Secophragmalin-Type Limonoids from Trichilia connaroides: Isolation, Semisynthesis, and Their Cytotoxic Activities

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.

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.

Design, synthesis, cytotoxic, and anti-inflammatory activities of some novel analogues of aloe-emodin isolated from the rhizomes of Rheum emodi

In connection with our continuous efforts in the synthesis of derivatives from major compounds isolated from traditional medicinal plants, in the present study we have attempted to synthesize the furan-conjugated aloe-emodin derivatives (5a-j) using a three-component reaction. The synthesized derivatives were assessed for anticancer activity against five different cancer cell lines using the in vitro MTT assay and the results showed that most of the derivatives are potent against cancer cells comparing with the control. Compounds 5a and 5e showed excellent activity against all the cancer cells with less than 12.5 µM and arrested the cell cycle at the G0/G1 phase in both CAL27 and SCC9 cells. Compound 5e induces the early apoptosis in CAL27 cells and compounds 5a and 5e induce early and late apoptosis, respectively, in SCC9 cells. Moreover, compounds 5b, 5c, 5i, and 5j showed excellent anti-inflammatory activity in LPS-stimulated RAW 264.7 cells by inhibiting IL-6 production. The molecular docking studies revealed that compound 5e has strong interaction with the CLK kinase and protein kinase II through hydrogen binding Asp325 and Lys290.

Structurally diverse limonoids and bio-active evaluation from Trichilia connaroides

Four new limonoids, named as trichiconlide G (1), 2-hydroxyltrijugin F (2), 23-oxo-21-hydroxyltrijugin F (3), 21-oxo-23-hydroxyltrijugin F (4), along with sixteen known analogues (5-20) were isolated from the leaves and twigs of Trichilia connaroides. Their structures and absolute configurations were determined by spectroscopic analyses, X-ray diffraction analysis, and TD-DFT-ECD calculations. Trichiconlide G (1) is one rare naturally occurring 1,2-seco phragmalin-type limonoid bearing a C-7/28 δ-lactone ring. Additionally, 2-hydroxyltrijugin F (2), 23-oxo-21-hydroxyltrijugin F (3), and 21-oxo-23-hydroxyltrijugin F (4) are three naturally occurring limonoids with a rare C-16/8 δ-lactone ring. All isolates were evaluated for their cytotoxic and anti-inflammatory activities. None of compounds exhibited cytotoxicity against five human cancer cell lines A-549, HepG2, 5-8F, Siha, and SCC-4 at the concentration of 40 μM. Compounds 16 and 17 showed moderate anti-inflammatory activity with IC₅₀ values of 28.45 ± 2.51 and 22.66 ± 2.01 μM, respectively.

Investigation of Cytotoxic Constituents from Seed Pulp of Entada Phaseoloides and Metabolite Profiling Using UPLC-QTOF-MSE

BACKGROUND

Entada phaseoloides (Linn.) Merr. (Family: Fabaceae) is a well-known, traditional, medicinal plant that has been extensively used in the Ayurvedic system of medicine for centuries to combat a wide range of ailments.

OBJECTIVE

The goal of this work was to investigate the bioactive constituents from n-butanol extracts of Entada. phaseoloides and develop a method for the comprehensive characterization of saponins using liquid chromatography with an electrospray ionization quadrupole time-of-flight mass spectrometer (LC-ESI-QTOF-MS).

METHODS

A hyphenated technique, ultra-performance liquid chromatography quadrupole time-of-flight mass spectrometry (UPLC-QTOF-MS/MS), has been proposed to integrate LC and MS together with NMR for structural elucidation. This method allowed comprehensive characterization of saponin glycosides from E. phaseoloides based on their MS/MS fragmentation study.

RESULTS

The phytochemical study of E. phaseoloides resulted in the isolation and identification of three bio-active constituents. Further, the UPLC-QTOF-MS/MS method led the structure elucidation of saponin constituents directly from crude extracts via comparison of the exact molecular masses from their MS/MS spectra. Identified common fragments m/z 648, 630, 498, 366, and 204 were used for the screening of saponin components.

