The biosynthesis,metabolism and translocation of β-amyrin in Sorghum bicolor

The biosynthesis of [¹⁴C] β-amyrin and three other labelled 3β-hydroxypentacyclic triterpenes from [2-^14C] acetate in leaves of Sorghum bicolor was demonstrated. Evidence for the metabolism of [¹⁴C] β-amyrin to the corresponding C-3 ketone (β-amyrone) and for the transport of [¹⁴C] β-amyrin in leaves was also obtained.     

Triterpenoids of Cnidosculus urens

The ethanol extract of Cnidosculus urens yielded β-amyrin cinnamate and germanicol acetate. Also, using ¹³C NMR spectroscopy, mixtures of β-amyrin, germanicol and lupeol as well as their acetates were identified.     

Distribution of some triterpenes and phenolic compounds in the extractives of endemic dipterocarpaceae species of Sri Lanka

Extractives of bark and/or timber of 11 species belonging to the genera Cotylelobium, Hopea, Shorea, Vateria and Vatica yielded a fatty-acid ester, a sitosteryl ester, β-amyrin acetate, β-amyrin, dipterocarpol, ursolic acetate, lupeol, sitosterol, ursolic acid, betulinic acid, hexamethyl-coruleoellagic acid, tetramethylellagic acid, chrysophanol and scopoletin. The distribution of these compounds in 18 other species was examined by TLC screening.     

First report of triterpenes pathway in Calotropis procera revealed to accumulate beta-amyrin

The major reports on Calotropis procera (C. procera) indicated the importance of this plant as a resource of pharmaceutically active ingredients as well as its medical advantages. β-amyrin (BA) is a significant substance in this plant and has a pharmacological effects in some frameworks, like focal and fringe sensory system, digestive and immune systems. In this study, the impact of sunlight before and after irrigation on the BA production in C. procera is studied its pathway with involved eight key enzymes. The eight enzymes' genes were characterized and successfully submitted to NCBI; AAS (acc.no. KU997645) for α-amyrin synthase, BAS (acc.no. MW976955) for β-amyrin synthase, SE (acc.no. MW976956) for squalene epoxidase, SS (acc.no. MW976957) for squalene synthase, GPPS, (acc.no. MW976958) for geranyl pyrophosphate synthase, FPPS (acc.no. MW976959) for farnasyl pyrophosphate synthase, CAS1, (acc.no. MZ00598) for cycloartenol synthase1 and LS (acc.no. MZ005982) for lupeol synthase. qRT-PCR analysis revealed high expression levels of GPPS, FPPS, SS, SE, and BAS genes at all times specially midday. Otherwise, CAS1, LS and BAS expression levels were very low at all daylight periods. The UPLC β-amyrin data are in accordance with qRT-PCR results. This indicates that triterpenes biosynthetic pathway in C. procera is going to β-amyrin accumulation with the highest level at midday.     

Aided-efflux and high production of β-amyrin realized by β-cyclodextrin in situ synthesized on surface of Saccharomyces cerevisiae

As a plant-derived pentacyclic triterpenoid, β-amyrin has been heterogeneously synthesized in Saccharomyces cerevisiae. However, β-amyrin is intracellularly produced in a lower gram scale using recombinant S. cerevisiae, which limits the industrial applications. Although many strategies have been proven to be effective to improve the production of β-amyrin, the intracellularly accumulation is still a challenge in reaching higher titer and simplifying the extraction process. To solve this problem, the amphiphilic β-cyclodextrin (β-CD) has been previously employed to aid the efflux of β-amyrin out of the cells. Nevertheless, the supplemented β-CD in the medium is not consistent with β-amyrin synthesis and has the disadvantage of rather high cost. Therefore, an aided-efflux system based on in situ synthesis of β-CD was developed in this study to enhance the biosynthesis of β-amyrin and its efflux. The in situ synthesis of β-CD was started from starch by the surface displayed cyclodextrin glycosyltransferase (CGTase) on yeast cells. As a result, the synthesized β-CD could capture 16% of the intracellular β-amyrin and improve the total production by 77%. Furthermore, more strategies including inducing system remodeling, precursor supply enhancement, two-phase fermentation and lipid synthesis regulation were employed. Finally, the production of β-amyrin was increased to 73 mg/L in shake flask, 31 folds higher than the original strain, containing 31 mg/L of extracellular β-amyrin. Overall, this work provides novel strategies for the aided-efflux of natural products with high hydrophobicity in engineered S. cerevisiae.     

