Investigation of borneols sold in Taiwan by chiral gas chromatography

Ho, Tsung‐Jung; Hung, Chien-Che; Shih, Tzenge‐Lien; Yiin, Lih‐Ming; Chen, Hao‐Ping

doi:10.1016/j.jfda.2016.10.012

Cited by 15 publications

(17 citation statements)

References 11 publications

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“…It is interesting to note that the derivatives of (−)‐isoborneol and (+)‐isoborneol split into two peaks (Figure C,D). The purity of synthetic (−)‐ and (+)‐isoborneol has been checked by chiral GC . In accordance with this result, only one peak was observed in the chromatograph of the ( R )‐(+)‐MTPA‐Cl derivative of (−)‐isoborneol (Figure C).…”

Section: Resultsmentioning

confidence: 99%

“…Therefore, (+)‐borneol is the safest one among these samples . Unfortunately, the retail price of pure (+)‐borenol is much higher than that of synthetic borneol …”

Section: Introductionmentioning

confidence: 88%

“…Generally speaking, the main drawbacks of chiral column are high cost and durability. Our unpublished results also showed that applications of samples extracted from fermentation media or herbal ointment complexes usually led to irreversible damage of the β‐cyclodextrin‐based chiral GC column after several runs . Thus, a more reliable method is strongly needed for routine analysis of traditional Chinese herbal medicine complexes on the market.…”

Section: Introductionmentioning

confidence: 97%

“…The separation of enantiomers, (+)‐ and (−)‐ borneol as well as (+)‐ and (−)‐isoborneol by chiral gas chromatography (GC) was reported by us and other groups previously . Generally speaking, the main drawbacks of chiral column are high cost and durability.…”

Section: Introductionmentioning

confidence: 99%

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Resolution of isoborneol and its isomers by GC/MS to identify “synthetic” and “semi‐synthetic” borneol products

et al. 2018

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Borneol is a plant terpene commonly used in traditional Chinese medicine. Optically pure (+)-borneol and (-)-borneol can be obtained by extraction from the plants Dipterocarpaceae and Blumea balsamifera, respectively. "Synthetic borneol" is obtained from the reduction of (±)-camphor to lead to four different stereoisomers: (+)-isoborneol, (-)-isoborneol, (+)-borneol, and (-)-borneol. In contrast, "semi-synthetic borneol" is produced from the reduction of natural camphor, (+)-camphor, to afford two isomers: (-)-isoborneol and (+)-borneol. We established a convenient method to identify them by treating the four stereoisomers with two chiral reagents, (R)-(+)-α-methoxy-α-trifluoromethylphenylacetyl chloride ((R)-(+)-MTPA-Cl) and (1S)-(-)- camphanic chloride. The resulting derivatives from the above mentioned method were analyzed by gas chromatography. The enantiomers of (+)- and (-)-isoborneol were successfully separated from (+)- and (-)-borneol isomers in this study to make this a useful method in the identification of "synthetic" and "semi-synthetic" borneols. Furthermore, we also examined five different commercial borneols. During this course, a novel and unprecedented partial epimerization from isoborneol-camphanic ester to borneol-camphanic ester was observed. However, this phenomenon did not occur in isoborneol-MTPA esters epimerization to borneol-MTPA case under the same conditions. The DFT calculation of activation energies for both reactions was in a good agreement with the results obtained from GC analysis.

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Section: Resultsmentioning

confidence: 99%

“…Therefore, (+)‐borneol is the safest one among these samples . Unfortunately, the retail price of pure (+)‐borenol is much higher than that of synthetic borneol …”

Section: Introductionmentioning

confidence: 88%

Section: Introductionmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

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Resolution of isoborneol and its isomers by GC/MS to identify “synthetic” and “semi‐synthetic” borneol products

et al. 2018

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“…Enantiomers show significant differences in sensory qualities, odor threshold, pharmacology activities, metabolic processes, and toxicities . Since chiral monoterpene compounds possess few or no functional groups and high volatility, their chiral analysis studies have been mainly performed by gas chromatography with cyclodextrin derivatives as chiral selectors . In order to obtain optically active stereoisomers in batch, several research groups tried to develop direct HPLC separation methods with chiral columns.…”

Section: Introductionmentioning

confidence: 99%

Reliable HPLC separation, vibrational circular dichroism spectra, and absolute configurations of isoborneol enantiomers

et al. 2017

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Resolution of chiral compounds has played an important role in the pharmaceutical field, involving detailed studies of pharmacokinetics, physiological, toxicological, and metabolic activities of enantiomers. Herein, a reliable method by high-performance liquid chromatography (HPLC) coupled with an optical rotation detector was developed to separate isoborneol enantiomers. A cellulose tris(3, 5-dimethylphenylcarbamate)-coated chiral stationary phase showed the best separation performance for isoborneol enantiomers in the normal phase among four polysaccharide chiral packings. The effects of alcoholic modifiers and column temperature were studied in detail. Resolution of the isoborneol racemate displayed a downward trend along with an increase in the content of ethanol and column temperature, indicating that less ethanol in the mobile phase and lower temperature were favorable to this process. Moreover, two isoborneol enantiomers were obtained via a semipreparative chiral HPLC technique under optimum conditions, and further characterized by analytical HPLC, and experimental and calculated vibrational circular dichroism (VCD) spectroscopy, respectively. The solution VCD spectrum of the first-eluted component was consistent with the Density Functional Theory (DFT) calculated pattern based on the SSS configuration, indicating that this enantiomer should be (1S, 2S, 4S)-(+)-isoborneol. Briefly, these results have provided reliable information to establish a method for analysis, preparative separation, and absolute configuration of chiral compounds without typical chromophoric groups.

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Simple Plug‐In Synthetic Step for the Synthesis of (−)‐Camphor from Renewable Starting Materials

et al. 2021

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Racemic camphor and isoborneol are readily available as industrial side products, whereas (1R)-camphor is available from natural sources. Optically pure (1S)-camphor, however, is much more difficult to obtain. The synthesis of racemic camphor from α-pinene proceeds via an intermediary racemic isobornyl ester, which is then hydrolyzed and oxidized to give camphor. We reasoned that enantioselective hydrolysis of isobornyl esters would give facile access to optically pure isoborneol and camphor isomers, respectively. While screening of a set of commercial lipases and esterases in the kinetic resolution of racemic monoterpenols did not lead to the identification of any enantioselective enzymes, the cephalosporin Esterase B from Burkholderia gladioli (EstB) and Esterase C (EstC) from Rhodococcus rhodochrous showed outstanding enantioselectivity (E > 100) towards the butyryl esters of isoborneol, borneol and fenchol. The enantioselectivity was higher with increasing chain length of the acyl moiety of the substrate. The kinetic resolution of isobornyl butyrate can be easily integrated into the production of camphor from α-pinene and thus allows the facile synthesis of optically pure monoterpenols from a renewable side-product.

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Investigation of borneols sold in Taiwan by chiral gas chromatography

Cited by 15 publications

References 11 publications

Resolution of isoborneol and its isomers by GC/MS to identify “synthetic” and “semi‐synthetic” borneol products

Resolution of isoborneol and its isomers by GC/MS to identify “synthetic” and “semi‐synthetic” borneol products

Reliable HPLC separation, vibrational circular dichroism spectra, and absolute configurations of isoborneol enantiomers

Simple Plug‐In Synthetic Step for the Synthesis of (−)‐Camphor from Renewable Starting Materials

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