Three New Ionone Glycosides from Rhododendron capitatum Maxim.

Six ionone glycosides (1-3 and 5-7), including three new ones, named capitsesqsides A-C (1-3), together with an eudesmane sesquiterpenoid glycoside (4) and three known triterpenoid saponins (8-10) were isolated from Rhododendron capitatum. The structures of these compounds were determined by extensive spectroscopic techniques (MS, UV, 1D-NMR, and 2D-NMR) and comparison with data reported in the literature. The absolute configurations were determined by comparison of the experimental and theoretically calculated ECD curves and LC-MS analyses after acid hydrolysis and derivatization. The anti-inflammatory activities of these compounds were evaluated in the LPS-induced RAW264.7 cells. Molecular docking demonstrated that 2 has a favorable affinity for NLRP3 and iNOS.

A new megastigmane glycoside, a new organic acid glycoside and other constituents with anticomplementary activity from Artemisia halodendron.

A new megastigmane glycoside, (1R,5R,6S,7E)-megastigman-3,9-dione-7-en-6,11-diol 11-O-ß-D-glucopyranoside (1), and a new organic acid glycoside, methyl (4 R)-4-O-ß-D-glucopyranosyl-decanoate (2), together with eight known compounds (3-10), were isolated from the aerial parts of Artemisia halodendron Turcz. ex Bess. (Asteraceae). Their chemical structures were elucidated by 1 D and 2 D NMR and HR-ESI-MS spectra and DP4+ probability analysis. Among the identified compounds, compounds 5, 6 and 10 were isolated from the family Asteraceae, and compounds 3, 4 and 7-9 were identified from the genus Artemisia for the first time. All of the compounds were evaluated for their anticomplementary activity against the classical pathway (CP) and the alternative pathway (AP). Compounds 7 and 9 showed anticomplementary activity with the CH50 values of 0.31 ± 0.08 and 0.50 ± 0.09 mM, respectively.

Mutagenesis of Dimer Interfacial Residues Improves the Activity and Specificity of Methyltransferase for cis-α-Irone Biosynthesis.

Promiscuous enzymes show great potential to establish new-to-nature pathways and expand chemical diversity. Enzyme engineering strategies are often employed to tailor such enzymes to improve their activity or specificity. It is paramount to identify the target residues to be mutated. Here, by exploring the inactivation mechanism with the aid of mass spectrometry, we have identified and mutated critical residues at the dimer interface region of the promiscuous methyltransferase (pMT) that converts psi-ionone to irone. The optimized pMT12 mutant showed ∼1.6-4.8-fold higher kcat than the previously reported best mutant, pMT10, and increased the cis-α-irone percentage from ∼70 to ∼83%. By one-step biotransformation, ∼121.8 mg L-1 cis-α-irone was produced from psi-ionone by the pMT12 mutant. The study offers new opportunities to engineer enzymes with enhanced activity and specificity.

The role of the local environment on the structural heterogeneity of carotenoid ß-ionone rings.

Our analysis of the X-ray crystal structure of canthaxanthin (CAN) showed that its ketolated ß-ionone rings can adopt two energetically equal, but structurally distinct puckers. Quantum chemistry calculations revealed that the potential energy surface of the ß-ionone ring rotation over the plane of the conjugated π-system in carotenoids depends on the pucker state of the ß-ring. Considering different pucker states and ß-ionone ring rotation, we found six separate local minima on the potential energy surface defining the geometry of the keto-ß-ionone ring-two cis and one trans orientation for each of two pucker states. We observed a small difference in energy and no difference in relative orientation for the cis-minima, but a pronounced difference for the position of trans-minimum in alternative pucker configurations. An energetic advantage of ß-ionone ring rotation from a specific pucker type can reach up to 8 kJ/mol ([Formula: see text]). In addition, we performed the simulation of linear absorption of CAN in hexane and in a unit cell of the CAN crystal. The electronic energies of [Formula: see text] transition were estimated both for the CAN monomer and in the CAN crystal. The difference between them reached [Formula: see text], which roughly corresponds to the energy gap between A and B pucker states predicted by theoretical estimations. Finally, we have discussed the importance of such effects for biological systems whose local environment determines conformational mobility, and optical/functional characteristics of carotenoid.

First Occurrence of Megastigmane Glucosides in a Plant of Retama Genus.

