684. Solanum alkaloids. Part IX. The relation between constitution and basicity in solasodine, its derivatives, and solanidine

Bloom, Harold; Briggs, Lindsay H.

doi:10.1039/jr9520003591

Cited by 9 publications

(2 citation statements)

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“…Figure 4 summarizes possible reactions on the F-ring of Rtomatine. It has been reported that the pK a value of solasodine, the C-22 isomer of dehydrotomatidine, is 7.7 (31). Assuming a similar pK a value for R-tomatine, and given the pH of tomato fruit of approximately 4.5, R-tomatine will reside mainly in the protonated form in tomato fruit.…”

Section: Resultsmentioning

confidence: 99%

C22 Isomerization in α-Tomatine-to-Esculeoside A Conversion during Tomato Ripening Is Driven by C27 Hydroxylation of Triterpenoidal Skeleton

Yamanaka

Vincken

Zuilhof

et al. 2009

J. Agric. Food Chem.

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Compositional analysis by liquid chromatography/mass spectrometry of triterpenoid glycosides in different tomato cultivars, ripening stages, and parts of fruits showed that alpha-tomatine was generally most abundant in the flesh of the mature green stage, whereas esculeoside A was predominant in that of the red ripe stage. The sum of these glycoalkaloids was more or less constant, suggesting that alpha-tomatine is converted to esculeoside A during ripening. Besides various substitutions, the C22alphaN --> C22betaN isomerization is an important step in this transformation. By quantum chemical calculations it was shown that hydroxylation at C27 of the triterpenoidal skeleton is the driving force behind the isomerization. For the protonated form of the glycoalkaloid (predominant at the pH of tomato tissue), the C22betaN configuration becomes more favorable than that of C22alphaN, through the extra energy provided by the hydrogen bond between the protonated nitrogen and the lone pair of the oxygen of the C27-OH.

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Section: Resultsmentioning

confidence: 99%

C22 Isomerization in α-Tomatine-to-Esculeoside A Conversion during Tomato Ripening Is Driven by C27 Hydroxylation of Triterpenoidal Skeleton

Yamanaka

Vincken

Zuilhof

et al. 2009

J. Agric. Food Chem.

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“…Glycoalkaloids are positively charged at a low pH, because of protonation of the nitrogen atom in their aglycone. It has been reported that the pK a value of solasodine, the C-22 isomer of dehydrotomatidine, is 7.7 (23). By performing cation-exchange chromatography at pH 5.5, the tomato glycoalkaloids might be separated from other (uncharged) constituents of the extract, thereby enabling an effective isolation.…”

Section: Analysis Of the Extract Of Unripe Tomatoes By Rp-hplcmentioning

confidence: 99%

Isolation, Characterization, and Surfactant Properties of the Major Triterpenoid Glycosides from Unripe Tomato Fruits

Yamanaka¹,

Vincken²,

Waard³

et al. 2008

J. Agric. Food Chem.

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Various triterpenoid glycosides were extracted from whole unripe tomato fruits ( Lycopersicon esculentum cv. Cedrico), using aqueous 70% (v/v) ethanol to study their surfactant properties. Cation-exchange chromatography using a Source 15S column and subsequent semipreparative HPLC using an XTerra RP18 were employed to purify individual triterpenoid glycosides from the extract. The structure of the purified compounds was established by mass spectrometry and nuclear magnetic resonance spectroscopy. The furostanol glycoside tomatoside A (749 mg/kg of DW) and the glycoalkaloids alpha-tomatine (196 mg/kg of DW) and esculeoside A (427 mg/kg of DW) were the major triterpenoid glycosides present. Furthermore, minor amounts of a new dehydrofurostanol glycoside, dehydrotomatoside, were found. The critical micelle concentrations of the major triterpenoid glycosides, alpha-tomatine, tomatoside A, and esculeoside A, were determined as 0.099, 0.144, and 0.412 g/L, respectively. The results show that tomatoside A, and not the more well-known alpha-tomatine, is the predominant triterpenoidal surfactant in unripe tomato fruits.

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Solanum Alkaloids, 124. Preparation of N‐Hydroxyspirosolane Alkaloids

Ripperger

1992

Liebigs Ann. Chem.

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The N-Hydroxyspirosolane alkaloids N-hydroxysolasodine (1) and N-hydroxytomatidine (10) as well as the N-hydroxy-22,26epiminocholestene 7 have been prepared by oxidation of the respective amines 2, 11, and 5 with hydrogen peroxide in the presence of selenium dioxide.In the course of our investigations in the alkaloid field, sometimes hydroxylamines have been isolated, e.g. mayfoline from the aerial parts of Maytenus buxifolia (A. Rich.) Griseb.'21 or N-hydroxysolasodine (1) from the roots of Solanum robustum Wendl.['I. Wc wanted to confirm structure 1 by oxidation of steroid alkaloids. As described"], 1 is in equilibrium with the ring-E-open nitrone (azomethine N-oxide) 3. Therefore, our original plan was the conversion of a corresponding epiminocholestane into the nitrone.The reduction of (25R)-3~,16~-diacetoxy-22,26-epiminocholesta-5,22(N)-diene [31 (4) with sodium tetrahydroborate gives the 22(N)saturated (22S,25R)-and (22R,25R)-epiminocholestenes 5 and 8 in 60 and 12% yields, respectively. The configurations at C-22 of both compounds have been established by hydrolysis to the known diols 6[41 and 9[5,61. The diacetate 5 has also been described19], but the published melting point does not agree with that of our product. The yield of the (22R,25R)-epiminocholestene 8 is relatively high in comparison with that of the corresponding compounds obtained by reduction of 4 by catalytic hydrogenation (to the 5a,6-dihydro or of solasodine (2) by different methods (to the ring-E-opened 22,26-epiminocholestane-3~-16~-diol with or without a

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684. Solanum alkaloids. Part IX. The relation between constitution and basicity in solasodine, its derivatives, and solanidine

Cited by 9 publications

References 0 publications

C22 Isomerization in α-Tomatine-to-Esculeoside A Conversion during Tomato Ripening Is Driven by C27 Hydroxylation of Triterpenoidal Skeleton

C22 Isomerization in α-Tomatine-to-Esculeoside A Conversion during Tomato Ripening Is Driven by C27 Hydroxylation of Triterpenoidal Skeleton

Isolation, Characterization, and Surfactant Properties of the Major Triterpenoid Glycosides from Unripe Tomato Fruits

Solanum Alkaloids, 124. Preparation of N‐Hydroxyspirosolane Alkaloids

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