Trijugin- and mexicanolide-type limonoids from the fruits of Heynea trijuga that reverse multidrug resistance in MCF-7/DOX cells

Meliasanines A-L, tirucallane-type triterpenoids from Melia toosendan with anti-inflammatory properties via NF-κB signaling pathway

Meliasanines A-L, twelve previously unreported tirucallane-type triterpenoids, together with fifteen known ones, have been isolated from the stem bark of Melia toosendan. Their structures and absolute configurations were determined based on HRESIMS, and NMR, combined with calculated ECD and single-crystal X-ray diffraction analyses. Subsequently, all compounds except 10 were evaluated for their inhibitory effect on the production of nitric oxide induced by lipopolysaccharide in RAW264.7 macrophage cells. The results indicated that seven compounds (1, 13, 14, 16, 20, 22, and 23) exhibited significant NO inhibitory effects, with IC50 values ranging from 1.35 to 5.93 μM, which were more effective than the positive control indomethacin (IC50 = 13.18 μM). Moreover, the corresponding results of Western blot analysis revealed that meliasanine A (1) can significantly suppress the protein expression of inducible nitric oxide synthase and cyclooxygenase 2 in a concentration-dependent manner. The mechanism study suggested that meliasanine A exerts an anti-inflammatory effect via the nuclear factor-κB signaling pathway by suppressing phosphorylation of P65 and IκBα.

Secotrijugins A-D, four highly oxidized and rearranged limonoids from Trichilia sinensis and their anti-inflammatory activity

Four undescribed highly oxidized and rearranged limonoids, secotrijugins A-D, were purified from the leaves and twigs of Trichilia sinensis. Within them, secotrijugin A was characterized as a rare 30-nortrijugin-type limonoid with an unusual cleavage of 1,14-ether bond, secotrijugins B and C represented new examples with the cleavage of δ-lactone ring D, and secotrijugin D was a rare trijugin-type limonoid with an unusual 2,6-oxygen bridge. The structures of limonoids were characterized by means of spectroscopic analysis and ECD calculations. The cellular screening revealed that secotrijugin B was the most active against LPS-stimulated NO production in BV-2 cells, which played an anti-inflammatory role by downregulating COX-2 and iNOS protein expression. The further in vivo experiments confirmed that secotrijugin B had strong in vivo anti-inflammatory effect via suppressing NO and ROS generation.

An overview of Fructus Meliae Toosendan: Botany, traditional uses, phytochemistry, pharmacology and toxicology

Fructus Meliae Toosendan (FMT) is the dried and mature fruit of MeLia toosendan Sieb.et Zucc. It contains a variety of chemical constituents and reported to possess a variety of pharmacological activities. This review aims to provide a thorough and organized summary of botany, traditional uses, chemical ingredients, pharmacological actions, toxicity, quality control, and uses. In this review, we have compiled the data regarding FMT from 1994 to 2022 in the databases: Web of Science, PubMed, Google Scholar, CNKI, and Baidu Scholar. The keywords: "Fructus Meliae Toosendan", "botany", "traditional uses","chemical components", "pharmacological activity", "toxicity", "quality control" and "clinical application" have been used to collected the literature published in the online bibliographic databases. Based on the correlation of these documents and FMT, 126 articles were finally selected as references. This paper provides a reasonable summary of the 190 chemical components of FMT and its pharmacological effects and toxicity. Moreover, this paper also compiled the quality control studies and clinical applications. In the future, more experimental studies on FMT are needed to achieve the purpose of toxicity reducing and efficacy enhancing. This comprehensive review of FMT can provide a reference for subsequent relevant studies.

