Metabolite Profiling and Quantitation of Cucurbitacins in Cucurbitaceae Plants by Liquid Chromatography coupled to Tandem Mass Spectrometry

Abstract

Cucurbitaceae is an important plant family because many of its species are consumed as food, and used in herbal medicines, cosmetics, etc. It comprises annual vines and is rich in various bioactive principles which include the cucurbitacins. These steroidal natural products, derived from the triterpene cucurbitane, are mainly the bitter principles of the family Cucurbitaceae. Their biological activities include anti-inflammatory, hepatoprotective, and anti-cancer activities. A total of 10 species belonging to 6 genera of the Cucurbitaceae family along with Cissampelos pareira (Menispermaceae) were included in this study. A comprehensive profiling of certain natural products was developed using HPLC-QTOF-MS/MS analysis and a distribution profile of several major natural products in this family was obtained. A total of 51 natural products were detected in both positive and negative ionization modes, based on accurate masses and fragmentation patterns. Along with this, quantitation of four bioactive cucurbitacins, found in various important plants of the Cucurbitaceae family, was carried out using multiple reaction monitoring (MRM) approach on an ion trap mass spectrometer. Cucurbitacin Q was found to be the most abundant in C. pareira, while Citrullus colocynthis contained all four cucurbitacins in abundant quantities. The developed quantitation method is simple, rapid, and reproducible.

Figure 1

Chemical structures of analytes 1–4 quantitated in various plants.

Figure 2

Extracted-ion chromatogram of standard analytes 1–4 analyzed by MRM.

Figure 3

Representative MRM extracted ion chromatograms and product ion spectra of standard analytes 1–4 at 50 ng/mL.

Figure 4

Heat map of compounds identified in positive ionization mode.

Figure 5

Heat map of compounds identified in negative ionization mode.