Major Plant Metabolites Research Articles

Chloroplastic ascorbate modifies plant metabolism and may act as a metabolite signal regardless of oxidative stress.

Ascorbate is a major plant metabolite that plays crucial roles in various processes, from reactive oxygen scavenging to epigenetic regulation. However, to what extent and how ascorbate modulates metabolism is largely unknown. We investigated the consequences of chloroplastic and total cellular ascorbate-deficiencies by studying chloroplastic ascorbate-transporter mutant lines lacking PHOSPHATE TRANSPORTER 4; 4 (PHT4; 4) , and the ascorbate-deficient vtc2-4 mutant of Arabidopsis (Arabidopsis thaliana). Under regular growth conditions, both ascorbate deficiencies caused minor alterations in photosynthesis, with no apparent signs of oxidative damage. In contrast, metabolomics analysis revealed global and largely overlapping alterations in the metabolome profiles of both ascorbate-deficiency mutants, suggesting that chloroplastic ascorbate modulates plant metabolism. We observed significant alterations in amino acid metabolism, particularly in arginine metabolism, activation of nucleotide salvage pathways, and changes in secondary metabolism. In addition, proteome-wide analysis of thermostability revealed that ascorbate may interact with enzymes involved in arginine metabolism, the Calvin-Benson cycle, and several photosynthetic electron transport components. Overall, our results suggest that, independently of oxidative stress, chloroplastic ascorbate modulates the activity of diverse metabolic pathways in vascular plants and may act as an internal metabolic signal.

Pharmacological and phytochemical insights on the pancreatic β-cell modulation by Angelica L. roots

Ethnopharmacological relevanceAngelica roots are a significant source of traditional medicines for various cultures around the northern hemisphere, from indigenous communities in North America to Japan. Among its many applications, the roots are used to treat type 2 diabetes mellitus; however, this application is not mentioned often. Ethnopharmacological studies have reported the use of A. japonica var. hirsutiflora, A. furcijuga, A. shikokiana, and A. keiskei to treat diabetes symptoms, and further reports have demonstrated the three angelica roots, i.e., A. japonica var. hirsutiflora, A. reflexa, and A. dahurica, exhibit insulin secretagogue activity. Aim of the studyThis study aimed to phytochemically characterize and compare angelica roots monographed in the European Pharmacopeia 11th, isolate major plant metabolites, and assess extracts and isolates' capability to modulate pancreatic β-cell function. Materials and methodsRoot extracts of Angelica archangelica, Angelica dahurica, Angelica biserrata, and Angelica sinensis were phytochemically profiled using liquid chromatography method coupled with mass spectrometry. Based on this analysis, simple and furanocoumarins were isolated using chromatography techniques. Extracts (1.6–50 μg/mL) and isolated compounds (5–40 μmol/L) were studied for their ability to modulate insulin secretion in the rat insulinoma INS-1 pancreatic β-cell model. Insulin was quantified by the homogeneous time-resolved fluorescence method. ResultsForty-one secondary metabolites, mostly coumarins, were identified in angelica root extracts. A. archangelica, A. dahurica, and A. biserrata root extracts at concentration of 12.5–50 μg/mL potentiated glucose-induced insulin secretion, which correlated with their high coumarin content. Subsequently, 23 coumarins were isolated from these roots and screened using the same protocol. Coumarins substituted with the isoprenyl group were found to be responsible for the extracts' insulinotropic effect. ConclusionsInsulinotropic effects of three pharmacopeial angelica roots were found, the metabolite profiles and pharmacological activities of the roots were correlated, and key structures responsible for the modulation of pancreatic β-cell function were identified. These findings may have implications for the traditional use of angelica roots in treating diabetes. Active plant metabolites may also become lead structures in the search for new antidiabetic treatments.

Biochemistry and Genetics of Floral Scent - A Historical Perspective.

