Sechul Chun

Phenolic Compound Concentration and Antioxidant Activities of Edible and Medicinal Mushrooms from Korea

A study was conducted to determine the content of phenolic compounds and the antioxidative activity of five edible and five medicinal mushrooms commonly cultivated in Korea. Phenolic compounds were analyzed using high performance liquid chromatography, and antioxidant activity was evaluated by 1,1-diphenyl-2-picrylhydrazyl radical scavenging activity and superoxide dismutase activity. A total of 28 phenolic compounds were detected in the mushrooms studied. The average total concentration of phenolic compounds was 326 microg/g, the average being of 174 microg/g in edible mushrooms and 477 microg/g in medicinal mushrooms. The average total flavonoids concentration was 49 microg/g, with averages of 22 and 76 microg/g in edible and medicinal mushrooms, respectively. The DPPH radical scavenging activities ranged between 15 (Pleurotus eryngii) and 70% (Ganoderma lucidum) when reaction time was for 1 min. When reaction time was 30 min, the values ranged between 5 (Pleurotus eryngii) and 78% (Agaricus bisporus). The SOD activity averaged 28% among the 10 mushroom species, averages for edible and medicinal mushrooms being comparable. DPPH activities was significantly correlated (p < 0.01) with total content of phenolic compounds in edible mushrooms, while in medicinal mushrooms there was a significant correlation (p < 0.01) between SOD activity and total concentration of phenolic compounds. Numerous significant positive correlations were observed between phenolic compounds detected and antioxidative potential.

Isolation and characterization of plant growth promoting endophytic diazotrophic bacteria from Korean rice cultivars

We have isolated 576 endophytic bacteria from the leaves, stems, and roots of 10 rice cultivars and identified 12 of them as diazotrophic bacteria using a specific primer set of nif gene. Through 16S rDNA sequence analysis, nifH genes were confirmed in the two species of Penibacillus, three species of Microbacterium, three Bacillus species, and four species of Klebsiella. Rice seeds treated with these plant growth-promoting bacteria (PGPB) showed improved plant growth, increased height and dry weight and antagonistic effects against fungal pathogens. In addition, auxin and siderophore producing ability, and phosphate solubilizing activity were studied for the possible mechanisms of plant growth promotion. Among 12 isolates tested, 10 strains have shown higher auxin producing activity, 6 isolates were confirmed as strains with high siderophore producing activity while 4 isolates turned out to have high phosphate-solubilizing activity. These results strongly suggest that the endophytic diazotrophic bacteria characterized in this study could be successfully used to promote plant growth and inducing fungal resistance in plants.

One-step, ultrasonication-mobilized, solvent-free extraction/synthesis of nanocurcumin from turmeric

Curcumins current solvent-based extraction and poor solubility in water are two unresolved obstacles that limit the harnessing of this medicinal resource. To date, the extraction of curcumin from turmeric in water remains a challenge. This work resolves both these problems via a simple, ultrasonication-based, one-step strategy. Two different sonication methods, water bath type and probe sonication, were employed (using varying variables such as sonication time and sonication frequencies) to develop this one-step, water-based technique for extracting curcumin directly from turmeric. The probe sonication technique with sonication time within 5 min and 20 kHz frequency led to 55% curcumin extraction yield in water. This yield is even higher than that achieved by solvent-based extraction methods using ethanol. The ultrasonic physical conversion of micro-curcumin to nano-curcumin is shown to be the reason for the enhanced solubility of curcumin in water, leading to effective extraction. The results of this study suggest the use of probe ultrasonication for water-based extraction of curcumin from turmeric in a one-step process. This study also provides a solution for the bioavailability problem of curcumin, owing to its insolubility in water through nano-sizing of the curcumin using ultrasonication methods. The results and validation of these findings are reported in this communication.

