Nortriterpenoids from Chukrasia tabularis var. velutina

Bioactivity-guided isolation of anti-inflammatory limonins from Chukrasia tabularis

Chukrasia tabularis is an economically important tree and widely cultured in the southeast of China. Its barks, leaves, and fruits are consumed as a traditional medicine and perceived as a valuable source for bioactive limonin compounds. The extracts from root barks of C. tabularis showed significant anti-inflammatory effect. The aim of this research was to explore the material basis of C. tabularis anti-inflammatory activity, and to purify and identify anti-inflammatory active ingredients. By a bioassay-guided isolation of dichloromethane fraction obtained two novel phragmalin limonins, Chukrasitin D and E (1 and 2), together with 12 known limonins (3-14). The chemical structure of these compounds is determined on the basis of extensive spectral analysis and chemical reactivity. In addition, the activities of these isolated limonins on the production of nitric oxide (NO), tumor necrosis factor alpha (TNF-α), and nuclear factor kappa B (NF-κB) in RAW264.7 cells induced by lipopolysaccharide (LPS) were evaluated. Limonins 1 and 2 indicated significant anti-inflammatory activity with IC50 values of 6.24 and 6.13 μM. Compound 1 notably inhibited the production of NF-κB, TNF-α and interleukin 6 (IL-6) in macrophages. The present results suggest that the root barks of C. tabularis exhibited anti-inflammatory effect and the limonins may be responsible for this activity.

Sarcanolides C–E: Three new lindenane sesquiterpenoid dimers with anti-inflammatory activities from Sarcandra glabra

Three new lindenane-type sesquiterpenoid dimers, sarcanolides C–E (1–3), were isolated from the roots of Sarcandra glabra. Sarcanolide C (1) possesses a unique decacyclic scaffold with an unusual orthoformate unit. The...

Chemical constituents from Tinospora sagittata and their biological activities

Six undescribed low-polarity compounds including three rare 14-methylergostane steroids (1-3), one euphane triterpenoid (4) and two octadecanoic acid ethyl esters (5 and 6), along with ten previously reported terpenyl cometabolites (7-16), were isolated from the stems of Tinospora sagittata. Their structures were determined by detailed spectroscopic analyses and comparison with structurally related known compounds, and all of them have been reported from T. sagittata for the first time. Compounds 4-6 and 16 showed potent in vitro inhibitory activity against the diabetes target α-glucosidase, while compounds 10 and 14 displayed promising antibacterial effect toward Staphylococcus aureus ATCC 25923.

Granatripodins A-B, limonoids featuring a Tricyclo[3.3.1.02,8]nonane motif: Absolute configuration and agonistic effects on human pregnane-X-receptor

Two unprecedented limonoids incorporating a sterically encumbered cyclopropane ring, named granatripodins A (1) and B (2), featuring the presence of a tricyclo[3.3.1.0^2,8]nonane motif, were obtained from seeds of the Thai Xylocarpus granatum. The planar structures and absolute configurations of these limonoids were unambiguously established by NMR investigations, TDDFT-ECD and DFT-NMR calculations, and single-crystal X-ray diffraction analysis (Cu Kα). Most notably, granatripodin A (1) exhibited agonistic effects on human pregnane-X-receptor at the concentration of 100.0 nM. The biosynthetic origins of these limonoids via a radical cascade reaction are proposed. This study exemplifies a universal approach for the stereochemical assignment of polycyclic compounds with a cyclopropane-embedded cage scaffold.

Phragmalin and mexicanolide limonoids with reversal of multidrug resistance from the seeds of Chukrasia tabularis A. Juss

Six undescribed 1,8,9-phragmalin limonoid orthoesters (chukorthoesters A-F, 1-6) and two undescribed mexicanolide-type limonoids (ivorenoids H and I, 7 and 8), together with ten known limonoids, were isolated from the seeds of common wood-source and greening plants Chukrasia tabularis A. Juss. Their chemical structures were elucidated using HR-ESI-MS, 1D and 2D NMR spectroscopic analysis, and that of 1 along with absolute configuration was confirmed by X-ray diffraction experiment with Cu Kα radiation. Bioactivities screening indicated the limonoid orthoesters 1 and 2 shown reversing resistance in MCF-7/DOX cells at 10 μM (RF:4-5 folds).

Two new phragmalin-type limonoids from Chukrasia tabularis and their α-glucosidase inhibitory activity

Phytochemical investigation on the stems of C. tabularis (Meliaceae) led to the isolation of two new phragmalin-type limonoids, named tabularisins S and T (1-2), along with five known ones (3-7). The structures of the new limonoids were established by spectroscopic methods including UV, IR, HRESIMS, and 1D and 2D NMR. All the compounds were evaluated for α-glucosidase inhibitory activity in vitro. Compounds 2 and 3 exhibited significant inhibitory activity against α-glucosidase with IC50 values of 0.15 and 0.03 mM, respectively (acarbose as positive control, IC50 0.95 mM).

