Trigonelline Content Research Articles

Effect of stress hormones on the metabolome of a suspension culture of the aromatic medicinal plant Cymbopogon schoenanthus subsp. proximus

The current study aimed to evaluate and compare the effect of different concentrations (0.0–200.0 µM) of jasmonic acid (JA), methyl jasmonate (MeJA), and salicylic acid (SA) on suspension culture mass production and untargeted metabolic profiling of the medicinal plant Cymbopogon schoenanthus subsp. proximus. The addition of 50 µM MeJA improved the fresh weight of embryogenic tissue significantly. MeJA and SA did not affect tissue dry weight, whereas JA significantly decreased it. Based on 1H and 1H–13C NMR data and NMR databases, 50 compounds were identified. The addition of stress hormones resulted in the biosynthesis of novel metabolites like theophylline and syringate that were absent in control samples. In addition, significant variations in the concentrations of numerous compounds, including sugars, amino acids, organic acids, phenols, and alkaloids, were observed. The upregulation of trigonelline concentration was observed upon the addition of a higher concentration of MeJA (200 µM), whereas all tested concentrations of SA resulted in its upregulation. Addition of JA and SA causes significant changes in aminoacyl-tRNA biosynthesis pathway and amino acid metabolism pathways, such as alanine-aspartate and glutamate metabolism and arginine and proline metabolism. MeJA had significant impacts on glycolysis and starch-glucose metabolism pathways in addition to amino acids metabolism pathways. The present findings were successful in demonstrating a correlation and distinction between the effects of JA, MeJA, and SA, on the metabolome of Cymbopogon schoenanthus, a valuable medicinal plant. The identified metabolites and their associated pathways would be valuable in future biotechnology applications of the genus Cymbopogon.

Formulation and evaluation of oxymel containing fenugreek extract

Introduction: Trigonella foenum-graecum is medicinal plant of family Fabaceae, consists of bitter principles and traditionally used in treatment of diabetes and hepatoprotective. To mask its bitter taste, it could be formulated in honey based oral formulations like oxymel. Honey, as a saturated solution of various sugars, as per Ayurvedic system of medicine, could be consumed along with drug. This research attempt was aimed towards aqueous extraction of fenugreek seeds; formulation of oxymel by addition to honey and evaluation for different parameters. Oxymel was formulated as per procedure mentioned in United State Pharmacopeia for squill oxymel; and evaluated for pharmaceutical parameters those applied for oral syrups. Results: The oxymel formulated was pale brownish with agreeable odour and sweet taste. It was pourable with viscosity of 80 CP measured at 100 rpm while density was found to be 1.47 g/cm³. There was also ease in cap opening of its container, also no crystallization of honey was observed. Its trigonelline content was found to be 3.6 µg/ml. Conclusion: Alkaloids of fenugreek have significant pharmacological activities in human being, if administered orally. To mask their bitter taste and facilitate their increase in absorption, Trigonella foenum-graecum can successfully be formulated in honey based oral formulation of oxymel.

Comparison of Characterization of Cold Brew and Hot Brew Coffee Prepared at Various Roasting Degrees

This investigation is aimed at elucidating the effects of roasting degree and extraction method on coffee beverages prepared with beans from Asia. According to the results with the improvement of the roasting degree, a decrease in titratable acidity, total phenolic compounds, the concentrations of chlorogenic acid and trigonelline, and total antioxidant capacity was observed. Cold coffee beverages showed higher total sugar and trigonelline. The volatile components, such as pyridine, furan-2-yl-methyl acetate, 2-furanemethanol, and 5-methylfurfural, were also affected by roasting degree and extraction methods. Cold brew coffee exhibited higher intensities of enzymatic flavor and sweetness. Furthermore, the principal component analysis revealed a distinct difference in coffee characterization in roasting degree in cold coffee brews than in hot ones. The results indicate that roasting degree affects physicochemical and sensory properties more than extraction temperature. Additionally, there were significant differences in coffee characteristics between cold and hot brew coffee.