Chemical investigation of Retama sphaerocarpa collected in Algeria resulted in the isolation of two megastigmane glucosides, compounds 1 and 2, along with a series of isoflavones and phenol derivatives. Compound 1, named retamoside, was new and its structure was determined by extensive application of spectroscopic methods, including HRMS, 1D and 2D NMR and CD. The anti-inflammatory properties of co-occurring main megastigmane, saurobaccioside B (2) and structurally related vomifoliol (3) on LPS-stimulated murine macrophages RAW 274.7 have been evaluated.

Ionones and lignans from the fresh roots of Rehmannia glutinosa.

Nine undescribed compounds, together with 21 known components, were isolated from the fresh roots of Rehmannia glutinosa. Their structures were elucidated based on spectroscopic data analysis, and the absolute configurations of undescribed compounds were determined by comparison of their calculated and experimental electronic circular dichroic (ECD) spectra and interpretation of their optical rotation data. The α-glucosidase inhibitory effects of the isolated compounds were investigated and all of them exhibited slightly inhibitory activities.

Megastigmane sesquiterpenoids from whole plants of Viola kunawurensis.

Investigation on the chemical constituents of Viola kunawurensis resulted in the isolation of seven undescribed megastigmane sesquiterpenoids including four bicyclic megastigmane glucosides, kunawuronoside A-D, two megastigmane glucosides, kunawuronoside E-F, and a megastigmane, kunawurone A, together with ten known megastigmane sesquiterpenoids. Their structures were established by comprehensive 1D, 2D-NMR and HRESIMS analyses, and their absolute configurations were determined by comparing their calculated ECD data with the experimental ones. Evaluations of the anti-inflammatory activity revealed that kunawuronoside A-D and compounds 14-15 inhibited COX-2 expression with inhibition rates ranging from 36.7% to 58.5%, while the NO production induced by lipopolysaccharide (LPS) was suppressed by the kunawuronoside A-D in a dose-dependent manner in RAW264.7 macrophage cell line.

Four ionones and ionone glycosides from the whole plant of Rehmannia piasezkii.

Four new ionones and ionone glycosides (1-4) were isolated from the whole plant of Rehmannia piasezkii Maxim. Their planar structures as well as absolute configuration were confirmed via spectroscopic analysis, ECD calculation, and X-ray crystallography. Compounds 1-4 were tested for their cytotoxicity against five human tumor cell lines and ability to inhibit LPS-activated NO production in the BV2 cell line.

The Allelopathic Activity of Extracts and Isolated from Spirulina platensis.

We determined the allelopathic effects of crude organic (hexane, ethyl acetate, and methanol) extracts of the cyanobacterial Spirulina platensis on barnyardgrass (Echinochloa crus-galli (L.) Beauv.) and Chinese amaranth (Amaranthus tricolor L.). The crude ethyl acetate extract showed the highest inhibitory activity and was subsequently fractionated by column chromatography into 23 fractions based on thin-layer chromatography band pattern similarities. Four concentrations (2000, 1000, 500, and 250 ppm) of each fraction were tested for their allelopathic activity. Fractions E6 and E13 exhibited the most significant inhibitory effects against Chinese amaranth. The constituents of the highly active E6F3-E6F5 fractions determined by GC-MS, chromatography, and spectroscopy included the fatty acids, γ-linolenic acid 15, oleic acid 12, and predominantly palmitic acid 7; minor constituents included 2-ethyl-3-methylmaleimide 9 and C11 norisoprenoids (dihydroactinidiolide 10 and 4-oxo-ß-ionone 13). Isolation of E13 fraction by column chromatography revealed four C13 norisoprenoids: 3-hydroxy-ß-ionone 17, 3-hydroxy-5α,6α-epoxy-ß-ionone 18, 3-hydroxy-5ß,6ß-epoxy-ß-ionone 19, and loliolide 20. Their structures were elucidated by NMR spectroscopy. All six isolated norisoprenoids inhibited seed germination and seedling growth of Chinese amaranth at concentrations of 250-1000 ppm. Allelochemicals from S. platensis could be utilized in the development of novel bioactive herbicides.

One-pot synthesis of dihydro-ß-ionone from carotenoids using carotenoid cleavage dioxygenase and enoate reductase.

