**Magnificamide, a** β**-Defensin-Like Peptide from the Mucus of the Sea Anemone** *Heteractis magnifica***, Is a Strong Inhibitor of Mammalian** α**-Amylases**

**Oksana Sintsova 1,\*, Irina Gladkikh 1, Aleksandr Kalinovskii 1,2, Elena Zelepuga 1, Margarita Monastyrnaya 1, Natalia Kim 1, Lyudmila Shevchenko 1, Steve Peigneur 3, Jan Tytgat 3, Emma Kozlovskaya <sup>1</sup> and Elena Leychenko 1,\***


Received: 19 August 2019; Accepted: 17 September 2019; Published: 21 September 2019

**Abstract:** Sea anemones' venom is rich in peptides acting on different biological targets, mainly on cytoplasmic membranes and ion channels. These animals are also a source of pancreatic α-amylase inhibitors, which have the ability to control the glucose level in the blood and can be used for the treatment of prediabetes and type 2 diabetes mellitus. Recently we have isolated and characterized magnificamide (44 aa, 4770 Da), the major α-amylase inhibitor of the sea anemone *Heteractis magnifica* mucus, which shares 84% sequence identity with helianthamide from *Stichodactyla helianthus*. Herein, we report some features in the action of a recombinant analog of magnificamide. The recombinant peptide inhibits porcine pancreatic and human saliva α-amylases with Ki's equal to 0.17 ± 0.06 nM and 7.7 ± 1.5 nM, respectively, and does not show antimicrobial or channel modulating activities. We have concluded that the main function of magnificamide is the inhibition of α-amylases; therefore, its functionally active recombinant analog is a promising agent for further studies as a potential drug candidate for the treatment of the type 2 diabetes mellitus.

**Keywords:** Cnidaria; sea anemones; venom; amylase inhibitors; defensin; diabetes