Exogenous abscisic acid fine-tunes heavy metal accumulation and plant’s antioxidant defence mechanism to optimize crop performance and secondary metabolite production in Trigonella foenum-graecum L. under nickel stress

Nickel (Ni) contamination of farming soil has become currently a recurring global menace to agriculture crop productivity. The purpose of the present study was to investigate the putative contributions of abscisic acid (ABA) to extemporize Ni tolerance in Trigonella foenum-graecum L. (fenugreek) plants. The outcomes of this study exposed that exogenous supplementation of ABA at 10, 20, 40 and 80 µM considerably enhanced the growth and physiological attributes of fenugreek under 80 mg Ni kg−1 soil, however, 40 µM of ABA exhibited the best results under normal and Ni-stressed conditions. ABA-mediated Ni tolerance was marked by reductions in Ni accumulation and consequent lowering of reactive oxygen species (ROS) like hydrogen peroxide and superoxide radicals. Contrarily, NO (nitric oxide) level increased in response to ABA application under Ni stress conditions, accompanied by promoted antioxidant activities through improved levels of secondary metabolites, proline, and perked-up ROS-detoxification enzymes activities. Exogenous ABA at 40 µM concentration applied to Ni-exposed plants (80 mg Ni kg−1 soil) improved the total content of alkaloids, phenolics, flavonoids and tannins by 14.3%, 10.2%, 15.4% and 7.0%, respectively, over Ni-stressed plants alone. Additionally, seed trigonelline content imparting several pharmacological actions to the fenugreek plant exhibited a remarkable escalation upto 3.6 and 2.6 mg g−1 DW under ‘40 µM ABA’ and ‘40 µM ABA + 80 mg Ni kg−1 soil’ treatments, respectively. The findings of the study suggest that ABA plays a key role in enhancing the overall performance of the fenugreek crop under excessive Ni stress.

Caffeine, trigonelline, chlorogenic acids, melanoidins, and diterpenes contents of Coffea canephora coffees produced in the Amazon

This study characterizes the composition profile of Coffea canephora coffees of good beverage quality produced in the Brazilian Western Amazon. Samples corresponded to 57 Robusta clones and 10 intervarietal hybrids of Conilon and Robusta (BRS 1216, BRS 2299, BRS 2314, BRS 2336, BRS 2357, BRS 3137, BRS 3193, BRS 3210, BRS 3213, BRS 3220). Roasted coffees were evaluated regarding the contents of caffeine, trigonelline, chlorogenic acids (CGA), melanoidins, and diterpenes (kahweol, cafestol, 16-O-methylcafestol). Data were analyzed by ANOVA and Scott-Knott test (p ≤ 0.05), and Principal Component Analysis. In general, coffees showed high contents of caffeine (1.63–3.57 g 100 g−1), trigonelline (0.60–1.15 g 100 g−1), CGA (3.93–6.37 g 100 g−1), and 16-O-methylcafestol (0.082–0.372 g 100 g−1). Results showed contents between 10 and 17.9 g 100 g−1 for melanoidins, 0.068 and 0.427 g 100 g−1 for cafestol, 0.218 and 0.707 g 100 g−1 for total diterpenes, and the presence of kahweol in 20% of the samples. The caffeine/ total diterpenes ratio supported identifying C. canephora species. Robusta coffees were characterized by the highest content of trigonelline, melanoidins, and 16-O-methylcafestol. Hybrid were characterized by the highest content of caffeine, CGA, cafestol, and total diterpenes.

