Rapid quantitative analysis of six flavonoids in licorice by ultra-performance convergence chromatography

In Silico Analysis of Selected Glycyrrhiza glabra (Licorice) Constituents: Exploring Their Modulatory Effects on Human Superoxide Dismutase, Human Phosphodiesterase-9 and Human Dipeptidyl Peptidase-4

Background Glycyrrhiza glabra (Licorice) has been known for its various biological activities. In the current investigation, we aimed to evaluate 11 (10 natural and one synthetic) selected constituents of G. glabra as potent modulatory agents of human superoxide dismutase (hSOD), human phosphodiesterase-9 (hPDE 9) and human dipeptidyl peptidase-4 (hDPP 4) using in silico method. Methodology The 11 selected constituents of G. glabra (Licorice) were investigated on the docking behaviour of hSOD, hPDE 9 and hDPP 4 by using the PatchDock method. In addition to docking, toxicity analysis was also carried out using the pkCSM free online server (University of Melbourne, Melbourne, AUS). Results Toxicity analysis has shown that four ligands (36%) of G. glabra (Licorice) are predicted to have human ether-a-go-go-related gene-2 (hERG 2) inhibition activity. The docking analysis showed that glabridin (-224.13 kcal/mol) has shown the highest atomic contact binding energy with the hSOD enzyme, whereas carbenoxolone has shown the maximum atomic contact binding energy with both the hPDE 9 and hDPP 4 enzymes (-239.57 and -173.50 kcal/mol) respectively. Conclusion Thus the present finding provides new information about 11 selected ligands of G. glabra (Licorice) as potent modulatory agents of hSOD, hPDE 9 and hDPP 4.

Application of Biotransformation-Guided Purification in Chinese Medicine: An Example to Produce Butin from Licorice

Natural compounds are considered treasures in biotechnology; however, in the past, the process of discovering bioactive compounds is time consuming, and the purification and validation of the biofunctions and biochemistry of compounds isolated from a medicinal herb are tedious tasks. In this study, we developed an economical process called biotransformation-guided purification (BGP), which we applied to analyze licorice, a traditional Chinese medicine widely used in many therapies. This medicinal herb contains various flavonoids and triterpenoids and, thus, is a suitable material used to assess the ability of BGP to identify and produce bioactive compounds. In the BGP process, the ethyl acetate extract of a commercial licorice medicine was partially purified into three fractions by Sephadex LH-20 chromatography, and Bacillus megaterium tyrosinase (BmTYR) was used to catalyze the biotransformation of the extract from each fraction. One of the products produced via BmTYR-driven biotransformation was purified from the biotransformation-positive extract using preparative C-18 high-performance liquid chromatography, and it was identified as butin (3′-hydroxyliquiritigenin) through nucleic magnetic resonance and mass spectral analyses. Butin was produced from liquiritigenin through BmTYR-catalyzed hydroxylation, with commercial liquiritigenin as the biotransformation precursor. The proposed alternative approach quickly identified and isolated the biotransformed butin from licorice. Moreover, butin demonstrated an antioxidant activity that is stronger by over 100-fold compared with that of its precursor (liquiritigenin). This study showed that the economical BGP process could quickly obtain and validate bioactive molecules from crude extracts of medicinal herbs.

Advanced Development of Supercritical Fluid Chromatography in Herbal Medicine Analysis

The greatest challenge in the analysis of herbal components lies in their variety and complexity. Therefore, efficient analytical tools for the separation and qualitative and quantitative analysis of multi-components are essential. In recent years, various emerging analytical techniques have offered significant support for complicated component analysis, with breakthroughs in selectivity, sensitivity, and rapid analysis. Among these techniques, supercritical fluid chromatography (SFC) has attracted much attention because of its high column efficiency and environmental protection. SFC can be used to analyze a wide range of compounds, including non-polar and polar compounds, making it a prominent analytical platform. The applicability of SFC for the separation and determination of natural products in herbal medicines is overviewed in this article. The range of applications was expanded through the selection and optimization of stationary phases and mobile phases. We also focus on the two-dimensional SFC analysis. This paper provides new insight into SFC method development for herbal medicine analysis.

