https://pubs.rsc.org/en/content/articlepdf/2019/NP/C8NP00092A

Marine natural products.

Natural products in drug discovery.

The rise of harmful cyanobacteria blooms: The potential roles of eutrophication and climate change

(2002). The Effects of Harmful Algal Blooms on Aquatic Organisms. Reviews in Fisheries Science: Vol. 10, No. 2, pp. 113-390.

The Effects of Harmful Algal Blooms on Aquatic Organisms

3.3.1. Potential of the “Metagenome” 3016 3.3.2. Cryptic Clusters in Bacteria and Fungi 3016 3.3.3. Cyanophytes 3017 3.3.4. Marine Microbes (Non-Cyanophytes) 3018 3.3.5. Extremophiles 3018 3.3.6. Microbial Symbionts 3019 3.3.7. Plant Endophytes 3020 3.3.8. Combinatorial Biosynthesis 3020 4. Development of Drugs from Natural Products 3020 4.1. Synthesis Based on Natural Products 3021 4.1.1. Derivatization and Semisynthesis 3021 4.1.2. Total Synthesis 3021 4.1.3. Diverted Total Synthesis 3021 4.2. Natural Product-Inspired Combinatorial Synthesis 3022

Impact of natural products on developing new anti-cancer agents

Bioactive natural products from marine cyanobacteria for drug discovery.

Publisher Summary Marine cyanobacteria are extraordinarily prolific in their elaboration of complex and bioactive secondary metabolites. The principle biogenetic theme in the natural products chemistry of marine cyanobacteria is the integration of non-ribosomal peptide synthetase (NRPS) and polyketide synthase (PKS) pathways, in a variety of configurations, so as to produce this great structural diversity. An assortment of unusual “tailoring” enzymes is evident in cyanobacterial metabolites, as revealed by the variety of bromine and chlorine functional groups. Methylation is a prominent characteristic of most marine cyanobacterial metabolites. Cyanobacterial peptides possess an extremely high level of N -methylation, a characteristic that could possibly be advantageous in molecular genetic studies. In polyketide sections, a pronounced theme of pendant methyl groups is also evident. However, available experimental evidence suggests either a or C-2 of acetate origin for these methyl group additions. Many marine cyanobacterial metabolites possess potent biological properties.

Nitrogen-containing metabolites from marine cyanobacteria.

A plethora of structurally novel bioactive secondary metabolites have been reported from the prokaryotic filamentous marine cyanobacteria in the past few decades. In addition to the production of harmful toxins, these marine blue-green algae are emerging as an important source of anticancer drugs. The majority of these potent biomolecules, including the dolastatins, curacin A, hectochlorin, the apratoxins, and the lyngbyabellins, belongs to the mixed polyketide–polypeptide structural class. Furthermore, a high proportion of these natural products target eukaryotic cytoskeleton, such as tubulin and actin microfilaments, making them an attractive source of potential anticancer drugs. In recent years, a number of potent marine cyanobacteria have also been reported to modulate cell death and apoptosis in cancer cells as well as target enzymes such as histone deacetylase. A number of marine cyanobacterial compounds have also served as structural templates for the generation of new drug leads, further attesting to the importance of these marine microbes as an important source of new pharmaceuticals. This review serves to highlight the chemistry and biology of selected anticancer marine cyanobacterial natural products exhibiting significant biological activities in the nanomolar or submicromolar range, and their discussion will be based on the different modes of action.

Filamentous tropical marine cyanobacteria: a rich source of natural products for anticancer drug discovery

Lagunamides A (1) and B (2) are new cyclic depsipeptides isolated from the marine cyanobacterium Lyngbya majuscula obtained from Pulau Hantu Besar, Singapore. The planar structural characterization of these molecules was achieved by extensive spectroscopic analysis, including 2D NMR experiments. In addition to Marfey’s method and 3JH−H coupling constant values, a modified method based on Mosher’s reagents and analysis using LC-MS was deployed for the determination of the absolute configuration. Lagunamides A and B displayed significant antimalarial properties, with IC50 values of 0.19 and 0.91 μM, respectively, when tested against Plasmodium falciparum. Lagunamides A and B also possessed potent cytotoxic activity against P388 murine leukemia cell lines, with IC50 values of 6.4 and 20.5 nM, respectively. Furthermore, these cyanobacterial compounds exhibited moderate antiswarming activities when tested against Pseudomonas aeruginosa PA01.

Lagunamides A and B: Cytotoxic and Antimalarial Cyclodepsipeptides from the Marine Cyanobacterium Lyngbya majuscula

Chemical investigation of the marine red alga (Rhodophyta) Ceratodictyon spongiosum containing the symbiotic sponge Sigmadocia symbiotica collected from Biaro Island, Indonesia, yielded two isomers of a new and bioactive thiazole-containing cyclic heptapeptide, cis,cis-ceratospongamide (1) and trans,trans-ceratospongamide (2). Isolation of these peptides was assisted by bioassay-guided fractionation using a brine shrimp toxicity assay (Artemia salina). The structures of the ceratospongamides, which each consist of two l-phenylalanine residues, one (l-isoleucine)-l-methyloxazoline residue, one l-proline residue, and one (l-proline)thiazole residue, were established through extensive NMR spectroscopy, including 1H−13C HMQC−TOCSY, and 1H−15N HMBC experiments, as well as chemical degradation and chiral analysis. cis,cis- and trans,trans-ceratospongamide are stable conformational isomers of the two proline amide bonds. Molecular modeling of these two ceratospongamide isomers showed the trans,trans isomer to be...

cis,cis- and trans,trans-Ceratospongamide, New Bioactive Cyclic Heptapeptides from the Indonesian Red Alga Ceratodictyon spongiosum and Symbiotic Sponge Sigmadocia symbiotica

Lik Tong Tan

Papers

Bioactive natural products from marine cyanobacteria for drug discovery.

Nitrogen-containing metabolites from marine cyanobacteria.

Filamentous tropical marine cyanobacteria: a rich source of natural products for anticancer drug discovery

Lagunamides A and B: Cytotoxic and Antimalarial Cyclodepsipeptides from the Marine Cyanobacterium Lyngbya majuscula

cis,cis- and trans,trans-Ceratospongamide, New Bioactive Cyclic Heptapeptides from the Indonesian Red Alga Ceratodictyon spongiosum and Symbiotic Sponge Sigmadocia symbiotica