• Microbiology and Biotechnology Letters
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• v.37 no.1
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• pp.49-54
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• 2009

Rhapontin is the glycosylated stilbene compound, and comprising major component of rhubarb root extract. Rhapontin has been used as a raw material of skin-whitening cosmetics in Korea. Rhapontigenin, the aglycone of rhapontin, has been suggested to be more active than its glycosylated form. Therefore, the rhubarb root extract was treated with commercial enzyme, Pectinex to remove glycosylated moiety of rhapontin and rhapontigenin was prepared. The resulting material was analysed and identified as rhapontigenin by proton NMR and MALDI-Mass. Rhapontigenin exhibited tyrosinase inhibitory activity with an $IC_{50}$ of $126.72{\mu}g/mL$. The tyrosinase inhibitory activity of rhapontigenin was six times higher than that of rhapontin. In melanin biosynthesis inhibition assay using Streptomyces bikiniensis, rhapontigenin showed wider inhibition zone than that of rhapontin. From these results, we expect that rhapontigenin has stronger skin whitening effect than rhapontin and has advantages in cosmetic industry.

• Journal of Microbiology and Biotechnology
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• v.20 no.1
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• pp.82-87
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• 2010

Biotransformation is often used to improve chemical activity. We evaluated the antimicrobial activity of rhapontigeuin, converted from rhapontin after treatment with Pectinex. Rhapontigenin showed 4-16 times higher antimicrobial activity than rhapontin. The activity was higher against Gram-positive strains than Gram-negative strains. Minimum inhibitory concentrations (MICs) of rhapontigenin, retinol, and five antibiotics were determined by the microbroth dilution method for antibiotic-sensitive and -resistant Propionibacterium acnes. We also investigated the in vitro antibacterial activity of rhapontigenin in combination with antibiotic against antibiotic-resistant P. acnes. The antibiotic combination effect against resistant P. acnes was studied by the checkerboard method. The combination formulations (rhapontigenin and clindamycin, retinol and clindamycin) showed synergistic effects on the inhibition of the growth of clindamycin-resistant P. acnes. It is predictable that the combination of antibiotics with rhapontigenin is helpful to treat acne caused by antibiotic-resistant P. acnes. The antibacterial activity of rhapontigenin was enhanced by biotransformation.

• Archives of Pharmacal Research
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• v.25 no.4
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• pp.528-533
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• 2002

To evaluate the antithrombotic and antiallergic properties of rhaponticin extracted from Rhei Rhizoma, the in vitro and ex vivo inhibitory activities of rhaponticin and its metabolite, rhapontigenin, were measured. These compounds inhibited in vitro ADP- and collagen-induced platelet aggregation. Rhapontigenin was more potent, with $IC_{50}$ values of 4 and $70{\;}{\mu}g/ml$, respectively. In ex vivo ADP- and collagen-induced rat platelet aggregation, these compounds also exhibited a potent inhibitory effect. The antiplatelet aggregation effects of rhaponticin and rhapontigenin were more potent than those of aspirin. Rhapontigenin showed significant protection from death due to pulmonary thrombosis in mice. Rhapontigenin also showed the strongest inhibitory activity against $\beta-hexosaminidase$ release induced by DNP-BSA. These compounds inhibited PCA reaction in mice. Rhapontigenin intraperitoneally administered showed the strongest inhibitory activity and significantly inhibited PCA at doses of 25 and 50 mg/kg, with inhibitory activities of 48 and 85%, respectively. The inhibitory activity of orally administered rhaponticin was stronger than that of intraperitoneally administered rhaponticin. These results suggest that rhaponticin, in the rhizome of Rhei Rhizoma, is a prodrug that has extensive antiallergic and antithrombotic properties.

• Archives of Pharmacal Research
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• v.22 no.4
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• pp.401-403
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• 1999

In continued studies on cultivated Korean rhubarb rhizomes (Rheum undulatum), three known stillbenes (desoxyrhapontigenin, rhapontigenin, piceatannol) have been screened for activity on blood platelet aggregation. Both rhapontigenin and desoxyrhapontigenin exhibited strong inhibition on the aggregation induced by arachidonic acid collagen. However, piceatannol did not show inhibition. These inhibitory effects may partially contribute to anti-blood stagnancy activity of rhubarb.

