Microbial melanin: Recent advances in biosynthesis, extraction, characterization, and applications.

Melanin is a common name for a group of biopolymers with the dominance of potential applications in medical sciences, cosmeceutical, bioremediation, and bioelectronic applications. The broad distribution of these pigments suggests their role to combat abiotic and biotic stresses in diverse life forms. Biosynthesis of melanin in fungi and bacteria occurs by oxidative polymerization of phenolic compounds predominantly by two pathways, 1,8-dihydroxynaphthalene [DHN] or 3,4-dihydroxyphenylalanine [DOPA], resulting in different kinds of melanin, i.e., eumelanin, pheomelanin, allomelanin, pyomelanin, and neuromelanin. The enzymes responsible for melanin synthesis belong mainly to tyrosinase, laccase, and polyketide synthase families. Studies have shown that manipulating culture parameters, combined with recombinant technology, can increase melanin yield for large-scale production. Despite significant efforts, its low solubility has limited the development of extraction procedures, and heterogeneous structural complexity has impaired structural elucidation, restricting effective exploitation of their biotechnological potential. Innumerable studies have been performed on melanin pigments from different taxa of life in order to advance the knowledge about melanin pigments for their efficient utilization in diverse applications. These studies prompted an urgent need for a comprehensive review on melanin pigments isolated from microorganisms, so that such review encompassing biosynthesis, bioproduction, characterization, and potential applications would help researchers from diverse background to understand the importance of microbial melanins and to utilize the information from the review for planning studies on melanin. With this aim in mind, the present report compares conventional and modern ideas for environment-friendly extraction procedures for melanin. Furthermore, the characteristic parameters to differentiate between eumelanin and pheomelanin are also mentioned, followed by their biotechnological applications forming the basis of industrial utilization. There lies a massive scope of work to circumvent the bottlenecks in their isolation and structural elucidation methodologies.

Recent Advances in the Discovery of GSK-3 Inhibitors from Synthetic Origin in the Treatment of Neurological Disorders.

BACKGROUND: Glycogen synthase kinase 3 (GSK-3) is a serine/threonine kinase enzyme that controls neuronal functions such as neurite outgrowth, synapse formation, neurotransmission, and neurogenesis. The enzyme has two subunits as GSK-3α and GSK-3ß. 4ACC, 1Q3D, 3AFG, 1UV5, and 1Q5K are the important GSK-3 receptors isolated from Homo sapiens and Mus musculus. This enzyme mainly phosphorylates Tau protein with the increased amount in neuronal fibres together with beta-amyloid plaques that cause neuronal diseases like Alzheimer's, Parkinson's and many more. OBJECTIVE: We investigated the developments of various synthetic GSK-3 inhibitors responsible for the prevention and treatment of neurological disorders, like Alzheimer's disease, bipolar disorders, acting as antidepressants, neuroprotective, etc. Results and Conclusion: It has been observed that structures of the GSK-3 inhibitors are comprised of benzopyridine, benzothiazole, pyrazole, pyrazine, dioxolo-benzoxazine, oxadiazole, and benzimidazole in the skeletal with cyclopropyl amide, phenyl carbamothioate, 3-[(propan- 2-yl)oxy]propan-1-amine in the side chain. The molecules were evaluated against the effectivity of GSK-3, human adenosine kinase, cyclin-dependent kinase, and phosphodiesterase-4 along with tail suspension test forced swim test, percent neuronal survival and other cognitive behaviours. The observations confirmed the remarkable effects of the synthesized molecules to conquer Alzheimer, Parkinson's depression, psychosis and other forms of neurological disorders.

GSK-3 Inhibitors: A New Class of Drugs for Alzheimer's Disease Treatment.

Alzheimer's disease (AD), a chronic neurodegenerative disease, is the most common form of dementia that causes cognitive function impairment, including memory, thinking, and behavioral changes that ultimately lead to death. The overactivation of GSK-3, an enzyme from the proline/serine Ki NS family, has been associated with hyper-phosphorylation of tau proteins. The self- -assembly of hyper-phosphorylated tau proteins to form tangles of straight and helical filaments is known to be involved in AD. Therefore, GSK-3 has been considered a potential target of novel drug discovery for AD treatment. Research on the development of GSK-3 inhibitors has received enormous attention from the vast scientific community because they are targeted for AD and other diseases, including type 2 diabetes, cancers, stroke, Parkinson's disease and bipolar disorder. Various drugs of both synthetic and natural origins have been designed to inhibit GSK-3 activity. However, there is a need to develop novel drug candidates that can selectively inhibit GSK-3. Hence, this review summarizes the potential of GSK-3 inhibitors for AD therapy and discusses the structure- activity relationship of current drug molecules and the potential problems associated with them.