Protocatechuic Acid Research Articles

Valorization of Potato Peels (Solanum tuberosum) Using Infrared-Assisted Extraction: A Novel Sprouting Suppressant and Antibacterial Agent

Recently, there has been a growing interest in reducing waste to promote environmental sustainability, with particular focus on agricultural by-products, especially fruits and vegetables. Potato, a widely used crop across various industries, generates a significant amount of peel waste. This study aims to valorize potato peels using water bath extraction (WBE) and infrared-assisted extraction (IRAE), both with distilled water as the solvent, followed by assessments of antioxidant, antibacterial, and anti-sprouting activities. Optimization using response surface methodology identified optimal extraction conditions for WBE (90 °C for 70 min) and IRAE (80 °C for 10 min), with both methods yielding 3.5 mg GAE/g DM in polyphenol content. IRAE demonstrated superior energy efficiency and enhanced antioxidant activity. The extracts exhibited antibacterial properties against both Gram-positive (Listeria monocytogenes) and Gram-negative bacteria (Proteus sp. and Salmonella sp.), with inhibition zones ranging from 10 to 14 mm. Furthermore, the potato peels extract showed significant anti-sprouting effects at room temperature, reducing both the number and size of sprouts compared with the control. HPLC analysis showed the presence of different phenolic compounds such as rutin, catechin, caffeic acid, protocatechuic acid, chlorogenic acid, p-coumaric acid, and gallic acid in one or both extracts. These findings suggest that potato peels extract holds potential for applications in the food industry as a natural preservative due to its antioxidant properties, as well as a sprout suppressant. The antibacterial activity of the extracts suggests their potential as a natural preservative as well, offering protection against both Gram-positive and Gram-negative bacteria that may be present in food.

Lignin valorization to bioplastics with an aromatic hub metabolite-based autoregulation system

Exploring microorganisms with downstream synthetic advantages in lignin valorization is an effective strategy to increase target product diversity and yield. This study ingeniously engineers the non-lignin-degrading bacterium Ralstonia eutropha H16 (also known as Cupriavidus necator H16) to convert lignin, a typically underutilized by-product of biorefinery, into valuable bioplastic polyhydroxybutyrate (PHB). The aromatic metabolism capacities of R. eutropha H16 for different lignin-derived aromatics (LDAs) are systematically characterized and complemented by integrating robust functional modules including O-demethylation, aromatic aldehyde metabolism and the mitigation of by-product inhibition. A pivotal discovery is the regulatory element PcaQ, which is highly responsive to the aromatic hub metabolite protocatechuic acid during lignin degradation. Based on the computer-aided design of PcaQ, we develop a hub metabolite-based autoregulation (HMA) system. This system can control the functional genes expression in response to heterologous LDAs and enhance metabolism efficiency. Multi-module genome integration and directed evolution further fortify the strain’s stability and lignin conversion capacities, leading to PHB production titer of 2.38 g/L using heterologous LDAs as sole carbon source. This work not only marks a leap in bioplastic production from lignin components but also provides a strategy to redesign the non-LDAs-degrading microbes for efficient lignin valorization.

Polyphenolic Compounds in the Stems of Raspberry (Rubus Idaeus) Growing Wild and Cultivated

The stems of Rubus idaeus L., a byproduct of the fruit–food industry, are known sources of bioactive compounds. The main objective of this study was to investigate the composition of polyphenolic compounds in R. idaeus stems. Seven cultivated raspberry varieties, thirteen garden samples, including five well-known raspberry varieties, and thirteen wild raspberry samples from different locations in Estonia were analyzed. The HPLC-MS method detected 62 substances, of which 42 were identified, 12 were tentatively identified, and 8 compounds remained unknown. Protocatechuic acid pentoside was dominant in most varieties and in all garden and wild raspberry samples. Dihydroxybenzoic acid hexoside 1, p-coumaroyl quinic acid 1, quercetin 4’-glucuronide, and p-coumaric acid glycoside were found in significant quantities. Correlations among the contents of individual compounds were established. When studying the dynamics of polyphenolic compound accumulation in, for example, the GR1 sample over a year, it was found that, in raspberry stems, the largest amount of them accumulated in April and slightly less in January and October. Investigating the dependence of the accumulation of polyphenols on the parts of the stem, it was found that the upper parts have the highest phenolic contents. Therefore, it is recommended to harvest approximately the upper third of the stem.