Cipacinerasins A-K, structurally diverse limonoids from Cipadessa baccifera

Eleven undescribed limonoids, cipacinerasins A-K, involving of four diverse carbon skeletal types, along with fifteen known analogues, were isolated from the branches and leaves of Cipadessa baccifera. Within them, cipacinerasins A and B feature a rearranged tetrahydropyranyl ring B formed between C-8 and C-30, are unusual miscellaneous-type limonoids. Cipacinerasins E and F are rare trijugin-type limonoids, of which the D-ring δ-lactone is cleaved. Their structures were elucidated on the basis of extensive spectroscopic data (HRESIMS, NMR, UV and IR), electronic circular dichroism (ECD) calculations, and single-crystal X-ray diffraction analysis. All compounds were evaluated in vitro cytotoxicity against five human tumor cell lines (K562, HeLa, PC3, LN-Cap and Hell), and cipacinerasin E showed moderate antitumor activity with IC₅₀ values ranging from 8.0 to 24.8 μM.

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.

Highly oxygenated and rearranged limonoids from the stem barks of Entandrophragma utile

Seventeen highly oxygenated and rearranged limonoids, including nine previously undescribed phragmalin-type limonoids with 1,8,9- and 8,9,30-orthesters (entanutilins C-K, 1-9), three undescribed limonoids with rare rearranged-6/6/7/5 skeleton (entanutilins L-N, 10-12), and 5 known limonoids, were isolated from the stem barks of Entandrophragma utile from Ghana (Africa). Their structures including absolute configurations were elucidated based on comprehensive spectroscopic analyses, such as HRESIMS, 1D/2D-NMR, CD exciton chirality method, time-dependent density functional theory (TDDFT)/ECD calculations, and single-crystal X-ray diffraction. Bioactivity screenings suggested that some of these compounds effectively reversed resistance in MCF-7/DOX cells at a nontoxic concentration of 30 μM with 6- to 19-fold enhancing effects.

Highly oxygenous trichilin-type limonoids from Trichilia sinensis

Six new trichilin-type limonoids (1-6) with C-19/29 lactol or acetal bridge and a new ring intact limonoid (7) were isolated from the desiccative ripe fruits of Trichilia sinensis. Their structures were determined by extensive spectroscopic methods including ¹H NMR, ¹³C NMR, HSQC, HMBC, ROESY experiments as well as HRESI-MS data. All isolated compounds were evaluated for toxicities against human pulmonary carcinoma A549 and Hela cell lines by sulforhodamine B (SRB) method. Compound 7 showed weak inhibitory activity in Hela cell line at 40 μmol·L^-1.

Tooniliatone A sensitizes multidrug resistant cancer cells by decreasing Bcl-xL via activation of JNK MAPK signaling

BACKGROUND

Multidrug resistance (MDR) refers to the phenotype of tumor cells that are resistant to various chemotherapeutic drugs with different structures and functions, which is clearly disadvantageous for patients. Finding a natural product that can effectively reverse the MDR of tumor cells is important for the treatment of patients.

PURPOSE

To prove that tooniliatone A (TA), a novel typical limonoid, can effectively reverse the MDR of tumor cells and to explore its mechanism of action.

METHODS

The MTT, CCK-8 and monoclonal formation assays, as well as flow cytometry, were used to evaluate the role of TA in reversing tumor multidrug resistance; then the mechanism of action for TA was explored by western blotting and real-time fluorescent quantitative PCR.

RESULTS

TA significantly reversed the MDR of the K562/MDR and MCF-7/MDR cell lines. TA can inhibit the anti-apoptotic protein Bcl-xL to make cells sensitive to common chemotherapeutic drugs and activate the SAPK/JNK pathway to promote phosphorylation of JNK and its downstream cJun protein. Small interfering RNA-mediated knockdown of JNK and cJun could antagonize the MDR reversal effect of TA and the inhibition of Bcl-xL by TA. Therefore, we hypothesized that TA activates the JNK pathway to increase the transcription of the proapoptotic protein Bim, thereby inhibiting Bcl-xL and reversing MDR in tumor cells.

CONCLUSION

Our study suggests that TA reverses tumor MDR by activating the SAPK/JNK pathway to inhibit the action of Bcl-xL. TA may be an effective tumor MDR reversal agent.