Bioactive compounds in blends of coffee defects originating from the harvesting

A coffee crop may consist of up to 1/5 of defective beans and finding a suitable destination for this material is economically interesting. Many coffee industries collect the selections - material containing coffee defects - and blend them with non-defective coffee fruits in specific proportions to obtain a marketable product. Studies on the composition of selections are scarce. Hydro- and liposoluble bioactive compounds were determined in five types of roasted and ground selections of coffee Arabica and in healthy Arabica and Robusta coffee species throughout an optimized HPLC-UV/Vis-MS-based method. Nicotinic acid and 4-CQA were not detected. Black and sour beans seem to increase the level of caffeine (variation from 1.3 to 2.4 g 100 g-1 of sample) in the selections. The occurrence of defects decreases the level of 5-CQA, the main representative chlorogenic acid. Trigonelline content is high in Arabica coffee, and the presence of defects does not promote a clear variation in its amount. Kahweol concentration (~74.6 to 76.9 mg g-1 of oil) was practicallythe same up the Arabica sample set; this diterpene was absent in Robusta coffee. Cafestol (variation between 12.4 and 16.4 mg g-1 of oil) is a good quality indicator. Kahweol and 16-O-methyl cafestol are species indicators, and caffeine can point out the species of coffee. PCA revealed that sour beans were associated with the presence of kahweol, while cafestol and trigonelline were correlated to the occurrence of coffee skin. The higher the proportion of black beans, the more balanced the contents of water-soluble and liposoluble compounds. Key words: PVA; Coffee harnessing; HPLC-based method; Selection of coffee; Water- and fat-soluble compounds.

Quality-controlled LC-ESI-MS food metabolomics of fenugreek (Trigonella foenum-graecum) sprouts: Insights into changes in primary and specialized metabolites

Fenugreek (Trigonella foenum-graecum L.) is an important food and spice with bioactive compounds against diabetes. In this study, fenugreek seeds germinating in darkness for 72 h were studied using quantification of trigonelline and 4-hydroxyisoleucine and an LC-ESI-MS/MS-based metabolomic approach capable of accurately estimating 237 features from various primary and specialized compound classes.During germination, the concentrations of trigonelline and 4-hydroxyisoleucine rose by 33.5% and 33.3%, respectively. At the same time, untargeted metabolomics revealed 9 putative flavonoids increasing 1.19- to 2.77-fold compared to the dormant seeds. A set of 19 steroid saponins rose by 1.08- to 31.86-fold. Primary metabolites however showed much more variability: abundance changes in amino acid derivatives, peptides and saccharides fell in the 0.09- to 22.25-fold, 0.93- to 478.79-fold and 0.36- to 941.58-fold ranges, respectively.To increase biosynthesis of specialized metabolites during germination, sprouts were exposed to 1–100 mM methyl jasmonate (MeJA) and methyl salicylate (MeSA). The hormone treatments affected normal metabolism: 67.1–83.1 % and 64.1–83.5 % of compounds showed a reduction compared to the controls in 100 mM MeJA and MeSA treatments at different sampling time points. Contrary to expectations, the abundance of flavonoids decreased, compared to the control sprouts (0.75- and 0.68-fold change medians, respectively). The same was observed for most, but not all steroid saponins.The quality-controlled untargeted metabolomics approach proved to yield excellent insight into the metabolic changes during germination of fenugreek. The results suggest that although fenugreek germination causes major shifts in plant metabolism, there are no major qualitative changes in bioactive specialized metabolites during the first three days. This stability likely translates into good bioactivity that is similar to that of the seeds. Because the large changes in the primary metabolites likely alter the nutritive value of the seed, further studies are warranted.

Influence of genotype and processing on bioactive compounds of Ethiopian specialty Arabica coffee

ABSTRACT Ethiopian specialty coffee is exported to the international market based on the cup quality classification; however, there is limited information on the chemical characteristics. In this study, dry and wet-processed sixteen Ethiopian specialty coffee genotypes were investigated for total polyphenols, chlorogenic acids, caffeine, and trigonelline at different stages using UV-Vis spectrophotometric and Rapid Separation Liquid Chromatographic methods. Cup qualities of green coffee beans and brewed coffee were also assessed by professional cuppers. The results indicated that the bioactive compounds and cup qualities were significantly influenced by genotypes, green bean processing methods, and medium roasted-ground and brewed coffees. It was shown that the percentage of reduction in total polyphenols, chlorogenic acids, caffeine, and trigonelline concentrations were 77.3%, 82.5%, 47.8%, and 70.6%, respectively as the beans are transformed to brew. This study also fills the gap of information on the influence of processes and correlation to cup quality with bioactive compounds.

Salt-tolerant PGPR strain Priestia endophytica SK1 promotes fenugreek growth under salt stress by inducing nitrogen assimilation and secondary metabolites.

