Spectroscopic Characterization and Cytotoxicity Assessment towards Human Colon Cancer Cell Lines of Acylated Cycloartane Glycosides from Astragalus boeticus L.

Abstract

In several European countries, especially in Sweden, the seeds of the species Astragalus boeticus L. were widely used as coffee substitutes during the 19th century. Nonetheless, data regarding the phytochemistry and the pharmacological properties of this species are currently extremely limited. Conversely, other species belonging to the Astragalus genus have already been extensively investigated, as they were used for millennia for treating various diseases, including cancer. The current work was addressed to characterize cycloartane glycosides from A. boeticus, and to evaluate their cytotoxicity towards human colorectal cancer (CRC) cell lines. The isolation of the metabolites was performed by using different chromatographic techniques, while their chemical structures were elucidated by nuclear magnetic resonance (NMR) (1D and 2D techniques) and electrospray-ionization quadrupole time-of-flight (ESI-QTOF) mass spectrometry. The cytotoxic assessment was performed in vitro by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assays in Caco-2, HT-29 and HCT-116 CRC cells. As a result, the targeted phytochemical study of A. boeticus enabled the isolation of three new cycloartane glycosides, 6-O-acetyl-3-O-(4-O-malonyl)-β-d-xylopyranosylcycloastragenol (1), 3-O-(4-O-malonyl)-β-d-xylopyranosylcycloastragenol (2), 6-O-acetyl-25-O-β-d-glucopyranosyl-3-O-β-d-xylopyranosylcycloastragenol (3) along with two known compounds, 6-O-acetyl-3-O-β-d-xylopyranosylcycloastragenol (4) and 3-O-β-d-xylopyranosylcycloastragenol (5). Importantly, this work demonstrated that the acetylated cycloartane glycosides 1 and 4 might preferentially inhibit cell growth in the CRC cell model resistant to epidermal growth factor receptor (EGFR) inhibitors.

Saponins as cytotoxic agents: an update (2010–2021). Part II—Triterpene saponins

“…These characteristics in monodesmosides made them more active than the respective 20,24-epoxycycloartane derivatives. In turn, Graziani et al (2019), suggested that the cytotoxic activity towards Caco-2, HT-29 and HCT-116 cell lines of 20,24-epoxycycloartane saponins could be significantly improved provided some essential structural requirements are met. These include the presence of C3-xylopyranosyl, along with the C6acetoxy group and the C25-free hydroxyl function.…”

Phytochemical profile, Antioxidant, Enzyme inhibitory and acute toxicity activity of Astragalus bruguieri

“…However, scientists have warned consumers about the aftermath of these synthetic antioxidants on human health because of their carcinogenic effect on human genes 7 . Thus, a recent plethora of works has shown interest in searching for natural antioxidant and anti-proliferative agents to replace chemical synthetics 8,9 .…”

Green Development of Titanium Dioxide Using Astragalus boeticus for the Degradation of Cationic and Anionic Dyes in an Aqueous Environment

“…The choice of this plant is justified by its numerous environmental and natural qualities, as well as the fact that it has never been used in wastewater treatment. Furthermore, it is worth noting that this plant is environmentally friendly, as evidenced by its historical use in various fields, including medicine [36,37], and its seeds have been used as a coffee substitute [38]. This plant offers the advantage of providing a safe and environmentally friendly extract for the reduction in and coating of nanoparticles, a crucial step in the preparation of nanoscale materials.…”