Contribution of Nudt12 enzyme to differentially methylated dinucleotides of 5'RNA cap structure.

Recent findings have substantially broadened our knowledge about the diversity of modifications of the 5'end of RNAs, an issue generally attributed to mRNA cap structure (m7GpppN). Nudt12 is one of the recently described new enzymatic activities involved in cap metabolism. However, in contrast to its roles in metabolite-cap turnover (e.g., NAD-cap) and NADH/NAD metabolite hydrolysis, little is known regarding its hydrolytic activity towards dinucleotide cap structures. In order to gain further insight into this Nudt12 activity, comprehensive analysis with a spectrum of cap-like dinucleotides was performed with respect to different nucleotide types adjacent to the (m7)G moiety and its methylation status. Among the tested compounds, GpppA, GpppAm, and Gpppm6Am were identified as novel potent Nudt12 substrates, with KM values in the same range as that of NADH. Interestingly, substrate inhibition of Nudt12 catalytic activity was detected in the case of the GpppG dinucleotide, a phenomenon not reported to date. Finally, comparison of Nudt12 with DcpS and Nud16, two other enzymes with known activity on dinucleotide cap structures, revealed their overlapping and more specific substrates. Altogether, these findings provide a basis for clarifying the role of Nudt12 in cap-like dinucleotide turnover.

Plants as Modulators of Melanogenesis: Role of Extracts, Pure Compounds and Patented Compositions in Therapy of Pigmentation Disorders.

The kingdom of plants as a "green biofabric" of valuable bioactive molecules has long been used in many ailments. Currently, extracts and pure compounds of plant origin are used to aid in pigmentation skin problems by influencing the process of melanogenesis. Melanin is a very important pigment that protects human skin against ultraviolet radiation and oxidative stress. It is produced by a complex process called melanogenesis. However, disturbances in the melanogenesis mechanism may increase or decrease the level of melanin and generate essential skin problems, such as hyperpigmentation and hypopigmentation. Accordingly, inhibitors or activators of pigment formation are desirable for medical and cosmetic industry. Such properties may be exhibited by molecules of plant origin. Therefore, that literature review presents reports on plant extracts, pure compounds and compositions that may modulate melanin production in living organisms. The potential of plants in the therapy of pigmentation disorders has been highlighted.