Triterpenes from Salvia argentea var. aurasiaca and their antibacterial and cytotoxic activities.

Five undescribed ursane-type triterpenes, identified as 1ß,3ß,15α-trihydroxy-urs-9(11)-12-diene (1), 1ß,3ß,15α,28-tetrahydroxy-urs-9(11),12-diene (2), 1ß,3ß-dihydroxy-urs-9(11),12-dien-28-al (3), 1ß,3ß,7ß,15α,28-pentahydroxy-urs-12-ene (4), and 1ß,3ß,15α-trihydroxy-urs-11-en-28-al (5), together with five known compounds (6-10), were isolated from the acetone extract of the dried aerial parts of Salvia argentea L. var. aurasiaca (Pomel) Batt. et Trab. (Lamiaceae). Structures were elucidated on the basis of extensive spectroscopic analysis including HR-ESI-MS, 1D- and 2D-NMR techniques and comparison with literature data. The antibacterial evaluation of compounds 1-10 of the acetone extract of the dried aerial parts, in addition to nine compounds (11-19) previously isolated from the extract of the fresh aerial parts, by bioautography on Staphylococcus aureus followed by the determination of MIC values of active compounds by serial dilution technique against five bacteria, revealed that two compounds have an antibacterial effect comparable to antibiotics. The cytotoxic activity evaluation of compounds 1-19 showed that Six compounds exhibited an antiproliferative activity against K562 and HT1080 cells with IC50 values ranging from 30.25 to 70.32 µM.

Triterpenoid saponins from Scabiosa stellata collected in North-eastern Algeria.

Eight undescribed triterpenoid saponins, scabiostellatosides A-H, together with three known compounds were isolated from the whole plant of Scabiosa stellata L. Their structures were established by spectroscopic analyses (1D, 2D-NMR and HRESIMS) and chemical methods. Scabiostellatosides A-H were evaluated for their cytotoxicity against human fibrosarcoma cell line (HT1080). Scabiostellatoside F, a heptasaccharide derivative of oleanolic acid, exhibited moderate cytotoxicity against HT1080 cell line with IC50 value of 12.0 µM.

Antibacterial, antioxidant and cytotoxic activities of triterpenes and flavonoids from the aerial parts of Salvia barrelieri Etl.

From the aerial parts of Salvia barrelieri Etl. (Lamiaceae), 12 compounds including a new triterpene, 3ß-acetoxy-olean-18-ene-2α-ol, were isolated. Their structures were established by the combination analyses of spectroscopy including 1D-, 2D-NMR and HRESIMS and in comparison with the reported data in the literature. The antibacterial activity of these compounds was evaluated by bioautography on Staphylococcus aureus followed by the determination of MIC values by serial dilution technique against five bacteria. Three compounds were active against Enterococcus faecalis, S. aureus, Staphylococcus epidermidis, Escherichia coli and Pseudomonas aeruginosa (MIC 15.1 to 125 µg/mL). Two compounds showed moderate DPPH radical scavenging activity (IC50 79.1 and 21.2 µg/mL). These compounds did not show significant tyrosinase inhibitory activities (IC50> 1.5 mg/mL). Their cytotoxic activity was evaluated against promyelocytic leukaemia (HL60), human erythromyeloblastoid leukaemia (K562) and fibrosarcoma (HT1080) cell lines and four compounds exhibited a moderate cytotoxic activity (IC50 28.75 to 85.0 µM).

Two new bis-iridoids isolated from Scabiosa stellata and their antibacterial, antioxidant, anti-tyrosinase and cytotoxic activities.

This study presents the chemical profile investigation of a 70% ethanol extract obtained from Scabiosa stellata, a medicinal herbaceous traditionally used to treat heel cracks. A 13C NMR-based dereplication methodology was firstly applied on centrifugal partition chromatography-generated fractions in order to quickly identify the major compounds of the extract. The dereplication process was then completed by semi-preparative high-performance liquid chromatography in order to identify unknown or minor compounds. Two new bis-iridoids, namely 7-O-caffeoyl-sylvestroside I (1) and 7-O-(p-coumaroyl)-sylvestroside I (2), together with ten known compounds (3-12) were isolated. Their structures were elucidated by spectroscopic methods including NMR and HR-ESI-MS. The antibacterial, anti-tyrosinase and DPPH radical scavenging activities of the crude extract, fractions, and isolated compounds were evaluated. A significant antibacterial activity was observed for nine isolated compounds, particularly 1 and 2 which yielded MIC values of 31.2µg/mL against Enterococcus faecalis and 62.5µg/mL against Staphylococcus epidermidis. The cytotoxic activity of these new bis-iridoids was evaluated on a fibrosarcoma cell line (HT1080) and only compound 1 exhibited a moderate cytotoxic activity (IC50 35.9µg/mL).

Oleanane-type triterpene saponins from Calendula stellata.

Five previously undescribed bisdesmosidic triterpenoid saponins named calendustellatosides A-E, along with fifteen known compounds were isolated from the 70% ethanol whole plant extract of Calendula stellata Cav. (Asteraceae). Their structures were determined by 1D- and 2D-NMR spectroscopy as well as high resolution mass spectrometry and acid hydrolysis. The saponins comprised oleanolic acid, echinocystic acid, morolic acid or mesembryanthemoidigenic acid as the aglycones and saccharide moieties at C-3 and C-28. Like most Calendula saponins, the sugar moiety linked at C-3 was either ß-d-glucose or ß-d-glucuronic acid which could be substituted at C-3 by a ß-d-galactose and/or C-2 by a supplementary ß-d-galactose or a ß-d-glucose. The sugar moiety linked to C-28 was determined as ß-d-glucose. The antibacterial evaluation of compounds 1-20 by bioautography on Staphylococcus aureus followed by the determination of MIC values of active compounds by serial dilution technique against 5 bacteria revealed that; calendustellatoside D was the most active against Enterococcus faecalis with an antibacterial effect comparable to antibiotics. The cytotoxic activities of isolated compounds were evaluated against fibrosarcoma cell line (HT1080) and human lung cancer cell line (A549). Calendustellatosides B and D exhibited a low cytotoxic activity against HT1080 cell line with IC50 values of 47 ± 0.6 and 39 ± 0.5 µM, respectively.