Triterpenes from Tripterygium wilfordii Hook

Pentacyclic Triterpenoids Isolated from Celastraceae: A Focus in the 13C-NMR Data

The Celastraceae family comprises about 96 genera and more than 1.350 species, occurring mainly in tropical and subtropical regions of the world. The species of this family stand out as important plant sources of triterpenes, both in terms of abundance and structural diversity. Triterpenoids found in Celastraceae species display mainly lupane, ursane, oleanane, and friedelane skeletons, exhibiting a wide range of biological activities such as antiviral, antimicrobial, analgesic, anti-inflammatory, and cytotoxic against various tumor cell lines. This review aimed to document all triterpenes isolated from different botanical parts of species of the Celastraceae family covering 2001 to 2021. Furthermore, a compilation of their ¹³C-NMR data was carried out to help characterize compounds in future investigations. A total of 504 pentacyclic triterpenes were compiled and distinguished as 29 aromatic, 50 dimers, 103 friedelanes, 89 lupanes, 102 oleananes, 22 quinonemethides, 88 ursanes and 21 classified as others.

Friedelane-type triterpene cyclase in celastrol biosynthesis from Tripterygium wilfordii and its application for triterpenes biosynthesis in yeast

Celastrol is a promising bioactive compound isolated from Tripterygium wilfordii and has been shown to possess many encouraging preclinical applications. However, the celastrol biosynthetic pathway is poorly understood, especially the key oxidosqualene cyclase (OSC) enzyme responsible for cyclisation of the main scaffold. Here, we report on the isolation and characterisation of three OSCs from T. wilfordii: TwOSC1, TwOSC2 and TwOSC3. Both TwOSC1 and TwOSC3 were multiproduct friedelin synthases, while TwOSC2 was a β-amyrin synthase. We further found that TwOSC1 and TwOSC3 were involved in the biosynthesis of celastrol and that their common product, friedelin, was a precursor of celastrol. We then reconstituted the biosynthetic pathway of friedelin in engineered yeast constructed by the CRISPR/Cas9 system, with protein modification and medium optimisation, leading to heterologous production of friedelin at 37.07 mg l^-1 in a shake flask culture. Our study was the first to identify the genes responsible for biosynthesis of the main scaffold of celastrol and other triterpenes in T. wilfordii. As friedelin has been found in many plants, the results and approaches described here have laid a solid foundation for further explaining the biosynthesis of celastrol and related triterpenoids. Moreover, our results provide insights for metabolic engineering of friedelane-type triterpenes.

Further Study of Influence of Panax notoginseng on Intestinal Absorption Characteristics of Triptolide and Tripterine in Rats with Tripterygium wilfordii

Background:

Tripterygium wilfordii (TW) is widely employed to treat rheumatoid arthritis and autoimmune disorders clinically, which, however, accompany with disturbing hepatotoxicity and nephrotoxicity. The previous research showed that Panax notoginseng (PN) compatibly and significantly reduces the TW-induced hepatotoxicity.

Objective:

To explore the underlying mechanism, the present study was designed to reveal the influence of PN on the intestinal absorption process of TW-derived active components in rat.

Materials and Methods:

An in situ single-pass intestinal perfusion technique was established and preformed to obtain the perfusate samples of triptolide (TP), tripterine (TE), TW extract, and TW-PN extract. A rapid and sensitive ultra-performance liquid-chromatography tandem mass spectrometry method was subsequently developed and validated to determine the concentrations of TP and TE in the perfusate samples. Then, the absorption parameters, effective permeability, absorption rate constant, and percentage of 10 cm intestinal absorption were calculated strictly.

Results:

The final data indicated that both TP and TE have no special absorption site in the intestine and are primarily absorbed in a passive manner. Otherwise, the absorption of TP was decreased from compatibility of PN, but the absorption of TE was enhanced.

Conclusion:

The absorption reduction of TP and absorption elevation of TE from TW initiated by the combination of PN are contributed to attenuate the toxicity and reinforce the therapeutic efficacy of TW. It is practically reasonable of usage of TW compatibility with PN clinically.

SUMMARY

Panax notoginseng (PN) regulated the absorption process of Tripterygium wilfordii (TW) in intestine

Both triptolide (TP) and tripterine (TE), two typical components of TW, have no special absorption site in the intestine and are primarily absorbed in a passive manner

PN decreased the absorption of TP and enhanced the absorption of TE in the intestine.

Abbreviations used: 10 cm% ABS: percentage of 10 cm intestinal absorption, DMARDs: Disease-modifying antirheumatic drugs, GU: Glycyrrhiza uralensis, K_a: Absorption rate constant, NSAIDs: Nonsteroidal anti-inflammatory drugs, P_eff: Effective permeability, PN: Panax notoginseng, QC: Quality control, RA: Rheumatoid arthritis, RG: Rehmannia glutinosa, SPIP: Single-pass intestinal perfusion, TE: Tripterine, TP: Triptolide, TW: Tripterygium wilfordii, UPLC-MS/MS: Ultra-performance liquid-chromatography tandem mass spectrometry.

