Fast determination of harmala alkaloids in edible algae by capillary electrophoresis mass spectrometry

Abstract

The use of algae as a foodstuff is rapidly expanding worldwide from the East Asian countries, where they are also used for medical care. Harmala alkaloids (HAlk) are a family of bioactive compounds found in the extracts of some plants, including wakame (Undaria pinnatifida), an edible marine invasive algae. HAlks are based on a characteristic β-carboline structure with at least one amino ionizable group. In this work, we report the successful separation of a mixture of six HAlks (harmine, harmaline, harmol, harmalol, harmane, and norharmane) by capillary electrophoresis ion-trap mass spectrometry (CE-IT-MS) in less than 8 min. Optimum separation in fused-silica capillaries and detection sensitivity in positive-ion mode were achieved using a background electrolyte (BGE) with 25 mmol L(-1) ammonium acetate (pH 7.8) and 10% (v/v) methanol, and a sheath liquid with 60:40 (v/v) isopropanol-water and 0.05% (v/v) formic acid. The separation method was validated in terms of linearity, limits of detection and quantification, repeatability, and reproducibility. Later, a sample pretreatment was carefully optimized to determine HAlks in commercial wakame samples with excellent recovery and repeatability. For the complex wakame extracts, the MS-MS fragmentation patterns of the different HAlks were useful to ensure a reliable identification. The complete procedure was validated using the standard-addition calibration method, determining matrix effects on the studied compounds. Harmalol, harmine, and harmaline were naturally present in the samples and were quantified at very low concentrations, ranging from 7 to 24 μg kg(-1) dry algae.

Capillary electrophoresis in phytochemical analysis (2014–2017)

“…Although UV had been the most frequently used detection method in CE, MS was also widely used due to the high sensitivity and selectivity. Few examples are determination of mushroom toxins ibotenic acid, muscimol and muscarine in human urine , fingerprinting analysis of flavonoids in Ginkgo biloba herbal supplements , and fast determination of harmala alkaloids in edible algae by CE‐MS; Differential detection of Rhizoma coptidis by CE‐MS with a nanospray interface ; Characterization of hydrothermally isolated xylan from beech wood by CE‐laser‐induced fluorescence (LIF) and MS detection ; Analysis of paspalic acid, lysergic acid, and iso‐lysergic acid with UV and Q‐TOF/MS detection ; Dereplication of known nucleobase and nucleoside compounds in natural product extracts by CE‐high resolution mass spectrometry (HR‐MS) ; Separating and determining physcion, chrysophanol and aloe‐emodin in rhubarb and quantifying palmatin, columbin, cepharanthine, menisperine, magnoflorine and 20‐hydroxyecdysone in Radix tinosporae by NACE‐MS.…”

Recent advances in CE‐MS coupling: Instrumentation, methodology, and applications

“…An effect of pasteurization or high‐pressure processing on the contents of free nucleotide monophosphates in human milk was analyzed . Harmala alkaloids (found in the seeds of Peganum harmala ), harmine, harmaline, harmol, harmalol, harmane, and norharmane were determined in edible algae .…”

A rapid and simple method for the determination of psychoactive alkaloids by CE‐UV: application to Peganum Harmala seed infusions

“…Since HAlks are ionizable compounds, CE methods have been certainly explored by a few authors, either using the free capillary zone electrophoresis mode (CZE) and also using micellar electrokinetic chromatography (MEKC). [28] The method was applied to determine low amounts of harmine, harmaline, and harmalol in wakame (U. pinnatifida), an edible marine invasive brown algae originally from East Asian countries that is commonly used as a foodstuff, as well as by traditional oriental medicine practitioners. However, the optimization of variables used in these cases allowed only to achieve baseline separation of few HAlks, with limited resolution and requiring very long analysis times.…”

“…However, the optimization of variables used in these cases allowed only to achieve baseline separation of few HAlks, with limited resolution and requiring very long analysis times. [28] The method was applied to determine low amounts of harmine, harmaline, and harmalol in wakame (U. pinnatifida), an edible marine invasive brown algae originally from East Asian countries that is commonly used as a foodstuff, as well as by traditional oriental medicine practitioners. However, despite the advantages of MS detection, on the one hand the requirements imposed by the ESI ionization to the background electrolyte, i.e., volatility, restrict the complete baseline resolution between all the members of HAlks family.…”