Supercritical fluid chromatography for the analysis of natural dyes: From carotenoids to flavonoids

Plant-derived natural dyes are used in a variety of formulated products, from food to cosmetics and pharmaceutics. In addition to their color, they also provide some bioactivity. While they are mostly analyzed with high-performance liquid chromatography, supercritical fluid chromatography was also employed for several dye families, mostly for carotenoids and chlorophylls, and more recently for anthraquinones and flavonoids. These supercritical fluid chromatography methods are described in this review. Because the dyes have different structures and structural variations (polarity, isomers, etc.), the best chromatographic system to achieve their separation is not always the same. Hydrophobic stationary phases are preferred for the most hydrophobic dyes (chlorophylls and carotenoids) while polar stationary phases are preferred for the polar dyes (anthraquinones and flavonoids). Regarding the mobile phase composition, chlorophylls and carotenoids are best eluted with moderate proportions of co-solvent in CO₂ (about 40%), while the most polar glycosylated flavonoids require higher proportions of co-solvent and acidic additives. Because dyes are colorful, ultraviolet-visible detection is often sufficient, while mass spectrometry offers additional structural information. Furthermore, fundamental information can also be gained through chromatographic analysis of dyes: either solubility in supercritical fluids, in view of their extraction, or retention behavior providing an understanding of stationary phase properties.

Analysis of flavonoids with unified chromatography-electrospray ionization mass spectrometry-method development and application to compounds of pharmaceutical and cosmetic interest

In this project, we aimed at analysing flavonoid-type compounds with unified chromatography (joining supercritical fluid chromatography and enhanced fluidity liquid chromatography with carbon dioxide-methanol mobile phases covering a wide range of compositions) and diode-array and electrospray ionization mass spectrometric detection (UC-DAD-ESI-MS). First, the chromatographic method was developed for 9 standard flavonoid molecules from three different families (flavanols, flavanones and flavonols, glycosylated or not), with a strong focus on mobile phase composition to achieve the elution of a wide range of flavonoids with good chromatographic quality (efficiency and resolution). For this purpose, two stationary phases were selected (ACQUITY UPC² DEA and Diol), and five different additives (formic acid, citric acid, phosphoric acid, methanesulfonic acid and ammonium hydroxide) were successively introduced in the methanol co-solvent. The composition containing 0.1% methanesulfonic acid in methanol was retained as it provided the best chromatographic quality together with the possibility of hyphenating the chromatography to mass spectrometry. The DEA column appeared to provide the best efficiency and was retained for further method development. The gradient method was then optimized to achieve a fast analysis, which involved elution with a wide range of mobile phase composition (from 20 to 100% co-solvent in methanol) together with reversed flow rate and reversed pressure gradients at fixed temperature. The final gradient lasted 10 min, followed by 2.5 min of re-equilibration. Then, ESI-MS detection was optimized. Because the single-quadrupole mass spectrometer employed (ACQUITY UPC² QDa) allowed the variation of only a few parameters, a design of experiments was used to define the best compromise for three parameters (probe temperature, cone voltage and capillary voltage). The make-up fluid introduced before entering the MS was also varied: different compositions of methanol-water containing either formic acid, ammonium hydroxide or sodium chloride were tested. The best results in terms of signal-to-noise ratio were obtained with methanol containing 20 mM ammonium hydroxide and 2% water. The optimal UC-DAD-ESI-MS method was then applied to two different flavonoid formulation ingredients. The first one, hidrosmin (5-O-(β-hydroxyethyl)diosmin), is known for its vasoprotective properties and therefore employed in pharmaceutical formulations. The second one, α-glucosyl-hesperidin (sometimes referred to as vitamin P), is employed in cosmetic formulations. Identification of the major compounds in each sample was achieved with the help of MS detection. Graphical abstract.