New ent-Kaurane and cleistanthane diterpenoids with potential cytotoxicity from Phyllanthus acidus (L.) Skeels

Phyllanfranins A-F, anti-inflammatory ent-cleistanthane diterpenoids from Phyllanthus franchetianus

A comprehensive chemical investigation of the EtOAc extract derived from the dried branches and leaves of Phyllanthus franchetianus H. Lév had successfully resulted to the isolation of six undescribed cleistanthane diterpenoids phyllanfranins A-F (1-6), along with three known compounds phyllarheophol C (7), phyacioid C (8), and spruceanol (9). The chemical structures of these compounds were elucidated by combined means of HRESIMS, 1D and 2D NMR spectra, together with ECD calculations. The absolute configuration of phyllanfranin A (1) was established by single crystal X-ray diffraction analysis. Notably, phyllanfranin F (6) represents the first ent-cleistanthane diterpenoid with the unique 6/6/6/6 tetracyclic system occurring in nature. Additionally, all the isolates were evaluated for anti-inflammatory activities. As a result, compounds 4 and 8 showed notable inhibitory activity against NO production in LPS-stimulated macrophages RAW264.7 cells, with IC50 values of 19.03 and 18.14 μM, respectively.

Naturally Occurring Cleistanthane Diterpenoids and Their Biological Activities

Cleistanthane diterpenoids, an important class of active natural products, are characterized by a 6/6/6 tricycle system and contain a variety of functional groups. Studies have shown that cleistanthane diterpenoids are widespread in various higher plants and endophytic fungi and exhibit a wide range of biological activities. This review provides extensive coverage of naturally occurring cleistanthane diterpenoids discovered from 1973 to 2024 and sheds light on the sources, structures, biological effects, and primary molecular mechanisms of them and provides a useful reference for the further study and development of these compounds.

Pacidusin B isolated from Phyllanthus acidus triggers ferroptotic cell death in HT1080 cells

Cancer cells generally exhibit 'iron addiction' phenotypes, which contribute to their vulnerability to ferroptosis inducers. Ferroptosis is a newly discovered form of programmed cell death caused by iron-dependent lipid peroxidation. In the present study, pacidusin B, a dichapetalin-type triterpenoid from Phyllanthus acidus (L.) Skeels (Euphorbiaceae), induces ferroptosis in the HT1080 human fibrosarcoma cell line. Cells treated with pacidusin B exhibited the morphological characteristic 'ballooning' phenotype of ferroptosis. The biochemical hallmarks of ferroptosis were also observed in pacidusin B-treated cells. Both oxidative stress and ER stress play significant roles in pacidusin B-induced ferroptosis. The activation of the PERK-Nrf2-HO-1 signaling pathway led to iron overload, while inhibition of GPX4 further sensitized cancer cells to ferroptosis. Furthermore, the molecular docking study showed that pacidusin B docked in the same pocket in xCT as the ferroptosis inducer erastin. These results revealed that pacidusin B exerts anticancer effects via inducing ER-mediated ferroptotic cell death.

Identification of New Diterpenoids from the Pulp of Coffea arabica and Their α-Glucosidase Inhibition Activity

Six new (1, 2, 3, 5, 6, and 8) and seven known (4, 7, 9, 10, 11, 12, and 13) diterpenoids have been identified in the pulp of Coffea arabica. The structures of new diterpenoids were elucidated by extensive spectroscopic analysis, including 1D, 2D NMR (HSQC, HMBC, 1H-1H COSY, and ROESY), HRESIMS, IR, DP4+, electronic circular dichroism, and X-ray crystallography analysis. Compound 1 is ent-labdane-type diterpenoid, whereas compounds (2-13) are ent-kaurane diterpenoids. The result of α-glucosidase inhibitory assay demonstrated that compounds (1, 3, 5, 7, and 10) have moderate inhibitory activity with IC50 values of 55.23 ± 0.84, 74.02 ± 0.89, 66.46 ± 1.05, 49.70 ± 1.02, and 76.34 ± 0.46 μM, respectively, compared to the positive control (acarbose, 51.62 ± 0.21 μM). Furthermore, molecular docking analysis has been conducted to investigate the interaction between the compounds and the receptors of α-glucosidase to interpret their mechanism of activity. This study is the first investigation that successfully discovered the presence of diterpenoids within the coffee pulp.

Bioactive compounds from Vellozia pyrantha A.A.Conc: A metabolomics and multivariate statistical analysis approach

The chemical composition of V. pyrantha resin (VpR) and fractions (VpFr1-7 and VpWS) were assessed by LC-MS and NMR. Twenty-eight metabolites were identified, including 16 diterpenoids, seven nor-diterpenoids, one fatty acid, one bis-diterpenoid, one steroid, one flavonoid, and one triterpenoid. The pharmacological potential of VpR, VpFr1-7, and isolated compounds was assessed by determining their antioxidant, antimicrobial, and cytotoxic activities. VpFr4 (IC50 = 205.48 ± 3.37 μg.mL-1) had the highest antioxidant activity, whereas VpFr6 (IC50 = 842.79 ± 10.23 μg.mL-1) had the lowest. The resin was only active against Staphylococcus aureus (MIC 62.5 μg.mL-1) and Salmonella choleraesius (MIC and MFC 500 μg.mL-1), but fractions were enriched with antibacterial compounds. V. pyrantha resin and fractions showed great cytotoxic activity against HCT116 (IC50 = 20.08 μg.mL-1), HepG2 (IC50 = 20.50 μg.mL-1), and B16-F10 (12.17 μg.mL-1) cell lines. Multivariate statistical analysis was used as a powerful tool to pinpoint possible metabolites responsible for the observed activities.

New seco-anthraquinone glucoside from the roots of Rumex crispus

A new seco-anthraquinone, crispuside A (1), and three new 3,4-dihydronaphthalen-1(2H)-ones, napthalenones A-C (2-4), were isolated from the roots of Rumex crispus L., along with 10 known anthraquinones (6-14) and naphthalenone (5). Their structures were fully determined by extensive spectroscopic analyses, including ECD, and X-ray crystallography in case of compound 5, whose absolute configuration was determined for the first time. The isolates 1, 6-14 were evaluated for their anti-inflammatory and anti-fungal activity against three skin fungi, e.g., Epidermophyton floccosum, Trichophyton rubrum, and Microsporum gypseum. Most of the isolates showed weak anti-fungal and anti-inflammatory activity. Only compound 9 exhibited obvious anti-fungal activity against E. floccosum (MIC₅₀ = 2.467 ± 0.03 μM) and M. gypseum (MIC₅₀ = 4.673 ± 0.077 μM), while the MIC₅₀ values of the positive control terbinafine were 1.287 ± 0.012 and 0.077 ± 0.00258 μM, respectively. The results indicated that simple emodin type anthraquinone is more potential against skin fungi than its oxyglucosyl, C-glucosyl and glycosylated seco analogues.