Decoding the bitter taste of Idesia polycarpa var. vestita Diels fruit: Bitterness contribution and mechanisms.

To comprehensively explore the contribution and mechanisms of identified low-threshold bitter substances in Idesia polycarpa var. vestita Diels (I. vestita) fruit, we performed quantification and elucidated their interactions with main bitter taste receptors through molecular docking. The established method for quantifying bitter compounds in I. vestita fruit was validated, yielding satisfactory parameters for linearity, stability, and accuracy. Idescarpin (17.71-101.05 mg/g) and idesin (7.88-77.14 mg/g) were the predominant bitter compounds in terms of content. Taste activity values (TAVs) exceeded 10 for the bitter substances, affirming their pivotal role as major contributors to overall bitterness of I. vestita fruit. Notably, idescarpin with the highest TAV, played a crucial role in generating the bitterness of I. vestita fruit. Hydrogen bonds and hydrophobic interactions were the main driving forces. This study holds potential implications for industrial development of I. vestita fruit by providing novel insights into the mechanism underlying its bitterness formation.

MbEOMT1 regulates methyleugenol biosynthesis in Melaleuca bracteata F. Muell.

Methyleugenol, a bioactive compound in the phenylpropene family, undergoes its final and crucial biosynthetic transformation when eugenol O-methyltransferase (EOMT) converts eugenol into methyleugenol. While Melaleuca bracteata F. Muell essential oil is particularly rich in methyleugenol, it contains only trace amounts of its precursor, eugenol. This suggests that the EOMT enzyme in M. bracteata is highly efficient, although it has not yet been characterized. In this study, we isolated and identified an EOMT gene from M. bracteata, termed MbEOMT1, which is primarily expressed in the flowers and leaves and is inducible by methyl jasmonate (MeJA). Subcellular localization of MbEOMT1 in the cytoplasm was detected. Through transient overexpression experiments, we found that MbEOMT1 significantly elevates the concentration of methyleugenol in M. bracteata leaves. Conversely, silencing of MbEOMT1 via virus-induced gene silencing led to a marked reduction in methyleugenol levels. Our in vitro enzymatic assays further confirmed that MbEOMT1 specifically catalyzes the methylation of eugenol. Collectively, these findings establish that the MbEOMT1 gene is critical for methyleugenol biosynthesis in M. bracteata. This study enriches the understanding of phenylpropene biosynthesis and suggests that MbEOMT1 could serve as a valuable catalyst for generating bioactive compounds in the future.

Characterization of key bitter compounds in Idesia polycarpa var. vestita Diels fruit by sensory-guided fractionation.

Idesia polycarpa var. vestita Diels (I. vestita) has become a promising oil crop due to its easily digestible and highly nutritious fruit oil. However, the intense bitter taste of its fruit greatly limits its development and promotion in the food industry. Herein, five key bitter compounds from I. vestita fruit were isolated by sensory-guided fractionation and characterized using ultra-high performance liquid chromatography-quadrupole time of flight-mass spectrometer and nuclear magnetic resonance. The bitter taste of the identified compounds was subsequently validated by threshold tests and computational molecular docking. The bitterness threshold in water of idesin was the lowest (12.051 mg/L), and all bitter substances spontaneously bound to the bitter receptors hTAS2R16 and hTAS2R14, with a stronger affinity for the latter (approximately -6.5 - -9.0 kcal/mol). This is the first systematic study of bitter compounds in I. vestita fruit, providing a scientific basis for revealing the mechanism of bitterness formation and bitterness control.

The Role of MbEGS1 and MbEGS2 in Methyleugenol Biosynthesis by Melaleuca bracteata.

Many aromatic plant volatile compounds contain methyleugenol, which is an attractant for insect pollination and has antibacterial, antioxidant, and other properties. The essential oil of Melaleuca bracteata leaves contains 90.46% methyleugenol, which is an ideal material for studying the biosynthetic pathway of methyleugenol. Eugenol synthase (EGS) is one of the key enzymes involved in the synthesis of methyleugenol. We recently reported two eugenol synthase genes (MbEGS1 and MbEGS2) present in M. bracteata, where MbEGS1 and MbEGS2 were mainly expressed in flowers, followed by leaves, and had the lowest expression levels in stems. In this study, the functions of MbEGS1 and MbEGS2 in the biosynthesis of methyleugenol were investigated using transient gene expression technology and virus-induced gene silencing (VIGS) technology in M. bracteata. Here, in the MbEGSs genes overexpression group, the transcription levels of the MbEGS1 gene and MbEGS2 gene were increased 13.46 times and 12.47 times, respectively, while the methyleugenol levels increased 18.68% and 16.48%. We further verified the function of the MbEGSs genes by using VIGS, as the transcript levels of the MbEGS1 and MbEGS2 genes were downregulated by 79.48% and 90.35%, respectively, and the methyleugenol content in M. bracteata decreased by 28.04% and 19.45%, respectively. The results indicated that the MbEGS1 and MbEGS2 genes were involved in the biosynthesis of methyleugenol, and the transcript levels of the MbEGS1 and MbEGS2 genes correlated with the methyleugenol content in M. bracteata.