Soil salinity is a huge obstacle in crop production worldwide. Saline soil can reduce active chemical contents in medicinal plants of the Leguminosae family through crippled normal nodule function. Intensive efforts are underway to improve yield and medicinal value of leguminous herbs under salt stress condition by using benign microbes. Here, an attempt was made to explore the salt-tolerant bacteria associated with rhizosphere of fenugreek plant (Trigonella foenum-graecum L.) and to evaluate their impact on host plant growth and metabolite of pharmaceutical importance. A salt-tolerant plant growth promoting rhizobacterial (PGPR) strain Priestia endophytica SK1 isolated from fenugreek rhizospheric soil, which increased biomass and metabolite content in plants grown under saline stress. SK1 bacterial application induced nodule formation and enhanced nitrogen and phosphorus content under salt (100 mM NaCl) stress as compared to control plants. H2 O2 production and lipid peroxidation as a measure of stress were observed high in control plants, while a reduction in these parameters was observed in plants inoculated with SK1. In addition, a significant effect was found on the phenolic compounds and trigonelline content in fenugreek plant inoculated with SK1 bacterium. An increased trigonelline content of about 54% over uninoculated control was recorded under salt stress. The results of this study revealed that the application of salt-tolerant PGPR strain P. endophytica SK1 induced nitrogen fixation machinery that leads to alleviate salt stress and improved the biosynthesis of trigonelline content in fenugreek. This study extends our understanding on the significance of rhizosphere microbiome and their beneficial role in plant health under environmental stress to promote agro-eco-farming practices.

Green Coffee Extract Microencapsulated: Physicochemical Characteristics, Stability, Bioaccessibility, and Sensory Acceptability through Dairy Beverage Consumption.

This study aimed to investigate the effect of spray drying (SD) and freeze-drying (FD) on the microencapsulation of green coffee extracts by using polydextrose (PD) and inulin (IN) as encapsulating agents and their physicochemical, bioactive compounds’ stability, phenolic compounds’ bioaccessibility after digestion, and sensory effects in unfermented dairy beverages. The extract encapsulated with IN by FD had lower moisture content, water activity, and hygroscopicity, while particles encapsulated by SD exhibited a spherical shape and the structure of the FD products was irregular. No difference was observed in phenolic compounds’ bioaccessibility. Dairy beverages with added encapsulated extracts had higher total phenolic content and antioxidant activity. Microencapsulation allowed a controlled release of the bioactive compounds with an increase in the content of caffeine, chlorogenic acid, and trigonelline during storage. The dairy beverage with added extract encapsulated with IN by FD had the highest scores of acceptability regarding the overall impression and purchase intent.

Sensory characterization of coffee brew with consumer‐based methodology and sensometrics

Coffee brew is widely consumed for its sensory properties, so sensory evaluation is essential for quality control. This study used CATA (check-all-that-apply) and preference ranking test (PRT) to evaluate four coffee brews. The quantification of caffeine, trigonelline, and chlorogenic acid was performed with high-performance liquid chromatography (HPLC). Four distinct groups were identified using the correspondence analysis (CA). Samples A and C had similar characteristics: lower caffeine and melanoidins, higher contents of trigonelline and chlorogenic acids, higher pH, and titratable acidity. Such features were associated with a sweet odor and less intense color. Samples B and K showed high levels of melanoidins and caffeine and low concentrations of trigonelline and chlorogenic acids. These samples had a dark color, bitter and intense flavor. The PRT indicated that coffee brew K was preferred, and coffee A was the least preferred coffee sample. Novelty impact statement Applying consumer-based methodologies and sensometrics allows obtaining a reliable and fast sensory characterization of food products. The correlations found between the coffee brew composition and the attributes indicated as important by consumers can be used by the coffee industry to develop its products.