Ultrasonic-Assisted Extraction and Antioxidant Evaluation of Resveratrol from Peanut Sprouts

The orthogonal array design method was used to optimize ultrasonic-assisted extraction of resveratrol from peanut sprouts. The results showed that the highest extraction yield of resveratrol using ultrasonic-assisted extraction could be up to 1.1%. The optimal extraction conditions were liquid to solid ratio of 30:1 (mL/g) and ethanol concentration of 80% (v/v) as solvent for 40 min at the temperature of 70 °C. AB-8 macroporous adsorption resin was used to purify the crude extract and the resveratrol content increased to 47.5% after one treatment run. The optimal adsorption parameters were initial concentrations in the sample solution of 2 mg/mL, a pH of 5.0, a flow rate of 2 mL/min, and a temperature of 25 °C. The optimal desorption parameters were 60% ethanol and a flow rate of 1 mL/min. The chemical composition of the peanut sprout’s resveratrol sample was investigated via HPLC, and the predominant constituents were found to be protocatechuic acid, catechins, caffeic acid, epicatechuic acid, resveratrol, and rutin. The antioxidant activities of the resveratrol were measured via the following different analytical methods: reducing power, 2,2-diphenyl-1-picrylhdrazyl (DPPH), hydroxyl radical-scavenger activity, superoxide radical-scavenger activity, the β-carotene bleaching test, and the scavenging nitrite test. The results indicated that the resveratrol in peanut sprouts have significant antioxidant activities and can be used as a source of potential antioxidant. And peanut sprout’s resveratrol has the potential and valuable application to be used as a new type of resveratrol resource. The finding of this study can provide some theoretical reference for the comprehensive utilization of peanut resources in the development of antioxidant health foods.

Synergistic wall digestion and cuproptosis against fungal infections using lywallzyme-induced self-assembly of metal-phenolic nanoflowers

Fungi are very common infectious pathogens, which may cause invasive and potentially life-threatening infections. However, the efficacy of antifungal medications remains limited. Herein, a Cu2+-phenolic nanoflower is designed to combat fungal infections by combining cuproptosis and cell wall digestion. Firstly, protocatechuic acid (PA)-Cu2+ (PC) nanopetals are prepared by coordination interaction. Lywallzyme (Lyw) is then added to induce the self-assembly of PC to form Lyw loaded PC (PCW) nanoflowers. PCW nanoflowers can effectively adhere to fungal surface and Lyw can digest fungal cell walls to facilitate Cu2+ to penetrate into fungal interior, thereby exerting a synergistic fungicidal effect. PCW nanoflowers exhibit excellent fungicidal activity even in protein-rich and high-salt conditions, where dissociative Cu2+ completely loses fungicidal activity. Transcriptome sequencing analysis reveals that PCW can lead to fungal cuproptosis. The in vivo fungicidal effect of PCW nanoflowers is confirmed on a murine skin fungal infection model and a murine fungal keratitis model.

Simultaneous Qualitative and Quantitative Analyses of 41 Constituents in Uvaria macrophylla Leaves Screen Antioxidant Quality-Markers Using Database-Affinity Ultra-High-Performance Liquid Chromatography with Quadrupole Orbitrap Tandem Mass Spectrometry.

To date, no study has focused on Uvaria macrophylla leaves with various traditional efficiencies. This paper therefore applied a database affinity ultra-high-performance liquid chromatography with quadrupole Orbitrap tandem mass spectrometry (UHPLC-Q-Orbitrap-MS/MS) strategy to analyze the lyophilized aqueous extract of U. macrophylla leaves. Through database comparison and MS fragment elucidation, this study has putatively identified 41 constituents belonging to flavonoid, phenolic acid, steroid, and saccharide natural product classifications. Significantly, four groups of isomers (liquiritigenin vs. isoliquiritigenin vs. pinocembrin; oroxylin A vs. wogonin vs. galangin 3-methyl ether; isoquercitrin vs. hyperoside; protocatechuic acid vs. 2,5-dihydroxybenzoic acid) have been successfully distinguished from each other. All of 41 constituents were then subjected to a quantitative analysis based on linear regression equation established by the above UHPLC-Q-Orbitrap-MS/MS strategy and an ABTS+•-scavenging antioxidant assay. Finally, the chemical content was multiplied by the corresponding ABTS+•-scavenging percentage to calculate the antioxidant contribution. It was shown that the chemical contents of 41 constituents varied from 0.003 ± 0.000 to 14.418 ± 1.041 mg/g, and gallic acid showed the highest antioxidant contribution. Gallic acid is considered as a suitable antioxidant quality-marker (Q-marker) of U. macrophylla leaves. These findings have scientific implications for the resource development and quality control of U. macrophylla leaves.