Effect of multiple-frequency ultrasound-assisted transglutaminase dual modification on the structural, functional characteristics and application of Qingke protein.

Qingke protein rich in restricted amino acids such as lysine, while the uncoordination of ratio of glutenin and gliadin in Qingke protein has a negative impact on its processing properties. In this study, the effect of multiple-frequency ultrasound combined with transglutaminase treatment on the functional and structural properties of Qingke protein and its application in noodle manufacture were investigated. The results showed that compared with the control, ultrasound-assisted transglutaminase dual modification significantly increased the water and oil holding capacity, apparent viscosity, foaming ability, and emulsifying activity index of Qingke protein, which exhibited a higher storage modulus G' (P < 0.05). Meanwhile, ultrasound combined with transglutaminase treatment enhanced the cross-linking degree of Qingke protein (P < 0.05), as shown by decreased free amino group and free sulfhydryl group contents, and increased disulfide bond content. Moreover, after the ultrasound-assisted transglutaminase dual modification treatment, the fluorescence intensity, the contents of α-helix and random coil in the secondary structure of Qingke protein significantly decreased, while the ß-sheet content increased (P < 0.05) compared with control. SDS-PAGE results showed that the bands of Qingke protein treated by ultrasound combined with transglutaminase became unclear. Furthermore, the quality of Qingke noodles made with Qingke powder (140 g/kg dual modified Qingke protein mixed with 860 g/kg extracted Qingke starch) and wheat gluten 60-70 g/kg was similar to that of wheat noodles. In summary, multiple-frequency ultrasound combined with transglutaminase dual modification can significantly improve the physicochemical properties of Qingke protein and the modified Qingke proteins can be used as novel ingredients for Qingke noodles.

A comprehensive study on physicochemical properties, bioactive compounds, and emulsified lipid digestion characteristics of Idesia polycarpa var. Vestita Diels fruits oil.

Idesia polycarpa var. vestita Diels fruits oil (IPO) has the potential to broaden the availability of healthy vegetable oil and relieve pressure on the edible oil supply. In this study, we compared the physicochemical, bioactivity, and digestive properties of IPO, olive oil (OO), and soybean oil (SO) to comprehensively evaluate the edible potential of IPO. The results revealed no significant differences in relative density or refractive index among the three oils. IPO was rich in ß-sitosterol (366.74 mg/100 g), ß-tocopherol (8.42 mg/100 g), and α-tocopherol (37.10 mg/100 g). The digestive properties of IPO emulsion were investigated for the first time using in vitro simulated digestion. The IPO emulsion stood out regarding its free fatty acid release (88.03 %). Finally, the IPO emulsion released mainly unsaturated fatty acids and had a higher monoacylglycerol content. This study provides new insights into IPO as a high-quality edible vegetable oil.

Multiomics strategy reveals the accumulation and biosynthesis of bitter components in Zanthoxylum schinifolium Sieb. et Zucc.

The perceptible bitterness of Zanthoxylum schinifolium Sieb. et Zucc is an important factor limiting its consumption. Metabolomics was used to identify potentially bitter metabolites during the development of Z. schinifolium, and dynamic changes in 17 key bitter components were characterized. The key bitter components in Z. schinifolium at different developmental stages were mainly synthesized through the "phenylpropanoid biosynthesis", "flavonoid biosynthesis", and "flavone and flavonol biosynthesis" pathways. In combination with transcriptomic data, the expression of related genes regulates the accumulation process of these bitter components; based on this, a biosynthetic pathway of bitter components in Z. schinifolium was constructed. In addition, quercetin-3-galactoside, isoquercitin, quercitrin, kaempferol, and isorhamnetin were identified as the main sources of bitterness in mature Z. schinifolium based on an evaluation of taste activity value. These findings provide valuable information for understanding mechanisms underlying Z. schinifolium bitterness and promoting the further development of high-quality Z. schinifolium.

Evaluation of cultivars diversity and lipid composition properties of Idesia polycarpa var. vestita Diels.

