Quassinoids from the twigs and thorns of Castela polyandra

Quassinoids: Phytochemistry and antitumor prospect

Quassinoids, originating from the oxidative degradation of tetracyclic tirucallane triterpene, are a diverse class of secondary metabolites identifying from nature mostly in Simaroubaceae family. The crucial pharmacological activities and structural complexity of quassinoids have long fascinated scientists due to their medicinal uses, infamous toxicity, and unique biosynthesis. In the past few decades, 482 quassinoids, assigned to 6 skeletons, have been isolated and identified from plants. The names, classes, molecular formula, and plant sources of these secondary metabolites are collated here. This review will be a detailed update of the naturally occurring quassinoids reported from the plant kingdom, providing an in-depth discussion of their diversity, antitumor activities, structure-activity relationship.

Chemical constituents and synergistic anti-gout studies on Eurycoma longifolia and potential mechanisms evaluation based on systemic analysis approach

37 compounds mainly including triterpenoids with the quassinoid skeleton and β-carboline alkaloids have been isolated from the roots of Eurycoma longifolia Jack (EL), which has been used as traditional medicine for a long history. It has been demonstrated that the total extracts from EL could significantly inhibit the joint swelling in MSU-induced acute gout arthritis rat model at middle and high doses (P < 0.05, P < 0.01), as meanwhile, better performance than that of positive control (P < 0.05, P < 0.01) has been observed at the dose of 10 g/kg. Aiming to search potential compounds and probable mechanisms, network pharmacology, molecular docking and Kyoto encyclopedia of genes and genomes (KEGG) pathway enrichment analysis were adopted, leading to the hypothesis of 17 targets related to different pathogenesis of gout and 5 potential compounds (C36, C107, C124, C125 and C130) among 156 selected compounds, playing synergetic role with multiple targets. Instead of the guiding ideology of "a gene, a drug, a disease", varieties of compounds but not a single one from EL display holistic performance through multiple pathways with multi-targets. It was noteworthy that Xanthine dehydrogenase/oxidase (XDH), Prostaglandin G/H synthase 2 (PTGS2), Fatty acid-binding protein, liver (FABP1), Purine nucleoside phosphorylase (PNP), and Peroxisome proliferator activated receptor alpha (PPARA) were the key targets with intensely interaction. Furthermore, the functional enrichment analysis indicated that EL probably produced the gout protection effects by synergistic regulation in multiple biological pathways, including Toll-like receptor signaling pathway, MAPK signaling pathway, and NOD-like receptor signaling pathway, etc.

Four new quassinoids from the roots of Eurycoma longifolia Jack

Seven compounds were isolated from the roots of Eurycoma longifolia, and characterized by comprehensive analysis of 1D and 2D NMR experiments along with single crystal X-ray diffraction. Among them, four new quassinoids were identified and three of them were diastereomers for each other. Compounds 1-7 were evaluated for cytotoxicities against HT-29, MCF-7, LOVO, BGC-823, MGC-803, HepG2, HeLa, and A549 cancer cell lines. Compounds 2 and 5 exhibited the lowest IC50 values of 24.9 μM, 11.8 μM, and 44.1 μM, 14.1 μM towards MCF-7, MGC-803 cancer cell lines, respectively, while compound 6 exhibited moderate cytotoxicity towards all the selected cancer cell lines.

Three new quassinoids, ailantinol E, F, and G, from Ailanthus altissima

Three new quassinoids, ailantinol E (1), ailantinol F (2), and ailantinol G (3), and related compounds were isolated from Ailanthus altissima grown in Taiwan. Their structures were elucidated from spectral evidence. Each new quassinoid was evaluated for its antitumor promoting effects against Epstein-Barr virus early antigen activation introduced by 12-O-tetradecanoylphorbol-13-acetate in Raji cells. The new quassinoids were found to show potent activity without showing any cytotoxicity. The screening for inhibitors against nitric oxide donor action was also conducted using the new quassinoids and some standard samples.

Non-quassinoid constituents from the twigs and thorns of Castela polyandra

The structures of two new constituents, a beta-glycoside (1) and a steroid (2), isolated from the twigs and thorns of Castela polyandra, were established by a combination of spectroscopic and single-crystal X-ray analysis.