Protocatechuic acid grafted chitosan/oxidized glucomannan hydrogel with antimicrobial and anti-inflammatory effects for enhancing wound repair

Oxidative stress, inflammation, and bacterial infection are critical barriers to wound healing. In this work, a composite wound dressing was designed to promote wound healing and reduce complications. A hydrogel with antibacterial, anti-inflammatory, and antioxidant properties was prepared by crosslinking chitosan (CS) and oxidized konjac glucomannan with Mg2+. We named the prepared hydrogel CPO/Mg2+. The proposed hydrogel demonstrated a significant capacity for promoting wound healing. Experimental results indicate that the CPO/Mg2+ composite hydrogel exhibits a bacteriostatic rate of over 95 % against S. aureus and P. aeruginosa. Furthermore, CPO/Mg2+ reduced oxidative damage to L929 cells in an H2O2-induced ROS microenvironment and promoted the polarization of macrophage M2. In vivo full-thickness skin defect experiments revealed that the CPO/Mg2+ composite hydrogel enhances collagen deposition and angiogenesis, achieving a closure rate of over 95 % for infected wounds within 14 days. This novel composite hydrogel offers an effective strategy for the repair of infected wounds.

Pomegranate peel-derived activated carbon: An effective adsorbent for protocatechuic acid removal and environmental remediation

Pomegranate peel-derived activated carbon: An effective adsorbent for protocatechuic acid removal and environmental remediation

Research Progress on the Mechanisms of Protocatechuic Acid in the Treatment of Cognitive Impairment

Cognitive impairment (CI) is a type of mental health disorder that mainly affects cognitive abilities, such as learning, memory, perception, and problem-solving. Currently, in clinical practice, the treatment of cognitive impairment mainly focuses on the application of cholinesterase inhibitors and NMDA receptor antagonists; however, there is no specific and effective drug yet. Procatechuic acid (PCA) possesses various functions, including antibacterial, antiasthmatic, and expectorant effects. In recent years, it has received growing attention in the cognitive domain. Therefore, by summarizing the mechanisms of action of procatechuic acid in the treatment of cognitive impairment in this paper, it is found that procatechuic acid has multiple effects, such as regulating the expression of neuroprotective factors, inhibiting cell apoptosis, promoting the autophagy-lysosome pathway, suppressing oxidative stress damage, inhibiting inflammatory responses, improving synaptic plasticity dysfunction, inhibiting Aβ deposition, reducing APP hydrolysis, enhancing the cholinergic system, and inhibiting the excitotoxicity of neuronal cells. The involved signaling pathways include activating Pi3K-akt-mTor and inhibiting JNK, P38 MAPK, P38-ERK-JNK, SIRT1, and NF-κB/p53, etc. This paper aims to present the latest progress in research on procatechuic acid, including aspects such as its chemical properties, sources, pharmacokinetics, mechanisms for treating neurodegenerative diseases.

Physical, functional and bioactive properties of microencapsulated powders from banana pseudostem and inflorescence extracts

Application of agricultural by-products in the functional food and beverage industry is currently gaining prominence. Banana (Musa spp) is a popular tropical fruit with global production of 124.97 million tonnes. The banana production industry contributes to large amount of solid waste/ banana by-products, such as, pseudostem and inflorescence. Palayankodan (Musa × paradisiaca Mysore AAB group), Nendran (Musa × paradisiaca AAB group) and Njalipoovan (Musa × paradisiaca AB group) are three popular and common cultivars in Kerala, a state in South India. The present study was aimed to extract the potential bioactive compounds from the pseudostem and inflorescence of the above-mentioned cultivars and to standardise the process of microencapsulation using spray drying. Ultrasonication assisted extraction using ethanol as solvent was carried out. The extract and wall material parameters were standardised for microencapsulation. The encapsulated powders were analysed for encapsulation yield, retention efficiency, physical properties, phytochemical composition, antioxidant potential and anti-diabetic activity. The encapsulation yields and retention efficiencies of the encapsulated powders were found to be approximately 75 and 70.51%, respectively. Results revealed that the powders exhibited lower bulk density, good solubility and reconstitutability. Scanning electron microscopy was also conducted to reveal the particle morphology. All the powders exhibited smooth, spherical shape, with no pores. The phenolic and flavonoid contents of the encapsulated pseudostem and inflorescence extract powders ranged from 2.75 to 3.13 mg GAE/ g of powder and 34.83 to 46.67 mg QE/g of powder, respectively. The present study also reported the in vitro bioactive properties, in terms of antioxidant and anti-diabetic activities of the encapsulated powders. The HPLC analysis of the microencapsulated powders revealed the presence of gallic acid, protocatechuic acid, trans cinnamic acid, trans ferulic acid, epicatechin and syringic acid. It is clear from the study that the encapsulated powders from banana by-products have a great potential to be utilised by the functional food industry.Graphical