Biological and Phytochemical Responses of Trigonella foenum-graceum Plants to Silver Nanoparticles

ABSTRACT The present study aimed to investigate the effects of applying different concentrations of AgNPs on plant yield, protein and phytochemical compound in Trigonella foenum-graecum. For this purpose, an experiment was carried out based on a completely randomized design (CRD) with six concentrations of AgNPs (0, 2.5, 5, 10, 20 and 40 mg/L). The results showed that the highest biomass (2.14 ± 0.02 g) and chlorophyll content (52.80 ± 2.51 µg·g−1 FW) were obtained in 10 mg/L of AgNPs, while the highest protein content (3.3 ± 0.12 mg·g−1 FW) was obtained in 20 mg/L of AgNPs. The highest amount of trigonelline (TG) and nicotinic acid (NT) contents were obtained in 10 mg/L of AgNPs. Treatments with an AgNPs concentration higher than 10 mg L−1 led to reduced growth, biomass, chlorophyll, protein, TG and NA contents. AgNPs application caused considerable increase in seed yield and TG content. Therefore, the use of low concentration of AgNPs (10 mg/L) could be recommended to improve the T. foenum-graecum growth, biomass, protein content and phytochemical compound production.

Increase of Trigonelline in Trigonella persica Plant under Drought Stress

Trigonella persica is a valuable medicinal plant which comprises trigonelline that is secondary metabolite and important component in cosmetic and medicine. This research was conducted in order to evaluation the drought stress effect on growth parameters, root anatomical changes and trigonelline content in T. persica. Plants were grown under soil moisture corresponding to 100%, 75%, 50% and 25% field capacity for two weeks. The data showed that drought stress was significantly decreased fresh weight and dry weight of shoot and root. In addition, leaf area was declined due to drought stress. Interestingly, root length was enhanced by drought stress. Root microscopic study demonstrated that drought stress increased thickness of epidermal, endodermal, vascular bundle, central cylinder and parenchyma in T. persica. Drought stress caused a significant increment in alkaloid and trigonelline content in aerial parts and roots of T. persica. These results revealed that T. persica responded to drought stress by increasing the alkaloid and trigonelline, as well as the anatomical changes in root. Considering the importance of trigonline and alkaloids, this work may open prospects for production of the pharmaceutically valuable secondary metabolites thereby drought stress.

Impact of environmental variables on yield related traits and bioactive compounds of the Persian fenugreek (Trigonella foenum-graecum L.) populations.

Trigonella foenum-graecum is widely distributed worldwide and grown under a wide range of climatic conditions. The current research was conducted to study the effects of the environmental variables on yield related traits and metabolite contents of 50 different Persian fenugreeks at various geographical locations. Accordingly, multivariate statistical techniques including canonical correspondence analysis (CCA), hierarchical clustering on principal components, and partial least squares regression (PLSR) were applied to determine important proxy variables and establish a relevant model to predict bioactive compounds in fenugreeks. The interrelation of clustered groups emphasized the importance of functional groups of bioactive compounds and several yield related traits. The CCA indicated that two climatic variables of temperature and solar irradiation contributed prominently to 4-hydroxyisoleucine accumulation. The predicted model based on PLSR revealed climatic variables such as temperature, solar, and rain. The precursor of isoleucine was the predictive power for 4-hydroxyisoleucine accumulation while seed weight predicted trigonelline content. The current study's findings may provide helpful information for the breeding strategies of this multipurpose crop.

SNP markers identification by genome wide association study for chemical quality traits of coffee (Coffea spp.) Germplasm.

Coffee quality is an important selection criterion for coffee breeding. Metabolite profiling and Genome-Wide Association Studies (GWAS) effectively dissect the genetic background of complex traits such as metabolites content (caffeine, trigonelline, and 5-caffeoylquinic acid (5-CQA)) in coffee that affect quality. Therefore, it is important to determine the metabolic profiles of Coffea spp. genotypes. This study aimed to identify Single Nucleotide Polymorphisms (SNPs) within Coffea spp. genotypes through GWAS and associate these significant SNPs to the metabolic profiles of the different genotypes. A total of 1,739 SNP markers were obtained from 80 genotypes using the DArTseq™ method. Caffeine, trigonelline, and 5-CQA content were determined in coffee leaves using Ultra-Performance Liquid Chromatography/tandem mass spectrometry (UPLC-MS/MS) analyses. The GWAS was carried out using the Genome Association and Prediction Integrated Tool (GAPIT) software and a compressed mixed linear model. Finally, a total of three significant SNP markers out of ten were identified. One SNP, located in the coffee chromosome (Chr) 8, was significantly associated with caffeine. The two remaining SNPs, located in Chr 4 and 5, were significantly associated with trigonelline and six SNPs markers were associated with 5-CQA in Chr 1, 5 and 10, but these six markers were not significant. These significant SNP sequences were associated with protein ubiquitination, assimilation, and wall receptor kinases. Therefore, these SNPs might be useful hits in subsequent quality coffee breeding programs.