Dihydro-ß-ionone is a characteristic aroma compound of Osmanthus fragrans and is widely applied in the flavor & fragrance industry. However, the main focus is on chemical synthesis due to the metabolic pathways of dihydro-ß-ionone is still unclear. Here, we explored the one-pot synthesis system for dihydro-ß-ionone production using carotenoid cleavage dioxygenase (CCD) and enoate reductase. After screening the CCD enzyme, PhCCD1 from the Petunia hybrid was identified as the suitable enzyme for the first step of dihydro-ß-ionone synthesis due to the high enzyme activity for carotenoid. The PhCCD1 was expressed in Escherichia coli and further characterized. The optimal activity of PhCCD1 was observed at pH 6.8 and 45 °C. The enzyme was stable over the pH range of 6.0-8.0 and had good thermal stability below 40 °C. Then, we optimized the coupled reaction conditions for dihydro-ß-ionone production by PhCCD1 and enoate reductase AaDBR1 from Artemisia annua. Furthermore, we introduced the NADPH regeneration system with a 1.5-fold enhancement for dihydro-ß-ionone production. Collectively, approximately 13.34 mg/L dihydro-ß-ionone was obtained by the one-pot biosystem with a corresponding molar conversion of 85.8%. For the first time, we successfully designed and constructed a new synthesis pathway for dihydro-ß-ionone production in vitro. The coupled catalysis reported herein illustrates the feasibility of producing dihydro-ß-ionone from carotenoids and guides further engineering in the food industry.

Chemical constituents and absolute configuration of megastigmanes' isolated from Sedum sarmentosum Bunge.

Phytochemical investigation of a methanolic extract of Sedum sarmentosum collected from Vietnam resulted in the isolation of a new megastigmane glucoside, named sedumoside K (1), together with 17 previously reported compounds (2-18). Structural elucidation of the new compound was achieved by HRFABMS, NMR spectroscopic analysis, acid hydrolysis and quantum ECD calculations. The absolute configuration of compounds 2-6 has been revised. The major isolates were tested for cytotoxic activity against HeLa human cervical cancer cells, and all showed moderate activities.

Cloning and Characterization of a Novel Carotenoid Cleavage Dioxygenase 1 from Helianthus annuus.

Natural ß-ionone, a high-value flavoring agent, has been widely applied in the food, cosmetics, and perfume industry. However, attempts to overproduce ß-ionone in microorganisms have been limited by the efficiency of carotenoid cleavage dioxygenases (CCDs), which catalyzes ß-carotene in the biosynthesis pathway. In order to obtain CCD genes responsible for the specific cleavage of carotenoids generating ß-ionone, a novel carotenoid cleavage dioxygenase 1 from Helianthus annuus was cloned and overexpressed in Escherichia coli BL21(DE3). The recombinant CCD was able to cleave a variety of carotenoids at the 9, 10 (9', 10') sites to produce C13 products in vitro, including ß-ionone, pseudoionone, 3-hydroxy-4-oxo-ß-ionone, 3-hydroxy-ß-ionone, and 3-hydroxy-α-ionone, which vary depending on the carotenoid substrates. In comparison with lycopene and zeaxanthin, HaCCD1 also showed the high specificity for ß-carotene to cleave the 9, 10 (9', 10') double bond to produce ß-ionone in E. coli accumulating carotenoids. Finally, the expression of HaCCD1 in E. coli was optimized, and biochemical characterizations were further clarified. The optimal activity of HaCCD1 was at pH 8.8 and 50 °C. The Vmax for ß-apo-8'-carotenal was 10.14 U/mg, while the Km was 0.32 mM. Collectively, our study provides a valuable enzyme for the synthesis of natural ß-ionone by biotransformation and synthetic biology platform.

Alkaloid derivative ION-31a inhibits breast cancer metastasis and angiogenesis by targeting HSP90α.

Breast cancer has become the number one killer of women. In our previous study, an active compound, ION-31a, with potential anti-metastasis activity against breast cancer was identified through the synthesis of ionone alkaloid derivatives. In the present study, we aimed to identify the therapeutic target of ION-31a. We used a fluorescence tag labeled probe, molecular docking simulation, and surface plasmon resonance (SPR) analysis to identify the target of ION-31a. The main target of ION-31a was identified as heat shock protein 90 (HSP90). Thus, ION-31a is a novel HSP90 inhibiter that could suppress the metastasis of breast cancer and angiogenesis significantly in vitro and in vivo. ION-31a acts via inhibiting the HSP90/hypoxia inducible factor 1 alpha (HIF-1α)/vascular endothelial growth factor (VEGF)/VEGF receptor 2 (VEGFR2) pathway and downregulating downstream signal pathways, including protein kinase B (AKT)/mammalian target of rapamycin (mTOR), AKT2/protein kinase C epsilon (PKCζ), extracellular regulated kinase 1/2 (ERK1/2), focal adhesion kinase (FAK), and mitogen-activated protein kinase 14 (p38MAPK) pathways. ION-31a affects multiple effectors implicated in tumor metastasis and has the potential to be developed as an anti-metastatic agent to treat patients with breast cancer.

