Important Metabolites Research Articles

Microbiota and other detrimental metabolites in colorectal cancer.

Increasing scientific evidence demonstrates that gut microbiota plays an essential role in the onset and development of Colorectal cancer (CRC). However, the mechanisms by which these microorganisms contribute to cancer development are complex and far from completely clarified. Specifically, the impact of gut microbiota-derived metabolites on CRC is undeniable, exerting both protective and detrimental effects. This paper examines the effects and mechanisms by which important bacterial metabolites exert detrimental effects associated with increased risk of CRC. Metabolites considered include heterocyclic amines and polycyclic aromatic hydrocarbons, heme iron, secondary bile acids, ethanol, and aromatic amines. It is necessary to delve deeper into the mechanisms of action of these metabolites in CRC and identify the microbiota members involved in their production. Furthermore, since diet is the main factor capable of modifying the intestinal microbiota, conducting studies that include detailed descriptions of dietary interventions is crucial. All this knowledge is essential for developing precision nutrition strategies to optimise a protective intestinal microbiota against CRC.

Acid-promoted fluorescent probe for monitoring endogenous methylglyoxal in tumors and gastritis

An acid-promoted “turn-on” fluorescent probe is reported for real-time detection of methylglyoxal in tumors and gastritis with high sensitivity and selectivity.

Brain Short-Chain Fatty Acids Induce ACSS2 to Ameliorate Depressive-Like Behavior via PPARγ–TPH2 Axis

Short-chain fatty acids (SCFAs) have been increasingly evidenced to be important bioactive metabolites of the gut microbiota and transducers in controlling diverse psychiatric or neurological disorders via the microbiota–gut–brain axis. However, the precise mechanism by which brain SCFAs extert multiple beneficial effects is not completely understood. Our previous research has demonstrated that the acetyl-coenzyme A synthetase short-chain family member 2 (ACSS2) is a novel target of the rapid and long-lasting antidepressant responses. Here, we show that micromolar SCFAs significantly augment both total cellular and nuclear ACSS2 to trigger tryptophan hydroxylase 2 (TPH2) promoter histone acetylation and its transcription in SH-SY5Y cells. In chronic-restraint-stress-induced depression mice, neuronal ACSS2 knockdown by stereotaxic injection of adeno-associated virus in the hippocampus abolished SCFA-mediated improvements in depressive-like behaviors of mice, supporting that ACSS2 is required for SCFA-mediated antidepressant responses. Mechanistically, the peroxisome-proliferator-activated receptor gamma (PPARγ) is identified as a novel partner of ACSS2 to activate TPH2 transcription. Importantly, PPARγ is also responsible for SCFA-mediated antidepressant-like effects via ACSS2–TPH2 axis. To further support brain SCFAs as a therapeutic target for antidepressant effects, d -mannose, which is a naturally present hexose, can significantly reverse the dysbiosis of gut microbiota in the chronic-restraint-stress-exposure mice and augment brain SCFAs to protect against the depressive-like behaviors via ACSS2–PPARγ–TPH2 axis. In summary, brain SCFAs can activate ACSS2–PPARγ–TPH2 axis to play the antidepressive-like effects, and d -mannose is suggested to be an inducer of brain SCFAs in resisting depression.

Analysis of Fiber Content and Antioxidant Activity of Bamboo Shoots (Dendrocalamus asper) to Support Functional Foods

The purpose of food consumption extends beyond meeting the body's nutritional requirements, increasingly emphasizing the potential of food as a form of medicine or health enhancer. Functional foods, which can be integrated into daily menus without specific dosage requirements, present a favorable nutritional option. In the archipelagic region of Southeast Sulawesi, characterized by extensive forests, bamboo shoots thrive abundantly. Consequently, the local community in this area has acknowledged and incorporated bamboo shoots as a dietary component. This study aims to explore the content of bamboo shoots and analyze protein, carbohydrate, and fiber levels. The research employs various methods, including phytochemical screening, alkaloid testing, flavonoid testing, saponin, tannin, triterpenoid, and steroid assessments, as well as content analysis, proximate analysis, carbohydrate analysis, and fiber level analysis. The study outcomes reveal the presence of alkaloids and flavonoids in bamboo shoots, with protein levels at 2.6 g/100 g, carbohydrate levels at 4.10 g/100 g, and fiber levels at 2.40 g/100 g. It can be concluded that bamboo shoots have important secondary metabolites, namely flavonoids and alkaloids, which may have health benefits such as being anti-inflammatory, antiviral, and inhibitory of allergies.

