Ophiobolin-O reverses adriamycin resistance via cell cycle arrest and apoptosis sensitization in adriamycin-resistant human breast carcinoma (MCF-7/ADR) cells.

Multidrug-resistance is a major obstacle facing cancer chemotherapy. This paper demonstrates that novel compound Ophiobolin-O reverses MCF-7/ADR resistance to adriamycin (ADM). The IC50 of ADM treated MCF-7 cells was 2.02 ± 0.05 µM and 74.00 ± 0.18 µM treated MCF-7/ADR cells, about 37-fold, compared to the former. However, 0.1 µM Ophiobolin-O (less than 20% inhibition concentration) combined with ADM caused the decreased IC50 of ADM to 6.67 ± 0.98 µM, indicating it reversed ADM resistance of MCF-7/ADR cells (11-fold). Furthermore, Ophiobolin-O increased ADM-induced mitochondrial pathway apoptosis and G2/M phase arrest, which is partly due to the elevation level of ROS in MCF-7/ADR cells. As we described in this paper, the reversal effect of Ophiobolin-O may be due to the reduction of resistance-related protein P-Glycoprotein (P-gp, also known as MDR1) through inhibiting the activity of the multidrug resistance 1 (MDR1) gene promoter, which makes MCF-7/ADR cells more sensitive to ADM treatment. Assays in nude mice also showed that the combination of ADM and Ophiobolin-O significantly improved the effect of ADM.

Induced production of mycotoxins in an endophytic fungus from the medicinal plant Datura stramonium L.

Epigenetic modifiers, including DNA methyltransferase (DNMT) or histone deacetylase (HDAC) inhibitors, are useful to induce the expression of otherwise dormant biosynthetic genes under standard laboratory conditions. We isolated several endophytic fungi from the medicinal plant Datura stramonium L., which produces pharmaceutically important tropane alkaloids, including scopolamine and hyoscyamine. Although none of the endophytic fungi produced the tropane alkaloids, supplementation of a DNMT inhibitor, 5-azacytidine, and/or a HDAC inhibitor, suberoylanilide hydroxamic acid, to the culture medium induced the production of mycotoxins, including alternariol, alternariol-5-O-methyl ether, 3'-hydroxyalternariol-5-O-methyl ether, altenusin, tenuazonic acid, and altertoxin II, by the endophytic fungus Alternaria sp. This is the first report of a mycotoxin-producing endophytic fungus from the medicinal plant D. stramonium L. This work demonstrates that treatments with epigenetic modifiers induce the production of mycotoxins, thus providing a useful tool to explore the biosynthetic potential of the microorganisms.

Molecular cloning and characterization of copper amine oxidase from Huperzia serrata.

A cDNA encoding a novel copper amine oxidase (CAO) was cloned and sequenced from the Chinese club moss Huperzia serrata (Huperziaceae), which produces the Lycopodium alkaloid huperzine A. A 2043-bp open reading frame encoded an Mr 76,854 protein with 681 amino acids. The deduced amino acid sequence shared 44-56% identity with the known CAOs of plant origin, and contained the active site consensus sequence of Asn-Tyr-Asp/Glu. The phylogenetic tree analysis revealed that HsCAO from the primitive vascular plant H. serrata is closely related to Physcomitrella patens subsp CAO. The recombinant enzyme, heterologously expressed in Escherichia coli, catalyzed the oxidative deamination of aliphatic and aromatic amines. Among them, the enzyme accepted cadaverine as the best substrate to catalyze the oxidative deamination to Δ(1)-piperideine, which is the precursor of the Lycopodium alkaloids. Furthermore, a homology modeling and site-directed mutagenesis studies predicted the active site architecture, which suggested the crucial active site residues for the observed substrate preference. This is the first report of the cloning and characterization of a CAO enzyme from the primitive Lycopodium plant.

[Cloning, expression and functional identification of a type III polyketide synthase gene from Huperzia serrata].

A cDNA encoding novel type III polyketide synthase (PKS) was cloned and sequenced from young leaves of Chinese club moss Huperzia serrata (Thunb.) Trev. by RT-PCR using degenerated primers based on the conserved sequences of known CHSs, and named as H. serrata PKS2. The terminal sequences of cDNA were obtained by the 3'- and 5'-RACE method. The full-length cDNA of H. serrata PKS2 contained a 1212 bp open reading frame encoding a 46.4 kDa protein with 404 amino acids. The deduced amino acid sequence of H. serrata PKS2 showed 50%-66% identities to those of other chalcone synthase super family enzymes of plant origin. The recombinant H. serrata PKS2 was functionally expressed in Escherichia coli with an additional hexahistidine tag at the N-terminus and showed unusually versatile catalytic potency to produce various aromatic tetraketides, including chalcones, benzophenones, phloroglucinols, and acridones. In particular, the enzyme accepted bulky starter substrates N-methylanthraniloyl-CoA, and carried out three condensations with malonyl-CoA to produce 1, 3-dihydroxy-N-methylacridone. Interestingly, H. serrata PKS2 lacks most of the consensus active site sequences with acridone synthase from Ruta graveolens (Rutaceae).

[Simultaneous determination of six zeranols in milk samples by immunoaffinity solid phase extraction coupled with ultra-performance convergence chromatography-tandem mass spectrometry].

A method was developed for the simultaneous determination of α-zearalanol, ß-zearalanol, α-zearalenol, ß-zearalenol, zearalenone and zearalanone residues in milk samples by ultra-performance convergence chromatography-tandem mass spectrometry (UPC2-MS/MS) after immunoaffinity column-solid phase extraction (IAC-SPE). The sample was diluted with deionized water and cleaned with IAC-SPE. The chromatographic separation was performed on an ACQUITY UPC2 Torus 2-PIC column (50 mm×3.0 mm, 1.7 µm) using the mobile phases of supercritical carbon dioxide and methanol containing 0.1% (v/v) formic acid with gradient elution. The separated compounds were detected in negative electrospray ionization (ESI-) mode. The results showed no significant matrix effect after cleaning by IAC-SPE. The calibration curves of the six compounds were linear in the range of 1-200 ng/mL (correlation coefficients (r2) ≥ 0.9957). The recoveries were 75.9%-106.5% in the three spiked levels, and the intra-day and inter-day precisions were no more than 11.4%. The method is specific, environment friendly, and is suitable for the rapid determination of α-zearalanol, ß-zearalanol, α-zearalenol, ß-zearalenol, zearalenone and zearalanone residues in milk samples.