Triterpenoid saponins from Scabiosa stellata collected in North-eastern Algeria

Recent progress on triterpenoid derivatives and their anticancer potential

Cancer poses a significant global public health challenge, with commonly used adjuvant or neoadjuvant chemotherapy often leading to adverse side effects and drug resistance. Therefore, advancing cancer treatment necessitates the ongoing development of novel anticancer agents with diverse structures and mechanisms of action. Natural products remain crucial in the process of drug discovery, serving as a primary source for pharmaceutical leads and therapeutic advancements. Triterpenoids are particularly compelling due to their complex structures and wide array of biological activities. Recent research has demonstrated that naturally occurring triterpenes and their derivatives have the potential to serve as promising candidates for new drug development. This review aims to comprehensively explore the anticancer properties of triterpenoids and their synthetic analogs, with a focus on recent advancements. Various aspects, such as synthesis, phytochemistry, and molecular simulation for structure-activity relationship analyses, are summarized. It is anticipated that triterpenoid derivatives will emerge as notable anticancer agents following further investigation into their mechanisms of action and in vivo studies.

A new triterpene saponin and known compounds from the polar extract of Salvia argentea L. and evaluation of their antioxidant activity

A new triterpene saponin, 2, 3, 21, 23-tetrahydroxyolean-12-en-28-oic-acid-28-O-β-D- glucosyl-(2''→1')-β-D-glucoside (1), was isolated from the n-butanol extract of dried aerial parts of Salvia argentea L. (Lamiaceae) in addition to two known flavonoids, apigenin 7-O-β-D-glucoside (2), threo-guaiacylglycerol 3-O-[6-O-p-hydroxybenzoyl]-β-D-glucoside (3), luteolin 7-O-β-D-glucoside (4), verbascoside (5) and rosmarinic acid (6). The structure elucidation of these compounds was based on analyses of spectroscopic data including 1D-, 2D-NMR and HR-ESI-MS techniques and by comparing their NMR data with those reported in the literature. Compound 6 exhibited the highest antioxidant activity in DPPH assay (IC50<3.00 µg/mL) which was better than the standards BHA, BHT, Trolox and ascorbic acid.

Selectivity Screening and Structure-Cytotoxic Activity Observations of Selected Oleanolic Acid (OA)-Type Saponins from the Amaranthaceae Family on a Wiade Panel of Human Cancer Cell Lines

Plants from the Amaranthaceae family are a source of oleanolic acid (OA)-type saponins with cytotoxic activity. Two known OA-type saponins, calenduloside E and chikusetsusaponin IVa, were isolated from the roots of Chenopodium strictum Roth. Their structures were confirmed using MS and NMR techniques. This constitutes the inaugural report of the saponins in Ch. strictum. Both the isolated saponins and structurally similar compounds, momordin Ic and OA, were compared for their cytotoxicity against various cancer and normal cell lines (including skin, breast, thyroid, gastrointestinal, and prostate panels). Their effects were dose- and time-dependent, varying with the specific cell line and compound structure. A chemometric approach demonstrated the effects of the compounds on the cell lines. The study discusses the structure-activity observations. The key structural elements for potent cytotoxic activity included the free carboxyl group 28COOH in the sapogenin structure (OA) and the presence of a sugar moiety. The monodesmosides with glucuronic acid (GlcA) at the C3 position of OA were generally more cytotoxic than bidesmosides or OA alone. The addition of xylose in the sugar chain modified the activity towards the cancer cells depending on the specific cell line. OA-type saponins with GlcA (particularly calenduloside E and momordin Ic) represent a promising avenue for further investigation as potential anticancer agents.

Oleanolic Acid Glycosides from Scabiosa caucasica and Scabiosa ochroleuca: Structural Analysis and Cytotoxicity

