Cascarosides A and B

Area of Science:

• Natural Product Chemistry
• Spectroscopic Analysis
• Pharmacognosy

Background:

• Cascara is a traditional laxative derived from Rhamnus species.
• The chemical constituents of cascara, including cascarosides, are important for its pharmacological activity.
• Accurate identification and quantification of these compounds are crucial for quality control.

Purpose of the Study:

• To elucidate the precise chemical structures of cascarosides A and B.
• To confirm their isomeric relationship to 8-O-(beta-D-glucopyranosyl)barbaloin.
• To evaluate the implications of these findings for the European Pharmacopoeia assay of cascara.

Main Methods:

• Electron-impact mass spectrometry (EIMS)
• Field desorption mass spectrometry (FDMS)
• Nuclear Magnetic Resonance (NMR) spectroscopy
• Circular Dichroism (CD) spectroscopy

Main Results:

• Cascarosides A and B were structurally confirmed as C-10 isomers.
• The identity was established relative to 8-O-(beta-D-glucopyranosyl)barbaloin.
• Oxidative hydrolysis yielded aloe-emodin, further supporting the structural assignments.

Conclusions:

• The structural confirmation of cascarosides A and B provides a clearer understanding of cascara's chemical profile.
• The findings necessitate a review of analytical methods for cascara, particularly the assay described in the European Pharmacopoeia.
• Precise structural data is essential for reliable quality assessment and standardization of herbal medicines.