Data mining technique for medical informatics: detecting gastric cancer using case-based reasoning and single nucleotide polymorphisms

: Although data mining and knowledge discovery techniques have recently been used to diagnose human disease, little research has been conducted on disease diagnostic modelling using human gene information. Furthermore, to our knowledge, no study has reported on diagnosis models using single nucleotide polymorphism (SNP) information. A disease diagnosis model using data mining techniques and SNP information should prove promising from a practical perspective as more information on human genes becomes available. Data mining and knowledge discovery techniques can be put to practical use detecting human disease, since a haplotype analysis using high-density SNP markers has gained great attention for evaluating human genes related to various human diseases. This paper explores how data mining and knowledge discovery can be applied to medical informatics using human gene information. As an example, we applied case-based reasoning to a cancer detection problem using human gene information and SNP analysis because case-based reasoning has been applied in medicine relatively less often than other data mining techniques. We propose a modified case-based reasoning method that is appropriate for associated categorical variables to use in detecting gastric cancer.

Bactericidal activity of green tea extracts: the importance of catechin containing nano particles.

When we drink green tea infusion, we believe we are drinking the extract of the green tea leaves. While practically each tea bag infused in 300 mL water contains about 50 mg of suspended green tea leaf particles. What is the role of these particles in the green tea effect is the objective of this study. These particles (three different size ranges) were isolated via varying speed centrifugation and their respective inputs evaluated. Live oral bacterial samples from human volunteers have been screened against green tea extracts and macro, micro and nano sized green tea particles. The results showed that the presence/absence of the macro and mico sized tea particles in the green tea extract did not contribute much. However, the nano sized particles were characterized to be nature’s nano stores of the bioactive catechins. Eradication of these nano tea particles resulted in decrease in the bactericidal property of the green tea extracts. This is a curtain raiser investigation, busting the nano as well as green tea leaf particle contribution in green tea extracts.

Onion extract structural changes during in vitro digestion and its potential antioxidant effect on brain lipids obtained from low- and high-fat-fed mice.

Abstract This study investigated the effects of onion (Allium cepa, L.) extract on the antioxidant activity of lipids in low-and high-fat-fed mouse brain lipids and its structural change during in vitro human digestion. The onion extracts were passed through an in vitro human digestion model that simulated the composition of the mouth, stomach, and small intestine juice. The brain lipids were collected from low- and high-fat-fed mouse brain and then incubated with the in vitro-digested onion extracts to determine the lipid oxidation. The results confirmed that the main phenolics of onion extract were kaempferol, myricetin, quercetin, and quercitrin. The quercetin content increased with digestion of the onion extract. Antioxidant activity was strongly influenced by in vitro human digestion of both onion extract and quercetin standard. After digestion by the small intestine, the antioxidant activity values were dramatically increased, whereas the antioxidant activity was less influenced by digestion in the stomach for both onion extract and quercetin standard. The inhibitory effect of lipid oxidation of onion extract in mouse brain lipids increased after digestion in the stomach. The inhibitory effect of lipid oxidation of onion extract was higher in the high-fat-fed mouse brain lipids than that in the low-fat-fed mouse brain lipids. The major study finding is that the antioxidative effect of onion extract may be higher in high-fat-fed mouse brain lipids than that in low-fat-fed mouse brain lipids. Thus, dietary onion may have important applications as a natural antioxidant agent in a high-fat diet.

Mating Types and Optimum Culture Conditions for Sexual State Formation of Fusarium fujikuroi Isolates.

Twenty-five isolates of Fusarium fujikuroi acquired from rice seeds and rice plants evidencing symptoms of Bakanae disease were evaluated to determine their mating types and characterize the formation of their sexual state. The mating types of the isolates were evaluated via multiplex PCR with the diagnostic primers of the mating-type (MAT) region: GFmat1a, GFmat1b, GFmat2c, and GFmat2d. Among the 25 isolates, 11 were identified as MAT-1 (male), and 14 as MAT-2 (female). Four MAT-1 isolates and three MAT-2 isolates were mated and cultured to evaluate the optimal culture conditions for the production of their sexual states. Among four tested media, 10% V8 juice agar proved optimal for the perithecial production of the isolates. The isolates also generated the largest numbers of perithecia when incubated at 23°C in alternating cycles of 12 hr fluorescent light and NUV fluorescent light and 12 hr darkness.