Integrated transcriptome and metabolome analysis reveals the podophyllotoxins accumulation and formation mechanisms in Juniperus sabina L. leaves

AbstractPodophyllotoxin is an important secondary metabolite because of its remarkable anticancer and anti‐Condyloma acuminatum activities. Juniperus sabina L. (J. sabina) has been proven as a new plant source of podophyllotoxins. However, the mechanism of podophyllotoxins accumulation and synthesis in J. sabina is unclear, which greatly limits their applications. Based on this, transcriptomic and metabolomic analyses were performed on different developmental stages of J. sabina leaves to determine the molecular mechanism of the biosynthesis of podophyllotoxins in this study. Firstly, 8 podophyllotoxins and 54 differentially accumulated compounds were identified from metabolomic analysis of J. sabina leaves at different developmental stages. The total lignans and podophyllotoxin contents were determined by HPLC, clarifying that May to September was the critical period for the accumulation of podophyllotoxins in J. sabina leaves. Transcriptome and metabolic analysis showed that 47 DEGs encoded 16 key enzymes involved in podophyllotoxin biosynthesis, among which 8 key enzyme genes (PAL, HCT, CCR, C4H, DIR, PLR, OMT and CYP82) were identified. Furthermore, JsPLR was proven to be a key rate‐limiting enzyme cytoplasmic‐localized. JsPLR overexpression significantly increased matairesinol and podophyllotoxin content.. The findings of qRT‐PCR study indicated that the differential expression of JsPLR gene might be a key factor leading to the differential accumulation of podophyllotoxin. Overall, the study brings new insight into the accumulation and formation mechanisms of podophyllotoxins and the comprehensive development and utilization of J. sabina resources.

Penicillium chrysogenum: Beyond the penicillin.

Almost one century after the Sir Alexander Fleming's fortuitous discovery of penicillin and the identification of the fungal producer as Penicillium notatum, later Penicillium chrysogenum (currently reidentified as Penicillium rubens), the molecular mechanisms behind the massive production of penicillin titers by industrial strains could be considered almost fully characterized. However, this filamentous fungus is not only circumscribed to penicillin, and instead, it seems to be full of surprises, thereby producing important metabolites and providing expanded biotechnological applications. This review, in addition to summarizing the classical role of P. chrysogenum as penicillin producer, highlights its ability to generate an array of additional bioactive secondary metabolites and enzymes, together with the use of this microorganism in relevant biotechnological processes, such as bioremediation, biocontrol, production of bioactive nanoparticles and compounds with pharmaceutical interest, revalorization of agricultural and food-derived wastes or the enhancement of food industrial processes and the agricultural production.

A Circular Network of Coregulated L-Threonine and L-Tryptophan Metabolism Dictates Acute Lower Limb Ischemic Injury.

Lower limb ischemia is characterized by reduced arterial perfusion in the lower limbs, leading to tissue ischemia and cell death. It is primarily caused by thrombosis and the rupture of arterial plaques, resulting in damage to ischemic muscle tissues. Metabolic processes are crucial in its development. Herein we combined single-cell data with metabolomics data to explore the pathways and mechanisms influencing lower limb ischemia. We analyzed single-cell and metabolomics data. In single-cell analysis, we identified different cell subpopulations and key regulatory genes, and biological enrichment analysis was performed to understand their functions and relationships. For metabolomics, mass spectrometry and chromatography techniques were employed to analyze metabolites in clinical samples. We performed differential analysis, correlation analysis, and Mendelian randomization to determine the relationships between key metabolites and genes. Nebl, Dapl1, Igfbp4, Lef1, Klrd1, Ciita, Il17f, Cd8b1, Il17a, Cd180, Il17re, Trim7, and Slc6a19 were identified to play a crucial role in lower limb ischemia. Important metabolites included L-threonine and L-tryptophan. The metabolism of L-threonine and L-tryptophan is linked to lower limb ischemia and thrombosis. B0AT1, encoded by SLC6A19, is closely related to these metabolites and appears to play a key role in lower limb ischemia development. Our analysis revealed the roles of key genes and metabolites in lower limb ischemia. These findings enhance our understanding of the pathogenesis of lower limb ischemia and provide new insights into its prevention and treatment.

