Imidazole Alkaloids from the South China Sea Sponge Pericharax heteroraphis and Their Cytotoxic and Antiviral Activities.

Kai-Kai Gong,Xu-Li Tang,Yi-Sheng Liu,Guo-Qiang Li,Ping-Lin Li

doi:10.3390/molecules21020150

Kai-Kai Gong, Xu-Li Tang + Show 3 more

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https://doi.org/10.3390/molecules21020150

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Abstract

Marine sponges continue to serve as a rich source of alkaloids possessing interesting biological activities and often exhibiting unique structural frameworks. In the current study, chemical investigation on the marine sponge Pericharax heteroraphis collected from the South China Sea yielded one new imidazole alkaloid named naamidine J (1) along with four known ones (2–5). Their structures were established by extensive spectroscopic methods and comparison of their data with those of the related known compounds. All the isolates possessed a central 2-aminoimidazole ring, substituted by one or two functionalized benzyl groups in some combination of the C4 and C5 positions. The cytotoxicities against selected HL-60, HeLa, A549 and K562 tumor cell lines and anti-H1N1 (Influenza a virus (IAV)) activity for the isolates were evaluated. Compounds 1 and 2 exhibited cytotoxicities against the K562 cell line with IC50 values of 11.3 and 9.4 μM, respectively. Compound 5 exhibited weak anti-H1N1 (influenza a virus, IAV) activity with an inhibition ratio of 33%.

Highlights

Marine sponges belonging to the Class Calcarea have been studied since the 1980s and have yielded a large number of bioactive alkaloids containing an imidazole heterocycle typically substituted with two benzylic fragments at the C-4, C-5, or N-3 positions and at various oxidation states
It was reported that this kind of alkaloid showed cytotoxic [2,3,4], antimicrobial [5,6], and antifungal [7] properties, as well as leukotriene B4 receptor [8] and epidermal growth factor (EGF)
In 2007, Ali et al reported the isolation and antimicrobial activity of three 2-aminoimidazole alkaloids from Pericharax heteroraphis which is the only report about the chemical investigation of Pericharax heteroraphis [6]

Summary

Introduction

Marine sponges belonging to the Class Calcarea have been studied since the 1980s and have yielded a large number of bioactive alkaloids containing an imidazole heterocycle typically substituted with two benzylic fragments at the C-4, C-5, or N-3 positions and at various oxidation states. It was reported that this kind of alkaloid showed cytotoxic [2,3,4], antimicrobial [5,6], and antifungal [7] properties, as well as leukotriene B4 receptor [8] and epidermal growth factor (EGF). To discover new bioactive 2-aminoimidazole alkaloids, the marine sponge Pericharax heteroraphis (genus Pericharax family Leucettidae) drew our attention, as the UV characteristics of MeOH extracts showed the existence of 2-aminoimidazole alkaloids; in addition, its extracts were reported to have broad activity on cancer cell lines [10] and showed significant. Based on the above evidence, we aimed to Molecules 2016, 21, 150; doi:10.3390/molecules21020150 www.mdpi.com/journal/molecules

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