The stereospecificity of biosynthesis of squalene and β-amyrin in Pisum sativum

The distribution of deuterium in squalene and β-amyrin, biosynthesized from mevalonic acid-6,6,6-d₃ in Pisum sativum, has been examined b     

β-amyrin-induced apoptosis in Candida albicans triggered by calcium

The emergence of drug-resistant pathogens has urged researchers to discover alternatives for traditional antibiotics. β-amyrin, which is included in the category of triterpenoids extracted from plants, is known for its antimicrobial activity, although the underlying mechanism has not yet been revealed. This study was conducted to elucidate the antifungal mode of action of β-amyrin against Candida albicans. Based on the relevance between triterpenoids and oxidative molecules, reactive oxygen species (ROS) concentrations were detected, which showed a noticeable increment. Disruption of Ca²⁺ homeostasis in the cytosol was additionally analyzed, which was supported by interactions between two. Subsequently, decrease in mitochondrial membrane potential, increment of mitochondrial Ca²⁺, and ROS concentration were monitored, which suggested mitochondrial dysfunction modulated by Ca²⁺. Further investigation confirmed oxidative damage through glutathione reduction and DNA fragmentation. Accumulation of lethal damages resulted in the activation of caspases and externalization of phosphatidylserine, indicating the induction of yeast apoptosis by β-amyrin in C. albicans.     

Triterpenoids in epicuticular waxes of Dudleya species

The pentacyclic triterpenoids, β-amyrin acetate and taraxerone, are major components in the epicuticular wax of the genus Dudleya.     

Three isoflavonoids from Iris germanica

From the rhizome of Iris germanica one new hexaoxygenated isoflavone, two new polyoxygenated isoflavone glucosides, the known isoflavonoids irisolidone, irigenin and iridin and acetovanillone, sitosterol, α-amyrin and β-amyrin were isolated. The structures of the new compounds were established by chemical and spectroscopic means and by correlation with known constitutents.     

Identification of a product specific β-amyrin synthase from Arabidopsis thaliana

Triterpene skeletons are produced by oxidosqualene cyclases (OSCs). The genome sequencing of Arabidopsis thaliana revealed the presence of thirteen OSC homologous genes including At1g78950, which has been revised recently as two independent ORFs, namely At1g78950 and At1g78955. The cDNA corresponding to the revised At1g78950 was obtained by RT-PCR, ligated into Saccharomyces cerevisiae expression vector pYES2, and expressed in a lanosterol synthase deficient S. cerevisiae strain. LC-MS and NMR analyses of the accumulated product in the host cells showed that the product of At1g78950 is β-amyrin, indicating that At1g78950 encodes a β-amyrin synthase (EC 5.4.99.-).     

A new tropane alkaloid and other constituents of Erythroxylum rimosum (Erythroxylaceae)

A new tropane alkaloid, named the 7β-acetoxy-3β,6β-dibenzoyloxytropane (1), was isolated from a methanol extract of Erythroxylum rimosum O.E. Schulz leaves. Other known compounds were detected, including quercetin, kaempferol-3-O-α-l-arabinofuranoside, (+)-catechin, epicatechin, quercetin-3-O-α-arabinofuranoside, quercetin-3-O-α-arabinopyranoside, quercetin-3-O-β-arabinopyranoside, quercetin-3-β-glucopyranoside, kaempferol, quercetin-3-O-β-galactopyranoside, β-sitosterol, α-amyrin, β-amyrin, and the ester derivatives of these two amyrins. Compound 1 exhibited weak inhibition of acetylcholinesterase. Structural identification was performed using IR, ESIHRMS and one- and two-dimensional NMR data analyses and confirmed by comparison with literature data.     

