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Ubiquitin ligase HcPUB30 targets HcWRKY1 to regulate monoterpenoids synthesis in Hedychium coronarium.

Hedychium coronarium, a perennial herb belonging to the genus Hedychium Koenig within the family Zingiberaceae, is renowned for its pleasant fragrance. The volatile compounds of flowers are primarily terpenoids, which are catalyzed by terpenoid synthase (TPS). Earlier studies have shown that HcWRKY1 transcription factor can bind to the promoter of HcTPS1, regulating the metabolism of terpenoids. To further investigate the upstream molecular mechanisms that regulate the release of volatile compounds in Hedychium, we focused on a crucial U-box type of E3 ubiquitin ligase involved in regulating transcription factors. This study utilized genomic data to identify HcPUB gene family. In combination with transcriptome data, seven candidate HcPUB genes were identified and cloned with subsequent functional analysis. Yeast two-hybrid assay demonstrated that HcPUB30 was the sole interactor of HcWRKY1 among the seven HcPUB candidates. In vivo and in vitro ubiquitination assays demonstrated that HcPUB30 ubiquitinates and promotes the degradation of HcWRKY1 via the 26S proteasome pathway. Multi-alignment analysis revealed that HcPUB30 possesses a conserved U-box domain and ARM motifs, which are implicated in plant growth and development. Subcellular localization indicated that HcPUB30 is localized in both the nucleus and cytoplasm. Quantitative real-time PCR analysis revealed that HcPUB30 exhibited the highest expression in petal tissues, and its expression peaked during floral senescence stage. Virus-induced gene silencing of HcPUB30 in Hedychium petals resulted in a significant decrease in monoterpenoid content, accompanied by a significant reduction in the relative expression levels of HcWRKY1 and HcTPS1. These findings indicate that HcPUB30 participates in the regulation of monoterpenoid biosynthesis by mediating HcWRKY1 in Hedychium petals.

Plant Proteins

Genome-wide association studies reveal genetic variants associated with antineoplastic monoterpenoid indole alkaloid accumulation in Catharanthus roseus.

Catharanthus roseus produces pharmacologically important monoterpenoid indole alkaloids (MIAs), yet their natural accumulation is low, limiting therapeutic exploitation. To dissect the genetic basis of natural variation in MIA accumulation, we integrated phenotypic, chemotypic, and genomic analyses of 93 C. roseus accessions sampled from six locations across India, including New Delhi, Lucknow, Jodhpur, Bangalore, and two locations in Gujarat: Navsari and Bardoli. Morphological characterization showed limited differentiation among locations, whereas accessions from Gujarat tended to be taller compared to other locations and more frequently white-flowered. Quantitative HPLC profiling revealed substantial accession- and location-dependent variation in total indole alkaloid levels, with Gujarat accessions showing the highest accumulation, largely driven by vindoline and catharanthine. Genotyping-by-sequencing generated 10,801 high-quality variants comprising 10,087 SNPs and 714 InDels corresponding to an average density of 19.34 variants per Mbp of the genome, revealing three genetic subgroups with overall admixed ancestry and weak geographic stratification. Genome-wide association study (GWAS) using five benchmark models identified 47 variants potentially associated with catharanthine, vindoline, and vinblastine content. These putative candidate loci were located near genes implicated in hormone signaling, mitochondrial function, nitrogen metabolism, and RNA processing, suggesting complex regulatory control of MIA biosynthesis. Notably, two missense variants in a carboxylesterase-like gene were associated with vindoline accumulation, and highly significant intergenic SNP clusters suggested putative regulatory hotspots for vinblastine biosynthesis. These results provide GWAS-based insights into the genetic architecture of MIA metabolism in C. roseus and nominate candidate variants for precision breeding and metabolic engineering to enhance pharmaceutical alkaloid production.

Catharanthus roseus

[New monoterpenoids from Cynanchum hancockianum].

