7-OX0-10α-Cucurbitadienol from the seeds of Trichosanthes kirilowii and its anti-inflammatory effect
摘要:
The structure of a new triterpene isolated from the seeds of Trichosanthes kirilowii was determined to be 7-oxo-10 alpha-cucurbita-5,24-dien-3 beta-ol (7-oxo-10 alpha-cucurbitadienol) by spectral and chemical methods. 7-0xo-10 alpha-cucurbitadienol, and its acetyl and 24-dihydro derivatives showed marked inhibitory activity against 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced ear inflammation in mice. The 50% inhibitory dose of these compounds for TPA-induced inflammation (1 mu g ear(-1)) was 0.4-0.7 mg ear(-1).
Functional Characterization of Cucurbitadienol Synthase and Triterpene Glycosyltransferase Involved in Biosynthesis of Mogrosides from Siraitia grosvenorii
作者:Longhai Dai、Can Liu、Yueming Zhu、Jiangsheng Zhang、Yan Men、Yan Zeng、Yuanxia Sun
DOI:10.1093/pcp/pcv043
日期:2015.6
Mogrosides, the major bioactive components isolated from the fruits of Siraitia grosvenorii, are a family of cucurbitane-type tetracyclic triterpenoid saponins that are used worldwide as high-potency sweeteners and possess a variety of notable pharmacological activities. Mogrosides are synthesized from 2,3-oxidosqualene via a series of reactions catalyzed by cucurbitadienol synthase (CbQ), Cyt P450s (P450s) and UDP glycosyltransferases (UGTs) in vivo. However, the relevant genes have not been characterized to date. In this study, we report successful identification of SgCbQ and UGT74AC1, which were previously predicted via RNA-sequencing (RNA-seq) and digital gene expression (DGE) profile analysis of the fruits of S. grosvenorii. SgCbQ was functionally characterized by expression in the lanosterol synthase-deficient yeast strain GIL77 and was found to accumulate cucurbitadienol as the sole product. UGT74AC1 was heterologously expressed in Escherichia coli as a His-tag protein and it showed specificity for mogrol by transfer of a glucose moiety to the C-3 hydroxyl to form mogroside IE by in vitro enzymatic activity assays. This study reports the identification of CbQ and glycosyltransferase from S. grosvenorii for the first time. The results also suggest that RNA-seq, combined with DGE profile analysis, is a promising approach for discovery of candidate genes involved in biosynthesis of triterpene saponins.
Oxidation of Cucurbitadienol Catalyzed by CYP87D18 in the Biosynthesis of Mogrosides from<i>Siraitia grosvenorii</i>
作者:Jiangsheng Zhang、Longhai Dai、Jiangang Yang、Can Liu、Yan Men、Yan Zeng、Yi Cai、Yueming Zhu、Yuanxia Sun
DOI:10.1093/pcp/pcw038
日期:2016.5
Mogrosides, the principally bioactive compounds extracted from the fruits of Siraitia grosvenorii, are a group of glycosylated cucurbitane-type tetracyclic triterpenoid saponins that exhibit a wide range of notable biological activities and are commercially available worldwide as natural sweeteners. The biosynthesis of mogrosides involves initial cyclization of 2,3-oxidosqualene to the triterpenoid skeleton of cucurbitadienol, followed by a series of oxidation reactions catalyzed by Cyt P450s (P450s) and then glycosylation reactions catalyzed by UDP glycosyltransferases (UGTs). We previously reported the identification of a cucurbitadienol synthase (SgCbQ) and a mogrol C-3 hydroxyl glycosyltransferase (UGT74AC1). However, molecular characterization of further transformation of cucurbitadienol to mogrol by P450s remains unavailable. In this study, we report the successful identification of a multifunctional P450 (CYP87D18) as being involved in C-11 oxidation of cucurbitadienol. In vitro enzymatic activity assays showed that CYP87D18 catalyzed the oxidation of cucurbitadienol at C-11 to produce 11-oxo cucurbitadienol and 11-hydroxy cucurbitadienol. Furthermore, 11-oxo-24,25-epoxy cucurbitadienol as well as 11-oxo cucurbitadienol and 11-hydroxy cucurbitadienol were produced when CYP87D18 was co-expressed with SgCbQ in genetic yeast, and their structures were confirmed by liquid chromatography–solid-phase extraction–nuclear magnetic resonance–mass spectrometry coupling (LC-SPE-NMR-MS). Taken together, these results suggest a role for CYP87D18 as a multifunctional cucurbitadienol oxidase in the mogrosides pathway.
ides生物合成中的作用。
Promiscuous Oxidosqualene Cyclases from <i>Neoalsomitra integrifoliola</i> Catalyzing the Formation of Tetracyclic, Pentacyclic, and Heterocyclic Triterpenes
cyclases (NiOSC1–NiOSC6) from Neoalsomitra integrifoliola were characterized for the biosynthesis of diverse triterpene scaffolds, including tetracyclic and pentacyclic triterpenesfrom the 2,3-oxidosqualene (1) and oxacyclic triterpenesfrom the 2,3:22,23-dioxidosqualene (2). NiOSC1 showed high efficiency in the production of naturally rare (20R)-epimers of oxacyclic triterpenes. Mutagenesis results revealed
来自Neoalsomitra integrifoliola的六种氧化角鲨烯环化酶 ( Ni OSC1– Ni OSC6) 被表征用于生物合成多种三萜支架,包括来自 2,3-氧化角鲨烯 ( 1 ) 的四环和五环三萜和来自 2,3:22,23 的氧杂环三萜-二氧化角鲨烯( 2 )。 Ni OSC1 在生产天然稀有的氧杂环三萜 (20 R )-差向异构体方面表现出高效率。诱变结果表明,与野生型相比, Ni OSC1-F731G 突变体显着增加了 (20 R )-差向异构体的产量。同源建模和分子对接阐明了环氧化物加成步骤中 (20 R )-构型的起源。
Acid-catalyzed isomerization of cycloartane triterpene alcohols. The formation of cucurbitane- and lanostane-type isomers
residues in cycloartenolsynthase and cucurbitadienol synthase that were primarily responsible for switching product specificities between the two compounds. The mutation of tyrosine 118 to leucine in cycloartenolsynthase resulted in the production of cucurbitadienol as a majorproduct, while the mutation of the corresponding residue leucine 125 to tyrosine in cucurbitadienol synthase resulted in