Antioxidant and Antifungal Activities and Characterization of Phenolic Compounds Using Ultra-High Performance Liquid Chromatography and Mass Spectrometry (UPLC-MS) of Aqueous Extracts and Fractions from Verbesina sphaerocephala Stems.

The Verbesina gender represents the second most diverse group from the Asteraceae family in Mexico; Verbesina sphaerocephala is one of the most distributed species along the Mexican territory. This species has been poorly studied, reporting the presence of some bioactive compounds with antioxidant and antibacterial activity. In this study, phenolic and flavonoid contents and composition, antioxidant and antifungal activities of aqueous extracts of the stem of V. sphaerocephala and its fractions were determined. The results showed that the highest antifungal activity against Botrytis cinerea was shown by the aqueous extract (IC50: 0.10 mg/mL) and the ethyl acetate fraction (IC50: 14.8 mg/mL). In addition, the aqueous extract and the ethyl acetate fraction exhibited the highest phenolic (21.40 and 21.26 mg gallic acid equivalents per gram of dry extract, respectively) and flavonoid contents (11.53 and 3.71 mg rutin equivalents, respectively) and high antioxidant activity determined by the Total Antioxidant Capacity (20.62 and 40.21 mg ascorbic acid equivalents per gram of dry extract, respectively), Ferric Reducing Power (74.76 and 129.57 mg gallic acid equivalents per gram of dry extract, respectively), DPPH (IC50: 12.38 and 7.36 mg/mL, respectively), and ABTS (IC50: 5.60 and 7.76 mg/mL, respectively) methods. Twelve phenolic compounds were detected in the aqueous extract using UPLC-MS analysis, of which the major ones were protocatechuic, vanillic, and hydroxybenzoic acid, while in the ethyl acetate fraction, the presence of 18 phenolic compounds were identified, of which the majority were vanillin, rutin, and hydroxybenzoic acid. The results of this research demonstrate that the aqueous extract of V. sphaerocephala stems has phenolic compounds with antifungal and antioxidant activity.

Investigation of bioactive metabolites produced by the endophytic fungus Aspergillus iranicus from Houttuynia cordata Thunb

The endophytic fungus Aspergillus iranicus, capable of producing bioactive substances, was isolated from the roots of Houttuynia cordata Thunb. Through chromatographic methods, five compounds were isolated in this study for the first time from the fermentation broth and mycelia of the endophytic fungus Aspergillus iranicus obtained from Houttuynia cordata Thunb. using ethyl acetate extracts. These compounds were identified as palmitic acid (1), protocatechuic acid (2), 4-hydroxybenzophenone (3), stigmasterol (4), and β-sitosterol (5). The IC50 values for compound 2 was 1.32 mg/mL, which indicate strong DPPH radical scavenging activity. Compounds 2, 3, and 5 significantly inhibited the growth of Escherichia coli, demonstrating MIC values of 6.25, 3.13, and 3.13 mg/mL, respectively. Additionally, displaying a MIC value of 0.78 mg/mL, compound 3 demonstrated remarkable inhibition against Candida albicans growth. These findings suggest the presence of endophytic fungi in H. cordata, producing several valuable medicinal secondary metabolites.

