Influence of direct and sequential extraction methodology on metabolic profiling

Mycobacterium tuberculosis produces D-serine under hypoxia to limit CD8+ T cell-dependent immunity in mice

Adaptation to hypoxia is a major challenge for the survival of Mycobacterium tuberculosis (Mtb) in vivo. Interferon (IFN)-γ-producing CD8+ T cells contribute to control of Mtb infection, in part by promoting antimicrobial activities of macrophages. Whether Mtb counters these responses, particularly during hypoxic conditions, remains unknown. Using metabolomic, proteomic and genetic approaches, here we show that Mtb induced Rv0884c (SerC), an Mtb phosphoserine aminotransferase, to produce D-serine. This activity increased Mtb pathogenesis in mice but did not directly affect intramacrophage Mtb survival. Instead, D-serine inhibited IFN-γ production by CD8+ T cells, which indirectly reduced the ability of macrophages to restrict Mtb upon co-culture. Mechanistically, D-serine interacted with WDR24 and inhibited mTORC1 activation in CD8+ T cells. This decreased T-bet expression and reduced IFN-γ production by CD8+ T cells. Our findings suggest an Mtb evasion mechanism where pathogen metabolic adaptation to hypoxia leads to amino acid-dependent suppression of adaptive anti-TB immunity.

Unlocking the Potential of Substrate Quality for the Enhanced Antibacterial Activity of Black Soldier Fly against Pathogens

Globally, antibiotics are facing fierce resistance from multidrug-resistant bacterial strains. There is an urgent need for eco-friendly alternatives. Though insects are important targets for antimicrobial peptides, it has received limited research attention. This study investigated the impact of waste substrates on the production of antibacterial agents in black soldier fly (Hermetia illucens L.) larvae (HIL) and their implications in the suppression of pathogens [Bacillus subtilis (ATCC 6051), Staphylococcus aureus (ATCC 25923), Pseudomonas aeruginosa (ATCC 27853), and Escherichia coli (ATCC 25922)]. The 20% acetic acid (AcOH) extract from market waste had the highest antibacterial activity with an inhibition zone of 17.00 mm, followed by potato waste (15.02 mm) against S. aureus. Hexane extract from HIL raised on market waste also showed a significant inhibitory zone (13.06 mm) against B. subtilis. .Minimum inhibitory concentration (MIC) values recorded were 25 mg/mL against all test pathogens. The fastest time-kill of 20% AcOH extract was 4 h againstB. subtilis, E. coli, ,andP. aeruginosa. Lauric acid was also identified as the dominant component of the various hexane extracts with concentrations of 602.76 and 318.17 μg/g in HIL reared on potato and market waste, respectively. Energy from the market waste substrate correlated significantly (r = 0.97) with antibacterial activities. This study highlights the key role of substrate quality and extraction methods for enhancing the production of antibacterial agents in HIL, thus providing new insights into the development of potential drugs to overcome the alarming concerns of antimicrobial resistance.

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.

Profiles of Free and Bound Phenolics and Their Antioxidant Capacity in Rice Bean (Vigna umbellata)

Rice bean (Vigna umbellata) is a medicinal and dietary legume rich in polyphenols. In this study, the free and bound phenolics in rice bean were extracted by water, 80% methanol, and acid, base, and composite enzymatic hydrolysis, respectively. The polyphenol profiles of the extracted fractions were analyzed. The outcome demonstrated that base hydrolysis was the most effective way to liberate bound phenolics from rice bean (14.18 mg GAE/g DW), which was 16.68 and 56.72 folds higher than those extracted by acid and enzymatic hydrolysis, respectively. The bound polyphenols released by base hydrolysis contributed to 71.15% of the total phenolic content. A total of 35 individual phenolics was identified, of which isoquercitrin, procyanidin B1, rutin, taxifolin, and catechin were the main monomeric phenolics in the free fraction, while gallic acid, protocatechuic acid, p-hydroxybenzoic acid, catechin, and phloroglucinol were the main monomeric phenolics in the bound fraction. In comparison to the free phenolics extracted by water and 80% methanol and the bound phenolics extracted using acid and composite enzymatic hydrolysis, the bound phenolics from base hydrolysis had a superior antioxidant capacity. The antioxidant activity of rice bean is primarily attributed to individual phenolics such as catechin, abundant both in free and bound fractions, and also p-hydroxybenzoic acid, gallic acid, and protocatechuic acid in bound fractions. The bound phenolics of rice bean were first reported and showed large differences with the composition of free phenolics. This work suggests that the bound fraction of rice bean must be taken into account in assessing its potential benefits to health.