In the field of research on medicinal plants from the Armenian flora, the phytochemical study of two Scabiosa L. species, S. caucasica M. Bieb. and S. ochroleuca L. (Caprifoliaceae), has led to the isolation of five previously undescribed oleanolic acid glycosides from an aqueous-ethanolic extract of the roots: 3-O-α-L-rhamnopyranosyl-(1→3)-β-D-glucopyranosyl-(1→4)-β-D-glucopyranosyl-(1→4)-β-D-xylopyranosyl-(1→3)-α-L-rhamnopyranosyl-(1→2)-α-L-arabinopyranosyloleanolic acid 28-O-β-D-glucopyranosyl-(1→6)-β-D-glucopyranosyl ester, 3-O-β-D-xylopyranosyl-(1→2)-[α-L-rhamnopyranosyl-(1→4)]-β-D-glucopyranosyl-(1→4)-β-D-glucopyranosyl-(1→4)-β-D-xylopyranosyl-(1→3)-α-L-rhamnopyranosyl-(1→2)-α-L-arabinopyranosyloleanolic acid 28-O-β-D-glucopyranosyl-(1→6)-β-D-glucopyranosyl ester, 3-O-β-D-xylopyranosyl-(1→2)-[α-L-rhamnopyranosyl-(1→4)]-β-D-glucopyranosyl-(1→4)-β-D-glucopyranosyl-(1→4)-β-D-xylopyranosyl-(1→3)-α-L-rhamnopyranosyl-(1→2)-α-L-arabinopyranosyloleanolic acid, 3-O-β-D-xylopyranosyl-(1→2)-[α-L-rhamnopyranosyl-(1→4)]-β-D-xylopyranosyl-(1→4)-β-D-glucopyranosyl-(1→4)-β-D-xylopyranosyl-(1→3)-α-L-rhamnopyranosyl-(1→2)-α-L-arabinopyranosyloleanolic acid 28-O-β-D-glucopyranosyl-(1→6)-β-D-glucopyranosyl ester, 3-O-α-L-rhamnopyranosyl-(1→4)-β-D-glucopyranosyl-(1→4)-β-D-glucopyranosyl-(1→4)-β-D-xylopyranosyl-(1→3)-α-L-rhamnopyranosyl-(1→2)-α-L-arabinopyranosyloleanolic acid 28-O-β-D-glucopyranosyl-(1→6)-β-D-glucopyranosyl ester. Their full structural elucidation required extensive 1D and 2D NMR experiments, as well as mass spectrometry analysis. For the biological activity of the bidesmosidic saponins and the monodesmosidic saponin, their cytotoxicity on a mouse colon cancer cell line (MC-38) was evaluated.

Dipsacus and Scabiosa Species-The Source of Specialized Metabolites with High Biological Relevance: A Review

The genera Dipsacus L. and Scabiosa L. of the Caprifoliaceae family are widely distributed in Europe, Asia, and Africa. This work reviews the available literature on the phytochemical profiles, ethnomedicinal uses, and biological activities of the most popular species. These plants are rich sources of many valuable specialized metabolites with beneficial medicinal properties, such as triterpenoid derivatives, iridoids, phenolic acids, and flavonoids. They are also sources of essential oils. The genus Dipsacus has been used for centuries in Chinese and Korean folk medicines to treat bone (osteoporosis) and joint problems (rheumatic arthritis). The Korean Herbal Pharmacopoeia and Chinese Pharmacopoeia include Dipsaci radix, the dried roots of D. asperoides C.Y.Cheng & T.M.Ai. In addition, S. comosa Fisch. ex Roem & Schult. and S. tschiliiensis Grunning are used in traditional Mongolian medicine to treat liver diseases. The current scientific literature data indicate that these plants and their constituents have various biological properties, including inter alia antiarthritic, anti-neurodegenerative, anti-inflammatory, antioxidant, anticancer, and antimicrobial activities; they have also been found to strengthen tendon and bone tissue and protect the liver, heart, and kidney. The essential oils possess antibacterial, antifungal, and insecticidal properties. This paper reviews the key biological values of Dipsacus and Scabiosa species, as identified by in vitro and in vivo studies, and presents their potential pharmacological applications.

Scabiosa atropurpurea: A rich source of iridoids with α-glucosidase inhibitory activity evaluated by in vitro and in silico studies

Scabiosa atropurpurea L. subsp. maritima (L.) Arc. (Caprifoliaceae) is a plant widely distributed in the Mediterranean region and represented by 32 taxa in the flora of Turkey. In the present study, an in-depth phytochemical investigation of S. atropurpurea methanol extract of the whole plant was carried out using a combination of LC-ESI-FT-MS and NMR analysis. This approach allowed the isolation and structural elucidation of 28 compounds: 17 iridoids, 7 flavonoids, and 4 phenolic acids. Among these compounds, three previously unreported iridoids named secologanin-methyl-hemiacetal, atropurpurin A, and atropurpurin B were identified. The methanol extract of S. atropurpurea was assayed for its antioxidant and antihyperglycemic activity, showing a potent α-glucosidase inhibitory activity (IC₅₀ = 100 μg/mL), higher than that exerted by acarbose (IC₅₀ = 196 μg/mL), used as the positive control. Thus, the most abundant iridoids were selected to be tested for their antihyperglycemic activity, and molecular docking experiments were carried out to assess the possibility for selected compounds to form complexes with α-glucosidase enzyme active site.