New Phragmalin-Type Limonoids from Chukrasia tabularis and Their α-Glucosidase Inhibitory Activity

Phytochemical investigation on the stems of C. tabularis led to the isolation of five new phragmalin-type limonoids and six known ones. The structures of the new compounds 1–5, named chukbularisins A–E, were elucidated by spectroscopic techniques (IR, HRESIMS, 1D and 2D NMR) and comparisons with published data. All the compounds were evaluated for in vitro α-glucosidase inhibitory activity. Compounds 2, 3, 4, 5, and 8 exhibited inhibitory activity against α-glucosidase with IC₅₀ values of 0.06 ± 0.008, 0.04 ± 0.002, 0.52 ± 0.039, 1.09 ± 0.040, and 0.20 ± 0.057 mM, respectively (using acarbose as positive control, IC₅₀ 0.95 ± 0.092 mM).

Discovery of structurally diverse and bioactive compounds from plant resources in China

This review describes the major discoveries of structurally diverse and/or biologically significant compounds from plant resources in China, mainly from the traditional Chinese medicines (TCMs) since the establishment of our research group in 1999. In the past decade, a large array of biologically significant and novel structures has been identified from plant resources (or TCM) in our laboratory. The structural modification of several biologically important compounds led to more than 400 derivatives, some of which exhibited significantly improved activities and provided opportunities to elucidate the structure-activity relationship of the related compound class. These findings are important for drug discovery and help us understand the biological basis for the traditional applications of these plants in TCM.

Phragmalin-type limonoid orthoesters from Chukrasia tabularis var. velutina

Nine new phragmalin-type limonoid orthoesters, tabulalides F-N (1-9), together with three known compounds, tabulalides C and D, and tabularisin N (10-12), were isolated from the stem bark of Chukrasia tabularis var. velutina. Extensive spectroscopic technologies were applied to elucidate the structures of these new compounds, including the application of circular dichroism (CD) exciton chirality method for the determination of the absolute configurations of 1 and 2. Tabulalide F (1) has a rare orthoisobutylate moiety in phragmalin-type limonoid orthoesters. These compounds were evaluated for cytotoxic activity against five human cancer cell lines in vitro. Tabulalide G (2) exhibits moderate cytotoxic activity against MCF-7 with IC(50) value of 20.4 µmol/l, and other compounds have weak inhibitory effects on the growth of tested tumor cells.

Two new limonoids from the stem barks of Chukrasia tabularis var. velutina

Two new phragmalin-type limonoid orthoesters, C-15 enolic acyl type and 13/14/18-cyclopropanyl type, named chukvelutilide H (1) and tabularin R (2), together with three known limonoid orthoesters (3-5), were isolated from the stem barks of Chukrasia tabularis var. velutina. The structures of these two new compounds were elucidated on their extensive HR-ESI-MS, 1D, and 2D spectroscopic analysis including HSQC, HMBC, and ROESY experiments.

Chuktabularins E-T, 16-Norphragmalin Limonoids from Chukrasia tabularis var. velutina

Chuktabularins E-T (1-16), 16 new 16-norphragmalin limonoids, together with four known compounds, chuktabularins A-D, were isolated from the stem bark of Chukrasia tabularis var. velutina. These compounds possess a biosynthetically extended propionyl or acetyl group at C-15 and a characteristic ketal moiety between the limonoid skeleton and the acyl substituent at C-15. The structures of these compounds were established on the basis of detailed spectroscopic analysis, and that of 1 was confirmed by a single-crystal X-ray diffraction experiment, representing the first verification of the skeleton of 16-norphragmalin limonoids. Chuktabularins K-O (7-11) were found to be the first 19-acetoxylated 16-norphragmalin limonoids. Variable-temperature (1)H NMR experiments suggested that 7 exists as an equilibrium mixture of conformational isomers in solution. The absolute configuration of 5 was determined by the CD exciton chirality method on its 11,12-di-p-chlorobenzoate (5a), and those of 1-4 and 6-16 were proposed by correlating with 5 spectroscopically and biogenetically.

Triterpenoids

This review covers the isolation and structure determination of triterpenoids including squalene derivatives, protostanes, lanostanes, holostanes, cycloartanes, dammaranes, euphanes, tirucallanes, tetranortriterpenoids, lupanes, oleananes, friedelanes, ursanes, hopanes, isomalabaricanes and saponins; 574 references are cited.