Bioefficacy of isolated compound l-isoleucine, N-allyloxycarbonyl-, and dodecyl ester from entomopathogenic actinobacteria Actinokineospora fastidiosa against agricultural insect pests, human vector mosquitoes, and antioxidant activities

Spodoptera litura and Helicoverpa armigera are polyphagous pests of agricultural crops in the Asian tropics since these pests have been responsible for massive crop and carry economic losses and low commodity production. At the same time, mosquitoes are vectors for numerous dreadful diseases, which is the most important group of insect for their public health concern. Using synthetic insecticides to control the pests can lead to contamination of land surface and groundwater and impact beneficial soil organisms and nontarget species. Applications of bioactive compounds are received considerable attention across the world as alternatives to synthetic insecticides. In the current study, actinobacterial secondary metabolite was isolated from Actinokineospora fastidiosa for the first time. The effect of actinobacterial metabolite (l-isoleucine, N-allyloxycarbonyl-, and dodecyl ester) was assessed on agricultural pest S. litura and H. armigera, mosquito vectors larvae Ae. aegypti, An. stephensi, and Cx. quinquefasciatus. The bioactive fraction was characterized through UV, FTIR, and NMR analysis. GC-MS analyses reveal the existence of a bioactive compound with a respective retention time of 19.740 responsible for larvicidal activity. The bioefficacy of the l-isoleucine, N-allyloxycarbonyl-, and dodecyl ester showed high antifeedant activity on S. litura (80.80%) and H. armigera (84.49%); and larvicidal activity on S. litura (82.77%) and H. armigera (88.00%) at 25 μg/mL concentration, respectively. The effective LC₅₀ values were 8.07 μg/mL (F = 2.487, r² = 0.988, P ≤ 0.05) on S. litura and 7.53 μg/mL (F = 123.25, r² = 0.951, P ≤ 0.05) on H. armigera. The mosquito larvicidal effect of isolated compounds l-isoleucine, N-allyloxycarbonyl-, and dodecyl ester treated against Ae. aegypti, An. stephensi, and Cx. quinquefasciatus the obtained percentage mortality was 96.66, 83.24, 64.52, 50.00, and 40.00% against Ae. aegypti; 100.00, 86.22, 73.81, 65.37, and 56.24% against An. stephensi; 100.00, 90.00, 76.24, 68.75, and 56.23% against Cx. quinquefasciatus. The mosquito larvae of Ae. aegypti obtained LC₅₀ value was 13.25 μg/mL, F = 28.50, r² = 0.90; on An. stephensi was 10.19 μg/mL, F = 15.55, r² = 0.83, and Cx. quinquefasciatus was 9.68 μg/mL, F = 20.00, r² = 0.87. Furthermore, l-isoleucine-, N-allyloxycarbonyl-, and dodecyl ester-treated larvae produced significant pupicidal activity on S. litura (62.71%) and H. armigera (66.50%) at 25 μg/mL, along with increased larval and pupal duration as compared to control group. Treated larvae revealed obliteration in the midgut epithelial cells and destruction of microvilli was noticed as compared to the control. The isolated compounds l-isoleucine, N-allyloxycarbonyl-, and dodecyl ester did not produce any significant mortality on zebrafish embryos in all tested concentrations on biosafety observation. The potential microbial isolated molecule may fit well in IPM programs. Since the risk to human health, the environment, etc. is unknown.

