Total Synthesis and Antibacterial Activity of Marine Tris-indole Alkaloid Tulongicin A.

Bis-indole alkaloids from marine sponges are an intriguing class of natural products with a variety of activities. However, only a preliminary biological study of tulongicin A (), a related previously isolated marine tris-indole alkaloid, has been conducted. In this study, we accomplished the first asymmetric total synthesis of via the construction of an imidazoline-linked bis-indolylmethane skeleton using a Friedel-Crafts-type reaction.

Chemical Constituents and Anticancer Activities of Marine-Derived Fungus .

The fungal genus is a rich source of structurally diverse secondary metabolites with remarkable pharmaceutical properties. The chemical constituents and anticancer activities of the marine-derived fungus have never been investigated. In this study, a bioactivity-guided investigation led to the isolation of eleven compounds, including trichodermamide A (), trichodermamide B (), aspergillazine A (), DC1149B (), ergosterol peroxide (), cerebrosides D/C (), 5-hydroxy-2,3-dimethyl-7-methoxychromone (), nafuredin A (), and harzianumols E/F (/).

Transformation of Renieramycin M into Renieramycins T and S by Intramolecular Photoredox Reaction of 7-Methoxy-6-methyl-1,2,3,4-tetrahydroisoquinoline-5,8-dione Derivatives.

In connection with our studies of biologically active 1,2,3,4-tetrahydroisoquinoline marine natural products, we describe herein a useful intramolecular photoredox transformation of 7-methoxy-6-methyl-1,2,3,4-tetrahydroisoquinoline-5,8-dione tricyclic models into 5-hydroxy-tetrahydroisoquinol[1,3]dioxoles in excellent yields. We applied this methodology to the transformation of renieramycin M into renieramycins T and S and the transformation of saframycin A. The results of cytotoxicity studies are also presented.

A New Tetracyclic Bromopyrrole-Imidazole Derivative through Direct Chemical Diversification of Substances Present in Natural Product Extract from Marine Sponge () sp.

Chemical diversification of substances present in natural product extracts can lead to a number of natural product-like compounds with a better chance of desirable bioactivities. The aim of this work was to discover unprecedented chemical conversion and produce new compounds through a one-step reaction of substances present in the extracts of marine sponges. In this report, a new unnatural tetracyclic bromopyrrole-imidazole derivative, -6-Et-cylindradine A (), was created from a chemically diversified extract of the sponge sp.

Design, Synthesis, and Monoamine Oxidase B Selective Inhibitory Activity of -Arylated Heliamine Analogues.

Monoamine oxidase B (MAO-B) metabolizes monoamines such as dopamine regarding neural transmission and controls its level in the mammalian's brain. When MAO-B metabolizes dopamine abnormally, normal neurotransmission does not occur, and central nervous system disorders such as Parkinson's disease may develop. Although several MAO inhibitors have been developed, most of them have no selectivity between monoamine oxidase A (MAO-A) and MAO-B, or they work irreversibly against the enzyme.

Inhibition of BACE1 and amyloid β aggregation by polyketide from Streptomyces sp.

Alzheimer's disease (AD) causes cognitive impairment in the elderly and is a severe problem worldwide. One of the major reasons for the pathogenesis of AD is thought to be due to the accumulation of amyloid beta (Aβ) peptides that result in neuronal cell death in the brain. In this study, bioassay-guided fractionation was performed to develop seed compounds for anti-AD drugs that can act as dual inhibitors of BACE1 and Aβ aggregation from secondary metabolites produced by Streptomyces sp.

Chemistry of Renieramycins. Part 19: Semi-Syntheses of 22--Amino Ester and Hydroquinone 5--Amino Ester Derivatives of Renieramycin M and Their Cytotoxicity against Non-Small-Cell Lung Cancer Cell Lines.

Two new series of synthetic renieramycins including 22--amino ester and hydroquinone 5--amino ester derivatives of renieramycin M were semi-synthesized and evaluated for their cytotoxicity against the metastatic non-small-cell lung cancer H292 and H460 cell lines. Interestingly, the series of 22--amino ester derivatives displayed a potent cytotoxic activity greater than the hydroquinone derivatives. The most cytotoxic derivative of the series was the 22--(-Boc-l-glycine) ester of renieramycin M (: IC 3.

Naturally occurring biflavonoids with amyloid β aggregation inhibitory activity for development of anti-Alzheimer agents.

