Structural Characterization of Biologically Significant Phytochemical Constituents from the Roots of Citrullus colocynthis (L.) Schrad. Using Mass Spectrometric Techniques

Abstract

Citrullus colocynthis, more prominently bitter apple, is a desert vine of family Cucurbitaceae. Since ages, it has been famous for its toxic nature and various parts of plants have been used locally to cure boils, rheumatism, malaria, hepatitis, and diabetes. Keeping in view its biological importance, an in-depth survey of literature was canied out which revealed that no detailed mass spectrometric analysis was performed on Citrullus colocynthis roots. So, the aim of the present study was to perform an in-extenso mass spectrometric profiling oflipophilic and hydrophilic root extracts of Citrullus colocynthis. The root extracts as well as the regrouped fractions of the column were characterized by various mass spectrometric techniques like GC-MS, LC-MS and tandem mass spectrometry. A total of 25 phytochemical compounds were identified from the lipophilic and hydrophilic extracts and a total of 12 phytochemical constituents from the colmID1 fractions were identified using mass spectrometric profiles and their corresponding mass spectral fragmentation. Lipophilic extract analyzed by GC-MS resulted in the identification of three alkanes, two esters, one ether, one acid, and one ketone while the GC-MS analysis of regrouped fraction obtained from COIUllli1 chromatography resulted in four esters, one alkene and one ether. HPLC-DAD-ESI-MS analysis using negative ionization mode aided in proposing five new isoflavone-O-glycosides, two isoflavone 0 and C-glycosides, two gallic acid derivatives and one flavone-O-glycoside from root polar extracts and three new isoflavone-O-glycosides, two isoflavone-di O-glycosides and one flavone-O-glycoside from the polar fractions obtained from silica gel column chromatography. All the flavonoid glycosides were identified for the first time in the roots of Citrullus colocynthis using soft ionization technique like ESI-MS. Five cucurbitacins, a phenolic acid, an unsaturated fatty acid and a steroid were identified from tandem mass spectrometric analysis.The cucrbitacins identified from the root extract possess significant anticancer and antidiabetic activities. The identified flavonoids also have antioxidant potential. So, the present study is a beneficial addition to the existing literature related to Citrullus colocynthis as it unveils infonnation about the impOliant phytoconstituents of roots of the plant by the usage of modem mass spectrometric techniques.