A new amide from the marine sponge Haliclona baeri

Haliclomeroterpenes A-D: Four Meroterpenes with Unprecedented Skeletons from the Marine Sponge Haliclona sp

Four novel meroterpenes, haliclomeroterpenes A-D (1-4), were isolated from the marine sponge Haliclona sp. Their structures with absolute configurations were elucidated by spectroscopic methods, quantum chemical calculations, and X-ray diffraction. Compounds 1 and 2 are meroterpenes bearing a bicyclo[4.4.0]-1-decene coupled tetrahydrofuro[3,4-b]furanone with a C-4-spiro-fused 6/6/5/5 tetracyclic skeleton. Compound 3 is a meroterpene possessing a bicyclo[4.4.0]-1-decene coupled furanone with a C-4-spiro-fused 6/6/5 tricyclic skeleton. Compound 4 represents the unusual skeleton of furanone[3,2-b]bicyclo[4.4.0]-1-decene. The plausible biogenetic pathways of 1-4 were also proposed. The formation of all four of these compounds was proposed to arise from the condensation of cadinene sesquiterpene and 2,4-dimethyl-3-oxopentanoic acid or propionic acid, respectively. Notably, compounds 1 and 2 showed moderate inhibitory activities against the K562 cell line with IC50 values of 17.23 and 27.91 μM, respectively. In addition, compound 2 showed weak anti-NO activities with IC50 values of 40.22 μM.

Marine natural products

Covering: January to the end of December 2023This review covers the literature published in 2023 for marine natural products (MNPs), with 582 citations (541 for the period January to December 2023) referring to compounds isolated from marine microorganisms and phytoplankton, green, brown and red algae, sponges, cnidarians, bryozoans, molluscs, tunicates, echinoderms, the submerged parts of mangroves and other intertidal plants. The emphasis is on new compounds (1220 in 340 papers for 2023), together with the relevant biological activities, source organisms and country of origin. Pertinent reviews, biosynthetic studies, first syntheses, and syntheses that led to the revision of structures or stereochemistries, have been included. An analysis of the progress in the study of prokaryote involvement in macro-invertebrate MNP production is discussed.

Antioxidant and α-glucosidase inhibitory activities of compound isolated from Stachytarpheta jamaicensis (L) Vahl. leaves

Stachytarpheta jamaicensis is one of the folk medicines used for the treatment of diabetes in Ambon, Indonesia, but there are limited studies on the bioactivities of its constituents. This study aims to assess the antioxidant and antidiabetic activities of four extracts of S. jamaicensis leaves extracted using several solvents. Bioassay guided fractionation on each extract establishes for exploring S. jamaicensis leaves active compounds. The antioxidant was evaluated using the DPPH and ABTS methods, while the α-glucosidase inhibitory was carried out in vitro assay. The results showed that the methanol extract of S. jamaicensis leaves displays inhibition of DPPH, ABTS and α-glucosidase activity compared to other solvent extracts. Furthermore, 6β-hydroxyipolamiide was successfully isolated from the methanol extract of S. jamicensis leaves which was reported to have α-glucosidase inhibitory activity with an IC50 of 539.17 μg/mL. Based on the results, S. jamaicensis could be recommended as an antioxidant and antidiabetic agent.