoric acid which chemical formula is H3PO3. It is a weak acid. Phosphoric acid consists of different characteristics which makes it important in the living world. Phosphoric acid connects two of the diester to stabilize against hydrolyse and sustain the molecule in a lipid membrane.[1] 1.1.2 Monosaccharide All nucleotides are connected to either two of these monosaccharaides. 1. β- Ribofuranose 2. β-2-Deoxyribofuranose 1.1.2.1 β- Ribofuranose It is a five-carbon sugar with a hydroxyl group (-OH) on each carbon atom. It is mainly found in RNA. 1.1.1.2.1β-2-Deoxyribofuranose β-2-Deoxyribofuranose sugar is found in DNA. In this hydroxyl (-OH) group present at the 2' position of the ribose sugar is replaced by a hydrogen (-H). 1.1.3 Organic Bases It can be further characterized into two types. 1. Purins 2. Pyrimidines 1.1.3.1 Purines In DNA, two different nitrogen bases, which containing purine ring (made up of carbon and nitrogen), are present in DNA and RNA, adenine (6-aminopurine) and guanine (6-oxy-2-aminopurine. Adenine has an amino group (-NH2) on the C6 position of the ring, while Guanine has an amino group at the C2 position and carbonyl group at the C6 position. 1.1.1.3.2 Pyrimidines Thymine (5-methyl-2,4-dioxypyrimidine) and cytosine (2-oxy-4- aminopyrimidine) are present in DNA, and Uracil (2,4-dioxypyrimidine) and cytosine are found in RNA. The thymine contains carbonyl group at C4 and C2 positions and a methyl group at the C5 position. Uracil is a component of RNA nucleic acid and absents in DNA.