A novel indole alkaloid, misszrtine A (1), was isolated from marine sponge-derived fungus Aspergillus sp. SCSIO XWS03F03. The planar structure of 1 was assigned by analysis of spectroscopic data, the absolute configuration of which was unambiguously determined by total synthesis. Compound 1 represents the first example of N-isopentenyl tryptophan methyl ester with a phenylpropanoic amide arm, which exhibited a potent antagonistic activity on HL60 (IC50 = 3.1 μM) and LNCaP (IC50 = 4.9 μM) cell lines. Bioactivity evaluation reveals that functional group on indole nitrogen of 1 has a great effect on its cytotoxity, which provides a mean to probe the structure-activity relationships of 1.

Herein, we report the cytotoxicity of cyclopentapeptide analogues of marine natural product galaxamide towards breast carcinoma cells and the underlying mechanisms. We examined the effect of the novel galaxamide analogues on cancer cell proliferation by MTT assay and also further examined the most active compound for morphological changes using Hoechst33342 staining technique, induction of apoptosis, cell cycle phases, mitochondrial membrane potential (MMP), and reactive oxygen species (ROS) generation using flow cytometry in human breast cancer MCF-7 cells in vitro. Galaxamide and its analogues effectively induced toxicity in human hepatocellular carcinoma HepG2, human breast carcinoma MCF-7, human epitheloid cervix carcinoma HeLa, and human breast carcinoma MB-MDA-231 cell lines. Amongst them, compound 3 exhibited excellent toxicity towards MCF-7 cells. This galaxamide analogue significantly induced apoptosis in a dose-dependent manner in MCF-7 cells involves cell cycle arrest in the G1 phase, a reduction of MMP, and a marked increase in generation of ROS. Particularly, compound 3 of galaxamide analogues might be a potential candidate for the treatment of breast cancer.

Caulerpin was economically synthesized with a new easy‐handled procedure in higher overall yield of 25.4%, compared to overall yield of 11% in reported literature. Evaluation of caulerpin in new types of cancer cell lines was performed and generally excellent biological activities were observed. In which, caulerpin showed the most activity in human liver tumor cell line (Huh7: IC50 =0.7 μM).

The total synthesis of reniochalistatins A-E, along with a reniochalistatin E analogue (inverso-E) was successfully achieved through Fmoc-based solid-phase peptide synthesis and subsequent macrolactamization with PyBOP and DIEA. The biological activities of these reniochalistatins and a key linear peptide intermediate were systematically evaluated. Among these seven synthesized compounds, linear reniochalistatin B was found to have potent activity against several cancer cell lines not shown by the cyclic reniochalistatin B counterpart. In addition, linear reniochalistatin B was found to have antitubercular activity (IC =1.4 μm). Inverso-E possesses increasing cytotoxicity against the HeLa and LNCaP cell lines after simple alternation of the sequence of amino acids in reniochalistatin E. The results of these studies provide a feasible method to further investigate the structure-activity relationships (SARs) of reniochalistatins A-E.

The cover picture shows algae containing caulerpin in the shallow sea under sunshine. Caulerpin is a bis‐indole alkaloid, isolated mostly from algae of genus Caulerpa, it displayed several biological activities meanwhile lack of toxicity for it was found in mouse study. Additionally, caulerpin was also found to be a chemical agent as a rust inhibitor in mild steel. However, the current synthesis methods for caulerpin are not practical for relatively larger scale regarding both low overall yields and critical conditions used, which obviously restricted further exploration of its new applications. This work reported an economical synthesis of caulerpin and subsequently explored its new anticancer activity in several cell lines. More information can be found in the Communication by Hangbin Li et al. (DOI: 10.1002/slct.201802876). Artists: Prof. Liuqun Gu, Hangbin Li, Wenbiao Zhang and Weicong Huang.