Antimicrobial Activity of Extracts of the Oyster Culinary Medicinal Mushroom Pleurotus ostreatus (Higher Basidiomycetes) and Identification of a New Antimicrobial Compound.

Pleurotus ostreatus is an edible mushroom that also has high medicinal values. In this study, P. ostreatus was tested for its ability to inhibit the growth of fungi and bacteria. The freeze-dried fruiting body, broth from submerged culture, and mycelial biomass of P. ostreatus were extracted using alcohols and water as solvents. The extracts were then tested for their antimicrobial activity against the growth of fungi and bacteria. It was observed that the water extract from fruiting bodies had the strongest effect in inhibiting the growth of most fungi. The most sensitive test microfungi to the inhibition were Candida albicans, Cryptococcus humicola, and Trichosporon cutaneum, and the most sensitive test bacteria were Staphylococcus aureus followed by Escherichia coli. Water extracts from culture broth or mycelial biomass were moderately inhibitive to the growth of fungi and bacteria. The alcohol-based solvents from all samples had much less antimicrobial activity against most test microorganisms. An antimicrobial compound was purified from the water extracts of fruiting bodies with Sephadex G 100 column chromatography and characterized by infrared absorption spectrum (IR), nuclear magnetic resonance (NMR), and mass spectroscopic analysis. We have identified this compound to be 3-(2-aminopheny1thio)-3-hydroxypropanoic acid. This purified compound had a minimum inhibitory concentration of 30 µg/mL and 20 µg/mL against the growth of fungi and bacteria, respectively.

Medicinal Mushroom Extracts Possess Differential Antioxidant Activity and Cytotoxicity to Cancer Cells.

Many species of edible mushrooms are known to contain a wide array of compounds with high nutritional and medicinal values. However, these values vary widely among mushroom species because of the wide diversity of compounds with different solubilities to solvents used in extraction. We report here the comparison of antioxidant activity and cytotoxicity against cancer cells in extracts of Pleurotus ostreatus, P. sajor-caju, Agaricus campestris, and A. bisporus from 7 different solvents, including water, ethanol, ethyl acetate, acetone, chloroform, hexane, and petroleum ether. The extracts were analyzed for their antioxidant activities using the % DPPH (2,2-diphenyl-1-picrylhydrazylhydrate) scavenging activity method. Our results revealed that the water extracts exhibited the highest % DPPH scavenging activity in comparison to all other solvent extracts. The highest value was obtained from the water extract of P. sajor-caju (78.1%), and the lowest one was from the hexane extract of A. bisporus (0.8%). In general, extracts from nonpolar solvents exhibited much lower antioxidant activities than those from polar solvents. The cytotoxic effects of these extracts were evaluated using 2 cancer cell lines of larynx carcinoma (HEp-2) and breast carcinoma (MCF-7). When added into Hep-2 cells, the hexane extracts from P. ostreatus, P. sajor-caju, A. bisporus, and A. campestris yielded the highest IC50 values of 1.7 ± 1.56, 2.1 ± 2.82, 4.4 ± 1.71, and 2.2 ± 1.34 µg/mL, respectively, in comparison to all other solvent extracts. Similar IC50 values were obtained when the MCF-2 cancer cells were tested, suggesting that hexane is the preferred solvent to extract the anticancer compounds from these mushrooms. Our results also indicated that extracts from solvents with nonpolar or intermediate polarity were more potent than those with high polarity in their cytotoxicity against cancer cells, and extracts from different mushrooms by the same solvent possessed varied degrees of cytotoxicity.

In vitro propagation of Gentiana scabra Bunge - an important medicinal plant in the Chinese system of medicines.