Elicitation Induced α-Amyrin Synthesis in Tylophora indica In Vitro Cultures and Comparative Phytochemical Analyses of In Vivo and Micropropagated Plants.

Tylophora indica (Burm. f.) Merrill is an endangered medicinal plant that possesses various active agents, such as tylophorinine, kaempferol, quercetin, α-amyrin and beta-sitosterol, with multiple medicinal benefits. α-amyrin, a triterpenoid, is widely known for its antimicrobial, anti-inflammatory, gastroprotective and hepatoprotective properties. In this study, we investigated the metabolite profiling of tissues and the effects of cadmium chloride and chitosan on in vitro accumulation of alkaloids in T. indica. First, the callus was induced from the leaf in 2,4-D-, NAA- and/or BAP-fortified MS medium. Subsequent shoot formation through organogenesis and in vitro roots was later induced. Gas chromatography-mass spectrometry (GC-MS)-based phytochemical profiling of methanolic extracts of in vivo and in vitro regenerated plants was conducted, revealing the presence of the important phytocompounds α-amyrin, lupeol, beta-sitosterol, septicine, tocopherol and several others. Different in vitro grown tissues, like callus, leaf and root, were elicited with cadmium chloride (0.1-0.4 mg L-1) and chitosan (1-50 mg L-1) to evaluate the effect of elicitation on α-amyrin accumulation, measured with high-performance thin layer chromatography (HPTLC). CdCl2 and chitosan showed improved sugar (17.24 and 15.04 mg g-1 FW, respectively), protein (10.76 and 9.99 mg g-1 FW, respectively) and proline (7.46 and 7.12 mg g-1 FW), especially at T3 (0.3 and 25 mg L-1), in the leaf as compared to those of the control and other tissues. The antioxidant enzyme activities were also evaluated under an elicitated stress situation, wherein catalase (CAT), superoxide dismutase (SOD) and ascorbate peroxidase (APX) displayed the highest activities in the leaf at T4 of both of the two elicitors. The α-amyrin yield was quantified with HPTLC in all tested tissues (leaf, callus and root) and had an Rf = 0.62 at 510 nm wavelength. Among all the concentrations tested, the T3 treatment (0.3 mg L-1 of cadmium chloride and 25 mg L-1 of chitosan) had the best influence on accumulation, irrespective of the tissues, with the maximum being in the leaf (2.72 and 2.64 μg g-1 DW, respectively), followed by the callus and root. Therefore, these results suggest future opportunities of elicitors in scaling up the production of important secondary metabolites to meet the requirements of the pharmaceutical industry.

A new adsorptive 3D–printed sampling device for simultaneous determination of 63 urinary organic acids by LC–MS/MS

