Opuntisines, 14-membered cyclopeptide alkaloids from fruits of Opuntia stricta var. dillenii isolated by high-performance countercurrent chromatography. (1st January 2021)

• Record Type: Journal Article
• Authors: Surup, Frank; Minh Thi Tran, Thu; Pfütze, Sebastian; Budde, Jarmo; Moussa-Ayoub, Tamer E.; Rohn, Sascha; Jerz, Gerold
• Is Part Of: Food chemistry. Volume 334(2021)
• Publication Date: 2021-01-01
• Subjects: Opuntia stricta var. dillenii -- Cactaceae -- Structure elucidation -- Secondary metabolites -- Cyclopeptide alkaloids -- High-performance countercurrent chromatography -- 1D/2D-NMR; Food -- Analysis -- Periodicals; Food -- Composition -- Periodicals; 664
• DOI: 10.1016/j.foodchem.2020.127552
• Languages: English
• ISSNs: 0308-8146

Abstract

Highlights: Novel cyclopeptide alkaloids from fruits of Opuntia stricta var. dillenii. Isolation by high performance countercurrent chromatography. Structure elucidation of two major metabolites including stereochemistry. Antimicrobial and cytotoxicity evaluation. Detection of the metabolites in the pulp. Abstract: Extracts of Opuntia stricta var. dillenii fruits were fractionated by semi-preparative high-performance countercurrent chromatography (HPCCC) to study the secondary metabolite formation, whereby HPCCC showed a superior separation capacity to fractionate minor metabolites compared to HPLC. A family of new peptides was detected in semi-polar fractions when monitoring the HPCCC separation by off-line injections of fractions to ESI-MS/MS. Planar structures of the major compounds, two 14-ring-membered cyclopeptide alkaloids, which were named opuntisines A and B, were elucidated by 1D- and 2D-NMR spectroscopy and HR-ESI-MS/MS spectrometry, while a combination of chemical derivatisation and degradation revealed the stereo-configurations. Specifically, the methods of Marfey and Mosher indicated l -Glu, l -Ile, l -Phe and 1 S -configurations, respectively; ROESY correlations revealed 8 S, 9 S . The novel opuntisine A showed moderate activity against the Gram-negative bacterium Escherichia coli, but no further antibacterial, antifungal nor cytotoxic effects. This bioactive natural product class is reported for the first time in the plant family Cactaceae.