BACKGROUND: Gentiana scabra Bunge commonly known as 'Long dan cao' in China has been used in traditional Chinese medicines for more than 2000 years. Dry roots and rhizome of the herb have been used for the treatment of inflammation, anorexia, indigestion and gastric infections. Iridoids and secoiridoids are the main bioactive compounds which attribute to the pharmacological properties of this plant. The species is difficult to mass propagate by seed due to the low percentage of germination and limited dormancy period. Wild populations in some locations are considered to be in the endangered category due to over exploitation. RESULTS: In the present study, we report an efficient micropropagation system. Shoot apices of six weeks old in vitro grown G. scabra plants were used as explants for the in vitro propagation. Induction of multiple shoots (9.1/explant) was achieved on the culture of shoot apices on half strength Murashige and Skoog's basal medium (MSBM) containing 2.0 mg/L-1 6-benzylaminopurine (BA), 3% sucrose and 0.9% Difco agar. In vitro shoots induced profuse rooting on half strength of MSBM supplemented with 0.1 mg/L-1 1-naphthaleneacetic acid (NAA), 3% sucrose and 0.3% gelrite. A two-stage ventilation closure procedure during the in vitro culture, and transparent sachet technique enhanced the survival rate of G. scabra plantlets to 96% in the greenhouse. Tissue culture plants flowered after 5 months of transfer to pots. CONCLUSIONS: A simple and an efficient in vitro propagation protocol of Gentiana scabra Bunge by optimizing the medium composition and ventilation closure treatments has been developed. The protocol can be very useful in germplasm conservation and commercial cultivation of G. scabra plants.

Freeze-dried microalgae of Nannochloropsis oculata improve soybean oil's oxidative stability.

Marine microalga Nannochloropsis oculata possesses nutrients valuable for human health. In this study, we added freeze-dried N. oculata powder to soybean oil and observed a remarkable inhibition in oil oxidation. The amount of microalgae powder added was positively correlated to the increase in oil stability. The addition of 5.0 % (w/w) microalgae powder increased the oil stability index (OSI) values of soybean oil more than twofold at the tested temperatures 120 and 130 °C. N. oculata contains high levels of both phenolic compounds and α-tocopherols that could be the contributors to such an increase of the OSI. Two methods were conducted to assay the active ingredients released from microalgae: one employed three solvent systems to extract the microalgae and the other was the soybean oil added with microalgae. Analyses of free radical scavenging and reducing power suggested that the phenolic compounds dominated the antioxidation activities in soybean oil when it was infused with the microalgae powder. Our results suggest that N. oculata could potentially be used as an additive in cooking oil to increase the shelf life and nutritional value of the oil and to reduce the production of free radicals from lipid oxidation when the oil is used at high-temperature cooking processes.

Plant ferredoxin-like protein (PFLP) outside chloroplast in Arabidopsis enhances disease resistance against bacterial pathogens.

Protection of crops against bacterial disease is an important issue in agricultural production. One of the strategies to lead plants become resistant against bacterial pathogens is employing a transgene, like plant ferredoxin-like protein (PFLP). PFLP is a photosynthetic type ferredoxin isolated from sweet pepper and contains a signal peptide for targeting towards chloroplasts. Our previous reports indicated that transgenic plants with this protein are more resistant against bacterial pathogens. However, this heterologous protein was visualized not only inside the chloroplasts, but also in the cytoplasm. In this article, we moved to study its heterologous expression in Arabidopsis by expressing the protein in chloroplast, apoplast and cytoplasm. This work was achieved by engineering a chloroplast target (CPF), an apoplast target (ESF), and cytoplasm target (DF) plants. The expression and subcellular localization of PFLP were analyzed by Western blot and immuno-staining by confocal microscopy, respectively. We tested the ability of the transgenic Arabidopsis for resistance to two Ralstonia solanacearum strains and their ability to increase the hypersensitive response (HR) triggered by harpin (HrpZ) from Pseudomonas syringae. The DF and ESF plants conferred resistance against bacterial wilt strains and increased HR by harpin, but no resistance found in the CPF plants. In addition, we determined the level of reduced ascorbate in all transgenic plants and further analyzed the expression of two NADPH-oxidase genes (AtrbohD and AtrbohF) in ESF plant. Among the transgenic Arabidopsis plants, ESF plants confer the highest resistance to bacterial pathogens and followed by DF plants. We concluded that PFLP enhances disease resistance in Arabidopsis when expressed in the apoplast or in cytoplasm but not when targeted into the chloroplast. This study provides a strategy for molecular breeding to improve resistance of crops against bacterial pathogens.

[Wheat transformation by electroporation with ring electrode].

Electroporation has been used effectively to deliver DNA into the tissue of intact wheat immature embryos. The physical parameters of electroporation were 770 V/cm field strength, 800 microF capacitor and 100 microg/mL of plasmid DNA, containing bar and GUS gene. The electroporation was carried out by a portable and permanent ring electrode that can be fitted into the wells of 24-well plates. The samples were pulsed three times. Integration of the introduced genes into the genome of transgenic wheat plants was shown by PCR and Southern blot analysis. Transformation frequency was 7.5%, that is higher than that of the 4.2% frequency by microprojectile bombardment.