• Fashion & Textile Research Journal
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• v.14 no.5
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• pp.866-877
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• 2012

The natural dyeing of hanji cotton fabrics with guava leaf extract was investigated. The temperature and time of dyeing were $40^{\circ}C$ and $90^{\circ}C$ for eighty minutes, respectively. In addition, the dyebath has been set at pH 5. Sn pre-mordanted fabrics showed the highest K/S value. Regardless of dyeing temperature, K/S values were high when Al, Cu, Fe-mordanted fabrics were dyed in post-mordanting and Sn-mordanted fabrics in pre-mordanting. The dyeing equilibrium was shown at the fourth time of repeated dyeing. In the processing of hanji cotton fabrics, K/S value was high when hanji cotton fabric was treated with soybean milk at $90^{\circ}C$. Similar K/S value of dyeing was shown when fabrics were processed with chitosan, regardless of dyeing temperature. High K/S value of dyeing was seen when fabrics processed with gallnut tannin at 40. Fabrics dyed with acidic water extract showed yellowish color. Fabrics dyed with alkaline water extract showed reddish color, and fabrics dyed with ethanol extract showed greenish yellow color. In case of Sn-mordanted fabrics, the washing fastness level was between 3 to 4, and other dyed fabrics showed low fastness. The dry cleaning fastness also showed very excellent result with level 4-5. The rubbing fastness of the fabrics was better in dry rubbing than in wet rubbing. For the light fastness, all dyed fabrics showed low fastness. For antibacterial activity, the dyed fabrics with guava leaf extract showed 99.9% of high antibacterial activity. Hanji cotton fabric maintained certain deodorization in the state of raw fabric. All dyed fabrics showed higher UV protection rate than control fabric.

• Journal of Life Science
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• v.21 no.2
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• pp.165-175
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• 2011

This study investigates the effects of Psidium guajava L. leaf (Pg) extract, Lagerstroemia speciosa L. leaf (Ls) extract, and mixture A (Pg, Ls, Morus indica L. leaf, Pinus densiflora needles, Acanthopanax senticosus M. roots extract) on db/db mice. For four weeks, db/db mice were fed powdered extracts of Pg, Ls, and mixture A. Compared to the diabetic control, extracts of Pg, Ls and mixture A decreased body weight, glucose and insulin. The greatest decreases were caused by mixture A. These extracts decreased the levels of total cholesterol, triglyceride and free fatty acid compared to the diabetic control. The antihyperlipidemic effect of mixture A was the greatest. Mixture A also significantly decreased injuries of Langerhans' islets compared to the diabetic control. Mixture A showed a beneficial synergistic effect due to the supplementary pharmacological actions of the ingredients in contains, indicating that it improved hyperglycemia without the side effect of weight gain.

• The Plant Pathology Journal
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• v.29 no.3
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• pp.242-248
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• 2013

In the Northeast of Brazil, expansion of guava crops has been impaired by Meloidogyne enterolobii that causes root galls, leaf fall and plant death. Considering the fact that arbuscular mycorrhizal Fungi (AMF) improve plant growth giving protection against damages by plant pathogens, this work was carried out to select AMF efficient to increase production of guava seedlings and their tolerance to M. enterolobii. Seedlings of guava were inoculated with 200 spores of Gigaspora albida, Glomus etunicatum or Acaulospora longula and 55 days later with 4,000 eggs of M. enterolobii. The interactions between the AMF and M. enterolobii were assessed by measuring leaf number, aerial dry biomass, $CO_2$ evolution and arbuscular and total mycorrhizal colonization. In general, plant growth was improved by the treatments with A. longula or with G. albida. The presence of the nematode decreased arbuscular colonization and increased general enzymatic activity. Higher dehydrogenase activity occurred with the A. longula treatment and $CO_2$ evolution was higher in the control with the nematode. More spores and higher production of glomalin-related soil proteins were observed in the treatment with G. albida. The numbers of galls, egg masses and eggs were reduced in the presence of A. longula. Inoculation with this fungus benefitted plant growth and decreased nematode reproduction.

• Journal of the Korean Society of Food Science and Nutrition
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• v.38 no.12
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• pp.1773-1778
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• 2009

Guava (Psidium guajava L.) contains high amount of vitamins and minerals, and its leaves have been reported to be very effective on reducing blood pressure. In this study, antimicrobial characteristics of extracts from four different parts of guava (fruit, branch, leaf, and seed) with four different solvents (methanol, ethanol, acetone, and water) were evaluated. Four targeted food-borne microorganisms were selected; two Gram negatives (Escherichia coli O157:H7 and Salmonella Typhimurium) and two Gram positives (Staphylococcus aureus and Listeria monocytogenes). By the paper disc method, guava extracts showed stronger clear hollow zone against Gram positive bacteria than Gram negatives in nutrient broth agar plate. Especially, extracts of branches and leaves showed significant antibacterial activity. Guava extracts also showed significant inhibition activity on the growth of Gram positive food-borne bacteria in nutrient broth. For example, S. aureus did not grow at all at 200 ppm of acetone extracts of guava branch and leaf. In the case of L. monocytogenes, the same concentration of acetone extracts of guava branch and leaf inhibited the growth 33.5% and 55.4%, respectively, at 32 hrs of incubation time. The results indicated that extracts of guava branch and leaf showed significant antibacterial activities against food-borne Gram positive microorganisms, and that guava branches, the byproducts of guava, might be a valuable resource for antibacterial materials.

• Food Science and Preservation
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• v.18 no.1
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• pp.124-129
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• 2011

PC12 neuronal cell-protective effects of hot water extracts of guava fruit and leaf were evaluated. Total phenolic levels in fruit and leaf were 11.75 and 293.25 mg/g, respectively. Gallic acid, the predominant phenoic, was detected in both extracts. Intracellular reactive oxygen species (ROS) accumulation after $H_2O_2$ treatment was significantly reduced when the hot water extract of guava leaf was added to cell medium, compared to PC12 cells treated with $H_2O_2$ only. In a cell viability assay using 3-(4,5-dimethyl-thiazol-2-yl)-2,5-diphenyl- tetrazoliumbromide (MTT), the hot water extracts of fruit and leaf protected against $H_2O_2$-induced neurotoxicity. The leaf extract was more effective in terms of inhibition of lactate dehydrogenase (LDH) release into medium, compared to the fruit extract. These in vitro data suggest that hot water extracts of guava fruit and leaf may be useful in treatment of neurodegenerative conditions such as Alzheimer's disease.