Jasonol, a rare tricyclic eudesmane sesquiterpene and six other new sesquiterpenoids from Jasonia candicans

Sesquiterpenes from the aerial parts of Artemisia vachanica krasch. ex poljakov and their anti-inflammatory and anti-diabetic activities

Eleven undescribed sesquiterpenes, vachanins A-K covering types of germacrane, eudesmane, guaiacane, and cadinane, along with fifteen known analogs were isolated from the aerial parts of Artemisia vachanica Krasch. ex Poljakov. Their structures were established on the basis of HRMS and NMR data, and their absolute configurations were successfully determined by single-crystal X-ray diffraction analysis, 13C-NMR calculations and DP4+ probability analysis, and ECD data in corporation with quantum chemical calculations. Vachanin A is the first example of germacrane bearing an uncommon C5, C10-oxygen bridge. All isolated compounds were assayed for anti-inflammatory and anti-diabetic activities. Compounds 15 and 22 presented weak anti-inflammatory activity by inhibiting the release of NO in RAW 264.7 cells induced by LPS with IC50 values of 42.82 ± 1.43, and 63.37 ± 3.28 μM.

The sesquiterpenes with the COVID-19 Mpro inhibitory activity from the Carpesium abrotanoides L

The extract of the whole plant of Carpesium abrotanoides L. yielded four new sesquiterpenes including a novel skeleton (claroguaiane A, 1), two guaianolides (claroguaianes B-C, 2-3), and one eudesmanolide (claroeudesmane A, 4), together with three known sesquiterpenoids (5-7). The structures of the new compounds were elucidated by spectroscopic analysis especially 1D and 2D NMR spectroscopy and HRESIMS data. Additionally, all the isolated compounds were preliminarily evaluated for the inhibitive activity of COVID-19 Mpro. As a result, compound 5 showed moderate activity with an IC50 value of 36.81 μM and compound 6 exhibited a potent inhibitory effect with an IC50 value of 16.58 µM, while other compounds were devoid of noticeable activity (IC50 > 50 μM).

Sesquiterpene Acids and Lactones from Inula Confertiflora with their Antibacterial Activities

The phytochemical investigation of the leaves of Inula confertiflora, a medicinal plant endemic to Ethiopia, led to the isolation of 15 terpenoids; 1β-hydroxy-α-costic acid (1), 3α-hydroxycostic acid (2), isotelekin (3), asperilin (4), carabrone (5), carpesioline (6), graveolide (7), inuviscolide (8), 8-epi-inuviscolide (9), 1β,4β-dihydroxy-5α(H)-guaia-10(14),11(13)-dien-8α,12-olide (10), isoinuviscolide (11), 4β,10β-dihydroxy-5α(H)-1,11(13)-guaidien-8α,12-olide (12), 4β,10β-dihydroxy-1β(H)-5α(H)-guai-11(13)-en-8α,12-olide (13), 4β,10α-dihydroxy-1β(H)-5α(H)-guai-11(13)-en-8α,12-olide (14), 4β,10α-dihydroxy-1α(H)-5α(H)-guai-11(13)-en-8α,12-olide (15). Herein, structural elucidation and full NMR data for compound 1 are presented for the first time. The structures were elucidated using NMR, HRESIMS, and by comparison with literature data. The relative configurations were defined by NOESY correlations and single-crystal X-ray crystallography. Herein, crystallography data of 6 and 7 were reported for the first time. The antibacterial efficacy of some of the isolated compounds was evaluated against two commonly dispersed environmental strains of Escherichia coli and Staphylococcus aureus. Compounds 1, 3, 6, 7, and 8 exhibited moderate antibacterial activities against the tested organisms. The chemotaxonomic significance of compounds is discussed.

Germacrene A-A Central Intermediate in Sesquiterpene Biosynthesis

This review summarises known sesquiterpenes whose biosyntheses proceed through the intermediate germacrene A. First, the occurrence and biosynthesis of germacrene A in Nature and its peculiar chemistry will be highlighted, followed by a discussion of 6-6 and 5-7 bicyclic compounds and their more complex derivatives. For each compound the absolute configuration, if it is known, and the reasoning for its assignment is presented.

Nitric Oxide Inhibitory Dimeric Sesquiterpenoids from Artemisia rupestris

Twelve new dimeric sesquiterpenoids (1-12) were isolated from the dried whole plants of Artemisia rupestris. Their structures were determined using MS and NMR data, and the absolute configurations were elucidated on the basis of experimental and calculated ECD spectra. Compounds 1-9 are presumably formed via biocatalyzed [2+2] or [4+2] cycloaddition reactions. Stereoselectivity of the [4+2] Diels-Alder reaction dictated the formation of endo-products. The dimeric sesquiterpenoids exhibited moderate inhibition on NO production stimulated by lipopolysaccharide in BV-2 microglial cells, with IC50 values in the range 17.0-71.8 μM.