BackgroundThe detection and quantification of urinary metabolites play an important role in disease diagnosis. In most cases, urinary analyses are done with liquid urine samples, which must be quickly transported to the laboratory to avoid metabolites degradation that is associated with temperature fluctuations. Consequently, dried sampling devices have emerged to minimize analyte degradation. However, most commercial dried sampling devices are expensive, aggregate low volumes, and need better analytical sensitivity. Therefore, a new dry urine sampling device that is inexpensive, suitable for domestic sampling operation, and efficient for quantifying metabolites without requiring high–resolution instruments is proposed in the present study. ResultsThe newly designed dry urine sampling device was produced by 3D printing that efficiently determines 63 urinary organic acids using liquid chromatography coupled with mass spectrometry (LC–MS/MS). The system's efficiency was demonstrated with analytical figures of merit, such as precision, accuracy, and stability of analytes after the sampling and storing of ordinary urine samples. The limits of quantification ranged from 0.01 to 0.42 ng mL–1. Precision and accuracy tests showed relative standard deviations of less than 15 %. The urine stability in the sampling device was high within seven days without any significant degradation of the metabolites. The method was applied to the analysis of 10 human urine samples and compared to a conventional method without the use of the sampling device. The results showed no statistically significant differences, demonstrating the method's efficiency. SignificanceThe proposed 3–D printing device was developed with fast, low–cost manufacturing features and can be manufactured with different volumetric capacities, adaptable to the needs of each user. Furthermore, it is innovative because this is the first sampling device that is effective for the simultaneous storage and preservation of several important urinary metabolites. Thus, it is anticipated that its application would contribute significantly to the identification of metabolic disorders.

A toolbox for genetic manipulation in intestinal Clostridium symbiosum

Gut microbes are closely related with human health, but remain much to learn. Clostridium symbiosum is a conditionally pathogenic human gut bacterium and regarded as a potential biomarker for early diagnosis of intestinal tumors. However, the absence of an efficient toolbox that allows diverse genetic manipulations of this bacterium limits its in-depth studies. Here, we obtained the complete genome sequence of C. symbiosum ATCC 14940, a representative strain of C. symbiosum. On this basis, we further developed a series of genetic manipulation methods for this bacterium. Firstly, following the identification of a functional replicon pBP1 in C. symbiosum ATCC 14940, a highly efficient conjugative DNA transfer method was established, enabling the rapid introduction of exogenous plasmids into cells. Next, we constructed a dual-plasmid CRISPR/Cas12a system for genome editing in this bacterium, reaching over 60 % repression for most of the chosen genes as well as efficient deletion (>90 %) of three target genes. Finally, this toolbox was used for the identification of crucial functional genes, involving growth, synthesis of important metabolites, and virulence of C. symbiosum ATCC 14940. Our work has effectively established and optimized genome editing methods in intestinal C. symbiosum, thereby providing strong support for further basic and application research in this bacterium.

A study on molecular mechanism of Xihuang pill in the treatment of glioblastoma based on network pharmacology and validation in vitro and in vivo

Ethnopharmacological relevanceXihuang pill has been utilized to treat cancer for more than three hundred years in China. The molecular mechanisms of Xihuang pill in treating glioblastoma remains unclear. Aim of the studyThis study aimed to explore the core molecular mechanisms of Xihuang pill in treating glioblastoma by an integrative pharmacology-based investigation. Materials and methodsThe main active compounds of Xihuang pill were identified from TCMSP, BATMAN-TCM, TCMID and CNKI. Glioblastoma-related therapeutic targets were retrieved from GeneCards and UniProt. Subsequently, a protein-protein interaction (PPI) network analysis was constructed using STRING. GO and KEGG enrichment were performed to analyze the intersection targets between the active compounds of Xihuang pill and glioblastoma. Based on the above analysis, we built a CTP network. The in vitro and in vivo experiments were further performed to validate the crucial molecular targets of Xihuang pill for the treatment of glioblastoma. ResultsA total of sixty active compounds of Xihuang pill and ten potential targets related to glioblastoma were found. Based on topological analysis, fourteen ingredients were selected as the main active compounds, and MY11 might be the most important metabolite in Xihuang pill. PI3K/Akt signaling pathway and receptor tyrosine kinases were considered as crucial targets for Xihuang pill against glioblastoma through KEGG enrichment and CTP analysis. The present experiments indicated that Xihuang pill suppressed the activation of PI3K/Akt/mTOR signaling pathway in glioblastoma cells and mouse xenografts via modulating the expression of PTEN and Rheb proteins, the interaction between TSC2 and Rheb, and the production of PIP3. Meanwhile, after glioblastoma cells treatment with Xihuang pil, the release of IL-1β, INF-γ was increased and the production of IL-10, TGF-β1 was decreased in glioblastoma cells after incubated with Xihuang pill. In addition, the activation of the upstream positive modulators of PI3K/Akt/mTOR pathway including PDGF/PDGFR and FGF/FGFR signaling were down-regulated in glioblastoma cells and mouse xenografts after treatment with Xihuang pill. ConclusionTaken together, Xihuang pill inhibiting glioblastoma cell growth might be partly through down-regulating the activation of PDGF/PDGFR or FGF/FGFR-PI3K/Akt/mTOR signaling axis and improving immuno-suppressive micro-environment of glioblastoma.