Idesia polycarpa var. vestita Diels is a perennial deciduous tree widely distributed throughout China. Four I. polycarpa fruit of different cultivars with different fruit issues during the growth process were compared, which were on the basis of morphological characteristics and chemical compositions. The influencing factors of oil accumulation in I. polycarpa fruit and the correlation between different components were investigated, and the results revealed a negative correlation between oil content and total sugar (r = -0.930), ash (r = -0.606), and crude fiber (r = -0.952). Except for oil, none of the chemical components changed substantially during the growing phase, and most cultivars showed higher oil content in the pulp portion (14.14-43.99 g/100 g). Linoleic acid was the most abundant fatty acid in I. polycarpa oil (IPO), with values ranging from 52.18% to 66.65% (fruit), 55.44% to 65.15% (pulp), and 68.99% to 78.76% (seed). Principal component analysis revealed that Hubei varieties are more advantageous. Besides, the lipid composition of IPO was identified by ultrahigh-performance liquid chromatography coupled with electrospray ionization Q-Exactive Focus mass spectrometry. The glyceride components of IPO were mostly composed of 22 triacylglycerols, 30 diacylglycerols, and 8 monoacyglycerols. Meanwhile, linoleic acid was mainly distributed in sn-2 and sn-3 positions. PRACTICAL APPLICATION: Morphologic characteristics, chemical compositions, oil fatty acid profiles, and oil correlation factors of I. polycarpa were analyzed. The comprehensive score of oil quality by PCA in Hb fruit was the highest. The glyceride components of I. polycarpa oil were mainly composed of 22 triacylglycerols, 30 diacylglycerols, and eight monoacyglycerols.

Synthesis and bioactivity of phenyl substituted furan and oxazole carboxylic acid derivatives as potential PDE4 inhibitors.

In this present study, a series of 5-phenyl-2-furan and 4-phenyl-2-oxazole derivatives were designed and synthesized as phosphodiesterase type 4 (PDE4) inhibitors. In vitro results showed that the synthesized compounds exhibited considerable inhibitory activity against PDE4B and blockade of LPS-induced TNF-α release. Among the designed compounds, Compound 5j exhibited lower IC50 value (1.4 µM) against PDE4 than parent rolipram (2.0 µM) in in vitro enzyme assay, which also displayed good in vivo activity in animal models of asthma/COPD and sepsis induced by LPS. Docking results suggested that introduction of methoxy group at para-position of phenyl ring, demonstrated good interaction with metal binding pocket domain of PDE4B, which was helpful to enhance inhibitory activity.

Novel S-Thiazol-2-yl-furan-2-carbothioate Derivatives as Potential T3SS Inhibitors Against Xanthomonas oryzae on Rice.

Bacterial leaf blight (BLB) caused by Xanthomonas oryzae pv oryzae (Xoo) is considered as the most destructive disease of rice. The use of bactericides is among the most widely used traditional methods to control this destructive disease. The excessive and repeated use of the same bactericides is also becoming the reason behind the development of bactericide resistance. The widely used method for finding the new antimicrobial agents often involves the bacterial virulence factors as a target without affecting bacterial growth. Type III secretion system (T3SS) is a protein appendage and is considered as having essential virulence factors in most Gram-negative bacteria. Due to the conserved construct, T3SS has been regarded as an important mark for the blooming of novel antimicrobial drugs. Toward the search of new T3SS inhibitors, an alternative series of 1,3-thiazole derivatives were designed and synthesized. Their structures were characterized and confirmed by 1H NMR, 13C NMR, MS, and elemental analysis. All the title compounds inhibited the promoter activity of hpa1 gene significantly. Eight of them showed better inhibition than our previous T3SS inhibitor TS006 (o-coumaric acid, OCA). The treatment of Xoo with eight compounds significantly attenuated HR without affecting bacterial growth. The mRNA levels of some representative genes (hrp/hrc genes) were reduced up to different extents. In vivo bioassay results showed that eight T3SS inhibitors could reduce bacterial leaf blight and bacterial leaf streak symptoms on rice, significantly.

Synthesis and biological evaluation of 1,3,4-thiadiazole derivatives as type III secretion system inhibitors against Xanthomonas oryzae.