Floral scent plays a crucial role in the reproduction process of many plants. Humans have been fascinated by floral scents throughout history, and have transported and traded floral scent products, for which they have found multiple uses as food additives, hygiene and perfume products, and medicines. Yet the scientific study of how plants synthesize floral scent compounds began later than studies on most other major plant metabolites, and the first report of the characterization of an enzyme responsible for the synthesis of a floral scent compound - linalool in Clarkia breweri, a California annual - appeared in 1994. In the almost 30 years since, enzymes and genes involved in the synthesis of hundreds of scent compounds from multiple plant species have been described. This review recapitulates this history and describes the major findings relating to the various aspects of floral scent biosynthesis and emission, including genes and enzymes and their evolution, storage and emission of scent volatiles, and the regulation of the biochemical processes.

Endophytes from Panax species

Medicinal plants from the genus Panax has long been traditionally used to treat various diseases and therefore constitute very important resources for endophytes bioprospecting. Over the past decade (2007–2019) investigations have been conducted to analyse the microbial community inhabiting several species of this genus. We comprehensively summarized in this review available data regarding the diversity and biological activity of microbial species living inside Panax species without causing harm. Our investigation into literature revealed that although the number of studies is limited, an astonishing diversity of bacterial and fungal endophytes inhabiting Panax ginseng Meyer and Panax notoginseng (Burkill) F.H.Chen has already been uncovered. We also found that some of these endophytes can produce some major plant metabolites and also convert some of these major metabolites into minor or new compounds. This study also demonstrated that so far, more than 347 bacteria and 21 fungi have been identified with biocontrol abilities against pathogens of the root-rot disease complex in Panax species. Moreover, the phytochemical investigation of a very limited number of endophytes led to the characterization of more than 80 secondary metabolites, exhibiting antimicrobial, antioxidant, antiacetylcholinesterase, anti-inflammatory, and anticancer activities. We hope that this review provides the scientific community with useful information regarding the diversity and bioactive potential of endophytes of the Panax genus and motivate scientists to investigate other species of this genus.

The Structure and Function of Major Plant Metabolite Modifications

The Structure and Function of Major Plant Metabolite Modifications

Efficacy of e-beam irradiation on shelf-life and accompanied changes in major metabolites of Desmodium gangeticum (L.) DC., an Ayurveda medicinal plant

The effects of electron beam irradiation (5, 10 and 15 kGy) on shelf-life and major plant metabolites of an Ayurvedic medicinal plant Desmodium gangeticum was evaluated. Its root possesses incredible medicinal effects; hence powdered root sample (choorna) was subjected to radiation processing and thereby shelf-life extension. The root sample was found to possess an appreciable amount of phenolic and flavonoid compounds. Processing with radiation did not produce prominent changes in the phenolic content of samples even after storage for up to 12 months. In contrast, Calcium content was increased significantly (p < 0.05) on radiation processing wit 5 kGy and 15 kGy. Microbial status revealed that the untreated sample was acceptable only up to 4 months. A dose-dependent reduction in the microbial count resulted in all the radiation processed samples. Treatment with doses of 10 kGy and 15 kGy reduced the colony count to nil immediately after irradiation. Irradiation with 15 kGy kept the sample completely sterilized up to 2 months of storage and was acceptable even 12th month of storage. GC-MS analyses identified compounds with pharmacological importance such as methyl palmitate, mome-inositol, Neophytadiene, etc. Although, a slight change in mineral composition and phytochemicals were observed it could effectively decontaminate the medicinal herb and increase the shelf-life with minimum loss of major metabolites compared to other conventional methods of processing.

Modification of the existing maximum residue levels for etridiazole in various crops.

In accordance with Article 6 of Regulation (EC) No 396/2005, the evaluating Member State (EMS), the Netherlands, received an application from Arysta LifeScience Great Britain Limited to modify the existing maximum residue levels (MRLs) for the active substance etridiazole in various crops. To accommodate for the intended uses of etridiazole, the Netherlands proposed to raise the existing MRLs from the limit of quantification (LOQ) of 0.05* mg/kg to 0.4 mg/kg in gherkin, courgette and other cucurbits with edible peel, and to raise the existing MRL value of 0.1 mg/kg to 0.4 mg/kg in cucumber. The Netherlands drafted an evaluation report in accordance with Article 8 of Regulation (EC) No 396/2005, which was submitted to the European Commission and forwarded to EFSA. Although the intended uses on gherkin, courgette and other cucurbits with edible peel are supported by residue trials, EFSA did not derive MRL proposals because appropriate information on the toxicological profile and on the relevance of the major plant metabolites 5‐hydroxyethoxyetridiazole acid and 3‐hydroxymethyletridiazole has not been provided. Thus, the tentative risk assessment is affected by a high degree of uncertainty.