Five monoterpenoids have been isolated from the roots of Cynanchum hancockianum (Maxim) AI. Iljinski. Their structures were determined on the basis of spectral evidence. The three new compounds are: 4-p-menthane-1,7,8-triol (III), neohancoside A (IV), neohancoside B (V), and the two knowns: 4-p-menthene-1-8, 9-diol (I), and 4-p-menthane-1,8, 9-triol (II). Compound V was purified by acetylation.

Cyclohexane Monoterpenes

Haplotype-specific expression of a terpene synthase underlies linalool variation in the grapevine cultivar Riesling.

Grapevine cultivars vary widely in monoterpenoid content, yet the genetic and regulatory mechanisms underlying this variation remain poorly characterized beyond highly aromatic Muscat types. We profiled free volatiles and monoterpenoid glycosides in a Riesling × Cabernet Sauvignon F1 mapping population, revealing extensive variation and transgressive segregation consistent with multigenic control. QTL mapping identified 70 significant loci associated with 48 volatile compounds and monoterpene glycosides, including two major QTLs explaining 33.6% and 33.4% of phenotypic variance in (3S)-linalool accumulation. Integration of haplotype-resolved transcriptomics with metabolite data, enabled by a chromosome-scale diploid Riesling genome assembly, resolved a (3S)-linalool/nerolidol synthase cluster on chromosome 10 and identified VviTPS54 as the strongest candidate underlying linalool variation. VviTPS54 exhibited haplotype-specific expression strongly correlated with (3S)-linalool accumulation across genotypes, while no QTL was detected at the 1-deoxy-D-xylulose-5-phosphate synthase 1 (VviDXS1) locus previously identified in Muscat cultivars. In addition, VviDXS1 expression was not correlated with terpene levels, indicating that regulatory variation within terpene synthase clusters, rather than methylerythritol phosphate (MEP) pathway flux, drives monoterpenoid composition in this population. These results establish regulatory variation of terpene synthases as a key mechanism underlying monoterpenoid diversity in grapevine and demonstrate that resolving such variation requires haplotype-phased genome assemblies coupled with haplotype-resolved transcriptomics to detect allele-specific expression differences at complex, heterozygous loci.

Grapevine

Secondary metabolite biosynthesis in cultured cells of Catharanthus roseus (L.) G. Don immobilized by adhesion to glass fibres.

Suspension-cultured cells of Catharanthus roseus (L.) G. Don were immobilized on glass fibre mats and cultivated in shake flasks. The highly-aggregated immobilized cells exhibited a slower growth rate and accumulated reduced levels of tryptamine and indole alkaloids, represented by catharanthine and ajmalicine, in comparison to cells in suspension. The increased total protein synthesis in immobilized cells suggests a diversion of the primary metabolic flux toward protein biosynthetic pathways and away from other growth processes. In-vitro assays for the specific activity of tryptophan decarboxylase (TDC) and tryptophan synthase (TS) suggest that the decreased accumulation of tryptamine in immobilized cells was due to reduced tryptophan biosynthesis. The specific activity of TDC was similar in immobilized and suspension-cultured cells. However, the expression of TS activity in immobilized cells was reduced to less than 25% of the maximum level in suspension-cultured cells. The reduced availability of a free tryptophan pool in immobilized cells is consistent with the reduced TS activity. Reduced tryptamine accumulation, however, was not responsible for the decreased accumulation of indole alkaloids in immobilized cells. Indole alkaloid accumulation increased to a similar level in immobilized and suspension-cultured cells only after the addition of exogenous secologanin to the culture medium. The addition of tryptophan resulted in increased accumulation of tryptamine, but had no effect on indole alkaloid levels. Reduced biosynthesis of secologanin, the monoterpenoid precursor to indole alkaloids, in immobilized cells is suggested. Immobilization does not appear to alter the activity of indole alkaloid biosynthetic enzymes in our system beyond, and including, strictosidine synthase.

Alkaloids

Vortex-assisted liquid-liquid microextraction based on natural deep eutectic solvents for the determination of pyrethroid pesticides in urine.