NtERF4 promotes the biosynthesis of chlorogenic acid and flavonoids by targeting PAL genes in Nicotiana tabacum.

Chlorogenic acid (CGA) and flavonoids are important secondary metabolites, which modulate plant growth and development, and contribute to plant resistance to various environmental stresses. ERF4 has been shown to be a repressor of anthocyanin accumulation in grape, but its full roles in regulating the biosynthesis of other phenylpropanoid compounds still needs to be further studied. In the present study, two NtERF4 genes were identified from N. tabacum genome. The expression level of NtERF4a was higher than that of NtERF4b in all the tobacco tissues examined. Over-expression of NtERF4a significantly promoted the accumulation of CGA and flavonoids in tobacco leaves, while silencing of NtERF4a significantly repressed the biosynthesis of CGA and flavonoids. RNA-seq analysis of NtERF4a-OE and WT plants revealed 8 phenylpropanoids-related differentially expressed genes (DEGs), including 4 NtPAL genes that encode key enzymes in the phenylpropanoid pathway. Activation of NtERF4a-GR fusion protein in tobacco significantly induced the transcription of NtPAL1 and NtPAL2 in the presence of protein synthesis inhibitor. Chromatin immunoprecipitation and Dual-Luc assays further indicated that NtERF4a could bind to the GCC box presented in the promoters of NtPAL1 and NtPAL2, thereby activating their transcription. Moreover, ectopic expression of NtERF4a induced the transcription of NtGSK1, NtMYC2, and NtJAZ3 genes, and enhanced the resistance of tobacco seedlings to salt and drought stresses, indicating multiple roles of NtERF4a in plants. Our findings revealed new roles of NtERF4a in modulating the accumulation of phenylpropanoid compounds in tobacco, and provided a putative target for improving phenylpropanoids synthesis and stress resistance in plants.

Comprehensive Transcriptomic and Metabolomic Analysis Revealed the Functional Differences in Pigeon Lactation between Male and Female during the Reproductive Cycle.

Lactation is a unique reproductive behavior in pigeons, with the crop serving as the organ responsible for secreting pigeon milk. Both male and female pigeons can produce crop milk and rear their offspring through a division of labor. Since the time of the secretion of pigeon crop milk is different in the process of feeding the young, whether the metabolism and formation of pigeon milk use the same mechanism is a very interesting scientific question. However, the metabolic dynamics and underlying genetic mechanisms involved in the formation of pigeon crop milk remain unclear, particularly during the incubation-feeding reproductive cycle. In this study, we integrated lactation-associated metabolism and transcriptome data from the crop tissues of both male and female pigeons during the brooding and feeding stages. We mapped the changes in metabolites related to milk formation in the crop tissues during these stages. Through metabolome profiling, we identified 1413 metabolites among 18 crop tissues. During the breeding cycles, the concentrations of estrone, L-ergothioneine, and L-histidine exhibited the most dynamic changes in females. In contrast, estrone, L-anserine, 1-methylhistidine, homovanillate, oxidized glutathione, and reducing glutathione showed the most dynamic changes in males. Gender-specific differences were observed in the metabolome, with several metabolites significantly differing between males and females, many of which were correlated with cytokine binding, immunity, and cytochrome P450 activity. Using this dataset, we constructed complex regulatory networks, enabling us to identify important metabolites and key genes involved in regulating the formation of pigeon milk in male and female pigeons, respectively. Additionally, we investigated gender-associated differences in the crop metabolites of pigeons. Our study revealed differences in the modulation of pigeon crop milk metabolism between males and females and shed light on the potential functions of male and female pigeon milk in the growth, development, and immunity of young pigeons, an area that has not been previously explored. In conclusion, our results provide new insights into the metabolic regulation of pigeon crop milk formation during the brooding and breeding stages. Furthermore, our findings lay the foundation for the accurate development of artificial pigeon milk.

