• 한국식품영양학회지
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• 제32권1호
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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.

• 한국식품과학회지
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• 제38권5호
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• pp.679-683
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• 2006

저 용량 Streptozotocin(STZ)으로 유도한 제l형 당뇨 모델 생쥐에서 건조 구아바 잎과 발효 구아바 잎 에탄올 추출물의 혈당에 미치는 영향을 비교하였다. STZ로 유도된 쥐에서 발효 구아바 잎 추출물(500 mg/kg/day)은 투여 4주후에도 공복 혈당이 유의적으로 감소하였으며 내당능 장애도 개선되었음을 보여 주었다. 한편 건조 구아바 잎 추출물은 투여 후 2주 동안 공복 혈당이 낮게 나타났으며 내당능 장애도 개선되었지만 3주후부터 고혈당으로 약화되었다. 각 실험군에서 적출한 췌장 조직과 인슐린의 면역 조직 화학 분석 결과, 발효 구아바 잎 추출물은 STZ로 유도된 췌장섬 세포의 손상을 억제하는 것이 관찰되었으나 건조 구아바 잎 추출물은 베타 세포의 손상에 영향을 주지 못하였다. 본 연구 결과는 STZ로 유도된 당뇨 모델 생쥐에서 발효 구아바 잎 추출물이 췌장 베타 세포의 손상을 보호함으로서 혈당 개선 효과를 나타냄을 보여준다.

• 한국자원식물학회지
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• 제21권5호
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• pp.408-412
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• 2008

본 연구는 기능성소재 개발에 이용될 수 있는 유용한 기초자료를 얻고자 구아바 잎의 총페놀화합물의 함량, 항산화활성, tyrosinase 저해활성을 측정하였다. 1. 구이바잎 추출물의 총페놀화합물은 19.0(g/100g, D.W.)의 함량으로 강한 항산화활성을 보였다(radical 소거활성의 IC50는 $102.5{\mu}g/ml$, SOD 유사활성의 IC50는 $49.4{\mu}g/ml).$) 2. 용매분획물의 radical 소거활상을 측정한 결과, $100{\mu}g/ml$의 농도에선도 ethylacetate(G-E), butanol(G-B), 물분획(G-W)은 50% 이상의 높은 소거활성을 보였다 radical 소거 활성은 G-B>G-E>G-W 순으로 높은 활성을 보였고, 각 분획물의 농도가 증가할수록 소거능이 높아지는 경향을 나타냈다. hexane분획(G-H)의 소거활성은 보이지 않았다. 3. 용매분획별 SOD 유사활성에 대한 결과, $100{\mu}g/ml$의 농도에서 G-E, G-B, G-W는 각각 81.8, 84.7, 65.3%로 높은 활성을 나타냈으며, 각 분획물의 농도가 증가할수록 SOD 유사활성도 증가하는 경향을 나타냈다 G-H의 활성은 보이지 않았다. 4. 구아바잎의 추출물과 용매분획물의 tyrosinase저해 효과를 측정한 결과, 추출물 1mg/ml의 농도에서 60.8%의 저해효과을 보였으며, 용매분획은 G-E(65.2%), G-B(62.8%), G-W(51.6%), G-H(28.9%)의 순으로 tyrosinase 저해효과를 보였다.

• Nutrition Research and Practice
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• 제15권5호
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• pp.568-578
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• 2021

BACKGROUND/OBJECTIVES: Psidium guajava L. (guava) leaves have been shown to exhibit hypoglycemic and antidiabetic effects in rodents. This study investigated the effects of guava leaf extract on adipogenesis, glucose uptake, and lipolysis of adipocytes to examine whether the antidiabetic properties are mediated through direct effects on adipocytes. MATERIALS/METHODS: 3T3-L1 cells were treated with 25, 50, 100 ㎍/mL of methanol extract from guava leaf extract (GLE) or 0.1% dimethyl sulfoxide as a control. Lipid accumulation was evaluated with Oil Red O Staining and AdipoRed assay. Immunoblotting was performed to measure the expression of adipogenic transcription factors, fatty acid synthase (FAS), and AMP-activated protein kinase (AMPK). Glucose uptake under basal or insulin-stimulated condition was measured using a glucose analog 2-[N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl) amino]-2-deoxy-D-glucose. Lipolysis from fully differentiated adipocytes was measured by free fatty acids release into the culture medium in the presence or absence of epinephrine. RESULTS: Oil Red O staining and AdipoRed assay have shown that GLE treatment reduced lipid accumulation during adipocyte differentiation. Mitotic clonal expansion, an early essential event for adipocyte differentiation, was inhibited by GLE treatment. GLE inhibited the expression of transcription factors involved in adipocyte differentiation, such as peroxisome proliferator-activated receptor 𝛄 (PPAR𝛄), CCAAT/enhancer-binding protein α (C/EBPα), and sterol regulatory element-binding protein-1c (SREBP-1c). FAS expression was also decreased while the phosphorylation of AMPK was increased by GLE treatment. In addition, GLE increased insulin-induced glucose uptake into adipocytes. In lipid-filled mature adipocytes, GLE enhanced epinephrine-induced lipolysis but reduced basal lipolysis dose-dependently. CONCLUSIONS: The results show that GLE inhibits adipogenesis and improves adipocyte function by reducing basal lipolysis and increasing insulin-stimulated glucose uptake in adipocytes, which can be partly associated with antidiabetic effects of guava leaves.

