Polyoxygenated ursane and oleanane triterpenes from Siphonodon celastrineus

Pentacyclic Triterpenoids Isolated from Celastraceae: A Focus in the 13C-NMR Data

The Celastraceae family comprises about 96 genera and more than 1.350 species, occurring mainly in tropical and subtropical regions of the world. The species of this family stand out as important plant sources of triterpenes, both in terms of abundance and structural diversity. Triterpenoids found in Celastraceae species display mainly lupane, ursane, oleanane, and friedelane skeletons, exhibiting a wide range of biological activities such as antiviral, antimicrobial, analgesic, anti-inflammatory, and cytotoxic against various tumor cell lines. This review aimed to document all triterpenes isolated from different botanical parts of species of the Celastraceae family covering 2001 to 2021. Furthermore, a compilation of their ¹³C-NMR data was carried out to help characterize compounds in future investigations. A total of 504 pentacyclic triterpenes were compiled and distinguished as 29 aromatic, 50 dimers, 103 friedelanes, 89 lupanes, 102 oleananes, 22 quinonemethides, 88 ursanes and 21 classified as others.

Microbial transformation and inhibitory effect assessment of uvaol derivates against LPS and HMGB1 induced NO production in RAW264.7 macrophages

For the discovery of new pentacyclic triterpenes as a potential anti-inflammatory agent, microbial transformation of uvaol by Penicilium griseofulvum CICC 40293 and Streptomyces griseus ATCC 13273 was investigated. Stereoselective hydroxylation and epoxidation reactions were observed in the biotransformation. Moreover, six new metabolites were isolated and structurally elucidated by HR-ESI-MS and NMR spectrum. All the compounds were evaluated upon the inhibitory effects of nitric oxide (NO) release in RAW 264.7 cells induced by lipopolysaccharide (LPS) and high-mobility group box 1 (HMGB1). Among them, compound 3 (13, 28-epoxy-3β, 7β, 21β-trihydroxy-urs-11-ene) with the unique epoxy structure and compound 5 (3β, 21β, 24, 28-tetrahydroxy-urs-12-en-30-oic acid), exhibited a considerable inhibitory effect on both models while compound 2 (urs-12-ene-3β, 7β, 21β, 28-tetraol) showed a significant bias in the LPS-induced inflammatory response with IC₅₀ value of 2.22 μM. Therefore, this study could provide some insights on the discovery of the pentacyclic triterpene leads for the treatment of either DAMPs or PAMPs triggered inflammation.

New Polyesterified Ursane Derivatives from Leaves of Maesa membranacea and Their Cytotoxic Activity

Maesa membranacea A. DC. (Primulaceae) is a plant species that has been frequently used by practitioners of the traditional ethnobotany knowledge from northern and central Vietnam. However, the chemical constituents of the plant remained unknown until recently. Chromatographic separation of a chloroform-soluble fraction of extract from leaves of M. membranacea led to the isolation of two new polyesterified ursane triterpenes (1–2) and two known apocarotenoids: (+)-dehydrovomifoliol (3) and (+)-vomifoliol (4). The chemical structures of the undescribed triterpenoids were elucidated using 1D and 2D MNR and HRESIMS spectral data as 2α,6β,22α-triacetoxy-11α-(2-methylbutyryloxy)-urs-12-ene-3α,20β-diol (1) and 2α,6β,22α-triacetoxy-urs-12-ene-3α,11α,20β-triol (2). The newly isolated triterpenoids were tested for their cytotoxic activity in vitro against two melanoma cell lines (HTB140 and A375), normal skin keratinocytes (HaCaT), two colon cancer cell lines (HT29 and Caco-2), two prostate cancer cell lines (DU145 and PC3) and normal prostate epithelial cells (PNT-2). Doxorubicin was used as a reference cytostatic drug. The 2α,6β,22α-triacetoxy-11α-(2-methylbutyryloxy)-urs-12-ene-3α,20β-diol demonstrated cytotoxic activity against prostate cancer cell lines (Du145—IC₅₀ = 35.8 µg/mL, PC3—IC₅₀ = 41.6 µg/mL), and at a concentration of 100 µg/mL reduced viability of normal prostate epithelium (PNT-2) cells by 41%.

Uvarmicranones A and B, two new benzoquinones and cytotoxic constituents from the stems of Uvaria micrantha (A. DC.) Hook. f. & Thomson

Two novel benzoquinones, uvarmicranones A (1) and B (2), along with 15 known compounds (3 - 17) were isolated from the stems of Uvaria micrantha (Annonaceae). Their structures were elucidated by analyses of NMR and high-resolution mass data. A plausible biosynthetic pathway of uvarmicranone A (1) via Diels-Alder cycloaddition reaction was also proposed. Some isolated compounds were evaluated for their cytotoxic activities. Compounds 1, 14, and 15 showed moderate cytotoxic effects against T-cell acute lymphoblastic cells (MOLT-3), with IC₅₀ values of 7.83 ± 0.83, 6.53 ± 1.01, and 4.20 ± 0.29 μM, respectively. Additionally, compound 15 exhibited moderate cytotoxicity against cervical carcinoma cells (HeLa) with an IC₅₀ value of 7.00 ± 3.15 μM.

Siphonagarofurans A-J: Poly-O-acylated β-dihydroagarofuran sesquiterpenoids from the fruits of Siphonodon celastrineus

Ten poly-O-acylated β-dihydroagarofuran sesquiterpenoids, siphonagarofurans A-J, were obtained from the fruits of Siphonodon celastrineus using chromatographic techniques. Their structures were elucidated by extensive use of 2-D NMR spectroscopic methods. The absolute configurations of siphonagarofurans A-J were assigned following analysis of calculated and experimental ECD spectra. The absolute configuration of siphonagarofuran A was also confirmed by X-ray crystallographic analysis. Selected compounds were evaluated for their cytotoxic activity against KB, Vero and Hela cell lines with siphonagarofuran J identified as the most active compound, with IC₅₀ values ranging from 14 to 27 μM.