A Comparative Study of Diospyros malabarica (Gaub) Extracts in Various Polarity-Dependent Solvents for Evaluation of Phytoconstituents and Biological Activities

Keeping in mind the ascribed repute of Diospyros malabarica (D. malabarica), this investigation was commenced to assess the effect of diverse solvents on extraction yields, phytochemical components and antioxidant capability, and in vitro biological activities of D. malabarica for pharmaceutically active constituents to combat various infections. To screen phytochemicals both qualitatively (flavonoids, terpenoid, saponins, tannins) and quantitatively like total phenolic and flavonoid contents, Diospyros malabarica parts include the following: root, leaves, bark, stem, ripe, and unripe fruit were sequentially extracted with organic solvents such as petroleum ether, dichloromethane, ethyl acetate, ethanol, methanol, and water in increasing order of polarity from less polar to more polar solvents. Furthermore, biological activities such as antibacterial, antifungal, anticancer, antidiabetic, and anti-inflammatory were explored. The results revealed that all the tested solvents displayed a vital role in the extraction yield, the content of phytochemicals, and the studied biological activities. Methanol was found as the best solvent followed by the ethanol for the extraction, representing the highest extraction yield (18.3%), rich diversity of phytochemicals, and the highest total phenolic contents (602 ± 0.001 μg EAG/mg of extract) and total flavonoid contents (455 ± 0.6 μg EQ/mg of extract) in bark extract. Furthermore, methanol bark extract showed high in vitro antibacterial activity (30.25 mm ± 0.9), antifungal activity (18.25 mm ± 0.2), anticancer activity (48%), antidiabetic activity (68%) and anti-inflammatory activity (62%) followed by ethanol amongst other extracts of D. malabarica. Accordingly, methanol might be as an ideal solvent to get maximum content of phytochemicals, promising antioxidants, and in vitro biological activities from bark extract amongst other extracts of D. malabarica compared to pet ether, ethyl acetate, and dichloromethane and may act as free radical rummager because phytochemical constituents exhibit antioxidant capability. Our findings suggest that phytochemical compounds (flavonoids, tannins, phenols, saponins, and terpenoids) found in the bark extract of D. malabarica may be attributed to evaluate potent anti-inflammatory, anticancer, antidiabetic, antibacterial, and antifungal activities.

Susceptibility of Aedes albopictus Larvae to the Larvicidal Activity of Three Types of Derris elliptica Extract

<b>Background and Objective:</b> The methanol, ethyl acetate and n-hexane extracts of <i>D. elliptica</i> root have high larvicidal activity against <i>Aedes aegypti</i> larvae, the primary vector of dengue but have not been understood their potential against <i>Ae. albopictus</i> larvae, the secondary vector of dengue that also transmits Chikungunya and Zika viruses. This <i>in vitro</i> study aims to understand the larvicidal activity of the 3 extract types of <i>D. elliptica </i>root against <i>Ae. albopictus</i> larvae. <b>Materials and Methods:</b> The tuba root extract types were obtained from the sequential extraction process with 3 steps of liquid-liquid partition as described in the previous report. Six concentrations were occupied in this experiment ranging of 0.5, 1.0, 2.0, 4.0, 10.0 and 15.0 mg L<sup>1</sup> each concentration was 5 times replicated and placed in 250 mL plastic cups. As many as 20 of 3rd instar larvae of <i>Ae. albopictus</i> were subjected in each treatment cup and larval mortality was observed after 24 and 48 hrs of exposure. <b>Results:</b> Larval mortality rates based on concentration range of 13.75-97.00 and 43,75-100%, 14.00-44.00, 34.00-90.00%, 12.00-47.00 and 28.00-88.00%, with the LC<sub>50</sub> after 24 and 48 hrs of exposure were 2.925 and 0.414, 16.184, 2.900, 15.789 and 4.380 mg L<sup>1</sup>, respectively for methanol, ethyl acetate and n-hexane extracts. <b>Conclusion:</b> The methanol, ethyl acetate and n-hexane extract of tuba root have high larvicidal activity against <i>Ae. albopictus</i> larvae. Further study on prototype formulation of larvicide and elucidation of the specific phytochemical compounds of the extracts were necessarily conducted.