• 한국약용작물학회지
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• 제20권2호
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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.

• 한국의류산업학회지
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• 제13권5호
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• pp.778-789
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• 2011

The natural dyeing of silk fabrics with guava leaf extract was investigated. Mixed components of flavonoid and tannin seem to be the components of guava leaf extract. The temperature and time for dyeing of silk fabrics with guava leaf extract were $40^{\circ}C$ and $90^{\circ}C$ for eighty minutes, respectively. The dyeing equilibrium was shown at the fourth time of repeated dyeing. The highest K/S value was recorded at pH 3. Fe-mordanted fabrics showed the highest K/S value. High K/S values were shown in the post-mordanting of dyed fabrics at $40^{\circ}C$ and the pre-mordanting of dyed fabrics at $90^{\circ}C$. After repeated dyeing and mordanting, various color change occurred with mordant treatment. Surface colors were changed to YR color in alkaline water extract and to Y color in acidic water and ethanol extract, respectively. The washing fastness was level 3-4 for Sn-mordanted fabrics and level 4 for Fe-mordanted fabrics, and the dry cleaning fastness also showed very excellent result with level 4-5. The rubbing fastness was satisfactory with level 3-4. The light fastness was above level 4 only when Fe-mordanting was conducted, and the rest of dyed fabrics was not fast enough. In the antibacterial activity, the powder of guva leaf extract showed 99.9% of high antibacterial activity and Staphylococcus aureus showed 99.6% in dyed fabric. All dyed fabrics showed higher deodorization and UV protection rate than control fabric.

• 한국식품영양학회지
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• 제25권2호
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• pp.317-323
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• 2012

We investigated the quality characteristics of cookies prepared after the addition of various concentration of used guava leaf powder(0%, 1%, 3%, 5%, all w/w) as a substitute for flour. In this study, as guava leaf powder concentration rose, there was a decrease in the water content level. In addition, color, spread factor, hardness and sensory evaluation of the cookies were examined. The results showed that with an increase in guava leaf powder concentration, the L value decreased significantly, while the values for a and b of cookies increased when more guava leaf power was added to cookies. The spread factor of cookies decreased, but the hardness of cookies increased significantly, as guava leaf powder concentration increased. Cookies containing 0% and 3% of guava leaf powder showed a similar sensory evaluation score in terms of color, taste and flavor of the cookies. In the case of texture and overall consumer acceptability, cookies with 3% of guava leaf powder showed the highest score.

• 한국미생물·생명공학회지
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• 제47권1호
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• pp.43-53
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• 2019

The anticancer activity of guava (Psidium guajava L.) leaf extract (GLE) occurs via the induction of apoptosis in cancer cells. However, the mechanism behind GLE-induced apoptosis in the human hepatocellular carcinoma cell line HepG2 remains unclear. In the present study, we investigated the apoptotic effects and mechanism of action of GLE in cultured HepG2 cells. The results showed that GLE induced reactive oxygen species (ROS) synthesis and disrupted the mitochondrial membrane potential (${\Delta}{\Psi}m$). Moreover, GLE increased the expression of apoptotic pathway proteins, such as the cleaved forms of caspase-3, -8, and -9; the translocation of Bax and cytochrome c (cyt-c) from the mitochondria to the cytosol; and the downregulation of Bcl-2. In addition, p53 protein expression was increased upon GLE treatment. These observations indicate that the GLE-induced apoptosis in HepG2 cells is mediated by mitochondrial ROS generation, followed by caspase activation and cyt-c release, suggesting that GLE may be a promising candidate for the development of novel drugs for the treatment of liver cancers.

• 한국의류산업학회지
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• 제14권2호
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• pp.320-330
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• 2012

The natural dyeing of cotton fabrics with guava leaf extract was investigated. The temperature and time of dyeing are $40^{\circ}C$ 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 were dyed in pre-mordanting. The K/S value of dyeing fabrics could be increased with repetitive dyeing and mordanting. Compared to untreated dyed fabrics, the K/ S values of fabrics which had been treated with soybean milk, chitosan and gall nut tannin were increased. The changed surface colors of fabrics that were treated with soybean milk, chitosan and gall nut tannin were Y, YR and achromatic colors. Fabrics dyed with alkaline water extract showed reddish color. Sn-mordanted fabrics dyed with acidic water extract showed vivid yellowish color, and Cu-mordanted fabrics dyed with ethanol extract showed yellowish green color. In case of Sn-mordanted fabrics, the washing fastness was level 4. The dry cleaning fastness also showed very excellent result with level 4-5. The rubbing fastness was better in dry rubbing than in wet rubbing of the fabrics. For the light fastness, all dyed fabrics showed low fastness. For antibacterial activity, the powder of guava leaf extract and the dyed fabrics with guava leaf extract showed 99.9% of high antibacterial activity. All dyed fabrics showed higher deodorization and UV protection rate than control fabric.

• 한국의류산업학회지
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• 제14권5호
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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.