Polyphenol compounds contributing to the improved bioactivities of fermented Rubus chingii Hu

This research aims to evaluate the phenolic composition, antioxidant and enzyme inhibition activities of fermented Rubus chingii Hu wine, and explore the correlation between them. TPC (Total Phenolic content) and TFC (Total Flavonoid content) increased rapidly from 0 h to 72 h, followed by a slight decrease in TPC and a significant decrease in TFC. Fermentation could significantly increase the antioxidant activity and α-amylase/α-glucosidase enzyme inhibitory activity of Rubus chingii Hu. A total of 39 polyphenols and organic acids in fermented Rubus chingii Hu were identified by UPLC-ESI-Q-TOF-MS/MS and 11 of them were quantitatively analyzed. After fermentation, the contents of all the detected polyphenol compounds, except for quercetin and ellagic acid, significantly increased (p < 0.05). Correlation analysis showed that protocatechuic acid and catechin played an important role in the antioxidant activity of fermented Rubus chingii Hu, while protocatechuic acid and hypericin played an important role in the α-amylase inhibition activity. This study indicated that Rubus chingii Hu could be applided as a potential meterial for the wine production, and has the potential to be a functional food for promoting health.

Metabolomics and chemometrics-driven valorisation of mango leaves: Unveiling putative α-amylase and α-glycosidase inhibitory metabolites

This study presents a comprehensive investigation into the metabolite composition of various mango leaf samples using Ultra Performance Liquid Chromatography-High Resolution Mass Spectrometry (UPLC-HRMS). A total of 103 chromatographic peaks representing diverse metabolite groups were annotated, revealing significant variations in chemical composition among different mango varieties. Polyphenols emerged as the most abundant class, with mangiferin being the major polyphenol detected in most varieties, including Awis, Sukari, Sinara, Sedika, and Alfonse. Trihydroxybenzoyl mangiferin was predominant in Sedika and Alfonse varieties. Flavonoids, such as flavanone glycosides and flavone glycosides, were also prominent. O-methylnaringenin pentoside was the major flavanone glycoside detected in Awis, Sukari, and Sinara varieties, while naringenin-O-hexoside was predominant in Alfonse. Phenolic acids were detected across all varieties, with protocatechuic acid and gallic acid being major components. Protocatechuic acid was identified in all varieties except Sedika and Naomi, where gallic acid dominated. Kaempferol and di-O-methylquercetin were exclusively detected in the Naomi variety. In-vitro enzyme inhibition assays against α-amylase and α-glycosidase enzymes revealed dose-dependent inhibitory effects of mango leaf extracts, with variations in potency among varieties. The most potent inhibitors of α-amylase activity were found in extracts from Sukari and Alfonse leaves, while those from Sukari and Sedika leaves showed the strongest inhibition of α-glycosidase activity. Interestingly, the extracts that exerted the highest inhibition of α-amylase activity did not necessarily inhibit α-glycosidase activity significantly. Additionally, glucose uptake promotion assays identified Awis and Sedika leaves as the most potent promoters of glucose uptake.

Beneficial effect of Caesalpinia pulcherrima Linn., on diabetic neuropathy, cognitive dysfunction and cardiac complications in streptozotocin-induced diabetic rats

Pharmacological relevanceCaesalpinia pulcherrima L. is used in Indian Traditional Medicinal system to treat Diabetes. AimThis study was carried out to evaluate the standardized alcoholic extract of Caesalpinia pulcherrima seed (CPS) in Streptozotocin (STZ)-induced diabetic neuropathic and cardiac complications in rodents. Materials and methodsHPLC finger printing profile of CPS was performed to identify the bioactive molecules. Two doses of CPS (100 & 200 mg/kg b.w.) was orally administered daily once for six weeks to streptozotocin (50 mg/kg, i.v.)-induced diabetic rats. Every week intervals hot & cold immersion tests were carried to know the effect of CPS on peripheral neuropathy. In addition, blood glucose, body weight, food and water intake were also monitored. At the end of the study, sciatic nerve conduction velocity, diabetic cardiomyopathy and diabetic cognitive parameters were evaluated. Furthermore, histopathological studies of sciatic nerve and aortic strip were also carried out. ResultsHPLC finger print experiment showed the presence of gallic acid and protocatechuic acid. Administration of CPS for six weeks significantly prevented the development of diabetic peripheral neuropathy (DPN), cardiomyopathy and cognitive dysfunction in diabetic rats. The CPS treated rats displayed prominent (P<0.001) improvement in motor coordination, muscle grip, locomotor activity and memory in diabetic rats. CPS treatment restored elevated systolic, diastolic, mean arterial blood pressure (MABP), and heart rate to near normal in diabetic condition. These observed beneficial effects were well correlated and justified with histopathological studies. In addition, CPS treatment also exhibited significant (P<0.001) reduction of loss in body weight, and reduce the water and feed intake throughout the study. ConclusionTaken together, the present study provided a good insight in the therapeutic efficacy of Caesalpinia pulcherrima seed extract in dealing with diabetic complications. The study also scientifically justifies the ethnomedicinal/traditional claims of the title plant.