Fate of deoxynivalenol and deoxynivalenol-3-glucoside during cereal-based thermal food processing: a review study.

Deoxynivalenol (DON), the most commonly occurring trichothecene in nature, may affect animal and human health through causing diarrhea, vomiting, gastrointestinal inflammation, and immunomodulation. DON-3-glucoside (DON-3G) as a major plant metabolite of the mycotoxin is another "emerging" food safety issue in recent years. Humans may experience potential health risks by consuming DON-contaminated food products. Thus, it is crucial for human and animal health to study also the degradation of DON and DON-3G during thermal food processing. Baking, boiling, steaming, frying, and extrusion cooking are commonly used during thermal food processing and have promising effects on the reduction of mycotoxins in food. For DON, however, the observed effects of these methods, as reported in numerous studies, are ambiguous and do not present a clear picture with regard to reduction or transformation. This review summarized the influence of thermal processing on the stability of DON and the formation of degradation/conversion products. Besides this, also a release of DON and DON-3G from food matrix as well as the release of DON from DON-3G during processing is discussed. In addition, some conflicting findings as reported from the studies on thermal processing as well as cause-effect relationships of the different thermal procedures are explored. Finally, the potential toxic profiles of DON degradation products are discussed as well when data are available.

Hydrolysis Reactions of the Taccalonolides Reveal Structure–Activity Relationships

The taccalonolides are microtubule stabilizers isolated from plants of the genus Tacca that show potent in vivo antitumor activity and the ability to overcome multiple mechanisms of drug resistance. The most potent taccalonolide identified to date, AJ, is a semisynthetic product generated from the major plant metabolite taccalonolide A in a two-step reaction. The first step involves hydrolysis of taccalonolide A to generate taccalonolide B, and then this product is oxidized to generate an epoxide group at C-22-C-23. To generate sufficient taccalonolide AJ for in vivo antitumor efficacy studies, the hydrolysis conditions for the conversion of taccalonolide A to B were optimized. During purification of the hydrolysis products, we identified the new taccalonolide AO (1) along with taccalonolide I. When the same hydrolysis reaction was performed on a taccalonolide E-enriched fraction, four new taccalonolides, assigned as AK, AL, AM, and AN (2-5), were obtained in addition to the expected product taccalonolide N. Biological assays were performed on each of the purified taccalonolides, which allowed for increased refinement of the structure-activity relationship of this class of compounds.

