Studies in sesquiterpenes—XLIX

Virenscarotins A-M, thirteen undescribed carotane sesquiterpenes from the fungus Trichoderma virens

A document investigation on the fungus Trichoderma virens led to the isolation of thirteen undescribed carotane sesquiterpenes and homologous. All structures were elucidated on the basis of NMR and HRESIMS data, and their absolute configurations were assigned by ECD calculation. Especially, virenscarotins A and B were first ramifications forged by aldol condensation of 4-hydroxy-3-isopentenyl-benzaldehyde with two hydroxyl groups in ring A of traditional carotane sesquiterpenes. Ring rearrangement/expansion and oxidative cleavage of normal carotane sesquiterpenes lead to the six-membered ring A of compound virenscarotin C and the ring A cleavage of compound virenscarotin D. All compounds were evaluated for cytotoxic, anti-inflammatory, and seed germination inhibitory activities.

Antiausterity Activity of Secondary Metabolites from the Roots of Ferula hezarlalehzarica against the PANC-1 Human Pancreatic Cancer Cell Line

Human pancreatic cancer is one of the most aggressive types of cancer, with a high mortality rate. Due to the high tolerance of such cancer cells to nutrient starvation conditions, they can survive in a hypovascular tumor microenvironment. In this study, the dichloromethane extract of the roots of Ferula hezarlalehzarica showed potent preferential cytotoxic activity with a PC₅₀ value of 0.78 μg/mL. Phytochemical investigation of this extract led to the isolation of 18 compounds, including one new sesquiterpenoid (6) and one new monoterpenoid (18). All isolated compounds were evaluated for their preferential cytotoxicity against PANC-1 human pancreatic cancer cells by employing an antiausterity strategy. Among them, ferutinin (2) was identified as the most active compound, with a PC₅₀ value of 0.72 μM. In addition, the real-time effect of ferutinin (2) and compound 6 against PANC-1 cells, exposed to a nutrient-deprived medium (NDM), showed cell shrinkage, leading to cancer cell death within a short period of exposure. Compounds 2 and 6 also inhibited colony formation of PANC-1 cells. The present study indicates that the dichloromethane extract of the roots of F. hezarlalehzarica is a rich source of bioactive compounds for targeting PANC-1 cells.

Penigrisacids A-D, Four New Sesquiterpenes from the Deep-Sea-Derived Penicillium griseofulvum

Four new (penigrisacids A–D, 1–4) and one known (5) carotane sesquiterpenoids were isolated from the deep-sea-derived fungus Penicillium griseofulvum, along with four known compounds (6–9). The planar structures and relative configurations of the new compounds were determined by extensive analysis of the NMR and HRESIMS data. The absolute configurations were established by comparison of the experimental and calculated ECD (electronic circular dichroism) spectra or OR (optical rotation) value. Compound 9 exhibited potent anti-food allergic activity with IC₅₀ value of 28.7 μM, while 4 showed weak cytotoxicity against ECA-109 tumor cells (IC₅₀ = 28.7 μM).

A method for investigating the stereochemical course of terpene cyclisations

The products of three bacterial terpene cyclases were characterised and the mechanisms of their formations were investigated using isotopic labellings.

Feruhermonins A-C: three daucane esters from the seeds of Ferula hermonis (Apiaceae)

Seventeen daucane esters have been isolated from the seeds of Ferula hermonis Boiss (Apiaceae). Three of these sesquiterpenes, 4beta-hydroxy-6alpha-benzoyl-7-daucen-9-one (1), 4beta, 8beta-dihydroxy-6alpha-benzoyl-dauc-9-ene (2), and 4beta, 9alpha-dihydroxy-6alpha-benzoyl-dauc-7-ene (4), named feruhermonins A-C, respectively, are novel natural products. The structures of these compounds were elucidated unequivocally by a series of 1D and 2D NMR analyses. Although 4beta, 8beta-dihydroxy-6alpha-(4-hydroxy-3-methoxybenzoyl)-dauc-9-ene (3) was reported previously, the complete spectroscopic data for this compound are presented here for the first time.