• Food Science and Biotechnology
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• v.17 no.3
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• pp.675-678
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• 2008

Permeability of resveratrol, piceid, rhapontigenin, and rhaponticin in Caco-2 cell assays using high-performance liquid chromatography were compared. Caco-2 cell monolayers were used to evaluate the transport rates of stilbene analogues from the apical to the basolateral sides. All stilbenes experimented in this study were transported to the basolateral side by times. For comparing the permeability of 4 stilbenes, we calculated the slope of the cumulative concentration of each stilbene in basolateral sides over time, resulting in those values of resveratrol, piceid, rhapontigenin, and rhaponticin with $3.766{\times}10^{-5}$, $4.330{\times}10^{-6}$, $5.430{\times}10^{-5}$, and $2.458{\times}10^{-5}\;{\mu}M/sec$, respectively. Apparent permeability coefficient of resveratrol and rhapontigenin were calculated to $9.994{\times}10^{-6}$ and $1.441{\times}10^{-6}\;cm/sec$, respectively, while those of piceid and rhaponticin were to $1.149{\times}10^{-7}$ and $6.523{\times}10^{-7}\;cm/sec$, respectively. These results suggest that aglycones would be absorbed more effectively than glycosides in stilbenoids.

• Korean Journal of Organic Agriculture
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• v.28 no.1
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• pp.95-108
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• 2020

To develop an environment-friendly fungicide for controlling tomato wilt diseases, antifungal active substance was isolated Rheum australe D. Don roots against Fusarium oxysporum f. sp. lycopersici, a pathogen of tomato wilt, in this study. Methanol extract obtained from Rheum australe roots was successively fractionated with hexane, chloroform, ethyl acetate, butanol and water. The ethyl acetate fraction, which showed the highest antifungal activity, was separated by column chromatography, and 60 subfractions were obtained. The 60 subfractions were anlayzed for antifungal activities by bioassay. The active compound was identified as 5-[(E)-2- (3-hydroxy-4-methoxyphenyl)ethenyl]benzene-1,3-diol (rhapontigenin) by NMR and GC-MS analysis. As a result of testing antifungal activity of rhapontigenin against Fusarium oxysporum, EC₅₀ of rhapontigenin was showed strong antifungal activity at 7.48 mg/L. Therefore, this study showed that the Rheum australe roots extract can be a potential candidate which is a environment-friendly fungicide against Fusarium oxysporum.

• The Journal of Korean Medicine
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• v.19 no.1
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• pp.89-99
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• 1998

약효(藥效) 및 안정성(安定性)이 입증(立證)된 한약(韓藥)으로부터 새로운 항균제(抗菌劑)를 도출(導出)하고자, 임상(臨床)에서 청열작용(淸熱作用)이 있거나 염증성(炎症性) 질환(疾患)과 박테리아의 감염(感染)으로 비롯된 질환(疾患)에 자주 쓰이는 22개(個)의 처방(處方)에 대(對)해 paper disk 법(法)을 사용(使用)하여 항균(抗菌) 효능(效能)을 검색(檢索)하였다. 시료(試料)는 한약(韓藥)의 고용(股用) 방법(方法)을 고려(考慮)하여 물로 추출(抽出)하였으며, 사용(使用) 균주(菌柱)로는 그람 양성균(陽性菌)인 포도상구균(葡萄狀球菌)과 고초균(枯草菌) 그리고 그람 음성균(陰性菌)인 대장균(大腸菌)과 녹농균(綠膿菌)을 사용(使用)하였고, 대조물질(對照物質)로는 tetracycline을 사용(使用)하여 상법(常法)에 의(依)해 실험(實驗)하였다. 22개(個)의 처방(處方) 가운데 백두옹탕(白頭翁湯), 황연해독탕(黃連解毒湯), 증황연황연해독탕(增黃連黃連解毒湯), 사심탕(瀉心湯), 용담사간탕(龍膽瀉肝湯), 선방활명음(仙方活命飮) 등(等)의 처방(處方)이 탁월(卓越)한 항균(抗菌) 활성(活性)을 보였다. 이 가운데 본(本) 연구(硏究)에서는 탕제(湯劑)의 구성(構成) 약재(藥材)가 다른 처방(處方)들에 비(比)해 비교적(比較的) 다양(多樣)한 선방활명음(仙方活命飮)에 대(對)해 활성(活性) 성분(成分)의 규명(糾明) 및 구성(構成) 약재간(藥材間)의 상화작용(相互作用)을 밝히고자 하였다. 선방활명음(仙方活命飮) 5 kg을 메탄올 (MeOH)로 추출(抽出)한 뒤 우수(優秀)한 항균(抗菌) 활성(活性)을 보인 에칠아세테이트 (EtOAc) 분획(分劃)에 대(對)하여 silica gel 및 Sephadex LH-20 column chromatography를 반복(反復)하여 stilbene 계열(系列)의 화합물(化合物)인 Rhapontigenin (Compound 1)과 Rhaponticin (Compound 2)을 얻었다. S. aureus SG 511에 대(對)해 Rhapontigenin은 50 mg/ml 이상(以上) 농도(濃度)에서 항균(抗菌) 효과(效果)를 나타내었고, Rhaponticin은 $200\;mg/m{\ell}$ 농도(濃度)에서 미약(微弱)하게 유효(有效)한 항균(抗菌) 효과(效果)를 나타내었으며, B. subtilis ATCC 6633에 대(對)해 Rhapontigenin은 50 mg/ml 이상(以上) 농도(濃度)에서 항균(抗菌) 효과(效果)를 나타내었고, Rhaponticin은 200 mg/ml 농도(濃度)에서 우수(優秀)한 항균(抗菌) 효과(效果)를 나타내었으며, 100 mg/ml 농도(濃度)에서 미약(微弱)하게 유효(有效)한 항균(抗菌) 효과(效果)를 나타내었다. 또한 E. coli 055에 대(對)해서는 Rhapontigenin과 Rhaponticin 모두 200 mg/ml 농도(濃度)에서 미약(微弱)하게 유효(有效)한 항균(抗菌) 효과(效果)를 나타내었다. 이상(以上)의 결과(結果)로 보아 선방활명음(仙方活命飮)의 항균(抗菌) 효능(效能)은 군약(君藥)인 대황(大黃)의 성분(成分) 중(中)의 하나인 stilbene 계열(系列)의 화합물(化合物)인 Rhapontigenin과 Rhaponticin의 작용(作用)에 의(依)한 것이며, 이는 한의학(韓醫學) 방제(方劑) 원리(原理)인 군신좌사(君臣佐使) 이론(理論)에서 군약(君藥)이 주증(主症)에 주(主)로 작용(作用)하는 약물(藥物)이라는 것을 밝혀주는 것이라고 사료(思料)된다.