Xanthomonas oryzae pv. oryzae (Xoo) infection directly leads to a severe disease known as leaf blight, which is a major cause of yield loss of rice. Use of traditional bactericides has resulted in severe resistance in pathogenic bacteria. A new approach screening compounds that target the virulence factors rather than killing bacterial pathogens is imperative. In gram-negative bacteria, the type III secretion system (T3SS) is a conserved and significant virulence factor considered as a target for drug development. Therefore, we designed and synthesized a new series of 5-phenyl-2-furan carboxylic acid derivatives stitched with 2-mercapto-1,3,4-thiadiazole. Bioassays revealed that the title candidates attenuated the hypersensitive response through suppressing the promoter activity of a harpin gene hpa1 without affecting bacterial growth. Quantitative real time polymerase chain reaction (qRT-PCR) analysis demonstrated reduced the expression of several genes associated with T3SS, when title compounds were applied. Additionally, hrp gene cluster members, including hrpG and hrpX, had reduced mRNA levels. In vivo greenhouse tests showed that candidate compounds could alleviate the effects of Xoo infection in rice (Oryza sativa) and possess better protective activity against rice bacterial leaf blight than bismerthiazol and thiodiazole copper. All tested compounds were safe to rice. This work suggests there are new safe options for Xoo control in rice from these 1,3,4-thiadiazole derivatives.

Discovery of Ethyl 2-Nitro-3-Arylacrylates Molecules as T3SS Inhibitor Reducing the Virulence of Plant Pathogenic Bacteria Xanthomonas.

Xanthomonas oryzae pv. oryzae (Xoo) is a gram-negative pathogen which causes leaf blight disease. Known traditional bactericides are not much more effective in inhibiting this bacteria than before. Selecting the virulence factor of the bacteria as the target without affecting their growth has been considered as a novel method for developing new anti-microbial drugs. Type III secretion systems (T3SS) are one of the important and highly conserved virulence factors in most gram-negative pathogens, which has been considered as an effective target to develop new anti-microbial drugs. In order to discover potential anti-microbial drugs against Xoo pathogens, a series of ethyl 2-nitro-3-arylacrylates compounds were screened. Among them, the compounds I-9, I-12, and I-13 could highly inhibit the promoter activity of a harpin gene hpa1, which were used to further check for the influence on bacterial growth and on the hypersensitive response (HR) caused by Xoo bacteria on non-host plants. The results showed that above compounds could reduce HR without affecting bacterial growth and survival. Moreover, qRT-PCR analysis indicated that treatment with the three inhibitors (I-9, I-12, and I-13) could suppress the expression of the Xoo T3SS in different extent. The mRNA levels of representative genes in the hrp cluster, including the key regulatory genes hrpG and hrpX, were decreased. Last but not least, in vivo test ensured that the above compounds reduced the disease symptoms of Xoo on the rice and Xcc on the Chinese radish.

Synthesis and bioactivity of 1,3-thiazolidine-2-thione derivatives against type III secretion system of Xanthomonas oryzae.

Targeting virulence factors of bacterial without affecting their growth and survival, has been an initiative strategy for the development of novel anti-microbial agents. The type III secretion system (T3SS), one of essential and highly conserved virulence factors in most Gram-negative pathogenic bacteria, has been regarded as an effective target that developed new anti-microbial drugs. Xanthomonas oryzae pv. oryzae (Xoo) is one of the most important bacterial pathogens on rice, which causes leaf blight disease. To discover potential anti-virulence agents against the pathogens, a new series of 1,3-thiazolidine-2-thione derivatives containing 5-phenyl-2-furan were designed and synthesized. Their structures were characterized by 1H NMR, 13C NMR, MS, and elemental analysis. All the title compounds inhibited the promoter activity of a harpin gene hpa1, significantly, that were further checked for the impact on bacterial growth. The results indicated that treatment of Xoo with the title compound III-7 did not affect bacterial growth or survival. Moreover, quantitative reverse transcription-polymerase chain reaction (qRT-PCR) analysis showed that the expression of the Xoo T3SS was suppressed by treatment with the inhibitor. The mRNA levels of representative genes in the hrp (hypersensitive response and pathogenicity) cluster, as well as the regulatory genes hrpG and hrpX, were reduced. Finally, the in vivo test demonstrated that the compounds could reduce the disease symptoms of Xoo on the rice cultivar (Oryza sativa) IR24.

Small Molecule Inhibitors Specifically Targeting the Type III Secretion System of Xanthomonas oryzae on Rice.

