# Nutritional and Medicinal Properties of Microbial Oil
## 6 Applications of Microbial Oils in Cosmetics, Pharmacy, and Medicine
In the human body, arachidonic acid in its esterified form is essential for the maintenance and function of cell membranes. It serves as a precursor in the biosynthesis of eicosanoids, which are signaling molecules, such as prostaglandandins and leukotrienes. These molecules are considered proinflammatory and are responsible for stimulating the immune response and triggering oxidative stress [97; 98]. Eicosapentaenoic and docosahexaenoicenoic acids have 20 and 22 carbon atoms in their chain, respectively, and 5 and 6 unsaturated double bonds in their molecule, respectively. Their main source is algae, and the research conducted using EPA and DHA has confirmed their positive effect on the human body. First of all, lipids are abundantly present in the brain, making up more than 50% of the brain's dry weight, and, moreover, they have a unique ability to cross the blood-brain barrier, allowing them to readily access the brain [99]. The specific roles of DHA and EPA highlight the critical importance of lipids for proper brain health and cognition. Furthermore, their consumption helps to reduce the risk of cardiovascular diseases, osteoporosis, and inflammatory diseases. Additionally, EPA and DHA are involved in lowering the blood cholesterol levels, thereby reducing the risk of heart disease. A deficiency of these acids may have an impact on cell death, cognitive function, and brain disorders, as well as the prevention and treatment of Alzheimer's disease and other neurodegenerative diseases [99; 100; 101]. Over the past few years, numerous research teams have conducted cohort studies, meta-analyses, and systematic reviews that explore the link between the intake of polyunsaturated amonga-3 fatty acids and neurodegenerative conditions, such as Alzheimer's and Parkinson's diseases and various forms of dementia, as well as cognitive impairment and decline [102; 103; 104; 105]. [PERSON] et al. [102] observed that long-term users of omega-3 supplements have a 64% reduced risk of developing Alzheimer's disease. Additionally, they found that the intake of DHA could lower the risk of dementia and cognitive decline by up to 20%. They also noted that, for each 0.1 g/day increase in DHA or EPA intake, the risk of cognitive decline lowers by 8-9.9%. [PERSON] [103] analyzed the role of DHA in preventing vascular dementia induced by ischemic stroke. This study found that DHA and its metabolites, which are produced in cerebral vascular endothelial cells, have antioxidative and anti-inflammatory properties. These properties lead to a decrease in the production of the A9-42 (amyloid beta) peptide, which in turn may prevent the onset of the disease. Furthermore, preclinical studies have also been carried out on well-established animal models to verify the hypothesis that polyunsaturated fatty acids (PUFA--polyunsaturated fatty acids) have beneficial effects. These studies showed that DHA improved the performance of rodents in memory tests and cognition, provided neuroprotection, and reduced inflammation [104]. Lipid nanoparticles, which are useful in pharmaceuticals and, thus, in drug delivery, are composed of both solid and liquid lipids. The choice of lipids is influenced by various factors, including drug solubility, production costs, and stability. Lipids, with their ability to act as excellent solvents for poorly soluble drugs, as well as their taste-masking and non-toxic properties, have potential in the field. Different types of oils and fats have been applied in recent years in the formulation of lipid nanoparticles. However, novel formulations should explore oils, such as those derived from oleaginous microbial organisms, to meet the high demand for sustainable production [99].