Potential of ultrasound and nicotinic acid to improve physiological responses and trigonelline biosynthesis in fenugreek (Trigonella foenum-graecum L.)

Fenugreek (Trigonella foenum-graecum L.) is an important source of trigonelline, a valuable anti-diabetic metabolite. The main objective of this study was to investigate the possibility of ultrasonication and nicotinic acid feeding in stimulating trigonelline biosynthesis and antioxidant system. For this purpose, the seeds were ultrasonicated in three groups for 0, 5, and 10 min at 40 kHz at 25 °C. Seedlings were treated after the emergence of the first true leaves (10 days) with Hoagland's solution complemented with 0, 2, 4 mg L−1 nicotinic acid. The results showed that the 5 min ultrasound priming of fenugreek seeds improved germination-related traits compared with the control culture. However, the 10 min ultrasound priming negatively affected and reduced the germination traits. The highest values of growth indices of seedlings were recorded under effect of 5 min ultrasound and 4 mg L−1 nicotinic acid. Ultrasound and nicotinic acid individually and as combined decreased photosynthetic pigments (chlorophylls and carotenoids). The interaction between the two factors increased the antioxidant compounds and biochemical levels of seedlings compared with the control treatment. The highest increase in trigonelline content (170.9 mg/100 g FW) was observed under 5 min ultrasound and 2 mg L−1 nicotinic acid feeding. Generally, it appears that ultrasound potentiated the effect of nicotinic acid feeding on defense responses and the production of secondary metabolites, including trigonelline biosynthesis. Overall, it can be concluded that 5 min ultrasound seed priming and 2 mg L−1 nicotinic acid can improve growth indices, and therefore to achieve optimal biomass yield and trigonelline production is recommended in fenugreek cultivation.

Feasibility of Ultrasound-Assisted Extraction for Accelerated Cold Brew Coffee Processing: Characterization and Comparison With Conventional Brewing Methods.

A long extraction time for traditional cold coffee brewing considerably reduces the production efficiency of this type of beverage. Herein, a new ultrasound-assisted cold brewing (UAC) method was established. The feasibility of UAC was assessed by comparison with main physicochemical characteristics, non-volatile and volatile compounds in coffee extracts produced by hot brewing and conventional static cold brewing methods. Compared to the static cold brews, the levels of total dissolved solids, total lipids, proteins, and titrated acids of UAC coffee extracts increased by 6–26%, 10–21%, 26–31%, and 12–15%, respectively. Caffeine, chlorogenic acid, and trigonelline concentrations were also determined by HPLC. Based on the volatile profiles obtained by HS-SPME-GC/MS, the aroma compounds in UAC was significantly different (p < 0.05) from hot brews but similar to static cold ones, suggesting that ultrasonication compensated for the time of the static cold brewing, thereby considerably shortening the extraction time (1 h vs. 12 h). This work demonstrated that the combination of ultrasound-assisted with cold brew could produce coffee with good flavor and increase the extraction efficiency, which may provide an option for the acceleration of the cold brew coffee process.

