Nuclear Magnetic Resonance Data Research Articles

A Novel Method to Predict the Permeability of Heterogeneous Sandstones Using Multiple Echo Spacing NMR Measurements

Abstract We propose a novel method for estimating the permeability of heterogeneous sandstones based on the nuclear magnetic resonance (NMR) data with multiple echo spacings. The decaying curves and their corresponding spectra are obtained for different echo spacings to investigate the relaxation property, the diffusion term, and the signal loss contributed by higher echo spacing. Moreover, an empirical model is developed to correlate permeability with the differential decay rate. The result shows that the geometric transversal relaxation time is positively related to echo spacing, which disobeys the traditional cognition. Moreover, the absolute value of the differential decay rate is positively correlated with the echo spacing and exhibits a power law behavior. More interestingly, it is observed that the permeability diminishes in a power law behavior with respect to fitting parameters. This marks the first attempt to establish a relationship between the permeability and NMR data with different echo spacings, which is hopeful to be extended to other complex reservoirs with the availability of multiple echo spacing data.

Characterization and surrogate formulation of heavy fuel oil

Residual fuel oils have recently garnered attention as promising feedstocks for gasification processes. However, their complex compositions pose challenges for accurate characterization and simulation. This study addresses this issue by formulating a surrogate molecule for heavy fuel oil (HFO) with minimal components, aiming to replicate the average molecular formula and functional groups distribution found in the original fuel. To overcome challenges associated with Fourier transform-ion cyclotron resonance mass spectrometry (FT-ICR MS) detection limits, a distillation process was employed, yielding two fractions: residual distillate (enriched in heavy complex components) and volatile distillate (enriched in light components). Both fractions undergo comprehensive characterization through nuclear magnetic resonance (NMR) spectroscopy, FT-ICR MS for the residual distillate and gas chromatography-mass spectrometry (GC–MS) for the volatile distillate.The study highlights the importance of estimating average molecular weight (AMW) using both fractions to avoid overestimation when relying solely on FT-ICR MS. The developed six-component surrogate, based on elemental analysis, average molecular parameters (AMPs), and AMW of each fraction, demonstrates accuracy in replicating some properties of the original HFO. The surrogate proves effective compared to quantitative structure-property relationship (QSPR) calculations and holds potential for simulating HFO in gasification processes. The molecular design of the surrogate incorporates 1H and 13C NMR data, ensuring similarity in AMPs, AMW, and molecular formula to the target HFO. This comprehensive approach enhances the understanding and application of surrogate molecules for simulating residual oils in gasification processes.

Triterpenoids isolated from the aerial parts of Buxus latistyla Gagnep

Background: Buxus latistyla Gagnep. (Buxaceae) has been used as a remedy for treating malaria, haemoptysis, amoebic dysentery etc. However, its chemical constituents are still unknown. Thus, the aim of this study was to identify phytochemicals isolated from this plant. Materials and method: Aerial parts of B. latistyla were collected from Quang Tri province. Pure compounds were isolated using the combination of chromatographic methods. Structures of isolated compounds were identified by analyzing spectral data of nuclear magnetic resonance as well as by comparing with reported data. Results & Conclusion: Five triterpenes were isolated and identified including lupeol (1), lupenone (2), betulin (3), 20(29)-lupene-2α,3α-diol (4), 20(29)-lupene-2α,3α,28-triol (5). This is the first report about those phytochemicals of B. latistyla collected in Vietnam. Key words: Buxus latistyla, lupeol, lupenone, betulin, 20(29)-lupene-2α,3α-diol, 20(29)-lupene-2α,3α, 28-triol.

Fluorescence Activity-Guided Isolation of Aaptamine Derivatives From the Marine Sponge Aaptos suberitoides and Their Inhibitory Activity Against Transient Receptor Potential Ankyrin 1

Objective: The aim of this research was to isolate and identify the natural products responsible for the biological and fluorescence activity of the extract from the marine sponge Aaptos suberitoides. Methods: Fluorescence activity-guided separation was performed after validation of the inhibitory activity of the extract against human transient receptor potential ankyrin 1 (hTRPA1) and subsequent measurement of its fluorescence activity. Three previously reported marine alkaloids, aaptamine, isoaaptamine, and 9- O-demethylaaptamine, were obtained and identified based on their nuclear magnetic resonance and high-resolution mass spectrometry data. Results: Aaptamine showed emission of the fluorescent light at a wavelength of 485 nm with a quantum yield of 31%. Isoaaptamine and 9- O-demethylaaptamine showed marginal fluorescence activity but promising inhibitory activity against hTRPA1 with IC50 values of 3.1 and 3.9 μM, respectively. Conclusions: This research demonstrates that natural fluorophores can be discovered in living organisms through photoactivity-guided isolation. Aaptamine, isolated as a result, provides an additional 1,6-naphthyridine fluorophore, while isoaaptamine and 9- O-demethylaaptamine suggest a chemical scaffold that could be used to study the function of ion channels.

