• Korean Journal of Medicinal Crop Science
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• v.20 no.2
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• pp.94-100
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• 2012

Guava ($Psidium$ $guajava$) contain a great deal of polyphenol compound and work on the treatment of $Diabetes$ $mellitus$ effectively. In this study, the bioactivities of aqueous extract (GLEx) of guava leaf were investigated. Total phenolic contents of GLEx was 266.9 mg tan/g. The effects of GLEx on digestive enzymes, ${\alpha}$-amylase, maltase and sucrase were investigated. $IC_{50}$ values of GLEx against ${\alpha}$-amylase, maltase and sucrase were 0.65 mg/$m{\ell}$, 2.0 mg/$m{\ell}$ and 3.5 mg/$m{\ell}$ respectively. The effect of GLEx on oral glucose tolerance test (OGTT) was performed in normal ICR mouse, control (dstilled water) and GLEx (aqueous extract of Guava leaf) were co-administered orally with glucose, showed reducing effect on the blood glucose level. The guava is likely to useful for prevention or improvement of hyperglycemia by lowering the blood glucose level and inhibiting glycoside hydrolase activity.

• The Korean Journal of Food And Nutrition
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• v.32 no.1
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• pp.33-40
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• 2019

The purpose of this study was to evaluate the antioxidant and hepatocyte protective effects of guava (Psidium guajava L.) leaves cultivated in Korea. The contents of the total polyphenol of the extract was 271.57 mg gallic acid equivalent (GAE)/g residue. Antioxidant activities of leaf extract were evaluated by examining the free radical scavenging ability. 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and ${\alpha}-{\alpha}$-diphenyl-${\beta}$-picrylhydrazyl (DPPH) free radical scavenging activities of the extract were 1133.23 mg trolox equivalent antioxidant capacity (TEAC)/g residue and 721.68 mg TEAC/g residue, respectively. The hepatocyte protective effect of guava leaf extract was examined in HepG2 cells. Against tert-butyl hydroperoxide (TBHP), the viability of HepG2 cells were increased by the treatment of leaf extract. In addition, guava leaf extract led to the inhibition of reactive oxygen species (ROS) generated in HepG2 cells. The leaf extract increased the activity of glutathione (GSH), glutathione reductase (GR), and glutathione peroxidase (GPx) against oxidative stress. These results suggested that guava leaves might be regarded as a potential source natural antioxidant and a hepatoprotective material.

• Journal of Digital Convergence
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• v.16 no.12
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• pp.593-602
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• 2018

The purpose of this study was to investigate the coloring properties of non-mordant dyes by examining local literature on silk fabric dyeing using red-colored natural dyes. Natural dyes can be prepared from the following 8 materials: purple-fleshed sweet potato, Impatiens balsamina, mulberry, fruits of Ligustrum japonicum Thunb, guava leaves, dansam, hibiscus flowers, and pruned branches of Prunus persica. To examine the surface color calculated $L^*$, $a^*$, $b^*$, ${\Delta}E^*$, and K/S value and H V/C. The variables considered in the dyeing experiment were dye concentration, dyeing temperature, dyeing time, and number of dyeing iterations, which were varied to evaluate the dyeing properties and color characteristics. As a result, the abovementioned variables, dye affinity, and red color expression were directly proportional to one another. In this study, it was found that red coloring can be obtained with natural dyes; moreover, excellent dyeing was achieved without the need for repeated dyeing or mordanting processes, which cause environmental pollution.

• Journal of the Korean Society of Food Science and Nutrition
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• v.36 no.11
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• pp.1377-1384
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• 2007

A previous study suggested that the phyto-extract mixture (PEM381) containing Camellia sinensis (leaf), Psidium guajava (leaf), and Rosa hybrida (flower) inhibited not only arachidonic acid cascade-related enzymes (5-lipoxygenase and cyclooxygenase) in vitro but also degranulation and histamine release from rat peritoneal mast cells. In this study, the same PEM381 was used to investigate its inhibitory effects on the syntheses of leukotrienes and prostaglandins as well as on serum concentration of histamine and eosinophils infiltration in type I allergic reaction-induced mice. The PEM381 could decrease concentrations of serum cysteinyl leukotrienes from mice activated by anti-DNP IgE and DNP-albumin. The concentration of serum histamine by oral administration of PEM381 (25, 50, and 100 mg/kg of body weight) in type I allergic reaction-induced mice was $395.93{\pm}190.37$ nM, $315.59{\pm}164.23$ nM, and $325.07{\pm}112.02$ nM, respectively, while that of positive control (promethazine hydrochloride 10 mg/kg of body weight) was $270.12{\pm}24.02$ nM. In addition, the PEM381 also showed inhibitory effect on the eosinophils infiltration in the nasal mucosa of mice which were sensitized with ovalbumin. However, the effect of PEM381 on the syntheses of prostaglandins seemed to be insignificant. Consequently, these results suggest that PEM381 may be useful for the prevention and treatment of type I allergy-related diseases.

• Journal of the Korean Society of Food Science and Nutrition
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• v.36 no.2
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• pp.155-162
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• 2007

The purpose of this study is to investigate the anti type I allergic effects and mechanisms of the phyto extract mixture (PEM381) which contains Camellia sinensis (leaf), Psidium guajava (leaf), and Rosa hybrida (flower). PEM381 was tested for its inhibitory effects on arachidonic acid cascade related enzymes (5-lipoxygenase and cyclooxygenase), the mast cell mediated allergic reaction and passive cutaneous anaphylaxis. $IC_{50}$ value of PEM381 against 5-lipoxygenase was $14.11{\pm}0.51ppm$ while that of positive control (nordihy-droguaiaretic acid) was $0.54{\pm}0.08ppm$. PEM381 also exhibited considerable selective inhibition of cyclooxygenase-2. PEM381 could inhibit both degranulation and histamine release in a dose dependent manner from rat peritoneal mast cells activated by compound 48/80. In addition, oral administration of PEM381 showed an inhibitory effect on passive cutaneous anaphylaxis reaction activated by anti-dinitrophenyl IgE antibody in mice. These results suggest that PEM381 may be useful for the prevention and treatment of type Ⅰ allergy related diseases.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.53 no.2
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• pp.237-243
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• 2020

Listeria sp. is one of the pathogenic bacteria causes the infection listeriosis, through mainly raw food such as fishery food, dairy food and vegetables. Listeria sp. is a Gram-positive, non-spore-forming, motile, and facultative anaerobic bacterium. Because of the tolerance of Listeria sp. to low temperature and high salt concentration, it is very difficult to prevent them contaminated in the food, which do not require heating, especially, such as raw fishery products. So prevention and removal of bacterial contamination at the food manufacturing stage is the best method. In this study, therefore, several natural products including Psidium guajava and Geranium thunbergii were screened to investigate the antibacterial activity against Listeria sp., with expectation of fewer side effects and fewer resistance problems. Significant effects of two extracts were confirmed by well diffusion assay, MIC assay, and growth inhibition assay. P. guajava and G. thunbergii showed MIC values at 64-256 ㎍/mL meaning strong antibacterial activities against 6 kind of Listeria sp. tested. And the growth of Listeria sp. in the liquid media was actually inhibited by the addition of these two extracts.