Amyloid β (Aβ) aggregation plays an essential role in promoting the progression of Alzheimer's disease (AD). Therefore, the inhibition of Aβ aggregation is a potential therapeutic approach for AD. Herein, twenty-seven biflavonoids with different inter-flavonyl linkages and methoxy substitution patterns were isolated from several plants, and their Aβ aggregation inhibitory activity was evaluated by the thioflavin-T fluorescence assay.

Asymmetric Synthesis and Cytotoxicity Evaluation of Right-Half Models of Antitumor Renieramycin Marine Natural Products.

A general protocol for the asymmetric synthesis of 3--arylmethylated right-half model compounds of renieramycins was developed, which enabled structure⁻activity relationship (SAR) study of several 3--arylmethyl derivatives. The most active compound () showed significant cytotoxic activity against human prostate cancer DU145 and colorectal cancer HCT116 cell lines (IC = 11.9, and 12.

Chemistry of Renieramycins. 17. A New Generation of Renieramycins: Hydroquinone 5-O-Monoester Analogues of Renieramycin M as Potential Cytotoxic Agents against Non-Small-Cell Lung Cancer Cells.

A series of hydroquinone 5-O-monoester analogues of renieramycin M were semisynthesized via bishydroquinonerenieramycin M (5) prepared from renieramycin M (1), a major cytotoxic bistetrahydroisoquinolinequinone alkaloid isolated from the Thai blue sponge Xestospongia sp. All 20 hydroquinone 5-O-monoester analogues possessed cytotoxicity with IC values in nanomolar concentrations against the H292 and H460 human non-small-cell lung cancer (NSCLC) cell lines. The improved cytotoxicity toward the NSCLC cell lines was observed from the 5-O-monoester analogues such as 5-O-acetyl ester 6a and 5-O-propanoyl ester 7e, which exhibited 8- and 10-fold increased cytotoxicity toward the H292 NSCLC cell line (IC 3.

Renieramycin M Attenuates Cancer Stem Cell-like Phenotypes in H460 Lung Cancer Cells.

Background/aim: Cancer stem cells (CSCs) are a subpopulation of cancer cells that possess self-renewal and differentiation capacities. CSCs contribute to drug-resistance, cancer recurrence and metastasis, thus development of CSC-targeted therapeutic strategies has recently received significant attention in cancer research. In this study, the potential efficacy of renieramycin M (RM) isolated from the sponge Xestospongia species, was examined against lung CSCs.

Chemistry of Renieramycins. 15. Synthesis of 22-O-Ester Derivatives of Jorunnamycin A and Their Cytotoxicity against Non-Small-Cell Lung Cancer Cells.

Eighteen 22-O-ester derivatives of jorunnamycin A (2) were prepared via 2, and their cytotoxicity against human non-small-cell lung cancer (NSCLC) cells was evaluated. Preliminary study of the structure-cytotoxicity relationship revealed that the ester part containing a nitrogen-heterocyclic ring elevated the cytotoxicity of the 22-O-ester derivatives. Among them, 22-O-(4-pyridinecarbonyl) ester 6a is the most potent compound (IC50 1.

Renieramycin M Sensitizes Anoikis-resistant H460 Lung Cancer Cells to Anoikis.

Background/aim: Anoikis resistance plays a crucial role in the promotion of survival of circulating tumor cells. This study aimed to evaluate the mechanistic pathways of anoikis resistance in human lung cancer cells and test the possible therapeutic effect of renieramycin M (RM) from the sponge Xestospongia sp. in conversion of anoikis resistance.

Bromotyrosine Alkaloids with Acetylcholinesterase Inhibitory Activity from the Thai Sponge Acanthodendrilla sp.

Twenty bromotyrosine alkaloids, including a new compound, 13-oxosubereamolline D (5), were isolated from the Thai sponge Acanthodendrilla sp. Their structures were determined by analyses of 1D- and 2D-NMR, high-resolution mass, and circular dichroism data. The complete 1H and 13C NMR assignments of 5,7β-dichlorocavernicolin (19) and 5,7α-dichlorocavernicolin (20) are described herein for the first time.

Replacement of a quinone by a 5-O-acetylhydroquinone abolishes the accidental necrosis inducing effect while preserving the apoptosis-inducing effect of renieramycin M on lung cancer cells.

Renieramycin M (1), a bistetrahydroisoquinolinequinone alkaloid isolated from the marine sponge Xestospongia sp., has been reported to possess promising anticancer effects. However, its accidental necrosis inducing effect has limited further development due to concerns of unwanted toxicity.