A novel, facile, and environmentally friendly analytical method was developed based on vortex-assisted liquid-liquid microextraction and high-performance liquid chromatography with diode-array detection for detecting pyrethroid pesticides (PPs) in urine. Natural deep eutectic solvents (NADESs) were prepared using plant essential oil-derived monoterpenoids (thymol, carvacrol, and menthol) combined with aromatic primary alcohols (benzyl alcohol, phenethyl alcohol, and phenylpropyl alcohol) as hydrogen bond donors and acceptors. These solvents served as environmentally benign extraction media, thereby avoiding the use of conventional volatile, toxic organic solvents. NADESs are naturally derived, easy to prepare, biodegradable, and environmentally friendly solvents. Hydrophobic and π-π interactions between the NADESs and PPs may contribute to enhancing the affinity of PPs toward the NADESs phase. Vortex technology, accelerating mass transfer between the sample and extractant phases, enables fast extraction of PPs. Under optimized conditions, the method achieved a low detection limit (0.002 mg L-1), satisfactory precision with relative standard deviations (0.3%-2.4%), and acceptable recovery (80.7%-86.2%). The method demonstrated excellent performance in urine analysis and was feasible as a facile and green strategy for monitoring the content of PPs in biological matrices and assessing exposure risk.

Liquid Phase Microextraction

Association Between the Root Canal Microbiome and Apical Lesion Size: An Observational Shotgun Metagenomic Study.

AIM: The aim was to characterize the taxonomic and functional composition of the microbiome involved in primary endodontic infections and to evaluate their association with the periapical lesion size using shotgun metagenomic sequencing. METHODOLOGY: Samples from primary root canal infections diagnosed with apical periodontitis were analysed with shotgun sequencing. Samples were classified according to the lesion size as small (<&#x2009;3&#x2009;mm) or large (>&#x2009;7&#x2009;mm). The bacterial DNA copies in each group were quantified by qPCR. Taxonomic and functional annotations were made using Bracken/Kraken2 and HUMAnN3 software. Species richness, Shannon, Simpson and Pielou indices were used to measure alpha diversity. The similarity of the bacterial communities between study groups was evaluated by Principal Coordinate Analysis based on Bray-Curtis distances. The ALDEx2 package was used to infer the differences between species, and the edgeR package for KEGG pathways. For all statistical analyses, p&#x2009;<&#x2009;0.05 was considered as significant. RESULTS: A total of 49 samples were analysed, 27 with small lesions and 22 with large lesions. Species richness and Shannon indices showed differences between both groups, whereas no differences were seen according to Simpson and Pielou indices. A different community composition (PERMANOVA, p&#x2009;=&#x2009;0.0019) was observed between the two groups. Three species were significantly enriched in the large lesion samples, Filifactor alocis, Lachnospiraceae bacterium oral taxon 500 and Olsenella uli, while three others were enriched in small lesion samples, Acinetobacter baumannii, Acinetobacter pittii and Cutibacterium acnes. Functionally, benzoate, flavonoid and steroid degradation, the sphingolipid signalling pathway and proteasome function were enriched in samples with large lesions. Monoterpenoid biosynthesis, phospholipase D signalling, the sulphur relay system and staurosporine biosynthesis were enriched in small lesions. CONCLUSIONS: Teeth with large periapical lesions harbour greater bacterial loads and exhibit a more diverse microbial community than those with small lesions. Differences in species-level taxonomic composition were observed between both groups. Functionally, large lesions are enriched in pathways associated with immune evasion and pro-inflammatory activity, whereas small lesions are characterized by pathways related to apoptosis, metabolic adaptation and anti-inflammatory processes. These findings suggest that lesion severity is also shaped by the functional potential of the microbiome to modulate host inflammation.

Humans

Purification and properties of strictosidine synthase, the key enzyme in indole alkaloid formation.

