ABSTRACT
The highly oxygenated indole alkaloid speradine F (4) with a 6/5/6/5/5/5 hexacyclic skeleton was isolated from a culture of Penicillium palitans, together with its precursors ß-cyclopiazonic acid (ß-CPA, 5) and cyclopiazonic acid (CPA, 1). Gene deletion and heterologous expression led to the identification of the responsible five-gene spe cluster for the speradine skeleton formation. Precursor supply experiments proved that 1 was enzymatically converted, via 2-oxoCPA (2), to speradine A (3), which subsequently undergoes multistep nonenzymatic hydroxylations to 4.
Subject(s)
Indole Alkaloids , Penicillium , Oxidation-Reduction , Penicillium/metabolismABSTRACT
Cyclopenol (1) and viridicatol (6) with m-hydroxyl groups were isolated from a culture of Penicillium palitans. Genome mining and heterologous expression in Aspergillus nidulans led to the identification of their biosynthetic gene cluster and the cytochrome P450 enzyme VdoD responsible for the meta hydroxylation. Precursor feeding experiments into vdoD transformant proved the conversion of cyclopenin (2) to 1, which then undergoes a spontaneous or VdoA-catalyzed rearrangement to 6. A direct conversion of viridicatin (5) to 6 by VdoD was not detected.
Subject(s)
PenicilliumABSTRACT
Four new acylated triterpene glycosides with aliphatic chains (4-7) as well as five known triterpenoids were isolated from the flower buds of Staphylea bumalda with bioassay guidance. Their structures were determined on the basis of spectral techniques, including IR, 1D and 2D NMR, and HR-APCI-MS. Most compounds (except 8) were isolated from S. bumalda for the first time. Additionally, the neuroprotective effects of 1 and 4-9 on suckling rat primary cultured hippocampal neurons against H2O2-induced injury were evaluated in vitro. The four new triterpenoids (4-7) showed neuroprotective effects, which increased the cell viability to over 74% at different concentrations, which was higher than the negative control (59%), while compounds 1 and 8-9 exhibited cytotoxic activity.
Subject(s)
Glycosides/pharmacology , Hippocampus/drug effects , Hydrogen Peroxide/antagonists & inhibitors , Neurons/drug effects , Neuroprotective Agents/pharmacology , Triterpenes/pharmacology , Animals , Flowers/chemistry , Glycosides/chemistry , Glycosides/isolation & purification , Hippocampus/pathology , Hydrogen Peroxide/pharmacology , Magnoliopsida/chemistry , Neurons/pathology , Neuroprotective Agents/chemistry , Neuroprotective Agents/isolation & purification , Rats , Rats, Sprague-Dawley , Triterpenes/chemistry , Triterpenes/isolation & purificationABSTRACT
E2F3a is a transcription factor that has been shown to be overexpressed in liver cancer tissues. To characterize the function of E2F3a in hepatocellular carcinoma (HCC), effects of ectopic overexpression of E2F3a on cell cycle, apoptosis, and gene expression of HepG2 cells were studied. E2F3a significantly enhances the apoptotic rate of HepG2 cells by 33% but only has minor effects on cell proliferation. By using microarray analyses, we identified 162 target genes (160 upregulated and 2 downregulated) of the E2F3a. Differential expression of 11 genes was further confirmed by real-time PCR. Eight of these 11 genes, including XAF1, CEACAM1, STAT1, ATF3, TNFSF10, KLF6, CLDN1, and TAP1, were confirmed to be upregulated by more than twofold. Functional enrichments of differentially expressed genes retrieved 21 apoptosis-related genes and 32 transcriptional regulation-related genes. These results suggest that E2F3a induces apoptosis in HepG2 cells and plays important roles in regulating transcription. Finally, positive correlation was found between E2F3a and CEACAM1 mRNA levels in clinically well-differentiated human HCC specimens.
