• Journal of the Korean Society of Food Science and Nutrition
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• v.13 no.1
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• pp.117-126
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• 1984

Aflatoxins are toxic and carcinogenic secondary metabolites which are produced by trains of A. flavus and A. parasiticus during their growth on foods and feedstuffs. Aflatoxins are a group of closely related heterocyclic compounds of which $B_1$, $B_2$, and $G_2$ are the major members. Aflatoxins are synthesized via a polyketide pathway in which the general steps are acetate, an-thraquinones, xanthone and aflatoxins. Aflatoxin formation is favored by high moisture or high $a_w$(0.95${\sim}$0.99). The limiting $a_w$ for aflatoxin production on agricultural commodities is 0.83. Optimum temperature for aflatoxin production by the molds is $25{\sim}30^{\circ}C$ and the incubation time for the maximum production of the toxin is 7${\sim}$15 days. The limiting temperatures for aflatoxin production are ${\leq}7.5^{\circ}C\;and\;\geq40^{\circ}C$. Cycling temperatures may or may not stimulate aflatoxin production depending on the amplitude of cycling, substrate and strains of molds. Aflatoxin pro-ducing molds are aerobic organisms and thus have a requirement for oxygen. A decreasing $O_2$ concentration and/or increasing concentrations of $CO_2$ or $N_2$ depress the mold growth and aflatoxin formation. A. flavus grows competitively or associatively in the presence of other microorganisms and occasionally loses the competition with other microorganisms. Some lactic acid bacteria have been shown to reduce growth and aflatoxin production by A. parasiticus. Carbon source is the most important nutritional factors affecting aflatoxin formation by the molds. Sucrose, fructose and glucose are the most favorable carbon sources. Food substrates of plant derived products which have high carbohydrate content such as agricultural commodities and their products are most vulnerable to contamination by aflatoxins.

• Animal Bioscience
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• v.34 no.4
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• pp.594-602
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• 2021

Objective: An experiment was conducted to assess the effect of dragon fruit peel pellet (DFPP) as a rumen enhancer of dry matter consumption, nutrient digestibilities, ruminal ecology, microbial protein synthesis and rumimal methane production in Holstein crossbred bulls. Methods: Four animals, with an average live-weight of 200±20 kg were randomly assigned in a 4×4 Latin square design to investigate the influence of DFPP supplementation. There were four different dietary treatments: without DFPP, and with 200, 300, and 400 g/h/d, respectively. Results: Results revealed that dry matter consumption of total intake, rice straw and concentrate were not significantly different among treatments (p>0.05). It was also found that ruminal pH was not different among treatments (p>0.05), whilst protozoal group was reduced when DFPP increased (p<0.01). Blood urea nitrogen and NH3-N concentrations were increased at 400 g of DFPP supplementation (p<0.01). Additionally, volatile fatty acid production of propionate was significantly enhanced by the DFPP supplementation (p<0.05), while production of methane was consequently decreased (p<0.05). Furthermore, microbial protein synthesis and urinary purine derivatives were remarkably increased especially at 400 g of DFPP supplementation (p<0.05). Conclusion: Plant secondary compounds or phytonutrients (PTN) containing saponins (SP) and condensed tannins (CT) have been reported to influence rumen fermentation. DFPP contains both CT and SP as a PTN. The addition of 400 g of DFPP resulted in improved rumen fermentation end-products especially propionate (C3) and microbial protein synthesis. Therefore, DFPP is a promising rumen enhancer and indicated a significant potential of DFPP as feedstuff for ruminant feed to mitigate rumen methane production.

• Korean Journal of Environmental Agriculture
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• v.35 no.3
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• pp.216-222
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• 2016

BACKGROUND: Polychlorinated biphenyls (PCBs) are one of the most common environmental contaminants. Because of their recalcitrant properties and long-term toxicity, numerous studies have been performed. The toxicological concerns are focused on endocrinological effects of animal. Several different metabolites have been reported, including hydroxy PCBs, PCB quinones, and methylsulfonyl PCBs from animal tissues. However, details in plants have never been studied. It is well-known that plants can produce phytoalexin in response to chemical, physical, or pathological stress.METHODS AND RESULTS: In this study, the several PCBs and hydroxy derivatives were prepared by chemical syntheses. Their effects on secondary metabolite biosynthesis were determined in carrot roots. The levels of 6-methoxymellein were determined in several different treatments, using gas chromatography-mass spectrometry. In general, the concentration of 6-methoxymellein reached a maximum at 2 days and gradually decreased to trace level at 5 days in control experiments. However, the effects of PCBs or hydroxy derivatives were highly dependent on compounds. For example, the maximum concentrations of 6-methoxymellein were observed at 3 days for 2-hydroxy/4-hydroxybiphenyl, while 3,3',4,4',5-pentachlorobiphenyl and 3,5-dichloro-2-hydroxybiphenyl showed a rapid accumulation within 1 day, followed by rapid dissipation to undetectable levels.CONCLUSION: Biphenyl derivatives were effective elicitor of 6-methoxymellein accumulation. In general, hydroxybiphenyls (phenols) more efficiently induced phytoalexin biosynthesis than those without hydroxy groups. It can be concluded that PCBs or their possible metabolites could change the plant secondary metabolism.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.59 no.3
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• pp.385-389
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• 2014

