Natural Products among Brown Algae: The Case of Cystoseira schiffneri Hamel (Sargassaceae, Phaeophyceae)

Diversified Chemical Structures and Bioactivities of the Chemical Constituents Found in the Brown Algae Family Sargassaceae

Sargassaceae, the most abundant family in Fucales, was recently formed through the merging of the two former families Sargassaceae and Cystoseiraceae. It is widely distributed in the world's oceans, notably in tropical coastal regions, with the exception of the coasts of Antarctica and South America. Numerous bioactivities have been discovered through investigations of the chemical diversity of the Sargassaceae family. The secondary metabolites with unique structures found in this family have been classified as terpenoids, phlorotannins, and steroids, among others. These compounds have exhibited potent pharmacological activities. This review describes the new discovered compounds from Sargassaceae species and their associated bioactivities, citing 136 references covering from March 1975 to August 2023.

Brown seaweed Cystoseira schiffneri as a promising source of sulfated fucans: Seasonal variability of structural, chemical, and antioxidant properties

A fucoidan, sulfated polysaccharide, was extracted from the brown seaweed Cystoseira schiffneri during 4 harvest periods (December, April, July, and September) and studied for its structural and chemical properties. The Cystoseira schiffneri fucoidan (CSF) showed important variation in sulfate content ranging from 7.8% in December to 34.8% in July. This was confirmed by Fourier transform infrared and nuclear magnetic resonance spectroscopies showing characteristic signals of sulfated polysaccharides. Molecular mass of the CSF varied as a function of season from 3,745 in December to 26,390 Da in July. Gas chromatography-mass spectroscopy showed that CSF fractions were "mannogalactofucans" composed mainly of mannose, fucose, and galactose with low levels of other monosaccharides. Moreover, interesting in vitro antioxidant activities that depend on the harvest season were noted for CSF. Thus, the present work might contribute to establish criteria for extracting bioactive fucoidans from an endemic Tunisian seaweed C. schiffneri.

Cytotoxic activity, molecular docking, pharmacokinetic properties and quantum mechanics calculations of the brown macroalga Cystoseira trinodis compounds

In this study, nine compounds were isolated, eight of them were isolated for the first time from Cystoseira trinodis. The biological activity of the extract, fractions and pure compounds was evaluated. The antimicrobial activity was investigated against 3 fungi species, 3 gram + ve and 3 gram -ve bacteria. The crude extract and fractions showed moderate inhibition against some of the tested microorganisms, especially the butanol fraction exhibited the maximum inhibition zone against Salmonella typhimurium (16 ± 0.60 mm). Cytotoxicity was evaluated against HepG-2 and MCF-7 cell lines. Hexane fraction exhibited the highest cytotoxic effect against HepG-2 and MCF-7 cell lines with an IC₅₀ value of 14.3 ± 0.8 and 19.2 ± 0.7 µg/ml, respectively with compared to other fractions. The isolates were identified as octacosanoic acid (1), glyceryl trilinoleate (2), oleic acid (3), and the epimeric mixture of saringosterols (4, 5), β-sitosterol (6), glycoglycerolipid (7) and a mixture of kjellmanianone and loliolide (8, 9) by spectroscopic analysis. Among the all tested compounds kjellmanianone and loliolide mixture exhibited significant cytotoxic activity with an IC₅₀ value of 7.27 µg/ml against HepG-2 cells. The major and minor constituents of the extract and fractions were identified using GC-MS analysis. Molecular docking analysis confirmed that most of the studied compounds especially compounds 8 and 9 strongly interact with TPK and VEGFR-2 with highest binding energies supported that the high cytotoxicity of these compounds against human hepatocellular cancer in the experimental part. The energetic, geometric and topological properties of compounds 8 and 9 binding with cytosine base were computed by DFT methods. Molecular properties descriptors, bioactivity score and ADMET analysis confirmed that most of the studied compounds especially compounds 8 and 9 exhibit significant biological activities and have a better chance to be developed as drug leads. Communicated by Ramaswamy H. Sarma.

Marine natural products

Covering: January to December 2017This review covers the literature published in 2017 for marine natural products (MNPs), with 740 citations (723 for the period January to December 2017) referring to compounds isolated from marine microorganisms and phytoplankton, green, brown and red algae, sponges, cnidarians, bryozoans, molluscs, tunicates, echinoderms, mangroves and other intertidal plants and microorganisms. The emphasis is on new compounds (1490 in 477 papers for 2017), together with the relevant biological activities, source organisms and country of origin. Reviews, biosynthetic studies, first syntheses, and syntheses that led to the revision of structures or stereochemistries, have been included. Geographic distributions of MNPs at a phylogenetic level are reported.