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The flavonoid naringenin and a family of naringenin derivative Cu(II) complexes having phenanthroline-based second ligands were selected to study alkaline phosphatase activation. This enzyme plays a critical role in tissue formation, increasing the inorganic phosphate formation, favoring mineralization, and being essential to producing bone mineralization. The effects of those compounds on the function and structure of the enzyme were evaluated by kinetic measurements, fluorescence, FTIR, and UV-Vis spectroscopies. The results showed that naringenin did not affect alkaline phosphatase activity, having a value of the Michaelis-Menten-constant close to the enzyme (Km = 3.07 × 10 -6 ). The binary complex, Cu(II)-naringenin, and the ternary complex Cu(II)-naringenin-phenanthroline behaved as an enzyme activator in all the concentrations range used in this study. Those complexes increased in c.a. 1.9% the catalytic efficiency concerning enzyme and naringenin. The ternary complex Cu(II)-naringenin-bathophenanthroline, provokes an activator mixed effect, dependent on the substrate concentrations. The different kinetic behavior can be correlated with different conformational changes observed under the interaction with ALP. Fluorescence experiments showed a raising of the binding constant with temperature. FTIR determinations showed that the complex with bathophenanthroline modifies the ALP structure but maintains the helical structure. The other copper complexes provoked a structural unfolding, decreasing the α-helix content. None of them affect the dephosphorylation enzyme ability. Even though the interactions and structural modifications on ALP are different, it is evident that the presence of copper favors enzymatic activity. The observed electrostatic interactions probably benefit the dissociation of the bound phosphate. The results suggest potential biological applications for the studied compounds., (© 2023. The Author(s), under exclusive licence to Springer Nature B.V.)

Recent studies showed that vision and hearing in dolphins are mechanisms for perception of the environment, and transmission of information among individuals. Considering that Guiana dolphins (Sotalia guianensis) are distributed in costal regions, and Clymene dolphins (Stenella clymene) are found in oceanic environments, the objective of this study was to compare the morphology of the eyes of these two species, assessing the differences in eye structures in both environments. Five specimens of Sotalia guianensis and four specimens of Stenella clymene were analyzed. All the specimens were found stranded in the northeastern coast of Brazil. Samples were fixated in 10% formaldehyde, dissected, photographed, processed, and analyzed by optical microscopy. The inferior palpebral region of the two species showed a granular layer, subcutaneous lymphoid tissue, and innervation. Morphometric values of the eyelid structures and eye bulb were greater in S. clymene. The cornea showed four layers in S. clymene: anterior epithelium, anterior lamina, stroma, and posterior lamina. The sclera of S. guianensis showed more melanocytes and presence of mechanoreceptors next to the Harderian gland. It is possible to suggest that the geographical distribution of these cetaceans determine their eye morphology, which is an adaptation to the intrinsic characteristics of the aquatic environment.