Comparison of chemical compounds and their influence on the taste of coffee depending on green beans storage conditions

Currently, there is no technology for the storage of green coffee (GrC), that results in obtaining high-quality roasted coffee (RC). The aim of this study was to evaluate the effects of storage temperature (− 10, 5, 10, 18, 20 °C), postharvest treatment method (natural (N), washed (W)) and type of packaging material (GrainPro (G), jute (J) bags) on the content of chlorogenic acids (CQAs), caffeine and trigonelline as well as the sensory profile of RC from the specialty sector after 12 months of regulated storage. Sensory analysis showed that natural coffees have better taste and higher quality than washed coffees after 12 months of storage. The highest total scores were obtained from the natural coffee stored in a GrainPro bag at − 10 °C followed by coffee stored in a jute bag at 10 °C which had the smallest decreases compared to the initial recorded values. No notable differences among CQA contents in washed coffees stored in either type of bag was seen but natural coffees stored in jute bags at 10 °C and 18 °C displayed the lowest drops relative to the initial values.

Overexpression of a Gene Encoding Trigonelline Synthase from Areca catechu L. Promotes Drought Resilience in Transgenic Arabidopsis.

Areca catechu L. is a commercially important palm tree widely cultured in tropical and subtropical areas. Its growth and production are severely hindered by the increasing threat of drought. In the present study, we investigated the physiological responses of areca seedlings to drought stress. The results showed that prolonged drought-induced yellowing on the overall area of most leaves significantly altered the chlorophyll fluorescence parameters, including maximum chemical efficiency (Fv/Fm), photochemical efficiency of PSII (Y(II)), photochemical chlorophyll fluorescence quenching (qP) and non-photochemical chlorophyll fluorescence quenching (NPQ). On the 10th day of drought treatment, the contents of proline in the areca leaves and roots increased, respectively, by 12.2 times and 8.4 times compared to normal watering. The trigonelline levels in the leaves rose from 695.35 µg/g to 1125.21 µg/g under 10 days of water shortage, while no significant changes were detected in the content of trigonelline in the roots. We determined the gene encoding areca trigonelline synthase (AcTS) by conducting a bioinformatic search of the areca genome database. Sequence analysis revealed that AcTS is highly homologous to the trigonelline synthases in Coffea arabica (CaTS 1 and CaTS 2) and all possess a conserved S-adenosyl- L-methionine binding motif. The overexpression of AcTS in Arabidopsis thaliana demonstrated that AcTS is responsible for the generation of trigonelline in transgenic Arabidopsis, which in turn improves the drought resilience of transgenic Arabidopsis. This finding enriches our understanding of the molecular regulatory mechanism of the response of areca to water shortage and provides a foundation for improving the drought tolerance of areca seedlings.

Chemical Composition Analysis and Antioxidant Activity of Coffea robusta Monofloral Honeys from Vietnam.

Monofloral honey samples (Coffea robusta) from Vietnam were determined for their chemical compositions. This is the first report on the chemical composition and antioxidant activity of coffee honey from Vietnam. These samples were characterized by their high contents of total and reducing sugars, total phenolic contents, and total flavonoid contents. The contents of seven phenolic acids (PAs) were quantified by high performance liquid chromatography (HPLC) and analyzed with the assistance of principle component analysis (PCA) to differentiate the honey samples into groups. The hydroxymethylfurfural (HMF) (0.048–2.933 mg/kg) and free acid contents (20.326–31.163 meq/kg) of coffee honey were lower in Nepal, which reflected the freshness of the honey when conducting this survey. The coffee honey had total sugar and reducing sugar contents 831.711 g/kg and 697.903 g/kg, respectively. The high level of total phenolic (0.642 mg GAE/g) and flavonoid (0.0341 mg GE/g) contents of coffee honey contributed to their antioxidant activity of this honey sample. Among the coffee honey tested, the IC50 of DPPH radical-scavenging activities value was 1.134–17.031 mg/mL, while the IC50 of ABTS radical-scavenging activities value was 115.381–213.769 mg/mL. The phenolic acids composition analysis displayed that gallic acid appeared in high concentrations in all studied honey samples, ranging from 0.037–1.015 mg/kg, and ferulic acid content ranged from 0.193 to 0.276 mg/kg. The content of trigonelline and caffeine in coffee honey samples ranged from 0.314–2.399 mg/kg and 8.946–37.977 mg/kg. The data in this article highlight the relevance of coffee honey as a healthy substance.