Chemistry and biological activities of the marine sponges of the genera mycale (Arenochalina), Biemna and Clathria

Over the past seven decades, particularly since the discovery of the first marine-derived nucleosides, spongothymidine and spongouridine, from the Caribbean sponge Cryptotethya crypta in the early 1950s, marine natural products have emerged as unique, renewable and yet under-investigated pools for discovery of new drug leads with distinct structural features, and myriad interesting biological activities. Marine sponges are the most primitive and simplest multicellular animals, with approximately 8900 known described species, although more than 15,000 species are thought to exist worldwide today. These marine organisms potentially represent the richest pipeline for novel drug leads. Mycale (Arenochalina) and Clathria are recognized marine sponge genera belonging to the order Poecilosclerida, whereas Biemna was more recently reclassified, based on molecular genetics, as a new order Biemnida. Together, these sponge genera contribute to the production of physiologically active molecular entities with diverse structural features and a wide range of medicinal and therapeutic potentialities. In this review, we provide a comprehensive insight and up-to-date literature survey over the period of 1976–2018, focusing on the chemistry of the isolated compounds from members of these three genera, as well as their biological and pharmacological activities, whenever available. © 2018 by the authors.Acknowledgments: This work was supported by the mission sector of the Ministry of High Education of the Arab Republic of Egypt (Egyptian cultural bureau in Paris and Athens); Amr El-Demerdash’s, and Mohamed Tammam’s joint supervision were fully funded and supported

First-principle studies on the gas phase OH-initiated oxidation of O-toluidine

In the present work, the gas phase reaction of OH radical initiated O-toluidine (OTOD) oxidation is investigated at ROCBS-QB3. Different pathways for OH radical additions to the benzene ring sites and H-atom abstractions are explored in details. At 200 K, the oxidation mechanism of OTOD is thoroughly dominated by the OH-addition to the aromatic ring, whereas the main favorable route is the OH addition to C2 atom with a branching ratio of 52.76%. Raising temperature to 1000 K, the total abstraction of amine's hydrogens becomes the main oxidation pathway for OTOD with contributions of 29.29%. The atmospheric lifetimes of aniline and OTOD are calculated to be 20.74 and 11.23 min., respectively. The fate of OTOD-OH2 (P2) adduct with atmospheric O2 molecule is inspected using the unimolecular Rice-Ramsperger-Kassel-Marcus (RRKM-ME) to verify our results at transition state theory (TST) and shows pressure and temperature dependence of the secondary oxidation mechanism. - 2019 Elsevier B.V.Scopu