Triterpenoid saponins from Anagallis monelli ssp. linifolia (L.) Maire and their chemotaxonomic significance

Thirteen undescribed triterpenoid saponins named monellosides A-M, were isolated from the aerial parts of Anagallis monelli ssp. linifolia (L.) Maire, together with ten known oleanane-type glycosides. Their structures were elucidated by 1D and 2D-NMR spectroscopy (COSY, TOCSY, HSQC, HMBC and ROESY) as well as high resolution mass spectrometry (HR-ESI-MS) and acid hydrolysis. Monellosides A-M have a carbohydrate chain linked on the C-3 of the aglycone with a common β-d-glucopyranosyl-(1 → 4)-α-l-arabinopyranosyl sequence which was further glycosylated by a glucose and/or a xylose. The sequence β-d-xylopyranosyl-(1 → 2)-β-d-glucopyranosyl-(1 → 4)-[β-d-glucopyranosyl-(1 → 2)-]α-l-arabinopyranosyl was common to all the 13,28-epoxy-oleanane core skeleton except one compound. In order to discuss the reclassification of Anagallis in Primulaceae, we compared saponins from species of Myrsinaceae and Primulaceae families and showed that these species were characterized by a pentacyclic triterpenoid saponin with a 13,28-epoxy bridge skeleton. Our phytochemical results increase the knowledge of saponins of the genus Anagallis, their chemotaxonomy and stimulate the evaluation of the biological activities of these saponins.

Semipapposides A-M, triterpenoid bidesmosides saponins from the roots of Scabiosa semipapposa

Phytochemical investigations of the roots of Scabiosa semipapposa Salzem ex D.C. have led to the isolation of 12 undescribed triterpenoid saponins named semipapposides A-L, one undescribed saponin semipapposide M obtained as an inseparable mixture, together with three known oleanolic acid glycosides. Their structures were elucidated by analysis of 1D and 2D-NMR (¹H-¹H COSY, TOCSY, HSQC-TOCSY, HSQC, ROESY or NOESY, and HMBC) spectroscopic data and mass spectrometry (HR-ESI-MS), and by comparison with those of related metabolites. All saponins possess a partial sequence rhamnopyranosyl-(1 → 2)-xylopyranosyl or rhamnopyranosyl-(1 → 2)-arabinopyranosyl- at C-3 of the aglycon and a gentiobiose unit at C-28. These results represent a contribution to the knowledge of the saponins of Scabiosa species and their chemotaxonomy.

Isolation of a new monoterpenoid glycoside from Anhua dark tea based on an NMR-guided method and its cytotoxic activity against MDA-MB-231 and SH-SY5Y cell lines

Based on an NMR-guided method, one new monoterpenoid glycoside (1) was isolated from Anhua dark tea, together with five known compounds (2-6). The structure of the new compound was determined as 3-(5,5-dimethyltetrahydrofuranyl)-1-buten-3-ol primeveroside, and trivially named anhuaterpenoside A (1), on the basis of detailed spectroscopic analyses, and acidic hydrolysis. Compound 1 exhibits cytotoxic activity against MDA-MB-231 and SH-SY5Y cell lines with IC₅₀ value of 23.26 μM and 18.57 μM, respectively.

Cytotoxic triterpenoid saponins from Thalictrum atriplex

Two new cycloartane glycosides, cycloatriosides A and B (1-2), and a new oleanolic acid glycoside, thaliatrioside A (3), along with 7 known triterpenoids (4-10) were isolated from Thalictrum atriplex. The structures of the new compounds were established as 3-O-β-D-galactopyranosyl (20S, 24 R)-3β,16β,25,29-tetrahydroxy-20,24-epoxycycloartane-29-O-β-D-glucopyranoside (1), 3-O-β-D-glucopyranosyl-(1→2)-α-arabinopyranosyl-3β,22ξ,30-trihydroxycycloart-24-en-21-oic acid α-L-arabinopyranosyl-(1→6)-β-D-glucopyranoside (2) and 3-O-[α-L-rhamnopyranosyl-(1→3)-β-D-xylopyranosyl-(1→3)-α-L-rhamnopyranosyl-(1→2)-α-L-arabinopyranosyl]-oleanolic acid 28-O-β-D-glucopyranosyl ester (3) on the basis of extensive NMR and HR-ESI-MS analyses, along with acid hydrolysis. Their cytotoxic activities against human lung cancer cells A549 and human breast cancer cells MDA-MB-231 were evaluated using MTT method. Compound 9 showed cytotoxicity against MDA-MB-231 cell line with the IC₅₀ value of 72.53 ± 1.08 μM.

