Limonoids with modified furan rings from root barks of Toona sinensis

Traditional Uses, Chemical Constituents and Pharmacological Activities of the Toona sinensis Plant

Toona sinensis (A. Juss.) Roem., which is widely distributed in China, is a homologous plant resource of medicine and food. The leaves, seeds, barks, buds and pericarps of T. sinensis can be used as medicine with traditional efficacy. Due to its extensive use in traditional medicine in the ancient world, the T. sinensis plant has significant development potential. In this review, 206 compounds, including triterpenoids (1-133), sesquiterpenoids (134-135), diterpenoids (136-142), sterols (143-147), phenols (148-167), flavonoids (168-186), phenylpropanoids (187-192) and others (193-206), are isolated from the T. sinensis plant. The mass spectrum cracking laws of representative compounds (64, 128, 129, 154-156, 175, 177, 179 and 183) are reviewed, which are conducive to the discovery of novel active substances. Modern pharmacological studies have shown that T. sinensis extracts and their compounds have antidiabetic, antidiabetic nephropathy, antioxidant, anti-inflammatory, antitumor, hepatoprotective, antiviral, antibacterial, immunopotentiation and other biological activities. The traditional uses, chemical constituents, compound cracking laws and pharmacological activities of different parts of T. sinensis are reviewed, laying the foundation for improving the development and utilization of its medicinal value.

Inhibition of the P2X7/NLRP3 Inflammasome Signaling Pathway by Deacetylgedunin from Toona sinensis

Limonoids are considered the effective part in Meliaceae plants that exert anti-inflammatory effects. Gedunin-type limonoids specifically have anti-inflammatory effects. However, the role of gedunin-type limonoids in the inflammatory diseases mediated by NLRP3 inflammasome remains to be explored. We found that deacetylgudunin (DAG), a gedunin-type limonoid from Toona sinensis, had similar anti-inflammatory effects and lower toxicity than gedunin. Further studies showed that DAG down-regulated the NF-κB pathway, inhibited K⁺ efflux and ROS release, inhibited ASC oligomerization, and significantly weakened the interaction of NLRP3 with ASC and NEK7. Furthermore, DAG could not further inhibit IL-1β secretion and K⁺ efflux when combined with the P2X7 inhibitor A438079. In conclusion, our research revealed that DAG exerted an anti-inflammatory effect by inhibiting the P2X7/NLRP3 signaling pathway and enriched the application of gedunin-type limonoids in inflammatory diseases driven by the NLRP3 inflammasome.

Research progress of meliaceous limonoids from 2011 to 2021

Covering: July 2010 to December 2021Limonoids, a kind of natural tetranortriterpenoids with diverse skeletons and valuable insecticidal and medicinal bioactivities, are the characteristic metabolites of most plants of the Meliaceae family. The chemistry and bioactivities of meliaceous limonoids are a continuing hot area of natural products research; to date, about 2700 meliaceous limonoids have been identified. In particular, more than 1600, including thirty kinds of novel rearranged skeletons, have been isolated and identified in the past decade due to their wide distribution and abundant content in Meliaceae plants and active biosynthetic pathways. In addition to the discovery of new structures, many positive medicinal bioactivities of meliaceous limonoids have been investigated, and extensive achievements regarding the chemical and biological synthesis have been made. This review summarizes the recent research progress in the discovery of new structures, medicinal and agricultural bioactivities, and chem/biosynthesis of limonoids from the plants of the Meliaceae family during the past decade, with an emphasis on the discovery of limonoids with novel skeletons, the medicinal bioactivities and mechanisms, and chemical synthesis. The structures, origins, and bioactivities of other new limonoids were provided as ESI. Studies published from July 2010 to December 2021 are reviewed, and 482 references are cited.

Toonasindiynes A-F, new polyacetylenes from Toona sinensis with cytotoxic and anti-inflammatory activities

The plants of genus Toona are well known for diverse limonoid secondary metabolites, while polyacetylenes are rarely found from Toona species. In this work, six new polyacetylenes toonasindiynes A-F (1-6) and six known analogues (7-12) were isolated from the root bark of Toona sinensis. Their structures and absolute configurations were elucidated by HRESIMS, 1D and 2D NMR spectroscopic analysis, modified Mosher's method, and biosynthetic consideration. These polyacetylenes share the same 4,6-diyne moiety with different side chain length and different oxidation degree. Bioactivity screening revealed the cytotoxic activity of 3, 5, 9, and 11 against U2OS cells, and the inhibitory effects on nitric oxide (NO) production of 1, 2, 5, 8, 9, and 11 in lipopolysaccharide-induced RAW 264.7 cells.