The initiative strategy for the development of novel anti-microbial agents usually uses the virulence factors of bacteria as a target, without affecting their growth and survival. The type III secretion system (T3SS), one of the essential virulence factors in most Gram-negative pathogenic bacteria because of its highly conserved construct, has been regarded as an effective target that developed new anti-microbial drugs. Xanthomonas oryzae pv. oryzae (Xoo) causes leaf blight diseases and is one of the most important pathogens on rice. To find potential anti-virulence agents against this pathogen, a number of natural compounds were screened for their effects on the T3SS of Xoo. Three of 34 compounds significantly inhibited the promoter activity of the harpin gene, hpa1, and were further checked for their impact on bacterial growth and on the hypersensitive response (HR) caused by Xoo on non-host tobacco plants. The results indicated that treatment of Xoo with CZ-1, CZ-4 and CZ-9 resulted in an obviously attenuated HR without affecting bacterial growth and survival. Moreover, quantitative reverse transcription-polymerase chain reaction (qRT-PCR) analysis showed that the expression of the Xoo T3SS was suppressed by treatment with the three inhibitors. The mRNA levels of representative genes in the hypersensitive response and pathogenicity (hrp) cluster, as well as the regulatory genes hrpG and hrpX, were reduced. Finally, the in vivo test demonstrated that the compounds could reduce the disease symptoms of Xoo on the rice cultivar (Oryza sativa) IR24.

Synthesis and bioactivity of thiazolidin-2-cyanamide derivatives against type III secretion system of Xanthomonas oryzae on rice.

Targeting virulence factors of bacterial without affecting their growth and survival, has been an initiative strategy for the development of novel anti-microbial agents. The type III secretion system (T3SS), one of essential and highly conserved virulence factors in most Gram-negative pathogenic bacteria, has been regarded as an effective target that developed new anti-microbial drugs. Xanthomonas oryzae pv. oryzae (Xoo) is one of the most Important bacterial pathogens on rice, which causes leaf blight disease. To discover potential anti-virulence agents against the pathogens, a new series of thiazolidin-2-cyanamide derivatives containing 5-phenyl-2-furan were designed and synthesized. Their structures were characterized by 1H NMR, 13C NMR, MS, and elemental analysis. All the title compounds inhibited the promoter activity of a harpin gene hpa1, significantly, that were further checked for the impact on bacterial growth and on the hypersensitive response (HR) caused by Xoo on non-host tobacco plants. The results indicated that treatment of Xoo with the title compounds II-2, II-3 and II-4 resulted in significantly attenuated HR without affecting bacterial growth or survival. Moreover, quantitative reverse transcription-polymerase chain reaction (qRT-PCR) analysis showed that the expression of the Xoo T3SS was suppressed by treatment with the three inhibitors. The mRNA levels of representative genes in the hrp (hypersensitive response and pathogenicity) cluster, as well as the regulatory genes hrpG and hrpX, were reduced. Finally, the in vivo test demonstrated that the compounds could reduce the disease symptoms of Xoo on the rice cultivar (Oryza sativa) IR24.

[Chemical agents modulating bacterial biofilm formation and development].

Biofilm is a bacterial lifestyle ubiquitously in natural environments. Bacterial biofilm leads to drug resistance, a main reason why many infectious diseases are difficult to control. Due to the prominent points of biofilms implicated in infectious disease and the spread of multi-drug resistance, it is urgent to discover new antibacterial agents that can regulate biofilm formation and development. This review introduces chemical agents that could modulate bacterial biofilm formation and development.

[Progress in c-di-GMP inhibitors].

The cyclic dinucleotide c-di-GMP is known as an important second messenger in bacteria, which controls various important cellular processes, such as cell differentiation, biofilm formation and virulence factors production. It is extremely vital for the development of new antibacterial agents by virtue of blocking c-di-GMP signal conduction. Current research indicates that there are three potential targets for discovering new antibacterial agents based on c-di-GMP regulated signal pathway, which are c-di-GMP synthases, c-di-GMP degrading enzymes and c-di-GMP receptors. Herein, we review small molecules that have been developed to inhibit c-di-GMP related enzymes and indicate perspectives of c-di-GMP inhibitors.

Techno-economic analysis of glucosamine and lipid production from marine diatom Cyclotella sp.

A techno-economic analysis (TEA) was performed on glucosamine and lipid production from a marine diatom Cyclotella sp. in raceway open pond (RWP) and tubular photobioreactor (PBR) cultivation systems. Two PBR operating schemes were assessed: one to produce high lipid (HL) content, and another to produce high chitin (HC) content. In order to generate 1kg of glucosamine, 9700kg (RWP)/1050kg (PBR HL) freshwater, 40kg CO2, 0.70kg nitrogen, 0.18kg phosphorus, and 1.2kg silicon nutrients are required for algae cultivation with water and nutrient recovery. With a price of $1.5 for lipid as coproduct, the projected selling price of glucosamine were $35/kg, $106/kg and $82/kg for RWP, PBR HL, and PBR HC systems, respectively. Currently, these prices are not competitive with industrial shellfish-derived glucosamine, but can be reduced by technology improvements such as producing food grade lipid, increasing algal productivity or chitin content.