Defense Molecules of the Invasive Plant Species Ageratum conyzoides

Ageratum conyzoides L. is native to Tropical America, and it has naturalized in many other tropical, subtropical, and temperate countries in South America, Central and Southern Africa, South and East Asia, Eastern Austria, and Europe. The population of the species has increased dramatically as an invasive alien species, and it causes significant problems in agriculture and natural ecosystems. The life history traits of Ageratum conyzoides, such as its short life cycle, early reproductive maturity, prolific seed production, and high adaptive ability to various environmental conditions, may contribute to its naturalization and increasing population. Possible evidence of the molecules involved in the defense of Ageratum conyzoides against its natural enemies, such as herbivore insects and fungal pathogens, and the allelochemicals involved in its competitive ability against neighboring plant species has been accumulated in the literature. The volatiles, essential oils, extracts, residues, and/or rhizosphere soil of Ageratum conyzoides show insecticidal, fungicidal, nematocidal, and allelopathic activity. The pyrrolizidine alkaloids lycopsamine and echinatine, found in the species, are highly toxic and show insecticidal activity. Benzopyran derivatives precocenes I and II show inhibitory activity against insect juvenile hormone biosynthesis and trichothecene mycotoxin biosynthesis. A mixture of volatiles emitted from Ageratum conyzoides, such as β-caryophyllene, β-bisabolene, and β-farnesene, may work as herbivore-induced plant volatiles, which are involved in the indirect defense function against herbivore insects. Flavonoids, such as nobiletin, eupalestin, 5′-methoxynobiletin, 5,6,7,3′,4′,5′-hexamethoxyflavone, and 5,6,8,3,4′,5′-hexamethoxyflavone, show inhibitory activity against the spore germination of pathogenic fungi. The benzoic acid and cinnamic acid derivatives found in the species, such as protocatechuic acid, gallic acid, p-coumaric acid, p-hydroxybenzoic acid, and ferulic acid, may act as allelopathic agents, causing the germination and growth inhibition of competitive plant species. These molecules produced by Ageratum conyzoides may act as defense molecules against its natural enemies and as allelochemicals against neighboring plant species, and they may contribute to the naturalization of the increasing population of Ageratum conyzoides in new habitats as an invasive plant species. This article presents the first review focusing on the defense function and allelopathy of Ageratum conyzoides.

Diethyl phthalate removal in waste gas from plastic formulations by membrane biofilm reactor

Diethyl phthalate (DEP), the most extensively used plasticizer in plastic formulations, is categorized as a priority pollutant with carcinogenic, teratogenic, and mutagenic toxicity. A membrane biofilm reactor (MBfR) for diethyl phthalate removal in waste gas from plastic formulations was investigated, MBfR achieved effective DEP removal in 72 days of operation, DEP removal efficiency achieved 91.8 %. DEP hydrolyzing bacteria (Halomonas, Microbacterium, Pseudomonas, Rhodococcus) and phthalic acid (PA)-degrading bacteria (Chelativorans, Halomonas) along with protocatechuic acid-degrading bacteria (Pseudomonas, Microbacterium, Stappia, Rhodococcus, Dietzia, etc.) jointly completed the esterification, ring cleavage, and mineralization of DEP. Functional bacterial consortium formed a complex microbial symbiotic network of DEP degradation. The DEP biodegradation gene clusters, such as pht2345, ligABCIJK, and pcaGHLBCDIJF, encoded corresponding degradation enzymes to accomplish the conversion of DEP→PA, the ring cleavage of PA, and the degradation of protocatechuic acid. DEP was metabolized to PA by de-esterification and re-esterification, further degraded to hydroxyquinol by ring-cleavage before ring-opening, and then further converted into acetyl-CoA, which was eventually metabolized into CO2 and H2O by participating in the tricarboxylic acid (TCA) cycle. This provides a feasible and environmentally friendly biotechnology for the removal of diethyl phthalate in waste gas using a membrane biofilm reactor.

Chemical composition and potential pharmacological applications of Centaurea acaulis L.