Cytotoxic Limonoids from the Twigs and Leaves of Toona ciliata

Eight new limonoids, toononoids A-H (1-8), eight new B-seco-29-norlimonoids, toonanoronoids A-H (9-16), and seven known analogues were obtained from the EtOAc extract of the twigs and leaves of Toona ciliata. Compounds 2, 4, 8, and 16 are rare lactam-bearing limonoids. Compounds 1, 14, and 15 possess an unusual γ-methoxybutenolide moiety at C-17, while compounds 9, 10, and 15 have a rare 3β-hydroxy group. Their 2D structure and relative configurations were identified using spectroscopic data. The absolute configurations of 1, 9, 14, and 15 were established via X-ray diffraction crystallography or comparison of experimental and calculated ECD data. The cytotoxicity of the compounds was assessed toward five human tumor cell lines, and their anti-inflammatory activity was assessed based on NO production using LPS-stimulated RAW264.7 macrophages. Compounds 11 and 12 exerted inhibition toward two tumor cell lines (MCF-7, SW-480) with IC₅₀ values between 2.1 and 3.7 μM, while 18-22 inhibited the proliferation of HL-60, MCF-7, and SW-480 cells (IC₅₀ 0.6-4.0 μM). Only compound 4 exhibited weak anti-inflammatory activity with an IC₅₀ value of 28.3 μM.

Ciliatasecones A–C, three rearranged limonoids from Toona ciliata var. yunnanensis

Three rearranged limonoids with a novel ring-seco model and an unprecedented cycle system were isolated from Toona ciliata var. yunnanensis.

Natural Products Research in China From 2015 to 2016

This review covers the literature published by chemists from China during the 2015-2016 on natural products (NPs), with 1,985 citations referring to 6,944 new compounds isolated from marine or terrestrial microorganisms, plants, and animals. The emphasis is on 730 new compounds with a novel skeleton or/and significant bioactivity, together with their source organism and country of origin.

Anti-inflammatory activity of Khayandirobilide A from Khaya senegalensis via NF-κB, AP-1 and p38 MAPK/Nrf2/HO-1 signaling pathways in lipopolysaccharide-stimulated RAW 264.7 and BV-2 cells

BACKGROUND

Immunocytes-involved inflammation is considered to modulate the damage in various diseases. Herein, novel therapeutics suppressing over-activation of immunocytes could prove an effective strategy to prevent inflammation-related diseases.

PURPOSE

The objective of this study is to evaluate the anti-inflammatory activity of Khayandirobilide A (KLA), a new andirobin-type limonoid with modified furan ring isolated from the Khaya senegalensis (Desr.) A. Juss., and to explore its potential underlying mechanisms in LPS-stimulated inflammatory models.

METHODS

The structure of KLA was elucidated on the basis of 1D- and 2D-NMR spectroscopic data as well as HR-ESI-MS. As for its anti-inflammatory effect, the production of pro-inflammatory mediators and cytokines in LPS-stimulated RAW 264.7 and BV-2 cells were measured by Griess reagent, ELISA and qRT-PCR. The relevant proteins including nuclear factor κB (NF-κB), p-AKT, p-p38 and Nrf2/HO-1 were investigated by western blot. Nuclear localisations of NF-κB, activator protein-1 (AP-1) and Nrf2 were also examined by western blot and immunofluorescence.

RESULTS

KLA could inhibit the production of LPS-induced NO with IC₅₀ values of 5.04 ± 0.14 µM and 4.97 ± 0.5 µM in RAW 264.7 and BV-2 cells, respectively. KLA also attenuated interleukin-6 (IL-6), inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) at the protein and mRNA levels. Further mechanistic studies demonstrated the activation of NF-κB and AP-1 were reduced by KLA. Moreover, KLA elevated expression of heme oxygenase-1(HO-1) via inducing Keap1 autophagic degradation and promoting Nrf2 nuclear translocation. Despite KLA induced the phosphorylation of mitogen-activated protein kinases (MAPKs) family, inhibiting the phosphorylation of p38 by its specific inhibitor SB203580 attenuated the degradation of KLA-induced Keap1, and then reduced KLA-induced Nrf2 nuclear translocation and HO-1 expression. Furthermore, SB203580, Brusatol (a Nrf2 specific inhibitor) and ZnPP (a HO-1 specific inhibitor) could partly reverse the suppressive effects of KLA on LPS-induced NO production and mRNA levels of pro-inflammatory genes.

CONCLUSION

These data displayed that KLA possessed anti-inflammatory activity, which was attributed to inhibit the release of LPS-stimulated inflammatory mediators via suppressing the activation of NF-κB, AP-1, and upregulating the induction of p38 MAPK/Nrf2-mediated HO-1.

Recent progress in the chemistry and biology of limonoids

Significant limonoids: new isolated limonoids, and recent developments in the total chemical synthesis, and structural modifications of limonoids regarding the bioactivities have been summarised.