Isolation and characterisation of a dwarf rice mutant exhibiting defective gibberellins biosynthesis

We have isolated a severe dwarf mutant derived from a Ds (Dissociation) insertion mutant rice (Oryza sativa var. japonica c.v. Dongjin). This severe dwarf phenotype, has short and dark green leaves, reduced shoot growth early in the seedling stage, and later severe dwarfism with failure to initiate flowering. When treated with bioactive GA3 , mutants are restored to the normal wild-type phenotype. Reverse transcription PCR analyses of 22 candidate genes related to the gibberellin (GA) biosynthesis pathway revealed that among 22 candidate genes tested, a dwarf mutant transcript was not expressed only in one OsKS2 gene. Genetic analysis revealed that the severe dwarf phenotype was controlled by recessive mutation of a single nuclear gene. The putative OsKS2 gene was a chromosome 4-located ent-kaurene synthase (KS), encoding the enzyme that catalyses an early step of the GA biosynthesis pathway. Sequence analysis revealed that osks2 carried a 1-bp deletion in the ORF region of OsKS2, which led to a loss-of-function mutation. The expression pattern of OsKS2 in wild-type cv Dongjin, showed that it is expressed in all organs, most prominently in the stem and floral organs. Morphological characteristics of the dwarf mutant showed dramatic modifications in internal structure and external morphology. We propose that dwarfism in this mutant is caused by a point mutation in OsKS2, which plays a significant role in growth and development of higher plants. Further investigation on OsKS2 and other OsKS-like proteins is underway and may yield better understanding of the putative role of OsKS in severe dwarf mutants.

The ethanopharmacological aspect of carbon nanodots in turmeric smoke.

Smoke manifested ever since our ancient’s lit fire; today it has evolved to become an environmental concern. However, medicinal smoke is still part of man’s natural remedies, religious and cultural practices too. The Asiatic household practice of burning turmeric rhizomes to relieve nose and chest congestion is a well known yet never scientifically authenticated or studied practice. For the first time we investigate the components of these turmeric smudges, validate their antimicrobial and anticancer properties and their cell compatibility. With smoke there is always nanoparticulate carbon and turmeric smoke is no exception. If so, what is the role of the nano carbon (NC) in the turmeric smudge effect? This study isolated, characterized and exposed these secret natural NC undercover agents in turmeric smoke. Their unequivocal role in the ethanopharmocological activity of turmeric smudging has been demonstrated. This work opens a new avenue for use of such nano components of smoke for harnessing the ethanopharmacological property of various medicinal smokes, by excluding the smoke factor, through extracting the nano carbon material in them. This is a possibility to realizing the use of such naturally available nanomaterial, as an eco friendly substitute for the notorious anthropogenic nanomaterials.

Meta-analysis Reveals That the Genus Pseudomonas Can Be a Better Choice of Biological Control Agent against Bacterial Wilt Disease Caused by Ralstonia solanacearum

Biological control agents (BCAs) from different microbial taxa are increasingly used to control bacterial wilt caused by Ralstonia solanacearum. However, a quantitative research synthesis has not been conducted on the role of BCAs in disease suppression. Therefore, the present study aimed to meta-analyze the impacts of BCAs on both Ralstonia wilt disease suppression and plant (host) growth promotion. The analysis showed that the extent of disease suppression by BCAs varied widely among studies, with effect size (log response ratio) ranging from −2.84 to 2.13. The disease incidence and severity were significantly decreased on average by 53.7% and 49.3%, respectively. BCAs inoculation also significantly increased fresh and dry weight by 34.4% and 36.1%, respectively on average. Also, BCAs inoculation significantly increased plant yield by 66%. Mean effect sizes for genus Pseudomonas sp. as BCAs were higher than for genus Bacillus spp. Among antagonists tested, P. fluorescens, P. putida, B. cereus, B. subtilis and B. amyloliquefaciens were found to be more effective in general for disease reduction. Across studies, highest disease control was found for P. fluorescens, annual plants, co-inoculation with more than one BCA, soil drench and greenhouse condition were found to be essential in understanding plant responses to R. solanacearum. Our results suggest that more efforts should be devoted to harnessing the potential beneficial effects of these antagonists, not just for plant growth promoting traits but also in mode of applications, BCAs formulations and their field studies should be considered in the future for R. solanacearum wilt disease suppression.