Synergy of irofulven in combination with other DNA damaging agents: synergistic interaction with altretamine, alkylating, and platinum-derived agents in the MV522 lung tumor model

Antroxazole A, an oxazole-containing chamigrane dimer from the fungus Antrodiella albocinnamomea with immunosuppressive activity

Antroxazole A (1), a chamigrane type sesquiterpene dimer containing an oxazole moiety, has been characterized from cultures of the fungus Antrodiella albocinnamomea. The structure with absolute configuration was determined by extensive spectroscopic methods and single crystal X-ray diffraction. A plausible biosynthetic pathway for 1 was proposed. Compound 1 exhibits inhibition specifically against the LPS-induced proliferation of B lymphocyte cells with an IC₅₀ value of 16.3 μM.

Effect of sodium butyrate on ABC transporters in lung cancer A549 and colorectal cancer HCT116 cells

Histone deacetylase (HDAC) inhibitors and DNA alkylators are effective components of combination chemotherapy. The aim of the present study was to investigate the possible mechanism of their synergism by detecting the effect of HDAC inhibitors on the expression levels of drug transporters that export DNA alkylators. It was demonstrated that the HDAC inhibitor sodium butyrate (NaB) induced the differential expression of multidrug resistant ATP-binding cassette (ABC) transporters in lung cancer and colorectal cancer cells. Specifically, NaB increased the mRNA expression levels of ABC subfamily B member 1 (ABCB1), ABCC10 and ABCC12, and protein expression levels of multidrug resistance-1 (MDR1), multidrug resistance-associated protein 7 (MRP7) and MRP9. Moreover, NaB decreased the expression levels of ABCC1, ABCC2 and ABCC3 mRNAs, as well as those of MRP1, MRP2 and MRP3 proteins. The molecular mechanism underlying this process was subsequently investigated. NaB decreased the expression of HDAC4, but not HDAC1, HDAC2 or HDAC3. In addition, NaB promoted histone H3 acetylation and methylation at lysine 9, as well as MDR1 acetylation, suggesting that acetylation and methylation may be involved in NaB-mediated ABC transporter expression. Thus, the present results indicated that the synergism of the HDAC inhibitors with the DNA alkylating agents may due to the inhibitory effect of MRPs by HDAC inhibitors. The findings also suggested the possibility of antagonistic effects following the combined treatment of HDAC inhibitors with MDR1 ligands.

Sesquiterpenoids from Cultures of the Basidiomycetes Irpex lacteus

Eight previously undescribed sesquiterpenoids, tremutins A-H (1-8), together with three known ones (9-11), were isolated from cultures of the basidiomycetes Irpex lacteus. Structures of the new compounds together with absolute configurations were elucidated on the basis of extensive spectroscopic methods, as well as single-crystal X-ray diffractions and equivalent circulating density calculations. Compounds 1 and 2 possess an unusual 6/7-fused ring system that might be derived from a tremulane framework. Compounds 3-7 and 9-11 are tremulane sesquiterpenoids of which 4 and 5 are the first tremulane examples with a 1,2-epoxy moiety to be reported. Compounds 6, 7, 10, and 11 possess weak activities to several human cancer cell lines. Compound 8 shows a weak inhibitory effect on NO production with a half maximal inhibitory concentration (IC₅₀) value of 22.7 μM. Compound 1 inhibits the lipopolysaccharide (LPS)-induced proliferation of B lymphocyte cells with an IC₅₀ value of 22.4 μM, while 2 inhibits concanavalin A (Con A)-induced T cell proliferation and LPS-induced B lymphocyte cell proliferation with IC₅₀ values of 16.7 and 13.6 μM, respectively.

Mushrooms: an emerging resource for therapeutic terpenoids

Mankind has always been fascinated with nature and have heavily explored natural products since the ancient times. Evolution of diseases led to research on synthetic structure, specificity and activity-guided treatment. To combat threats of new developing diseases and the deleterious side effects posed by modern therapy, researchers have once again looked back towards natural resources. Although plants have been the main source of natural drugs, lower fungi are being recently paid attention to. Among them, mushrooms have emerged as an under-explored yet immensely rich resource, especially for bioactive terpenoids. A lot of research is going on around the world with mushroom-derived terpenoids especially their medicinal properties, some of which have even been used in pre- and post-clinical studies. From the literatures that are available, it was found that mushroom terpenoids have activity against a wide range of diseases. In this review, we have summarized different mushroom-derived terpenoids and their therapeutic properties.

Computational Study of Novel Natural Inhibitors Targeting O6-Methylguanine-DNA Methyltransferase

OBJECTIVE

To screen ideal lead compounds from a drug library (ZINC15 database) with potential inhibition effect against O⁶-methylguanine-DNA methyltransferase (MGMT) to contribute to medication design and refinement.

METHODS

A series of computer-aided virtual screening techniques were used to identify potential inhibitors of MGMT. Structure-based virtual screening by LibDock was carried out to calculate LibDock scores, followed by absorption, distribution, metabolism, and excretion and toxicity predictions. Molecule docking was employed to demonstrate binding affinity and mechanism between the selected ligands and MGMT protein. Molecular dynamics simulation was performed to evaluate stability of the ligand-MGMT complex under natural circumstances.

RESULTS

Two novel natural compounds, ZINC000008220033 and ZINC000001529323, from the ZINC15 database were found to bind with MGMT with a higher binding affinity together with more favorable interaction energy. Also, they were predicted to have less rodent carcinogenicity, Ames mutagenicity, and developmental toxicity potential as well as noninhibition with cytochrome P-450 2D6. Molecular dynamics simulation analysis demonstrated that the 2 complexes ZINC000008220033-MGMT and ZINC000001529323-MGMT had more favorable potential energy compared with reference ligand O⁶-benzylguanine, and they could exist stably in the natural environment.

CONCLUSIONS

This study elucidated that ZINC000008220033 and ZINC000001529323 were ideal lead compounds with potential inhibition targeting to MGMT protein. These compounds were selected as safe drug candidates and may contribute a solid basis for MGMT target medication design and improvement.

Enantioselective total synthesis of (-)-acylfulvene and (-)-irofulven

We report our full account of the enantioselective total synthesis of (-)-acylfulvene (1) and (-)-irofulven (2), which features metathesis reactions for the rapid assembly of the molecular framework of these antitumor agents. We discuss (1) the application of an Evans Cu-catalyzed aldol addition reaction using a strained cyclopropyl ketenethioacetal, (2) an efficient enyne ring-closing metathesis cascade reaction in a challenging setting, (3) the reagent IPNBSH for a late-stage reductive allylic transposition reaction, and (4) the final RCM/dehydrogenation sequence for the formation of (-)-acylfulvene (1) and (-)-irofulven (2).

Observations in the Synthesis of the Core of the Antitumor Illudins via an Enyne Ring Closing Metathesis Cascade

Observations concerning the synthesis of the core spirocyclic AB-ring system of illudins using an enyne ring closing metathesis (EYRCM) cascade are discussed. Substituent effects, in addition to optimization of the reaction conditions and the olefin tether for the key EYRCM reaction, are examined.