The Potential Effect of ß-Ionone and ß-Damascenone on Sensory Perception of Pinot Noir Wine Aroma.

Volatile compounds are responsible for driving the aroma of wine. Because of their low perception thresholds, norisoprenoids may play an important role in wine aroma. Studies have shown that ß-damascenone may act as an aroma enhancing compound. However, the direct impact on wine aroma is unclear. Our study examined the direct impact of ß-ionone and ß-damascenone on the aroma sensory perception of Pinot noir wines. Triangle tests were used to determine if assessors could distinguish between wines with varying concentrations of ß-ionone and ß-damascenone in three different Pinot noir wine matrixes. Descriptive analysis was performed on these treatments, perceived as different in triangle tests. Results show that ß-ionone acts as a significant contributor to aromas in Pinot noir wine, as individuals could differentiate both the low and high concentration wines from the control. How ß-ionone impacted wine aroma depends on the wine matrix, as different aroma descriptors were affected based on the model wine used, resulting in floral, red berry or dark berry aromas. The effect of ß-damascenone on Pinot noir aroma was less clear, as perception seems to be heavily influenced by wine matrix composition. This study contributes to our understanding of the complex chemical causation of fruity aromas in Pinot noir wine.

Discovery of Antimetastatic Chiral Ionone Alkaloid Derivatives Targeting HIF-1α/VEGF/VEGFR2 Pathway.

Novel chiral ionone alkaloid derivatives were synthesized and their antimetastatic effects were evaluated in human breast cancer cells using chemotaxis assay. Compared with positive control LY294002, a PI3 K inhibitor, derivatives 10 a, 11 a, 11 c, 11 g, 11 j, 11 k and 11 w exhibited significant inhibitory effects against cancer cell migration. Especially, the IC50 for compound 11 g was as low as 0.035±0.004 µM. Further investigations on compound 11 g revealed that it could exert inhibitory effects on the adhesion, migration and invasion of MDA-MB-231 cells. The mechanisms for the antitumor metastatic effects of 11 g might be through the inhibition of HIF-1α/VEGF/VEGFR2/Akt pathway, which suppressed the downstream signaling molecules, including Akt1/mTOR/p70S6K and Akt2/PKCζ/integrin ß1 pathways. Taken together, chiral ionone alkaloid derivative 11 g has the potential to be developed into an antitumor metastatic agent for breast cancer.

Effect of brewing conditions on phytochemicals and sensory profiles of black tea infusions: A primary study on the effects of geraniol and ß-ionone on taste perception of black tea infusions.

As a worldwide popular drink, black tea has always been one of the main focuses of tea studies. However, few studies have addressed the flavor profiles and related components, and most researches were based on a single factor. This study investigated the effects of multiple brewing conditions (temperature, time, water/tea ratio, and particle size) on the phytochemicals (non-volatile and volatile compounds) and sensory profiles of black tea infusions through response surface methodology. The regression models describing the brewing of detected indexes were significant (p ≤ 0.01) and reliable (R2 ≥ 0.902). The particle size led to the greatest variation of non-volatile compounds and presented negative correlations, while the water/tea ratio affected the composition of volatile compounds the most. Meanwhile, through the addition of the selected aroma compounds (geraniol and ß-ionone), an enhancement of black tea infusion sweetness was observed, proved the existence of odor-taste interaction in black tea infusions.

Meaningful Words in Crowd Noise: Searching for Volatiles Relevant to Carpenter Bees among the Diverse Scent Blends of Bee Flowers.

Olfactory cues constitute one of the most important plant-pollinator communication channels. Specific chemical components can be associated with specific pollinator functional groups due to pollinator-mediated selection on flower volatile (FV) emission. Here, we used multivariate analyses of FV data to detect an association between FVs and the worldwide distributed pollinator group of the carpenter bees (Xylocopa spp.). We compiled FVs of 29 plant species: 9 pollinated by carpenter bees, 20 pollinated by other bee pollinator functional groups. We tested whether FV emission differed between these groups. To rule out any phylogenetic bias in our dataset, we tested FV emission for phylogenetic signal. Finally, using field assays, we tested the attractive function of two FVs found to be associated with carpenter bees. We found no significant multivariate difference between the two plant groups FVs. However, seven FVs (five apocarotenoid terpenoids, one long-chain alkane and one benzenoid) were significantly associated with carpenter bee pollination, thus being "predictor" compounds of pollination by this pollinator functional group. From those, ß-ionone and (E)-methyl cinnamate presented the highest indicator values and had their behavioural function assessed in field assays. Phylogenetic signal for FVs emission was weak, suggesting that their emission could result from pollinator-mediated selection. In field assays, the apocarotenoid ß-ionone attracted carpenter bees, but also bees from other functional groups. The benzenoid (E)-methyl cinnamate did not attract significant numbers of pollinators. Thus, ß-ionone functions as a non-specific bee attractant, while apocarotenoid FVs emerge as consistent indicators of pollination by large food-foraging bees among bee-pollinated flowers.