Mode-Dependent Antiviral Activity of Medicinal Plant Extracts against the Mosquito-Borne Chikungunya Virus

The lack of specific treatment for chikungunya fever makes the need for anti-chikungunya virus agents more crucial. This study was conducted to evaluate 132 extracts obtained by sequential solvent extraction from 21 medicinal plants for cytopathic effect inhibitory activity using virus-infected Vero cells in two different sample introduction modes. Among the extracts, 42 extracts (31.8%) from 12 plants in the concurrent mode and three extracts (2.3%) from a plant in the non-concurrent mode displayed strong cytopathic effect inhibitory activity (cell viability ≥70%). Viral load quantification analysis unveiled that the extracts of Clinacanthus nutans (chloroform, ethyl acetate, and ethanol), Hydrocotyle sibthorpioides (ethanol), and Ocimum americanum (ethanol and methanol) hindered the release of viral progeny from the infected cells while the extracts of Ficus deltoidea (ethanol), Gynura bicolor (water), H. sibthorpioides (water), and O. americanum (chloroform and ethyl acetate) blocked the entry of virus into the cells. The extracts of Diodella sarmentosa (ethyl acetate), Diplazium esculentum (chloroform, ethyl acetate, and ethanol), and G. bicolor (ethanol) possessed virucidal effect and caused 5.41-log to 6.63-log reductions of viral load compared to the virus control. The results indicate that these medicinal plants are potential sources of anti-chikungunya virus agents that have varied modes of action.

Biostimulants for Plant Growth and Mitigation of Abiotic Stresses: A Metabolomics Perspective

Adverse environmental conditions due to climate change, combined with declining soil fertility, threaten food security. Modern agriculture is facing a pressing situation where novel strategies must be developed for sustainable food production and security. Biostimulants, conceptually defined as non-nutrient substances or microorganisms with the ability to promote plant growth and health, represent the potential to provide sustainable and economically favorable solutions that could introduce novel approaches to improve agricultural practices and crop productivity. Current knowledge and phenotypic observations suggest that biostimulants potentially function in regulating and modifying physiological processes in plants to promote growth, alleviate stresses, and improve quality and yield. However, to successfully develop novel biostimulant-based formulations and programs, understanding biostimulant-plant interactions, at molecular, cellular and physiological levels, is a prerequisite. Metabolomics, a multidisciplinary omics science, offers unique opportunities to predictively decode the mode of action of biostimulants on crop plants, and identify signatory markers of biostimulant action. Thus, this review intends to highlight the current scientific efforts and knowledge gaps in biostimulant research and industry, in context of plant growth promotion and stress responses. The review firstly revisits models that have been elucidated to describe the molecular machinery employed by plants in coping with environmental stresses. Furthermore, current definitions, claims and applications of plant biostimulants are pointed out, also indicating the lack of biological basis to accurately postulate the mechanisms of action of plant biostimulants. The review articulates briefly key aspects in the metabolomics workflow and the (potential) applications of this multidisciplinary omics science in the biostimulant industry.

Compositional Analysis of Non-Polar and Polar Metabolites in 14 Soybeans Using Spectroscopy and Chromatography Tools

There has been significant interest in soybean oil, fatty acid, and sugar composition to develop new value-added soybean products. Thus, compositional analysis is critical for developing value-added soybeans. In the present study, we showed simple screening tools (near infrared spectroscopy (NIR) and high-performance thin layer chromatography (HPTLC)) coupled with multivariate analysis for the sample classification of 14 soybeans as a proof-of-concept. We further determined major non-polar and polar metabolites responsible for differences between different soybeans using gas and ion chromatography. These differences in soybean profiles were attributed to lower levels of total oil content in wild soybeans (~9%) versus cultivated soybeans (16%–22%). In addition, higher levels of linolenic acid (~17%) and stachyose (~53%) were determined in wild type, whereas higher levels of oleic acid (~19%) and sucrose (~59%) were detected in cultivated soybeans. Interestingly, one cultivated soybean had a desirable sugar profile with a high amount of sucrose (86%) and a low abundance of stachyose (9%). The correlation studies showed a positive correlation between oil and soluble sugars (R² = 0.80) and negative correlations between methyl linolenate and soluble sugars (R² = −0.79), oil (R² = −0.94), and methyl oleate (R² = −0.94) content. Both polar and non-polar metabolites showed significant differences in wild and cultivated soybeans.