Pleurotus pulmonarius (Fr.) Quel. (Pleurotaceae): In vitro antioxidant evaluation and the isolation of a steroidal isoprenoid

This study is reporting the in vitro antioxidant activity of the fruiting body of the edible mushroom Pleurotuspulmonarius (Fr.) Quel. The fruiting body of the edible mushroom was defatted with n-hexane and furtherextracted by successive maceration in dichloromethane (DCM) and 80% aqueous ethanol (AQE) to obtainthe DCM and AQE extracts, respectively. The 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavengingand iron chelating assays were used for antioxidant evaluation in vitro with ascorbic acid as the referencestandard for comparison. Isolation and structural elucidation of the steroid were done using chromatographicand spectroscopic techniques, respectively. The trend for the DPPH radical scavenging activity: ascorbic acid[inhibition concentration (IC)50 = 0.012 mg/ml] > AQE (IC50 = 0.525 mg/ml) > DCM (IC50 = 1.820 mg/ml)and for the iron chelating activity: ascorbic acid (IC50 = 0.214 mg/ml) > AQE (IC50 = 1.318 mg/ml) > DCM(IC50 = 7.586 mg/ml) were observed. From the DCM was isolated a pure compound 1 elucidated to be theknown steroidal isoprenoid: ergosta-5, 7, 22-trien-3β-ol. This study aside reporting the isolation of the knowncompound 1 from this species of Pleurotus, has also shown that compound 1 has a significant iron chelatingactivity at 0.001 mg/ml of 77.06% compared to 4.56% at same concentration for DPPH scavenging activity.

Molecular cloning and characterisation of scavenger receptor class B in pearl oyster Pinctada fuctada martensii

Background: Molluscs can accumulate carotenoids in their body tissues by predominantly feeding on aquatic plant sources. Carotenoid transport and absorption are determined by the regulation of various proteins such as Scavenger receptor class B(SR-BI). We report the identification and characterisation of pearl oyster Pinctada fuctada martensii SR-BI (PmSR-BI). The correlation between total carotenoid content (TCC) and gene expression was also estimated. Results: The full-length cDNA of PmSR-BI was 1828 bp, including an open-reading frame encoding of 1518 bp with a pI value of 5.83. PmSR-BI protein contains a hydrophobic CD36 domain and four centrally clustered cysteine residues for the arrangement of disulphide bridges. The deduced amino acid sequence had an identity of 30% to 60% with the SR-B of other organisms. Reverse transcription polymerase chain reaction analysis showed that mRNA transcripts were expressed in multiple tissues of adult pearl oyster. A higher expression of PmSR-BI gene was observed in the hepatopancreas than in the adductor muscle, gill and mantle. The TCC and gene expression of PmSR-BI were significantly correlated (P b 0.05), with a correlation coefficient of 0.978. Conclusions: The results suggested that PmSR-BI is involved in the absorption of carotenoids in the pearl oyster P. fuctada martensii.

Research progress on bioreactors for plant isoprene / 中草药

Isoprenoid compounds, a kind of plant secondary metabolites, are widely distributed in nature. They play important roles not only in plant growth and development process, but also in the regulation of relationship between plants and environment. Besides its biological function, the isoprenoid compounds have great economic values in many fields, such as agriculture, medicine, chemical industry, and so on. However, the yield of many isoprenoid compounds with high ecnomic value in nature is very low, which limits the research and use of isoprenoid compounds. Now, using plant bioreactor to regulate the synthesis of isoprenoid compounds is a focus of life sciences, and there are many deep researches on synthesis and metabolic pathways of isoprenoid compounds, which could promote the isoprenoid compounds production technologies with plant bioreactor. At the same time, the development of these technologies bring more deep understanding of the isoprenoid compounds synthesis metabolic pathways. We reviewed the development of metabolic synthesis and regulation of isoprenoid compounds and research progress on bioreactor, which will provide a quick reference for isoprenoid compounds synthesis research.

Efficacy of geraniol but not of β-ionone or their combination for the chemoprevention of rat colon carcinogenesis

β-ionone (βI), a cyclic isoprenoid, and geraniol (GO), an acyclic monoterpene, represent a promising class of dietary chemopreventive agents against cancer, whose combination could result in synergistic anticarcinogenic effects. The chemopreventive activities of βI and GO were evaluated individually or in combination during colon carcinogenesis induced by dimethylhydrazine in 48 3-week-old male Wistar rats (12 per group) weighing 40-50 g. Animals were treated for 9 consecutive weeks with βI (16 mg/100 g body weight), GO (25 mg/100 g body weight), βI combined with GO or corn oil (control). Number of total aberrant crypt foci (ACF) and of ACF ≥4 crypts in the distal colon was significantly lower in the GO group (66 ± 13 and 9 ± 2, respectively) compared to control (102 ± 9 and 17 ± 3) and without differences in the βI (91 ± 11 and 14 ± 3) and βI+GO groups (96 ± 5 and 19 ± 2). Apoptosis level, identified by classical apoptosis morphological criteria, in the distal colon was significantly higher in the GO group (1.64 ± 0.06 apoptotic cells/mm²) compared to control (0.91 ± 0.07 apoptotic cells/mm²). The GO group presented a 0.7-fold reduction in Bcl-2 protein expression (Western blot) compared to control. Colonic mucosa concentrations of βI and GO (gas chromatography/mass spectrometry) were higher in the βI and GO groups, respectively, compared to the control and βI+GO groups. Therefore, GO, but not βI, represents a potential chemopreventive agent in colon carcrvpdate=20110329inogenesis. Surprisingly, the combination of isoprenoids does not represent an efficient chemopreventive strategy.

Effect of fosmidomycin on metabolic and transcript profiles of the methylerythritol phosphate pathway in Plasmodium falciparum

In Plasmodium falciparum, the formation of isopentenyl diphosphate and dimethylallyl diphosphate, central intermediates in the biosynthesis of isoprenoids, occurs via the methylerythritol phosphate (MEP) pathway. Fosmidomycin is a specific inhibitor of the second enzyme of the MEP pathway, 1-deoxy-D-xylulose-5-phosphate reductoisomerase. We analyzed the effect of fosmidomycin on the levels of each intermediate and its metabolic requirement for the isoprenoid biosynthesis, such as dolichols and ubiquinones, throughout the intraerythrocytic cycle of P. falciparum. The steady-state RNA levels of the MEP pathway-associated genes were quantified by real-time polymerase chain reaction and correlated with the related metabolite levels. Our results indicate that MEP pathway metabolite peak precede maximum transcript abundance during the intraerythrocytic cycle. Fosmidomycin-treatment resulted in a decrease of the intermediate levels in the MEP pathway as well as in ubiquinone and dolichol biosynthesis. The MEP pathway associated transcripts were modestly altered by the drug, indicating that the parasite is not strongly responsive at the transcriptional level. This is the first study that compares the effect of fosmidomycin on the metabolic and transcript profiles in P. falciparum, which has only the MEP pathway for isoprenoid biosynthesis.