Henrin A (1), a new ent-kaurane diterpene, was isolated from the leaves of Pteris henryi. The chemical structure was elucidated by analysis of the spectroscopic data including one-dimensional (1D) and two-dimensional (2D) NMR spectra, and was further confirmed by X-ray crystallographic analysis. The compound was evaluated for its biological activities against a panel of cancer cell lines, dental bacterial biofilm formation, and HIV. It displayed anti-HIV potential with an IC₅₀ value of 9.1 µM (SI = 12.2).

We report the isolation of a novel diterpene, designated as `amethane', from Isodon amethystoides (Lamiaceae). The diterpene [amethinol A; systematic name: (4aR,4bR,7R,10aS)-4b,7-dihydroxy-7-isopropyl-1,1-dimethyl-9-oxododecahydrobenzo[a]azulene-4a(2H)-carboxylic acid], possesses a unique skeleton containing a six/five/seven-membered tricyclic system. Intermolecular O—H...O close contacts were found to the carboxyl, carbonyl and hydroxy groups, connecting molecules into a two-dimensional structure. A possible biosynthetic pathway has been proposed. In addition, the compound was evaluated for its biological activities against different disease targets, and was found to significantly attenuate RORγt-dependent autoimmune responses.

A phytochemical investigation of the leaves of the medicinal plant Isodon rubescens led to the isolation of the two new degraded abietane lactone diterpenoids rubesanolides F (1) and G (2). Their structures were elucidated based on the analyses of the HRESIMS and 1D/2D NMR spectral data, and their absolute configurations were determined by ECD spectrum calculations and X-ray single crystal diffraction methods. Compounds 1 and 2, with a unique γ-lactone subgroup between C-8 and C-20, were found to form a carbonyl carbon at C-13 by removal of the isopropyl group in an abietane diterpene skeleton. Rubesanolide G (2) is a rare case of abietane that possesses a cis-fused configuration between rings B and C. The two isolates were evaluated for their biological activities against two cancer cell lines (A549 and HL60), three fungal strains (Candida alba, Aspergillus niger and Rhizopus nigricans) and three bacterial strains (Escherichia coli, Staphylococcus aureus and Bacillus subtilis).

Aim. To screen active sites from roots, stems, and leaves of Caesalpinia minax and study its antitumor effect. Methods. Human liver cancer HuH‐7 cells were used to screen the active sites of C. minax by MTT assay, and the polar extracts were analyzed by high‐performance liquid chromatography (HPLC). The medicated serum prepared from rats was used to investigate the effect on the proliferation of Hepa 1–6 mouse hepatoma cells. The H22 hepatoma‐bearing mice model was established and treated with the petroleum ether extract of stems and leaves (HY②) by intraperitoneal injection (20, 60 mg·kg⁻¹) and intragastric (100, 300 mg·kg⁻¹) for 12 days. Results. The petroleum ether extracts were the effective active site. The IC₅₀ value of the petroleum ether extract of stems and leaves (HY②) was 58.9 μg·ml⁻¹, and that of the roots (HG②) was 46.79 μg·ml⁻¹. The grey relational analysis cleared that the 11 common peaks of the active extracts had a close correlation with the antitumor activity. The medicated serum prepared by ip. administration had a significant inhibitory effect on the Hepa1‐6 cells, but it had no inhibitory effect by intragastric administration. High‐dose administration significantly reduced tumor size in H22 hepatoma‐bearing mice, and the tumor inhibition rates were 64.47% and 53.41%. Necrosis of tumor cells, infiltration of inflammatory cells, and fibrous tissue proliferation were promoted, and the expression of the proliferating cell nuclear antigen (PCNA) and vascular endothelial growth factor (VEGF) was reduced compared with the control group. Conclusion. The petroleum ether extract of C. minax had a significant antitumor activity. An immunohistochemical study showed that, through inhibiting the expression of the VEGF and growth of the tumor blood vessel, the proliferation of tumor cell and expression of PCNA can be inhibited.

C₃₀H₄₀O₅, orthorhombic, P2₁2₁2₁ (no. 19), a = 6.5012(3) Å, b = 15.3297(7) Å, c = 21.8138(14) Å, V = 2672.3(2) ų, Z = 4, R_gt(F) = 0.0537, wR_ref(F²) = 0.1355, T = 273(2) K.

C₁₈H₁₆O₇, monoclinic, P2₁/c (no. 14), a = 7.3948(3) Å, b = 24.2947(9) Å, c = 17.3201(6) Å, β = 93.063(1)°, V = 3107.2(2) ų, Z = 4, R _gt (F) = 0.0427, wR _ref (F ²) = 0.1241, T = 300(2) K.