• Korean Journal of Pharmacognosy
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• v.31 no.2
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• pp.245-248
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• 2000

As a series of the studies on cultivated Korean rhubarb rhizomes (Rheum undulatum), five stilbene derivatives were screened for inhibitory activity against $5{\alpha}-reductase$. Of these, desoxyrhapontigenin, rhapontigenin, and piceatannol exhibited inhibition, whereas, two other stilbene glycosides, rhaponticin and $piceatannol-3'-O-{\beta}-D-glucopyranoside$ did not show the inhibition.

• Journal of the Korean Society of Food Science and Nutrition
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• v.37 no.1
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• pp.124-128
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• 2008

This study was aimed to analyze the composition and to quantify the contents of stilbenoids in the leaves and fruits of Morus alba L. using high performance liquid chromatography with phodtodiode array detector and UV detector. Optimal wavelength for the detection of various stilbenoids such as resveratrol, piceatannol, rhapontigenin, astringin, pterostilbene, piceid, rhaponticin and vitisin A was screened by DAD detector and set to 308 nm. Seven kinds of stilbenoids except vitisin A were identified in fruits, while 5 kinds of stilbenoids in leaves. Total stilbenoids contents were $609.15{\pm}7.24$ mg/100 g d.w. in fruits and $188.57{\pm}1.70$ mg/100 g d.w in leaves. Stilbenoids contents in fruits were 3 times higher than those in leaves. Rhaponticin was the most profound stilbene, analyzed to $389.26{\pm}5.22$ mg/100 g d.w. (63.8% of total stilbenoids) in fruits and $99.17{\pm}2.79$ mg/100 g d.w. (52.5% of total stilbenoids) in leaves. Astringin and piceatannol were only detected in fruits and vitisin A was not detected. Contents of piceid and rhaponticin were higher than those of aglycone forms, rhapontigenin and resveratrol.

• Korean Journal of Pharmacognosy
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• v.34 no.1 s.132
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• pp.25-27
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• 2003

In order to clarify the anti-thrombosis activity of rhubarb, we investigated the effect of stilbene derivatives from rhizomes of Rheum undulatun on cyclooxygenase activity. Stilbene derivatives (desoxyrhapontigenin, rhapontigenin, piceatannol) exhibited the inhibitory effects on COX-1, and desoxyrhapontigenin showed inhibitory effect on COX-2. These inhibitory effect may partially contributed to anti-thrombosis activity of rhubarb.