Flavonols as a major kind of plant secondary metabolites are known for health-promoting compounds in onions (Allium cepa L.). The objectives of this study are to determine profiles of flavonol glycosides in different 75 onion accessions. A total of five flavonols (quercetin 3,4'-diglucoside, Q34'diG; quercetin 3-glucoside, Q3G; quercetin 4'-glucoside, Q4'G; isorhamnetin 4'-glucoside, I4'G; quercetin, Q) were identified from onion accessions. In positive ion mode using LC-ESI-MS, individual flavonols were confirmed from one and two glycosylation binding with aglycone such as quercetin and isorhamnetin. Total flavonol contents were distributed in white onion (range of 0.18-6.47 mg/g DW) and purple onion accessions (range of 2.39-6.47 mg/g), respectively. The mean of flavonol contents in purple onion (4.41 mg/g) showed 1.4-fold higher than white onion (3.23 mg/g). The Q34'diG and Q4'G were considered as the major compounds of flavonol glycosides in onion accessions.

• Korean Journal of Soil Science and Fertilizer
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• v.41 no.1
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• pp.38-43
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• 2008

Pepper plants (Capsicum annuum, cv. Manitta) were subjected to different intensities of UV-B radiation to understand alterations of primary- and secondary-metabolism such as carbohydrates, phenolic compounds and polyamines. UV-B doses with a UV-B lamp ($1.2W\;m^{-2}$) were adjusted between 0 to 9 hr. The soluble sugars and starch contents in pepper leaves were highly influenced by UV-B treatment. The soluble sugars altered from $6.7mg\;g^{-1}\;fw$ to $5.2mg\;g^{-1}\;fw$ after 9 hrs of UV-B exposure. The starch contents after 3 hrs of UV-B exposure changed from $17.7mg\;g^{-1}\;fw$ to $12.3mg\;g^{-1}\;fw$ and then remained unchanged. The absorbance of UV-absorbing compounds reached initially maximum at all wavelengths read. On the basis of this result, we analyzed total phenolics, anthocyanin and simple free phenolic acids. Anthocyanin and free phenolic acids responded sensitively with a steady increase during UV-B treatment, although anthocyanin contents declined highly after 3 hrs of treatment. Whereas, there is no alteration of total phenolics (as gallic acid equivalent) caused by UV-B. Free polyamine levels in leaves increased rapidly and highly when UV-B was treated. The most prominent changes in polyamine induction were putrescine and spermidine (+ 70 %) after 3 hrs and spermine (+ 150 %) after 6 hrs.

• Journal of Bio-Environment Control
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• v.31 no.4
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• pp.319-324
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• 2022

The objective of this study was to determine the proper night interruption of photoperiods and dark periods for accumulating bioactive compounds of Agastache rugosa without decreasing plant growth. Five-week-old seedlings were transplanted in a DFT system with white LEDs. A. rugosa was treated with night interruption time treatments of 18:1:2:3, 18:2:2:2, 18:3:2:1 (light:dark:light:dark), and 20:4 (control) for 4 weeks. There were no significant differences except for leaf length, leaf width, and the number of flowers. The content of antioxidants in the shoot of A. rugosa was high in tilianin and acacetin, and the content of rosmarinic acid (RA) was significantly higher in the underground part. The RA content per dry weight of A. rugosa was 47.92 and 51.46% higher than that of the control in 18:1:2:3 and 18:2:2:2, and tilianin and acactin per dry weight were significantly higher in 18:3:2:1. There was no significant difference in growth due to the same day light integral, but 18:2:2:2 showed high total polyphenol contents. Therefore, it is thought that the effect of increasing secondary metabolites of A. rugosa without degradation of growth can be expected through night interruption treatment in plant factory cultivation systems using artificial light.

• Korean Journal of Plant Resources
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• v.35 no.4
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• pp.435-444
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• 2022

Hibiscus hamabo Sieb. et Zucc. (yellow hibiscus) is a deciduous semi-shrub plant and mainly growing in Jeju Island. This is known the unique wild hibiscus genus and classified as an 2nd grade of endangered plant for Korean Red List. In previous studies, properties of germination, ecological, genetical and salt resistance have been reported. In this study, we investigated mass-proliferated adventitious root using bioreactor, antioxidant and whitening effects to conduct functional ingredients. Yellow hibiscus were collected from Gujwa, Jeju by prior permission and they were introduced by explant type and various medium composition after surface sterilization. As a result, seed response rates were evaluated at range of 51.17~51.83%, in terms of comprehensive efficiency of shoot and root formation. In the case of adventitious root propagation condition was confirmed in half strength Murashige and Skoog medium salts, 30 mg/L sucrose, and 2 mg/L indole-3-butyric acid for 8 weeks in 5,000 mL bioreactor. We also compared between relationship with biomass and secondary metabolites accumulation by total phenolics content, the flavonoid content, DPPH free radical scavenging activity and melanin content. The results indicated that adventitious root mass proliferation, antioxidant and whitening effect could develop value of the high-quality cosmeceutical ingredient and further metabolite studies.

