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

Marine natural products.

2,5-Diketopiperazines: synthesis, reactions, medicinal chemistry, and bioactive natural products.

Imidazole ring is an important five-membered aromatic heterocycle widely present in natural products and synthetic molecules. The unique structural feature of imidazole ring with desirable electron-rich characteristic is beneficial for imidazole derivatives to readily bind with a variety of enzymes and receptors in biological systems through diverse weak interactions, thereby exhibiting broad bioactivities. The related research and developments of imidazole-based medicinal chemistry have become a rapidly developing and increasingly active topic. Particularly, numerous imidazole-based compounds as clinical drugs have been extensively used in the clinic to treat various types of diseases with high therapeutic potency, which have shown the enormous development value. This work systematically gives a comprehensive review in current developments of imidazole-based compounds in the whole range of medicinal chemistry as anticancer, antifungal, antibacterial, antitubercular, anti-inflammatory, antineuropathic, antihypertensive, antihistaminic, antiparasitic, antiobesity, antiviral, and other medicinal agents, together with their potential applications in diagnostics and pathology. It is hoped that this review will be helpful for new thoughts in the quest for rational designs of more active and less toxic imidazole-based medicinal drugs, as well as more effective diagnostic agents and pathologic probes.

Comprehensive Review in Current Developments of Imidazole‐Based Medicinal Chemistry

Oceans have borne most of the biological activities on our planet. A number of biologically active compounds with varying degrees of action, such as anti-tumor, anti-cancer, anti-microtubule, anti-proliferative, cytotoxic, photo protective, as well as antibiotic and antifouling properties, have been isolated to date from marine sources. The marine environment also represents a largely unexplored source for isolation of new microbes (bacteria, fungi, actinomycetes, microalgae-cyanobacteria and diatoms) that are potent producers of bioactive secondary metabolites. Extensive research has been done to unveil the bioactive potential of marine microbes (free living and symbiotic) and the results are amazingly diverse and productive. Some of these bioactive secondary metabolites of microbial origin with strong antibacterial and antifungal activities are being intensely used as antibiotics and may be effective against infectious diseases such as HIV, conditions of multiple bacterial infections (penicillin, cephalosporines, streptomycin, and vancomycin) or neuropsychiatric sequelae. Research is also being conducted on the general aspects of biophysical and biochemical properties, chemical structures and biotechnological applications of the bioactive substances derived from marine microorganisms, and their potential use as cosmeceuticals and nutraceuticals. This review is an attempt to consolidate the latest studies and critical research in this field, and to showcase the immense competence of marine microbial flora as bioactive metabolite producers. In addition, the present review addresses some effective and novel approaches of procuring marine microbial compounds utilizing the latest screening strategies of drug discovery.

https://www.mdpi.com/1660-3397/8/10/2673/pdf

Immense Essence of Excellence: Marine Microbial Bioactive Compounds

Polyphasic taxonomy of the genus Talaromyces

Three new indole-containing diketopiperazine alkaloids, named variecolorins M–O (1–3), together with the eight known analogues 4–11, were isolated from a deep-ocean sediment-derived fungus, Penicillium griseofulvum. Their structures were determined by analysis of the spectroscopic data. The 2,2-diphenyl-1-picrylhydrazinyl (DPPH) radical-scavenging activities and the cell-proliferation inhibitory activities of the three new compounds 1–3 were investigated.

Three New Indole‐Containing Diketopiperazine Alkaloids from a Deep‐Ocean Sediment Derived Fungus Penicillium griseofulvum

Diorcinols B-E, new prenylated diphenyl ethers from the marine-derived fungus Aspergillus versicolor ZLN-60

/pdf/diorcinols-b-e-new-prenylated-diphenyl-ethers-from-the-3cm4e8p2qu.pdf

Two new cyclic pentapeptides, named versicotides A (1) and B (2), were obtained from a marine-derived fungus strain ZLN-60, identified as Aspergillus versicolor. Their structures were established on the basis of chemical and spectroscopic evidence. Versicotides are new cyclic pentapeptides which contain an L-alanine residue, two anthranilic acid (=2-aminobenzoic acid) residues, and two N-methyl-L-alanine residues. Antitumor activities were evaluated by the SRB and MTT methods.

Two New Cyclic Pentapeptides from the Marine‐Derived Fungus Aspergillus versicolor

One new penicillide derivative, prenpenicillide (1), and one new xanthone derivative, prenxanthone (2), were isolated from the culture extract of the marine-derived fungus Penicillium sp. ZLN29, together with six known polyketide compounds, 3–8. Their structures were elucidated on the basis of spectroscopic and spectrometric analyses. The cytotoxicities of these eight compounds were evaluated on four tumor-cell lines by SRB (=sulforhodamine B) or MTT (=3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) methods. Compounds 1 and 3 exhibited weak cytotoxicities against HepG2 cell line with IC50 values of 9.9 and 9.7 μM, respectively.

Li-Na Zhou

Papers

Three New Indole‐Containing Diketopiperazine Alkaloids from a Deep‐Ocean Sediment Derived Fungus Penicillium griseofulvum

Diorcinols B-E, new prenylated diphenyl ethers from the marine-derived fungus Aspergillus versicolor ZLN-60

Two New Cyclic Pentapeptides from the Marine‐Derived Fungus Aspergillus versicolor

New Cytotoxic Metabolites from the Marine‐Derived Fungus Penicillium sp. ZLN29