Poecillastrosides, Steroidal Saponins from the Mediterranean Deep-Sea Sponge Poecillastra compressa (Bowerbank, 1866).

The first chemical investigation of the Mediterranean deep-sea sponge Poecillastra compressa (Bowerbank, 1866) led to the identification of seven new steroidal saponins named poecillastrosides A-G (1-7). All saponins feature an oxidized methyl at C-18 into a primary alcohol or a carboxylic acid. While poecillastrosides A-D (1-4) all contain an exo double bond at C-24 of the side-chain and two osidic residues connected at O-2', poecillastrosides E-G (5-7) are characterized by a cyclopropane on the side-chain and a connection at O-3' between both sugar units. The chemical structures were elucidated through extensive spectroscopic analysis (High-Resolution Mass Spectrometry (HRESIMS), 1D and 2D NMR) and the absolute configurations of the sugar residues were assigned after acidic hydrolysis and cysteine derivatization followed by LC-HRMS analyses. Poecillastrosides D and E, bearing a carboxylic acid at C-18, were shown to exhibit antifungal activity against Aspergillus fumigatus.

Paulomycin G, a New Natural Product with Cytotoxic Activity against Tumor Cell Lines Produced by Deep-Sea Sediment Derived Micromonospora matsumotoense M-412 from the Avilés Canyon in the Cantabrian Sea.

The present article describes a structurally novel natural product of the paulomycin family, designated as paulomycin G (1), obtained from the marine strain Micromonospora matsumotoense M-412, isolated from Cantabrian Sea sediments collected at 2000 m depth during an oceanographic expedition to the submarine Avilés Canyon. Paulomycin G is structurally unique since-to our knowledge-it is the first member of the paulomycin family of antibiotics lacking the paulomycose moiety. It is also the smallest bioactive paulomycin reported. Its structure was determined using HRMS and 1D and 2D NMR spectroscopy. This novel natural product displays strong cytotoxic activities against different human tumour cell lines, such as pancreatic adenocarcinoma (MiaPaca_2), breast adenocarcinoma (MCF-7), and hepatocellular carcinoma (HepG2). The compound did not show any significant bioactivity when tested against a panel of bacterial and fungal pathogens.

Caerulines A and B, Flavonol Diacylglycosides from Persea caerulea.

Two undescribed 4'-O-methylkaempferol-[3″,4″-di-p-coumaroyl]-α-l-rhamnopyranosides, caerulines A and B (1-2), along with three known 4'-O-methylkaempferol diacylrhamnosides isomers (3-5) were isolated from an ethanol extract of the leaves of Persea caerulea, a native plant growing on the Colombian Caribbean coast. The chemical structures of 1 and 2 were elucidated by spectroscopic methods. The effect of compounds 1-5 against four pathogenic microorganisms [i.e., methicillin-resistant Staphylococcus aureus (MRSA), Acinetobacter baumannii, Candida albicans, and Aspergillus fumigatus] was tested in vitro. The compounds exhibited no activity against these pathogens except MRSA (MIC 12-48 µg/mL). Caeruline B (2) was found to be the most active compound with a modest anti-MRSA activity (MIC = 12 µg/mL).