Our study aimed to characterize the composition of the ethyl acetate extract obtained from Centaurea acaulis L. and assess its dermatoprotective and antioxidant properties. The secondary metabolite composition was established by high-performance liquid chromatography combined with mass spectrometry. The antioxidant activity was assessed using four different assays, including DPPH, β-carotene, CUPRAC, and reducing power assays. Furthermore, the in vitro photoprotective effect was evaluated by measuring sun protection. The HPLC-TOF/MS analysis identified the presence of 19 bioactive compounds in the ethyl acetate extract. Major components such as rosmarinic acid and 4-hydroxy benzoic acid were detected, along with other compounds including caffeic acid, cichoric acid, gentisic acid, p-coumaric acid, protocatechuic acid, ferulic acid, vanilic acid, gallic acid, apigenin-7-glucoside, catechin, kaempferol, and quercetin. The ethyl acetate extract of Centaurea acaulis L. exhibited strong antioxidant activity in DPPH, β-carotene, CUPRAC, and reducing power assays, outperforming standard antioxidants such as butylated hydroxytoluene (BHT) and butylated hydroxyanisole (BHA), tannic acid, and ascorbic acid. Additionally, the extract demonstrated a high ability to absorb UV radiation, with an average sun protection factor of 40.20 ± 0.11. These findings highlight the significant antioxidant and dermatoprotective potential of the ethyl acetate extract from Centaurea acaulis L., suggesting its potential use in cosmetic and dietary additive formulations.

Screening and engineering of a protocatechuic acid decarboxylase for efficient biosynthesis of catechol

Catechol (CA) is an important chemical and pharmaceutical intermediate with wide applications. At present, CA is produced by phenol hydroxylation with non-renewable petrochemical resources, which causes serious environmental pollution. Hence, the biosynthesis of CA attracts much attention recently. However, due to the low activities of protocatechuic acid (PCA) decarboxylases, the production efficiency of biosynthetic catechol is too low to meet the requirements of large-scale industrial production. To improve the yield of CA, we screened 21 PCA decarboxylases from different species. RbAroY originated from Rikenellaceae had the best catalytic performance. The whole-cell biocatalyst ER11 with RbAroY was able to produce CA at a titer of 13.54 g/L. Then, the online tool HotSpot Wizard was employed to measure the enzyme stability, which revealed 10 potential mutation sites causing significant decreases in Gibbs free energy. The whole-cell biocatalyst ERT01 with the mutated RbAroYG99A could produce CA at a titer of 15.16 g/L, which increased by 12% compared with that of the wild-type whole-cell biocatalyst. After optimization of the biocatalytic conditions, the whole-cell biocatalyst ERT01 was able to produce CA at a titer of 25.70 g/L with PCA as the substrate. Finally, with the fermentation broth of 3-dehydroshikimate as the substrate, the whole-cell biocatalyst DER03 expressing both 3-dehydroshikimate dehydratase and PCA decarboxylase realized the production CA at a titer of 29.55 g/L, which is currently the highest biosynthetic titer reported. This study provides a reference for the industrial production of CA by biosynthesis.

Cocoa bean metabolomics reveals polyphenols as potential markers relating to fine dark chocolate color shades.

This study aimed to evaluate the color and the discriminating compounds for two types of cocoa beans (black and brown beans) related to 70% dark chocolates of black and brown colors from a previous work of our group. Color analysis and untargeted high-resolution mass spectrometry-based metabolomic analysis were performed on eight beans of each type. Mass spectral data processing, univariate and multivariate statistical methods were conducted for classification of beans and selection of discriminant features. The results showed that the color difference already observed for black and brown chocolates preexists in the beans. Black and brown beans had 45 and 50 discriminant features, respectively, of which 16 and 41 were phenolic compounds. Most of them were also previously identified as discriminating compounds for black and brown chocolates. Black beans predominantly contained glycosylated flavanols, ranging from monomers to trimers, with dimers and trimers being A-type procyanidins, along with a phenolic acid (protocatechuic acid), and an O-glycosylated flavonol (quercetin-3-O-glucoside). In contrast, brown beans mostly contained non-glycosylated B-type procyanidins ranging from dimers to decamers, but also dimers and trimers of A-type procyanidins, and a glycosylated and sulfated flavanol ((epi) catechin hexoside-sulfate). These markers may be useful for quality control purposes and may contribute to the selection of beans that yield black or brown dark chocolates.