Histochemical Localization of Alkaloids in the Bulbs of In Vitro-Regenerated Snake’s Head Fritillary (Fritillaria meleagris L.): The Effect of a Temperature Regime

The genus Fritillaria is characterized by the production of alkaloids, primarily of the isosteroidal type. The aim of this preliminary study was to perform a histolocalization screening aimed at revealing the presence of alkaloids in the bulbs of F. meleagris, cultured in vitro under different growth regimes and at different developmental stages, as a powerful tool to identify preferable in vitro plant material for alkaloid isolation. Histochemical localization of alkaloids was performed using Wagner’s and Dragendorff’s reagents in fresh sections of bulbs cultured at 24 °C or 7 °C for 4 weeks, as well as those cultured at 24 °C following the 4-week chilling treatment, which were sampled at the beginning of sprouting. A positive reaction was observed with both reagents and was particularly intense in cold-treated bulbs. Alkaloids were mainly distributed in the bulbs and partly in the sprouts of the in vitro grown F. meleagris. The most intense staining, indicative of high alkaloid content, was observed in the bulb scales of pre-chilled bulbs that sprouted at 24 °C, rendering them preferable as in vitro plant material for alkaloid isolation. The results suggest that alkaloid production in the bulbs of F. meleagris can be improved by manipulating growth in the microenvironment of in vitro cultures, in order to meet the increasing industrial demand for medicinally or commercially important metabolites used as traditional medicines and herbal remedies.

Chemical and biochemical characterization of Ipomoea aquatica: genoprotective potential and inhibitory mechanism of its phytochemicals against α-amylase and α-glucosidase.

Ipomea aquatica, also known as water spinach, is an aquatic non-conventional leafy vegetable and is considered a healthy and seasonal delicacy in ethnic food culture. The study revealed the presence of rich chemical and biochemical composition in I. aquatica and antioxidant activities. Moreover, the plant extracts demonstrated significant DNA damage prevention activity against UV/H2O2-induced oxidative damage. High-resolution mass spectrometric analysis by UPLC-qTOF-MS/MS resulted in the identification of over 65 different compounds and 36 important secondary metabolites. Most of the compounds identified represented polyphenolic compounds, viz. polyphenol glycosides and phenolic acids, followed by alkaloids and terpenoids. A UPLC-DAD method was developed and quantified for 10 different polyphenolic compounds. Out of all the metabolites examined, a significant number of compounds were reported to have various bioactive properties, including antibacterial, antiviral, antitumor, hepatoprotection, and anti-depressant effects. The plant extracts were found to contain various compounds, including euphornin, lucidenic acid, and myricitin glycosides, which possess significant medicinal value. Metabolite analysis utilizing GC-MS revealed the presence of various fatty acids, amino acids, sugars, and organic acids. The analysis revealed the presence of essential unsaturated fatty acids such as α-linolenic acid as well as beneficial substances such as squalene., The evaluation of glycemic control activity was carried out by comprehending the inhibitory potential of α-amylase and α-glucosidase, outlining the kinetics of the inhibition process. The inhibitory activities were compared to those of acarbose and revealed stronger inhibition of α-glucosidase as compared to α-amylase. Furthermore, the mechanism of inhibition was determined using in silico analysis, which involved molecular docking and molecular dynamic simulation of the identified IA phytochemicals complexed with the hydrolase enzymes. The study generates convincing evidence that dietary intake of I. aquatica provides a positive influence on glycemic control along with various health-protective and health-promoting benefits.

