The GABA receptors (GABA_A and GABA_B) respond to the neurotransmitter gamma-aminobutyric acid (GABA), the chief inhibitory compound in the mature vertebrate central nervous system. GABA receptors agonists produce typically sedative effects, and may also cause other effects such as anticonvulsant, anxiolytic and muscle relaxant effects. Antagonists of GABA receptors inhibit the action of GABA. In general they produce stimulant and convulsant effects. Therefore, small molecule compounds modulating GABA receptors activity may have significant therapeutic potential.

Beta-arrestins (ß-arrestin 1 and ß-arrestin 2) play central roles in the mechanisms regulating G protein-coupled receptors signalling and trafficking. They participate in agonist-mediated desensitization of GPCR and cause specific dampening of cellular responses to stimuli such as sensory signals, hormones or neurotransmitters [1].

Nuclear estrogen receptors (ERα and Erβ) are members of the nuclear receptor family of intracellular receptors. Estrogen receptors (ERs) are involved in modulation of biological activities, such as reproductive organ development, bone modeling, cardiovascular system functioning, metabolism and behavior in both females and males.

Alzheimer's disease (AD) is a complex neurodegenerative disorder of the central nervous system that usually starts slowly and gets worse over time. It is characterized by progressive loss of dementia, cognitive ability, and eventually death. Currently there is no cure for the disease.

Epigenetic targets are a major new category for successful drug research. Among them the protein methyltransferases (PMTs) which have crucial roles in gene transcription are an important group of enzymes that play key parts in normal physiology and human diseases. There has been a significant increase in attention towards protein arginine methyltransferases (PRMTs) which catalyze methylation of nitrogen of specific arginine residues in proteins and impact on numerous essential biological pathways by methylating different nuclear, cytoplasmic and membrane protein substrates.

The recent substantial progress in RNA biology underscores the importance of RNA in normal and aberrant cellular functions. Rather, it is now recognized that RNA is essential for transcriptional regulation, translational regulation, protein function, and catalysis, responsibilities that have classically been reserved for proteins.

A neurotoxic peptide β-amyloid (Aβ) is linked to the beginning of Alzheimer’s disease (AD). The accumulation of amyloid-beta inside mitochondria boosts production of free radical and activation of the apoptotic pathway. Human Presequence Protease (hPreP, PITRM1) is a mitochondrial ATP-independent metalloprotease. It degrades toxic peptides, including mitochondrial presequences and β-amyloid. This enzyme is an attractive target for Alzheimer’s disease drug design because enhancement of it's activity increases the level of Aβ proteolysis.

5-hydroxytryptamine receptors (serotonin receptors , 5-HT receptors) are a group of G protein-coupled receptors (GPCRs) and ligand-gated ion channels found in the central and peripheral nervous systems [1, 2]. They mediate both excitatory and inhibitory neurotransmission. The serotonin receptors are activated by the neurotransmitter serotonin, which acts as their natural ligand.

The sodium glucose cotransporter 2 (SGLT2) reabsorbs most of the glucose filtered by the kidneys. SGLT2 inhibitors reduce glucose reabsorption, thereby lowering blood glucose levels in patients with diabetes [1]. Type 2 diabetes is a chronic disease with disabling micro- and macrovascular complications that lead to excessive morbidity and premature mortality.

The enzyme 3-hydroxy-3-methyl-glutaryl-CoA reductase (3-hydroxy-3-methylglutaryl-coenzyme A, HMG-CoA, HMGCR) catalyzes the conversion of HMG-CoA to mevalonate, an early and rate-limiting step in cholesterol biosynthesis. The HMG-CoA reductase inhibitors, also known as statins, are the most effective class of drugs for lowering serum low-density lipoprotein cholesterol concentrations.