UPLC-PDA를 이용한 창포류의 분류 및 함량 분석

본 연구에서는 UPLC를 이용하여 석창포의 기원종을 비교하기 위하여 4종 창포류(A. gramineus, A. tatarinowii, A. calamus, Anemone altaica)의 <TEX>${\alpha}$</TEX>-asarone과 <TEX>${\beta}$</TEX>-asarone의 함량 분석을 실시하였고, 분석법 validation은 ICH 지침에 따라 검증하였다. 창포류 4종에 대한 함량분석에서는 모든 시료에 대해 2% 이하의 상대 표준편차를 나타내었고, <TEX>${\beta}$</TEX>-asarone의 함량은 석창포, 중국석창포, 창포, 구절창포 순으로 나타났으며, <TEX>${\alpha}$</TEX>-asarone은 창포, 중국 석창포, 석창포 순으로 나타났다. 특히, 구절창포에서는 <TEX>${\beta}$</TEX>-asarone이 미량이었고, <TEX>${\alpha}$</TEX>-asarone는 검출되지 않았다. PCA 분석에서도 4종의 창포류가 네 그룹으로 나누어 지는 것을 확인할 수 있었다. 이와 같이, 본 실험 결과를 통하여 석창포, 중국 석창포, 창포 및 구절창포를 명확히 구별할 수 있었고, 석창포의 품질평가에 응용할 수 있을 것이라 기대된다. A quantitative method using ultra performance liquid chromatography with a photodiode array detector (UPLCPDA) was established for the analysis of 2 major plant metabolites: <TEX>${\beta}$</TEX>-asarone and <TEX>${\alpha}$</TEX>-asarone from Acorus gramineus, A. tatarinowii, A. calamus and Anemone altaica, and their contents are compared with other herbs of Acorus species. The method was validated according to the International Conference on harmonization (ICH) guideline for validation of analytical procedures with respect to precision, accuracy, and linearity. The average content of <TEX>${\beta}$</TEX>-asarone in Acorus gramineus was significantly higher than that in others, with the second highest concentration observed in A. tatarinowii, and only a trace amounts found in A. calamus and Anemone altaica. In contrast, the average content of <TEX>${\alpha}$</TEX>-asarone in A. calamus was the highest, followed by that in Acorus gramineus and A. tatarinowii. principle component analysis (PCA) confirmed that <TEX>${\beta}$</TEX>-asarone and <TEX>${\alpha}$</TEX>-asarone content differed among the species. These results suggest that this UPLC-PDA method can be considered as good quality control criteria for Acorus gramineus.

Plant Metabolites and Nutritional Quality of Vegetables

Vegetables are an important part of the human diet and a major source of biologically active substances such as vitamins, dietary fiber, antioxidants, and cholesterol-lowering compounds. Despite a large amount of information on this topic, the nutritional quality of vegetables has not been defined. Historically, the value of many plant nutrients and health-promoting compounds was discovered by trial and error. By the turn of the century, the application of chromatography, mass spectrometry, infrared spectrometry, and nuclear magnetic resonance allowed quantitative and qualitative measurements of a large number of plant metabolites. Approximately 50000 metabolites have been elucidated in plants, and it is predicted that the final number will exceed 200000. Most of them have unknown function. Metabolites such as carbohydrates, organic and amino acids, vitamins, hormones, flavonoids, phenolics, and glucosinolates are essential for plant growth, development, stress adaptation, and defense. Besides the importance for the plant itself, such metabolites determine the nutritional quality of food, color, taste, smell, antioxidative, anticarcinogenic, antihypertension, anti-inflammatory, antimicrobial, immunostimulating, and cholesterol-lowering properties. This review is focused on major plant metabolites that characterize the nutritional quality of vegetables, and methods of their analysis.

Sorption and Desorption of Imazethapyr and 5-Hydroxyimazethapyr in Minnesota Soils

Laboratory batch equilibrium studies were conducted to evaluate the sorption-desorption behavior of imazethapyr and its major plant metabolite, 5-hydroxyimazethapyr, in three Minnesota soils. Sorption of both compounds on all soils was low, and pH did not significantly influence sorption in the range of 4,8 to 7.1. Less 5-hydroxyimazethapyr was sorbed than imazethapyr on the same soil. Once sorbed, both compounds were only partially desorbable from all soils. Significant hysteresis and formation of nonextractable residues indicate that the small amount of chemical sorbed is bound to selective surfaces with strong bonds. Webster clay loam had greater irreversibility than Waukegen silt loam and Estherville sandy loam soil. The hysteresis observed in desorption may be responsible for the difference between mobility estimations made from laboratory sorption studies and the limited mobility observed in field experiments.

Spectrometric Characterization of Metribuzin and its Metabolites

Metribuzin and its three major plant metabolites have been characterized by ultraviolet, infrared, and proton NMR spectroscopy and mass spectrometry. The reported structures for these compounds have been confirmed, except that deaminated Metribuzin (DA) exists mainly in the enol form rather than the keto form usually reported. Evidence is presented concerning the most probable sites of protonation during titration of these compounds. Whereas diketo Metribuzin (DK) does undergo protonation of the amino group, Metribuzin itself apparently does not. Keto/enol tautomerism as a function of pH greatly complicates interpretation of the spectra. Metribuzin appears to form a poorly soluble, hydrogen-bonded dimer (or polymer) when titrated from basic to acidic pH.