Antiviral activity of sulphated specialized metabolites from sea urchin Clypeaster humilis : in vitro and in silico studies.

Chemical investigations of the sea urchin Clypeaster humilis has led to separation of twelve compounds including one new sulfonic acid derivative (7 R ) tridec-1-en-7-yl hydrogen sulphate (1), first isolated from natural source, pyridine-3-yl methane sulfonate (2), and first isolated from marine organisms, boldine (12), in addition to nine known compounds (3-11), which were isolated for the first time from the genus Clypeaster. Their structures were elucidated based on spectroscopic analyses (1D and 2D NMR), HR-ESI-MS as well as comparison with the previously reported data. The antiviral activity of the crude extract and sulphated compounds were evaluated using MTT colorimetric assay against Coxsackie B4 virus. The crude extract and compound 1 showed very potent antiviral activity with a percentage of inhibition equal to 89.7 ± 0.53% and 86.1 ± 0.92%, respectively. Results of the molecular docking analysis of the isolated compounds within Coxsackie Virus B4 (COX-B4) X-ray crystal structure and quantum chemical calculation for three sulphated compounds are in a consistent adaptation with the in vitro antiviral results. The pharmacokinetic properties (ADME) of isolated compounds were determined.