• Korean Journal of Microbiology
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• v.49 no.2
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• pp.156-164
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• 2013

Actinomycetes produce diverse secondary metabolites which have the primary importance in medicine, agriculture and food production, and key to this is their ability to interact with other organisms in natural habitats. In this study, we have investigated the taxonomical and functional diversity of actinomycetes in fecal sample of rhinoceros beetle larvae (Allomyrina dichotoma L.) by using culture-dependent and -independent approaches. For the culture-independent approach, the community DNA was extracted from the sample and 16S rRNA genes of actinomycetes were amplified using actinomycetes-specific PCR primers. Thirty-seven clones were classified into 15 genera and 24 species of actinomycetes. For the culture-dependent approach, 53 strains were isolated from larval feces, of which 27 isolates were selected based on morphological characteristics. The isolates were classified into 4 genera and 14 species, and 24 isolates (89%) were identified as the genus Streptomyces. Many of the representative isolates had antimicrobial activities against plant pathogenic fungi and Gram-positive bacteria. In addition, most of the isolates (78%) showed biochemical properties to hydrolyze cellulose and casein. The results demonstrated that diverse and valuable actinomycetes could be isolated from insect fecal samples, indicating that insect guts can be rich sources for novel bioactive compounds.

• Analytical Science and Technology
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• v.32 no.6
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• pp.252-261
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• 2019

Pyrrolizidine alkaloids (PAs) are a group of secondary metabolites that are produced by plants all over the world as a defense mechanism against herbivores. To date, over 660 PAs have been identified from more than 6,000 plant species that have been reported to be widely present in plants belonging to Asteraceae, Boraginaceae, and Fabaceae. This study describes an analytical method based on UPLC-MS/MS for the quantitation of 7 pyrrolizidine alkaloids (Lycopsamine, Echimidine, Retrorsine, Retrorsine N-oxide, Senecionine, Heliotrine, and Trichodesmine) in honey, and was applied to 84 honey samples for validation. Quantitation was performed based on a matrix-matched calibration to compensate for the matrix effect on the electrospray ionization. Good linear calibrations were obtained for all 7 PAs in the spiked honey samples (2.575-202.14 ㎍/kg; R² ≥ 0.998). The extraction recoveries for most of the PAs in the honey samples were in the range of 81 %-108 %. The analysis showed that 6 of the 84 honey samples were contaminated by the PAs with the mean total sum of PAs being 47.19 ㎍/kg, and the concentrations of the PAs were observed to be in the range of 1.76-202.1 ㎍/kg. The retronecine type compounds (Echimidine, Lycopsamine) were the most frequently found PAs in honey. These data provide useful information for the assessment of human risk posed by the consumption of honey contaminated PAs.

• Korean journal of food and cookery science
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• v.26 no.1
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• pp.104-109
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• 2010

Korean Chinese cabbage (Brassica campestris L. ssp. pekinensis) is one of the major cruciferous vegetables. Cruciferous vegetables contain a series of relatively unique secondary metabolites of amino acids called glucosinolates. Although glucosinolates do not appear to be bioactive, they are hydrolyzed by plant myrosinase when the cells in plants are damaged, and release biologically active compounds such as isothiocyanates, nitriles, and thiocyanates. The objective of this study was to determine the myrosinase activity and total glucosinolate levels of Korean Chinese cabbages by different salting times (0, 12, 18, and 24 h) and salt concentrations (6, 10, 14%). The total water content, salt content, and pH of brined cabbages decreased with increasing salting time. The myrosinase activity as determined by a glucose kit, decreased with increasing salting time and salt content. The total glucosinolates were purified using an anion exchange column and measured by UV-visible spectrophotometer. The fresh Korean Chinese cabbages contained $25.38{\pm}1.45\;{\mu}mol/g$ dry weight of glucosinolates. However, the total glucosinolates of brined cabbages decreased with increasing salting time and salt concentration. After 24 h of salting time, the total glucosinolates of brined cabbages rapidly decreased by $16.12{\pm}11.09$, $11.25{\pm}10.91$, $9.29{\pm}10.73\;{\mu}mol/g$ in 6%, 10%, and 14% salt solution, respectively. Overall, the total glucosinolate levels of Korean Chinese cabbages were found to vary inversely with salting time and salt concentration.