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Caulerpa lentillifera (Bryopsidophyceae, Chlorophyta) is an edible seaweed attracting great attention for its expansion of farming scale and increasing consumption in these years. In the present study, a sulfated polysaccharide (CLSP-2) was isolated and separated from C. lentillifera , and its chemical structure was elucidated by a series of chemical and spectroscopic methods. Among these methods, mild acid hydrolysis and photocatalytic degradation were applied to release mono- and oligo-saccharide fragments which were further identified by HPLC-MS n analysis, affording the information of the sugar sequences and the sulfate substitution in CLSP-2. Results indicated that the backbone of CLSP-2 was constructed of →6)-β-Man p -(1→ with sulfated branches at C2, which were comprised of prevalent →3)-β-Gal p 4S-(1→, →3)-β-Gal p 2,4S-(1→, and minor Xyl. In addition, the virus neutralization assay revealed that CLSP-2 could effectively protect HeLa cells against SARS-CoV-2 infection with an IC 50 of 48.48 μg/mL. Hence, the present study suggests CLSP-2 as a promising agent against SARS-CoV-2.

Clinical trials have revealed that inhibition of sonic Hedgehog (SHH) signaling or histone deacetylase (HDAC) holds promise as a treatment for liver cancer. Based on our previous results, it was hypothesized that dual inhibition of SHH and HDAC may contribute to more efficient targeting of this disease. The effect of SHH inhibitor vismodegib as a single-agent or in combination with HDAC inhibitor entinostat was evaluated by Cell Counting Kit-8 (CCK-8) and flow cytometric assays, as well as immunoblotting. The synergistic effect on cell viability was assessed by combination indexes. Ex vivo cultured liver cancer tissues from a patient were treated with vismodegib as a single-agent or in combination with entinostat, and analyzed by histological and immunohistochemical methods. The results revealed that the dual use of the SHH inhibitor and the HDAC inhibitor effectively synergized to inhibit proliferation, and promote apoptosis in liver cancer cells. Furthermore, the effect of the combination of these drugs was confirmed in an ex vivo culture of human liver cancer tissue. Mechanistically, combined use of SHH and HDAC inhibitors resulted in significantly greater downregulation of SHH and PI3K/mTOR signaling. In conclusion, the combined use of SHH signaling and HDAC inhibitors may be an effective therapeutic strategy for liver cancer.