CONCLUSIONS

The present study summarizes the isolation and identification of bio-compounds from n-butanol extract and the demonstration of UPLC-QTOF-MS/MS analysis for the characterization of compounds in complex crude extracts. To the best of our knowledge, this is the first systematic study in structural characterization on complex saponins and other metabolites from crude extract of E. phaseoloides using UPLC-ESI-QTOF-MSE.

HIGHLIGHTS

Rapid analysis and characterizations of three new saponins from E. phaseoloides using UPLC-ESI-QTOF-MSE were tentatively identified based on the mass fragmentation study.

Design, synthesis, and biological evaluation of pyrazole-linked aloe emodin derivatives as potential anticancer agents

In connection with our continuous efforts to generate new derivatives from lead compounds isolated from traditional medicinal plants, a series of aloe-emodin derivatives (6a-6e) were synthesized and assessed for their potential anticancer activity against a panel of cancer cell lines. The results showed that most of the derivatives are more active than the aloe-emodin and particularly, 6b and 6e manifested potent activity with IC₅₀ values of 1.32 & 1.6 μM and 0.99 & 2.68 μM against MDA-MB-231 and MCF-7 cells, respectively. Moreover, 6b and 6e induce early and late apoptosis as well as arrest the cell cycle at the G2/M phase in MDA-MB-231 cells. In conclusion, the results confirmed that the aloe-emodin derivatives could be a potential drug candidate for better treatment of breast cancer.

UPLC-MSE Guided Isolation of New Antifeedant Limonoids from Fruits of Trichilia connaroides

UPLC-MS^E guided isolation of CHCl₃ extract from the fruits of Trichilia connaroides yielded two new mexicanolide-type limonoids trichanolide F (1) and trichanolide G (2) along with a known compound carapanolide U (3). The structures of the limonoids were characterized by extensive spectroscopic analysis (MS, IR, 2D NMR). These limonoids (1-3) were evaluated for their antifeedancy against Spodoptera litura F. To further explore and draw the meaningful structure activity relationship studies, secophragmalin-type limonoids, namely, secotrichagmalin B, C (4, 5) and semisynthetic derivatives (5a-5l) were also screened for antifeedancy. The results revealed that trichanolide F (1) displayed highest antifeedant index (AFI) and caused larval mortality at 24 h. Derivative 5b caused larval toxicity, whereas 3, 5a, 5d, and 5g lead to pupal mortality and 2, 5f, 5k, and 5l caused adult deformities. Overall, the study provided new insights into the antifeedant potential of isolated and chemically modified limonoids from T. connaroides for the control of spodopteran pests.

Synthesis and biological evaluation of Schizandrin derivatives as tubulin polymerization inhibitors

A series of oxime ester-derivatives were prepared by utilizing the schizandrin (1), a major compound isolated from Schisandra grandiflora, which is deployed in different traditional system of medicine. The in vitro antiproliferative activities of the synthesized compounds were assessed against a selected panel of human cancer cell lines (A549, RKO P3, DU145 and Hela) and normal cell (HEK293). Several of these derivatives were found more potent in comparison to parent compound, schizandrin (1). Particularly, 4a and 4b demonstrated potent activity against DU-145 and RKOP3 cell lines with IC₅₀ values of 3.42 µM and 3.35 µM respectively. To characterize the molecular mechanisms involved in antitumoral activity, these two compounds, 4a and 4b were selected for further studies. Cell cycle analysis revealed that both the compounds were able to induce apoptosis and cell cycle arrest at G₀/G₁ phase. To know the extent of apoptosis in DU145 and RKOP3 cell lines, Annexin V-FITC were performed. Moreover, the tubulin polymerization assay indicated that 4a and 4b exhibits potent inhibitory effect on the tubulin assembly. Molecular docking studies and competitive binding assay also indicated that 4a and 4b effectively bind at the colchicine binding site of the tubulin.