CLOT LYSIS AND MEMBRANE PROTECTION POTENTIALS OF CHEILANTHES TENUIFOLIA METHANOLIC LEAF EXTRACT

Cheilanthes tenuifolia is a little perennial fern that falls within the taxonomic classification of the Pteridaceae botanical family. The plant has a diverse array of phytochemical substances, including alkaloids, phenolic compounds, flavonoids, saponins, steroids, and triterpenoids, which have demonstrated promising medicinal properties. This study aimed to evaluate the in-vitro membrane-stabilizing and clot lysis activities of a methanol leaf extract of C. tenuifolia (MCT). For this, we performed hypotonic solution-induced erythrocyte lysing and human blood clot lysis methods to check the membrane stabilizing and clot lysis capacities of MCT using acetylsalicylic acid and streptokinase as standards, respectively. Additionally, we also checked its phytochemical groups. The results of a preliminary phytochemical screening indicate the presence of alkaloids, glycosides, tannins, flavonoids, and saponins in the plant. MCT inhibited hemolysis in a concentration-dependent manner and inhibited 78.93 ± 0.01% hemolysis (IC50 = 46 ± 2.11 µg/ml) at the higher concentration (160 μg/ml), whereas the standard drug, acetylsalicylic acid (IC50 = 64.10 ± 2.08 µg/ml) inhibited 97.71 ± 0.01% at the same concentration. It also exhibited clot lysis in a concentration-dependent manner, where the maximum percentage of clot lysis was observed at 160 μg/100 ml where the IC50 value was 198.41 ± 1.87 µg. The standard drug streptokinase showed 77.51 ± 0.01% clot lysis. C. tenuifolia possesses various important secondary metabolites and shows membrane stabilizing and clot lysis capacity. Further studies are required to elucidate its active principles and their biological effects.

Phytochemical screening and biological evaluation of Greek sage (Salvia fruticosa Mill.) extracts

This study explores the influence of extraction solvents on the composition and bioactivity of Salvia fruticosa extracts. Ultrasound-assisted extraction with water, ethanol and their mixtures in variable proportions was used to produce four different extracts. An untargeted UPLC/MS‑based metabolomics was performed to discover metabolites profile variation between the extracts. In the analyzed samples, 2704 features had been detected, of which 95 were tentatively identified. The concentrations of the important metabolites, namely, caffeic acid, carnosic acid, carnosol, rosmarinic acid, salvianolic acid B and scutellarin, were determined, using UPLC-PDA methods. Rosmarinic acid was the dominant metabolite and antioxidant in all tested extracts, except the aqueous extract, in which scutellarin was the most abundant compound. The extracts and standards were examined for antioxidant activity and xanthine oxidase (XO) inhibitory activity. The most diverse in terms of chemical composition and rich in antioxidant compounds was 70% ethanolic extract and the strongest antioxidant was caffeic acid. All analyzed extracts showed the ability to inhibit XO activity, but the highest value was recorded for 30% ethanolic extract. Among tested standards, the most potent XO inhibitor was caffeic acid. The results suggest that the leaves of Greek sage are a source of natural XO inhibitors and may be an alternative to drugs produced by chemical synthesis.

A metabolomics analysis reveals the potential mechanism of chilling tolerance of red side of mango fruit during low temperature storage

Previous studies demonstrated that there is difference of cold tolerance between red side and green side of mango fruit exocarp, but the related mechanism is not clear yet. Here, an ultrahigh-performance liquid chromatography/electrospray ionization tandem mass spectrometry (UPLC-ESI-MS/MS) based metabolomic approach was performed to explain possible mechanism of cold tolerance difference between two sides of fruit exocarp. Results showed that red side was more cold tolerant than green side, as indicated by higher Fv/Fm but lower membrane permeability and lipid peroxidation along with less chilling injury (CI) severity in red side compared to green side. Furthermore, a total of 925 metabolites were characterized in mango exocarp. Multivariate metabolomics analysis identified differentially accumulated metabolites in different exocarp sides. Specific metabolites, including hesperetin-5-O-glucoside, quercetin-4′-O-glucoside, quercetin-7-O-glucoside, cyanidin-3-O-glucoside, pelargonidin-3-O-glucoside, L-arginine, L-glutamic acid, L-tryptophan, protocatechuic acid-4-O-glucoside, 9,16-dihydroxypalmitic and putrescine, were observed more in red exocarp side, which might be involved in positive regulation of chilling tolerance of mango fruit. Our results are beneficial to identify important metabolite markers associated with cold tolerance in red pigments-enriched mango.