Phytochemical investigation of Scabiosa sicula guided by a preliminary HPLC-ESIMSn profiling

The genus Scabiosa (Caprifoliaceae) is represented by 80 species, widely used as medicinal plants for their positive effects on human diseases. On the basis of the interesting biological activity shown by Scabiosa spp., the phytochemical investigation of Scabiosa sicula L., never investigated before, was carried out. An initial LC-MS profile of the MeOH extract of S. sicula whole plant guided the isolation of 34 compounds, of which the structures were unambiguously elucidated by NMR analysis as phenolic compounds and triterpene saponins, among which eight undescribed compounds. Moreover, the total phenolic content of S. sicula methanol extract has been evaluated. On the basis of the pharmacological activities reported for Scabiosa species the antioxidant activity of the methanol extract was tested by TEAC and DPPH assays. Finally, the α-glucosidase inhibitory activity of the methanol extract was assayed, showing an IC₅₀ value (49 μg/mL) comparable to that exerted by acarbose (90 μg/mL), used as positive control.

Triterpene saponins from Silene gallica collected in North-Eastern Algeria

Eleven previously undescribed triterpene saponins, named silenegallisaponin A-K (1-11), were isolated from the aerial parts of Silene gallica L. Their structures were elucidated by analysis of 1D and 2D-NMR spectroscopic data and mass spectrometry (HR-ESI-MS). The saponins comprised caulophyllogenin, echinocystic acid, or quillaic acid substituted at C-3 by a β-d-glucuronic acid or β-d-galactopyranosyl-(1 → 3)-β-d-glucuronopyranoside and at C-28 by a β-d-fucopyranose substituted at C-2 by a β-d-glucose and at C-3 by a β-d-glucose or a β-d-quinovose.

Triterpene saponins from the roots of Parkia bicolor A. Chev

Five undescribed triterpene-type saponins, parkibicolorosides A-E, a cassane-type diterpene, and a known trimethoxy benzene glucoside were isolated from the roots of Parkia bicolor A. Chev. Their structures were elucidated by different spectroscopic methods including 1D- and 2D-NMR experiments as well as HR-ESI-MS analysis. Their cytotoxic activity against the chronic myeloid leukemia (K562) cell line was evaluated. The monosaccharides saponins exhibited a moderate antiproliferative activity with IC₅₀ ranging from 48.49 ± 0.16 to 81.66 ± 0.17 μM.

Neuroprotective effects of triterpenoid saponins from Medicago sativa L. against H2O2-induced oxidative stress in SH-SY5Y cells

Medicago sativa L. is a forage legume plant widely distributed in all continents. Six new triterpenoid saponins, Medicagosides A-F (1-6) and five known ones (7-11) were isolated from M. sativa. Their structures were determined via HRESIMS, 1D and 2D NMR analysis. Biologically, all the isolates displayed neuroprotective activities against H₂O₂-induced damage in SH-SY5Y cells. Among them, compounds 1, 3-5 and 10 exhibited striking neuroprotective activities at 100 μM, restoring cell viability range from 79.66% to 89.03%, relative to 79.46% (100 μM) of Trolox used as the positive control.

Scabiosa Genus: A Rich Source of Bioactive Metabolites

The genus Scabiosa (family Caprifoliaceae) is considered large (618 scientific plant names of species) although only 62 have accepted Latin binominal names. The majority of the Scabiosa species are widely distributed in the Mediterranean region and some Scabiosa species are used in traditional medicine systems. For instance, Scabiosa columbaria L. is used traditionally against diphtheria while S. comosa Fisch. Ex Roem. and Schult. is used in Mongolian and Tibetan traditional medical settings to treat liver diseases. The richness of Scabiosa species in secondary metabolites such as iridoids, flavonoids and pentacyclic triterpenoids may contribute to its use in folk medicine. Details on the most recent and relevant pharmacological in vivo studies on the bioactive secondary metabolites isolated from Scabiosa species will be summarized and thoroughly discussed.

Scabiosa stellata L. Phenolic Content Clarifies Its Antioxidant Activity

The phenolic profile of Scabiosa stellata L., a species used in Moroccan traditional medicine, is disclosed. To obtain that profile the species extract was analyzed by ultra-high-performance chromatography coupled to photodiode-array detection and electrospray ionization/ion trap mass spectrometry (UHPLC-DAD-ESI/MSn). Twenty-five phenolic compounds were identified from which isoorientin and 4-O-caffeoylquinic acid can be highlighted because they are the major ones. The antioxidant activity was significantly controlled by the fraction type, with the n-butanol fraction showing the highest antioxidant activity (FRS50 = 64.46 µg/mL in the DPPH assay, FRS50 = 27.87 µg/mL in the ABTS assay and EC50 = 161.11 µg/mL in the reducing power assay). A phytochemical study of the n-butanol fraction was performed, and some important flavone glycosides were isolated. Among them the tamarixetin derivatives-the less common ones-can be emphasized. This phytochemical study and polyphenolic profile can be correlated with S. stellata extracts in vitro antioxidant activity. Moreover, it can be regarded as an evidence of its medicinal use and can incentivize its consumption.