Lu Y, Zhu S, He Y, et al. Systematic characterization of flavonoids from Siraitia grosvenorii leaf extract using an integrated strategy of high-speed counter-current chromatography combined with ultra-high performance liquid chromatography and electrospray ionization quadrupole time-of-flight mass spectrometry. J Sep Sci. March 2020;43(5):852-864. doi: 10.1002/jssc.201900789.
Monk fruit (Siraitia grosvenorii, Cucurbitaceae) contains triterpene glycosides, which have been associated with the anti-asthma, antioxidant, anti-diabetes, and anti-tumor activities of the fruit. However, few studies have analyzed the full phytochemical profile of monk fruit leaves. According to the authors, conventional methods of column chromatography for separation and purification of bioactive ingredients from complex herbs are inefficient, time-consuming, and expensive. They propose that high-speed counter-current chromatography (HSCCC) could effectively and rapidly isolate target components from complex extracts and successfully be used to obtain high-purity compounds. Hence, the purpose of this study was to determine the phytochemicals in monk fruit leaves to support future therapeutic application.
Monk fruit leaves were collected from Guangxi Province; Yongfu County, China and verified for authenticity. Leaves were dried, ground, extracted with 70% ethanol, and then reconstituted as an aqueous solution. High-performance liquid chromatography (HPLC) was used to analyze the solution and determine the partition coefficient (K) of the extracted compounds. The K value was used to select the two-phase solvent system for HSCCC separation. Then ultra-high-performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UHPCL-Q-TOF-MS/MS) was conducted to analyzed flavonoid content.
Four compounds were purified via HPLC and HSCC; namely, a new kaempferol O-glycoside derivative, kaempferol 3-O-α-L-[4-O-(4-carboxy-3-hydroxy-3-methylbutanoyl)]-rhamnopyranoside-7-O-α-L-rhamnopyranoside, named kaempferitrin A (90% purity), and three known compounds, grosvenorine (93% purity), kaempferitrin (99% purity) and afzelin (98% purity). UHPCL-Q-TOF-MS/MS revealed 34 dominant flavonoids in the monk fruit leaf extract including 19 kaempferol O-glycosides, four quercetin O-glycosides, six flavanone derivatives, and five polymethoxyflavones. According to the authors, many of these flavonoids have not been previously reported in monk fruit leaf.
The authors conclude the method used in this study is efficient and effective for separation and analysis of complex extracts. They suggest compounds in monk fruit leaf have the potential for use as an antioxidant, anti-bacterial agent, antihypertensive agent, and for increasing body resistance. Thus, monk fruit leaf has therapeutic potential, which should be researched.
The authors declared no conflict of interest.
—Heather S. Oliff, PhD