Older and Young Adults Experience Similar Long-Term Olfactory Habituation.

Olfactory habituation corresponds to a decreased behavioral or perceptual response to an odor after a prolonged exposure to this odor. Our aim was to investigate whether long-term olfactory habituation and its recovery are similar in young (<35 years old) and older adults (>50). Fifty-seven participants were recruited for a 5-week longitudinal study. They were exposed to one of the two odors (manzanate alpha [MA], irone alpha [IA]) for 2 weeks at home. Olfactory detection thresholds for both odors were measured before and after exposure. Results showed that the two age groups behaved similarly. The long-term exposure to an odor led to a temporary increase of its detection threshold (lower sensitivity to the odor). IA thresholds were more sensitive to the duration of exposure with the odor than MA thresholds. One week after termination of exposure, participants fully recovered and even became more sensitive to both odors. No cross-habituation was found between the two odors. Our findings highlight that long-term habituation is specific to the odor exposed, behaves the same in young and older adults, and is fully reversible in both age groups after 1 week.

Identification of Aroma Composition and Key Odorants Contributing to Aroma Characteristics of White Teas.

The identification of aroma composition and key odorants contributing to aroma characteristics of white tea is urgently needed, owing to white tea's charming flavors and significant health benefits. In this study, a total of 238 volatile components were identified in the three subtypes of white teas using headspace solid-phase microextraction (HS-SPME) combined with comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry (GC × GC-TOFMS). The multivariate statistical analysis demonstrated that the contents of 103 volatile compounds showed extremely significant differences, of which 44 compounds presented higher contents in Baihaoyinzhen and Baimudan, while the other 59 compounds exhibited higher contents in Shoumei. The sensory evaluation experiment carried out by gas chromatography-olfactometry/mass spectrometry (GC-O/MS) revealed 44 aroma-active compounds, of which 25 compounds were identified, including 9 alcohols, 6 aldehydes, 5 ketones, and 5 other compounds. These odorants mostly presented green, fresh, floral, fruity, or sweet odors. Multivariate analyses of chemical characterization and sensory evaluation results showed that high proportions of alcohols and aldehydes form the basis of green and fresh aroma characteristic of white teas, and phenylethyl alcohol, γ-Nonalactone, trans-ß-ionone, trans-linalool oxide (furanoid), α-ionone, and cis-3-hexenyl butyrate were considered as the key odorants accounting for the different aroma characteristics of the three subtypes of white tea. The results will contribute to in-depth understand chemical and sensory markers associated with different subtypes of white tea, and provide a solid foundation for tea aroma quality control and improvement.

Ionone Is More than a Violet's Fragrance: A Review.

The term ionone is derived from "iona" (Greek for violet) which refers to the violet scent and "ketone" due to its structure. Ionones can either be chemically synthesized or endogenously produced via asymmetric cleavage of ß-carotene by ß-carotene oxygenase 2 (BCO2). We recently proposed a possible metabolic pathway for the conversion of α-and ß-pinene into α-and ß-ionone. The differences between BCO1 and BCO2 suggest a unique physiological role of BCO2; implying that ß-ionone (one of BCO2 products) is involved in a prospective biological function. This review focuses on the effects of ionones and the postulated mechanisms or signaling cascades involved mediating these effects. ß-Ionone, whether of an endogenous or exogenous origin possesses a range of pharmacological effects including anticancer, chemopreventive, cancer promoting, melanogenesis, anti-inflammatory and antimicrobial actions. ß-Ionone mediates these effects via activation of olfactory receptor (OR51E2) and regulation of the activity or expression of cell cycle regulatory proteins, pro-apoptotic and anti-apoptotic proteins, HMG-CoA reductase and pro-inflammatory mediators. α-Ionone and ß-ionone derivatives exhibit anti-inflammatory, antimicrobial and anticancer effects, however the corresponding structure activity relationships are still inconclusive. Overall, data demonstrates that ionone is a promising scaffold for cancer, inflammation and infectious disease research and thus is more than simply a violet's fragrance.