A new enzyme, strictosidine synthase, which catalyzes the synthesis of 3-alpha(S)-strictosidine from tryptamine and secologanin was isolated from the soluble protein extract of Catharanthus roseus cell suspension cultures and was purified approximately 50-fold by ammonium sulfate fractionation, column chromatography on DEAE-cellulose. Ultrogel AcA34 and isoelectric focusing. The apparent molecular weight of the enzyme was 34000. The pH optimum was 6.8, apparent Km values for tryptamine and secologanin were 2.3 mM and 3.4 mM respectively for the enzyme to synthesize strictosidine. Strictosidine synthase shows high substrate specificity. No apparent cofactor requirement could be demonstrated. Of several enzyme inhibitors tested, only p-chloromercuribenzoate inhibited the enzyme. The enzyme was relatively stable and could be stored at -20 degrees C for periods of up to 1 year without appreciable loss of catalytic activity. The enzyme was demonstrated to occur in suspension cultures of 15 different species belonging to 9 different genera of the indole-alkaloid-producing subfamily Plumerioideae of the Apocynaceae family. This enzyme is responsible for the synthesis of strictosidine the key intermediate in the formation of the majority of monoterpenoid indole alkaloids occurring in the plant kingdom.

Cells, Cultured

[Terpenoids and curcuminoids of the rhizoma of Curcuma xanthorrhiza Roxb].

The fresh rhizomes of Curcuma xanthorrhiza Roxb. were investigated for terpenoids and curcuminoids. Nine sesquiterpenoids, alpha-curcumene (1), arturmerone (2), xanthorrhizol (3), germacrone (4), beta-curcumene (6), beta-sesquiphellandrene (9), curzerenone (10), alpha-turmerone (11) and beta-turmerone (12), and three curcuminoids, curcumin (7), mono-demethoxycurcumin (8) and bis-demethoxycurcumin (13), were isolated and one monoterpenoid, camphor (5), was identified by capillary GC-MS. Four species of C. xanthorrhiza could be classified into two chemotypes by their bisabolane-type sesquiterpenoid compositions. The first type contained large amounts of 2, 11 and 12 (CX I type). The second type contained large amounts of 1, 3 and 6, and none of 2, 9, 11 and 12 (CX II type). These two chemotypes, CX I type and CX II type, were compared with the two chemotypes of C. longa L., CL I type and CL II type, on their contents by capillary GC and HPLC analysis. It was found that all of them contained curcuminoids, 7, 8 and 13 and large amounts of various bisabolane-type sesquiterpenoids.

Chromatography, Gas

Whole-Genome Sequence Dataset of Rhodococcus qingshengii IEGM 267-Terpenoid Biotransformer Toward Genetic Functional Annotation.

Background/Objectives: Microbial biotransformation of monoterpenoids is a promising approach for obtaining bioactive compounds. Rhodococcus species are attractive biocatalysts due to their metabolic versatility and ability to transform hydrophobic substrates. In this study, we investigated the catalytic potential of Rhodococcus qingshengii IEGM 267 toward carveol isomers and explored genomic features that may underlie this activity. Methods: The strain was cultivated in mineral medium supplemented with (-)-trans-carveol. Biotransformation products were analyzed by TLC and GC-MS. The draft genome was sequenced, assembled, taxonomically assigned, and annotated using standard bioinformatics tools. Results: Rhodococcus qingshengii IEGM 267 efficiently converted (-)-trans-carveol to carvone. Genome analysis confirmed the taxonomic assignment of the strain and revealed a large repertoire of oxidoreductases, including monooxygenases, hydroxylases, and dehydrogenases. Seven genes encoding cytochrome P450-dependent oxygenases were identified as candidate enzymes potentially involved in carveol oxidation. Conclusions: R. qingshengii IEGM 267 is an efficient and stereoselective biocatalyst for (-)-trans-carveol oxidation. The results of bioinformatics analysis suggest an alternative enzymatic basis for this transformation and provide a foundation for future functional characterization.

Rhodococcus

[Analysis of chemical constituent of essential oil in Lonicera japonnica Thunb. cultivated on the northern plain of Henan Province].

The chemical constituents of the essential oil in the dry flower and fresh flower of Lonicera japonica were analyzed by the GC-MS-DS technique and the superimposition of authentic samples. 27 and 30 monoterpenoids and sesquiterpenoids were identified from the essential oil of the dry flower and fresh flower respectively. The major constituents have been found to be linalool, geraniol, aromadendrene and eugenol etc.

Acyclic Monoterpenes