Ophiuroidine, the first indolo[2,1-b]quinazoline alkaloid from the Caribbean brittle star Ophiocoma riisei

Recent advances of tryptanthrin and its derivatives as potential anticancer agents

Tryptanthrin is one of the well-known natural alkaloids with a broad spectrum of biological activities and can act as anti-inflammatory, anticancer, antibacterial, antifungal, antiviral, antitubercular, and other agents. Owing to its potent anticancer activity, tryptanthrin has been widely explored for the therapy of various cancers besides being effective against other diseases. Tryptanthrin with a pharmacological indoloquinazoline moiety can not only be modified by different functional groups to achieve various tryptanthrin derivatives, which may realize the improvement of anticancer activity, but also bind with different metal ions to obtain varied tryptanthrin metal complexes as potential anticancer agents, due to their higher anticancer activities in comparison with tryptanthrin (or its derivatives) and cisplatin. This review outlines the recent advances in the syntheses, structures, and anticancer activities of tryptanthrin derivatives and their metal complexes, trying to reveal their structure-activity relationships and to provide a helpful way for medicinal chemists in the development of new and effective tryptanthrin-based anticancer agents.

Discovery of Tryptanthrin and Its Derivatives and Its Activities against NSCLC In Vitro via Both Apoptosis and Autophagy Pathways

In this study, a series of novel tryptanthrin derivatives were synthesized and their inhibitory activities against selected human cancer cell lines, namely, lung (A549), chronic myeloid leukemia (K562), prostate (PC3), and live (HepG2), were evaluated using a methyl thiazolyl tetrazolium colorimetric (MTT) assay. Among the tested compounds, compound C1 exhibited a promising inhibitory effect on the A549 cell line with an IC₅₀ value of 0.55 ± 0.33 µM. The observation of the cell morphological result showed that treatment with C1 could significantly inhibit the migration of A549 cells through the cell migration assay. Moreover, after treatment with C1, the A549 cells exhibited a typical apoptotic morphology and obvious autophagy. In addition, the detection of apoptosis and the mitochondrial membrane potential indicated that C1 induced A549 cell apoptosis via modulating the levels of Bcl2 family members and disrupted the mitochondrial membrane potential. Compound C1 also suppressed the expression of cyclin D1 and increased the expression of p21 in the A549 cells, inducing cell cycle arrest in the G2/M phase in a dose dependent manner. The further mechanism study found that C1 markedly increased the transformation from LC3-I to LC3-II. Taken together, our results suggest that C1 is capable of inhibiting the proliferation of non-small cell lung cancer (NSCLC) cells, inducing cell apoptosis, and triggering autophagy.

Cytotoxic and antimicrobial activities of two new sesquiterpenoids from red sea brittle star Ophiocoma dentata

Bioactive compounds were extracted from a locally available brittle star; Ophiocoma dentata, collected from the Red Sea, Egypt. Two new sesquiterpenoids; 8, 11-epoxy-9(15)-himachaladiene-4-ol (O8-ophiocomane) and, 11-epoxy-9(15)-himachaladiene-4-ol (O7-ophiocomane) were isolated and characterized using appropriate techniques. Structure elucidation was estimated via 1D NMR, 2D NMR, FT-IR and mass spectroscopy analyses. The isolated compounds were tested for cytotoxic, antibacterial and antifungal activities. Pure compounds showed a dose dependent reduction in MCF-7 cells viability with LC50 of 103.5 and 59.5 μg/ml for compounds 1 and 2 respectively compared to the chemotherapeutic drug cisplatin (47.4 µg/ml). In vivo experiments showed that O. dentate extract significantly reduced tumor progression and improved hematological parameters and liver functions of tumor-bearing mice when administered either before or after tumor cells' injection. The most remarkable antimicrobial effects of O. dentate crude extract were against Staphylococcus aureus, Vibrio damsela and Pseudomonas aeruginosa while the pure compounds showed activity against P. aeruginosa alone. Neither the crude extract nor the pure compounds have shown activity against Aeromonas hydrophila. These results indicates that O. dentata extract and newly isolated compounds have shown a promising cytotoxic, antiproliferative and antimicrobial activities that might be useful for pharmaceutical applications.

Low-dose action of tryptanthrin and its derivatives against developing embryos of the sea urchin Strongylocentrotus intermedius

Nine tryptanthrin derivatives, including tryptanthrin itself, were synthesized using different methods, including oxidation of the corresponding isatins to obtain 1-4, the reaction of tryptanthrin 1 with hydrazine and its derivatives to obtain 5-7, and aldol condensation of 1 with acetone and methylethylketone to obtain 8 and 9. The action of 1-9 in doses corresponding to the IC₅₀ against developing embryos of the sea urchin Strongylocentrotus intermedius and in the sperm test allowed us to estimate to potency of all the compounds and to determine which were cytotoxic. In addition, these studies showed that compounds 3, 4, 8, and 9 had a stimulatory effect at lower doses. In particular, the tryptanthrin derivatives stimulated the larval stages of development in surviving embryos at concentrations lower than the IC₅₀.

An efficient and convenient protocol for the synthesis of tetracyclic isoindolo[1,2-a]quinazoline derivatives

A convenient and one-pot synthesis of tetracyclic isoindolo [1,2-a]quinazoline derivatives via Lewis acid mediated sequential C–N bond formation reactions is reported.

Synthesis of 2-hydroxy-3-alkyl-2-phenyl-2,3-dihydroquinazolin-4(1H)-one via molybdenum hexacarbonyl mediated CO gas- and ligand free carbonylative reactions

Carbon monoxide gas and ligand-free condition were developed for the synthesis of 2-hydroxy-3-alkyl-2-phenyl-2,3-dihydroquinazolin-4(1H)-one via catalytic carbonylation with Mo(CO)₆ as an efficient carbonylating agent for the novel MCR reaction.

Marine Indole Alkaloids

Marine indole alkaloids comprise a large and steadily growing group of secondary metabolites. Their diverse biological activities make many compounds of this class attractive starting points for pharmaceutical development. Several marine-derived indoles were found to possess cytotoxic, antineoplastic, antibacterial and antimicrobial activities, in addition to the action on human enzymes and receptors. The newly isolated indole alkaloids of marine origin since the last comprehensive review in 2003 are reported, and biological aspects will be discussed.

Marine natural products

This review covers the literature published in 2007 for marine natural products, with 948 citations(627 for the period January to December 2007) referring to compounds isolated from marine microorganisms and phytoplankton, green algae, brown algae, red algae, sponges, cnidarians,bryozoans, molluscs, tunicates, echinoderms and true mangrove plants. The emphasis is on new compounds (961 for 2007), together with the relevant biological activities, source organisms and country of origin. Biosynthetic studies, first syntheses, and syntheses that lead to the revision of structures or stereochemistries, have been included.1 Introduction, 2 Reviews, 3 Marine microorganisms and phytoplankton, 4 Green algae, 5 Brown algae, 6 Red algae, 7 Sponges, 8 Cnidarians, 9 Bryozoans, 10 Molluscs, 11 Tunicates (ascidians),12 Echinoderms, 13 Miscellaneous, 14 Conclusion, 15 References.