Altering environmental conditions induce shifts in simulated deep terrestrial subsurface bacterial communities-Secretion of primary and secondary metabolites.

The deep terrestrial subsurface (DTS) harbours a striking diversity of microorganisms. However, systematic research on microbial metabolism, and how varying groundwater composition affects the bacterial communities and metabolites in these environments is lacking. In this study, DTS groundwater bacterial consortia from two Fennoscandian Shield sites were enriched and studied. We found that the enriched communities from the two sites consisted of distinct bacterial taxa, and alterations in the growth medium composition induced changes in cell counts. The lack of an exogenous organic carbon source (ECS) caused a notable increase in lipid metabolism in one community, while in the other, carbon starvation resulted in low overall metabolism, suggesting a dormant state. ECS supplementation increased CO2 production and SO4 2- utilisation, suggesting activation of a dissimilatory sulphate reduction pathway and sulphate-reducer-dominated total metabolism. However, both communities shared common universal metabolic features, most probably involving pathways needed for the maintenance of cell homeostasis (e.g., mevalonic acid pathway). Collectively, our findings indicate that the most important metabolites related to microbial reactions under varying growth conditions in enriched DTS communities include, but are not limited to, those linked to cell homeostasis, osmoregulation, lipid biosynthesis and degradation, dissimilatory sulphate reduction and isoprenoid production.

Physiology of γ-aminobutyric acid production by Akkermansia muciniphila.

Gut bacteria hold the potential to produce a broad range of metabolites that can modulate human functions, including molecules with neuroactive potential. One such molecule is γ-aminobutyric acid (GABA), the main inhibitory neurotransmitter of the central nervous system in animals. Metagenomic analyses suggest that the genomes of many gut bacteria encode glutamate decarboxylase (GAD), the enzyme that catalyzes GABA production. The genome of Akkermansia muciniphila, a mucin specialist and potential next-generation probiotic from the human gut, is predicted to encode GAD, suggesting a contributing role in GABA production in the human gut. In this study, A. muciniphila was grown in batch cultures with and without pH control. In both experiments, A. muciniphila was found to produce GABA as a response to acid (pH <5.5), although only when GABA precursors, either glutamate or glutamine, were present in the medium. Proteomic analysis comparing A. muciniphila grown with and without precursors at pH 4 did not show a difference in GAD expression, suggesting that it is expressed regardless of the presence of GABA precursors. To further investigate the function of A. muciniphila GAD, we heterologously expressed the gad gene (encoded by locus tag Amuc_0372) with a His tag in Escherichia coli and purified the GAD protein. Enzyme assays showed GAD activity in a pH range between 4 and 6, with the highest specific activity at pH 5 of 144 ± 16 µM GABA/min/mg. Overall, our results demonstrate the ability of A. muciniphila to produce GABA as an acid response and unravel the conditions under which GABA production in A. muciniphila occurs.IMPORTANCEAkkermansia muciniphila is considered to be a beneficial bacterium from the human gut, but the exact mechanisms by which A. muciniphila influences its host are not yet fully understood. To this end, it is important to identify which metabolites are produced and consumed by A. muciniphila that may contribute to a healthy gut. In the present study, we demonstrate the ability of A. muciniphila to produce γ-aminobutyric acid (GABA) when grown in an acidic environment, which often occurs in the gut. GABA is the major inhibitory neurotransmitter in the central nervous system and is present in the human gut. For this reason, it is considered an important bacterial metabolite. Our finding that A. muciniphila produces GABA in acidic environments adds to the growing body of understanding of its relationship with host health and provides an explanation on how it can survive acid stress in the human gut.