Aplotaxene epoxide from Cirsium hypoleucum

Aplotaxene epoxide (11,12-epoxyheptadeca-1,8,14-triene) was isolated from the roots of Cirsium hypoleucum. The pentacyclic tritepenes lupeol, taraxasterol and β-amyrin, and other acetates, were identified in C. hypoleucum, C. canum and C. carolinianum.     

Identification and expression profiling of a new β-amyrin synthase gene (<Emphasis Type="Italic">GmBAS3</Emphasis>) from soybean

Cyclization of 2,3-oxidosqualene by different oxidosqualene cyclase (OSC) genes is responsible for sapogenin heterogeneity. The very first phase is the conversion of 2,3-oxidosqualene into β-amyrin by β-amyrin synthase (BAS) gene, a member of OSC family, in soy saponin biosynthesis pathway. This paper reports the identification of a new BAS gene (GmBAS3) and its expression pattern in soybean (Glycine max (L.) Merr.). GmBAS3 gene was identified by PCR/RACE method with an open reading frame of 2286 bp nucleotides encoding a 762 amino acid long protein devouring a characteristic QW motif repeated five times and DCTAE motif. GmBAS3 shared 96 and 92% homology with Glycyrrhiza uralensis BAS and Lotus japonicus putative BAS respectively. Expression of the gene was detected by RT-PCR in regard to seedlings age and tissue type. A spatio-temporal expression of GmBAS3 was found in 21-day-old seedlings in the hypocotyls, young leaves and mature leaves but not observed in stem and root tissues. No expression was perceived in 10-day-old seedling. This study also support the premise that β-amyrin synthesis hang on more than one type of BAS genes with there expression in different plant parts at different times.     

Sterols and triterpenols in latex and cultured tissues of Euphorbia pulcherrima

The sterol and triterpenol constituents of Euphorbia pulcherrima latex and cultured callus tissues were examined by GLC and mass spectrometry. Latex extracts from different varieties contained sitosterol, β-amyrin, germanicol, cycloartenol, β-amyrin acetate, and germanicol acetate. Capillary GC profiles of these varieties indicated that the triterpene content was essentially identical for examined latices. Cultured tissues derived from petioles and stem internodes synthesized only sitosterol in significant quantities, although trace amounts of several sterols that occur in latex were also detected in cultured tissues. This study supports the interpretation that the pattern of triterpene synthesis in the laticifer of the normal plant is a highly controlled and stable phenomenon among varieties of this species.     

Triterpenoids from Hyptis suaveolens roots

A new natural triterpenoid, 3β-hydroxylup-12-en-28-oic acid, has been isolated from the roots of Hyptis suaveolens in addition to α- and β-amyrin.     

An Acyl Migration in Acetohalogenoglucosamines

Two triterpenoid alcohols, i.e., α- and β-amyrin have been isolated from the unsaponifiable fraction of the ethereal extract of Ilex latifolia Thunberg (Aquifoliaceae). The ratio of the amyrin contents, i.e., α-amyrin to β-amyrin was about 4:1. Stearic acid has also been isolated from the fatty-acid fraction of the hydrolysates.     

Triterpenes from Gymnosporia emarginata

Triterpene quinone-methides, lupenone, β-amyrin, dulcitol, and sitosterol have been isolated from the timber, root and leaf extracts of Gymnosporia emarginata. Their chemotaxonomic significance is discussed.     

Interspecific variation in leaf wax of Dudleya

The distribution of the pentacylic triterpenoids, β-amyrin acetate and taraxerone, in the glaucous epicuticular wax of Dudleya subgenus Dudleya is correlated with both the geographic distribution and corolla tube length of a particular species. This is significant in a genus with many systematic problems.     

A coumarin from Perezia coerulescens

The roots of Perezia coerulescens contain ψ-taraxasteryl acetate, β-amyrin acetate, 8-hydroxypereflorin, pereflorin B and a new compound identified as 3,4,8-trimethoxy-5-formyl coumarin.