Eudesmane-type sesquiterpene derivatives from Laggera alata

Ten eudesmane-type sesquiterpene derivatives (1-10), including six cuauhtemone derivatives (1-6), one di-norsesquiterpene (3-oxo-di-nor-eudesma-4-en-11-oic acid, 7), and three eudesmane glycosides (alatoside F-H, 8-10) were isolated from the whole plants of Laggera alata together with 12 known compounds. Their structures were elucidated on the basis of extensive spectroscopic analysis, acid hydrolysis, and compounds 1 and 7 were studied by single-crystal X-ray diffraction analysis. The absolute configuration of 1 was determined by the application of the modified Mosher's method. All of the isolated eudesmane-type sesquiterpenes were evaluated for their cytotoxic activities on six human cancer cell lines, but all of the compounds were inactive on the tested cell lines in the concentration of 100 μg/mL.

Contact sensitization to calocephalin, a sesquiterpene lactone of the guaianolide type from cushion bush (Leucophyta brownii, Compositae)

BACKGROUND

Cushion bush [Leucophyta brownii Cass. = Calocephalus brownii (Cass.) F. Muell.] is an Australian Compositae shrub that has been introduced into Scandinavia as a pot plant. The first case of sensitization occurred in a gardener, and the main allergen was identified as the guaianolide calocephalin.

OBJECTIVE

To present the identification of the main allergen, and to assess the prevalence of sensitization to calocephalin in Compositae-allergic patients.

MATERIALS AND METHODS

Calocephalin was isolated from a dichloromethane extract of aerial parts of cushion bush. Calocephalin 0.1% ethanol was included in the plant series in Malmö, Sweden, and Odense, Denmark.

RESULTS

Nuclear magnetic resonance (NMR) analysis of calocephalin resulted in a revision of its chemical structure to 4α-acetoxy-1α,2α-epoxy-5α,10αH-guai-11(13)-en-12,8β-olide. The prevalence of patch test positivity was up to 28% in aimed patch testing. Despite strongly positive patch test reactions, the relevance was unknown in the majority of cases, and only 1 person was occupationally sensitized.

CONCLUSION

Calocephalin is a potent contact allergen, but, as cushion bush is a low-maintenance pot plant, primary sensitization is most likely to occur through occupational exposure. Positive reactions in Compositae-sensitive persons probably occur because of cross-reactivity, and patients should be warned about contact with cushion bush plants.

Sesquiterpenoids from Carpesium divaricatum and their cytotoxic activity

In the course of searching for cytotoxic terpenoids from medicinal plants in China, two new eudesmane sesquiterpenoids, 5α-hydroxy-13-methoxy-7αH,11αH-eudesm-4(15)-en-12,8β-lactone (1) and 1β-hydroxy-7αH,11αH-eudesm-4(15)-en-12,8β-lactone (2), along with fourteen known sesquiterpenoids were isolated from the whole plant of Carpesium divaricatum. The structures of new compounds were determined using spectroscopic methods, including IR, HRESIMS, and 1D and 2D NMR spectroscopy. The cytotoxicity of selected sesquiterpene lactones against human oral epidermoid carcinoma (KB), human breast cancer (MCF-7) and human hepatoma (HepG-2) cells was also evaluated by MTT method.

Eudesmane sesquiterpenoids from the Asteraceae family

This review covers the structures and biological activities of eudesmane-type sesquiterpenoids from the plants of the Asteraceae family. Biosynthetic studies or chemical syntheses leading to the revision of structures or stereochemistries have also been included, and 593 references are cited.

A new alpha-methylene gamma-lactone sesquiterpene from Hedyosmum arborescens

A new sesquiterpene lactone, 7alpha,10alpha-epoxy-1alpha(H),5alpha(H)-guaia-3,11(13)-dien-8alpha,12-olide, was isolated from the leaves of Hedyosmum arborescens. The structure of this unusual 7,10-epoxy-guaianolide was determined by spectroscopic methods, particularly one- and two-dimensional 1H and 13C NMR.

Jasomontanone, a Novel Bicyclic Sesquiterpene from the Leaves of Jasonia montana

A novel rearranged eudesmane sesquiterpene with a new 5/7 membered bicyclic-ring-system, jasomontanone, was isolated from Jasonia montana. Its structure was determined as (3a R*, 6 R*, 8a R)-3a-(hydroxymethyl)-6-(2-hydroxy-propan-2-yl)-8a-methyl-octahydrazulen-4(5 H)-one by analysis of spectroscopic data (IR, HR-MS, 1H and 13C NMR), including 2D NMR (1H-1H COSY, HMQC, HMBC and NOESY), chemical transformation, and biogenetic consideration.