• Applied Biological Chemistry
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• v.40 no.6
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• pp.501-507
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• 1997

Chloroplasts isolated from Stevia rebaudiana Bertoni leaves contained an enzyme activity which catalyzed hydroxylation of ent-kaurenoic acid (ent-kaur-16-en-19-oic acid; ent-KA) to steviol (ent-13-hydroxy kaur-16-en-19-oic acid), the diterpenoid carboxylic alcohol which is the aglycone of sweet stevioside-related glycosides. $[^(14)C]-methylated$ ent-KA was used to localize ent-KA hydroxylase. $[^(14)C]-methyl-KA$ was most actively was transformed into methyl-steviol in chloroplast. The enzymatic activity was found in stroma fraction but not in thylakoid membrane in Stevia rebaudiana Bertoni. However, ent-KA 13-hydroxylase activity was not detected in stroma fraction of either Spinacia oleracea and Solidago altissima. The reaction products using $[^(14)C]-methyl-KA$ were purified and identified on TLC autoradiogram. The hydroxylation of ent-KA from stromal protein to form steviol required NADPH and oxygen. FAD and riboflavin stimulated the enzyme activity 1.5-and 1.7-fold, respectively. It also turned out that the activity of this enzyme using methyl-KA as a substrate was 16.7% that of ent-KA. The purified ent-KA 13-hydroxylase did not act on t-cinnamic acid, 4-hydroxyphenyl acetic acid, choline and resorcinol, known as monooxygenase and hydroxylase substrates.

• Natural Product Sciences
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• v.15 no.1
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• pp.50-54
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• 2009

A simple and reliable reversed phase HPLC method was developed to determine pharmacologically active compounds ent-continentalic acid, kaurenoic acid, and continentalic acid from the roots of Aralia cordata. Quantitative analysis of diterpenoids of A. cordata were performed by reverse phase C-18 column using a isocratic of acetonitrile : 0.1% trifluoroacetic acid(70:30) with UV detection at 205 nm. The correlation coefficients of each calibration curve of ent-continentalic acid, kaurenoic acid, and continentalic acid were 0.9987, 0.9983, and 0.9986, respectively. The detection limit of ent-continentalic acid, kaurenoic acid, and continentalic acid were $0.5{\sim}1.0\;{\mu}g/mL$, respectively. The contents of ent-continentalic acid (1), kaurenoic acid (2), and continentalic acid (3) of the roots of A. cordata collected from seventeen district markets in Korea were $0.09{\sim}0.75\;mg/g$, $1.09{\sim}5.43\;mg/g$, and $2.69{\sim}9.08\;mg/g$, respectively.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.43 no.4
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• pp.289-295
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• 2017

A. koreanum was investigated to identify the constituents possessing whitening effects. As anti-melanogenesis activities were screened for the ethanol extract and solvent fractions, n-hexane (Hex) and ethyl acetate (EtOAc) fractions showed the most potent activities. Three constituents were isolated from the n-Hex fraction of A. koreanum; kaurenoic acid (1), $16{\alpha}$-hydro-17-isovaleroyloxy-ent-kauran-19-oicacid (2), $16{\alpha}$-hydroxy-17-isovaleroyl-oxy-ent-kauran-19-oic acid (3). The chemical structures of the isolated compounds were elucidated based on the spectroscopic data including $^1H$ and $^{13}C$ NMR spectra, as well as comparison of the data to the literature values. Whitening effects were studied for the isolated compounds. Upon the anti-melanogenesis test using ${\alpha}-MSH$ stimulated B16F10 melanoma cells, the compounds 1, 2 and 3 inhibited the cellular melanogenesis and intracellular tyrosinase activities effectively. Based on these results, A. koreanum stems extract could be potentially applicable as whitening ingredients in cosmetic formulations.