7α-Hydroxyfriedelan-3-one-26-ol-29-oic acid and other Constituents from Pileostegia viburnoides var. glabrescens

Phytochemical investigation of the roots and rhizomes of Pileostegia viburnoides var. glabrescens led to the isolation and identification of 31 compounds (1-31), 25 of which (1-2, 4-7, 9-12, 15-18, 21-31) were isolated from the Pileostegia genus for the first time. 7α-Hydroxyfriedelan-3-one-26-ol-29-oic acid (1) is a new friedelane-type triterpene. The structure of n-butyl-β-D-fructopyranoside (2) was determined by single-crystal X-ray diffraction. Compounds 4 and 12 displayed marginal cytotoxicity against the P388 murine leukemia cell line with IC50 values of 13.4 μM and 25.0 μM, respectively. Compound 23 exhibited marginal anti-inflammatory activity by the inhibition of lipopolysaccharide induced nitric oxide production in RAW 264.7 macrophage cells, with an IC50 value of 32.0 μM. Compounds 3, 8-10, 25, and 27 were phytotoxic to the dicot Lactuca sativa (lettuce) and/or the monocot Agrostis stolonifera (bentgrass).

Three Novel Friedelane Triterpenes with Antimicrobial Activity from the Stems of Celastrus Monospermus

Three novel friedelane triterpenes, monospermonal, monospermonol and monospermondiol, along with six known friedelanes, 3-oxofriedelane, 3-oxofriedelan-28-al, 3,12-dioxofriedelane, 3-oxo-28-hydroxyfriedelane, 3-oxo-11 β-hydroxyfriedelane, 3-oxo-12 α-hydroxyfriedelane and an oleanane triterpenoid, 3 β-hydroxyolean-12-ene, were isolated from the stems of Celastrus monospermus Roxb. The structures of novel compounds, monospermonal, monospermonol and monospermondiol, were identified as 3,12-dioxofriedelan-28-al, 3,12-dioxo-28-hydroxyfriedelane and 3-oxo-12 α,28-dihydroxyfriedelane, respectively by spectroscopies including 2D NMR methods. These nine friedelane-type triterpenes were tested for antimicrobial activity against luminescent bacterium Photobacterium leiognathi N1 that had been isolated from “glowing” fish meat. Monospermonal and monospermonol showed moderate activity.

Studies of naturally occurring friedelane triterpenoids as insulin sensitizers in the treatment type 2 diabetes mellitus

Type 2 diabetes mellitus (T2DM) is a rapidly expanding public epidemic and frequently results in severe vascular complications. In an attempt to find anti-diabetic agents, we report herein on the isolation, structural elucidation and bioactivity of nine friedelane-type triterpenes (1-9) and twenty two known ones (10-31) from the root barks of Celastrus vulcanicola and Maytenus jelskii. Their structures were elucidated on the basis of spectroscopic analysis, including 1D and 2D NMR techniques. Two compounds from this series (1 and 3) exhibited increased insulin-mediated signalling, which suggests these friedelane triterpenes have potential therapeutic use in insulin resistant states.

Effect of triptolide on estradiol release from cultured rat granulosa cells

Triptolide, a major active component of Tripterygium wilfordii Hook F (TWHF), is known to have multiple pharmacological activities. However, studies have also shown that triptolide is highly toxic to the reproductive system by disrupting normal androgen and estrogen signaling. In the present study, we investigated the effect of triptolide (5, 10, or 20 nM for 24 h) on estradiol production by rat granulosa cells. Triptolide inhibited basal and human chorionic gonadotropin (HCG)- or 8-bromo-cAMP-stimulated estradiol production as revealed by RIA assay. Furthermore, the HCG-evoked increase in cellular cAMP content was also inhibited by triptolide, indicating that disruption of the cAMP/PKA signaling pathway may mediate the deleterious effects of triptolide on steroid hormone regulation. In addition, (3)H(2)O tests showed that aromatase activity was significantly inhibited by triptolide in granulosa cells. Western blot and quantitative real-time PCR (qRT-PCR) assays further revealed that triptolide decreased protein and mRNA expression of aromatase in granulosa cells. Moreover, mRNA expression of luteinizing hormone receptor (LHR) was induced by triptolide also using qRT-PCR method. In contrast, cell viability tests using Cell Counting Kit-8 (CCK-8) and 3-(4,5-dimethyl-thiazol-2-yl)-2,5- diphenyl-tetrazolium bromide (MTT) method indicated that triptolide did not cause measurable cell death at doses that suppressed steroidogenesis. The reproductive toxicity of triptolide may be mainly caused by disruption of cAMP/PKA-mediated expression of estrogen synthesis enzymes, leading to reduced estradiol synthesis and reproductive dysfunction.

Triterpenoids

This review covers the isolation and structure determination of triterpenoids including squalene derivatives, protostanes, lanostanes, holostanes, cycloartanes, dammaranes, euphanes, tirucallanes, tetranortriterpenoids, quassinoids, lupanes, oleananes, friedelanes, ursanes, hopanes, isomalabaricanes and saponins. The literature from January 2005 to December 2006 is reviewed and 478 references are cited.