Neosophoflavonoids A–C, A class of highly oxidized hybrid flavonoids from Sophora flavescens with antidiabetic effects

Three highly oxidized hybrid flavonoids neosophoflavonoids A–C (1, 2a, and 2b) were isolated from the roots of Sophora flavescens. Neosophoflavonoid A possesses a unique highly oxidized heptacyclic 6/6/6/6/6/6/5 system. Neosophoflavonoids B and C are isomers and share the same highly oxidized hexacyclic 6/6/6/6/6/6 systems. Their planar structures were elucidated from 1D/2D nuclear magnetic resonance (NMR), ultraviolet spectroscopy (UV), infrared spectroscopy (IR), and high resolution electrospray ionization mass spectroscopy (HRESIMS) data. Their absolute configurations were determined by thorough GIAO 13C NMR (DP4+) calculation protocol and electronic circular dichroism (ECD) calculation method. The plausible biosynthetic routes for the compounds were also proposed. All compounds exhibited significant protein tyrosine phosphatase-1B (PTP1B) inhibitory activity with half maximal inhibitory concentration (IC50) values 3.94 ± 0.01, 0.38 ± 0.13, and 0.70 ± 0.01 μmol/L, respectively. In addition, compared to a positive control fenofibrate (Feno) at 20 μmol/L, compounds 2a and 2b exhibited stronger inhibitory effects on lipid accumulation in the oleic acid (OA)-induced cell model at 5 and 10 μmol/L.

Time-optimized protein NMR assignment with an integrative deep learning approach using AlphaFold and chemical shift prediction.

Chemical shift assignment is vital for nuclear magnetic resonance (NMR)-based studies of protein structures, dynamics, and interactions, providing crucial atomic-level insight. However, obtaining chemical shift assignments is labor intensive and requires extensive measurement time. To address this limitation, we previously proposed ARTINA, a deep learning method for automatic assignment of two-dimensional (2D)-4D NMR spectra. Here, we present an integrative approach that combines ARTINA with AlphaFold and UCBShift, enabling chemical shift assignment with reduced experimental data, increased accuracy, and enhanced robustness for larger systems, as presented in a comprehensive study with more than 5000 automated assignment calculations on 89 proteins. We demonstrate that five 3D spectra yield more accurate assignments (92.59%) than pure ARTINA runs using all experimentally available NMR data (on average 10 3D spectra per protein, 91.37%), considerably reducing the required measurement time. We also showcase automated assignments of only 15N-labeled samples, and report improved assignment accuracy in larger synthetic systems of up to 500 residues.

6-Pentyl-α-Pyrone from Trichoderma gamsii Exert Antioxidant and Anti-Inflammatory Properties in Lipopolysaccharide-Stimulated Mouse Macrophages.

Filamentous fungi produce several beneficial secondary metabolites, including bioactive compounds, food additives, and biofuels. Trichoderma, which is a teleomorphic Hypocrea that falls under the taxonomic groups Ascomycota and Dikarya, is an extensively studied fungal genus. In an ongoing study that seeks to discover bioactive natural products, we investigated potential bioactive metabolites from the methanolic extract of cultured Trichoderma gamsii. Using liquid chromatography-mass spectrometry (LC-MS), one major compound was isolated and structurally identified as 6-pentyl-α-pyrone (6PP) based on nuclear magnetic resonance data and LC-MS analysis. To determine its antioxidant and anti-inflammatory activity, as well as the underlying mechanisms, we treated lipopolysaccharide (LPS)-stimulated Raw264.7 mouse macrophages with 6PP. We found that 6PP suppresses LPS-induced increase in the levels of nitric oxide, a mediator of oxidative stress and inflammation, and restores LPS-mediated depletion of total glutathione by stabilizing nuclear factor erythroid 2-related factor 2 (Nrf2), an antioxidative factor, and elevating heme oxygenase-1 levels. Furthermore, 6PP inhibited LPS-induced production of proinflammatory cytokines, which are, at least in part, regulated by heme oxygenase-1 (HO-1). 6PP suppressed proinflammatory responses by inhibiting the nuclear localization of nuclear factor kappa B (NF-κB), as well as by dephosphorylating the mitogen-activated protein kinases (MAPKs). These results indicate that 6PP can protect macrophages against oxidative stress and LPS-induced excessive inflammatory responses by activating the Nrf2/HO-1 pathway while inhibiting the proinflammatory, NF-κB, and MAPK pathways.

Effect of different thermal processing methods on sensory, nutritional, physicochemical and structural properties of Penaeus vannamei

The aim of this study was to investigate the effect of different thermal processing methods on the nutritional and physicochemical qualities of Penaeus vannamei. Three different thermal processing methods, namely, drying (DS, 120 °C/40 min), steaming (SS, 100 °C/2 min), and microwaving (MS, 600 W/2 min) were used to treat the shrimps. Low-field nuclear magnetic resonance data indicated that fixed water was the main component of Penaeus vannamei. The ratio of fatty acids in MS and DS samples was more in line with the FAO/WHO recommended health requirements; The myofibrillar protein carbonyl group increased, whereas sulfhydryl content decreased after thermal processing, indicating that the proteins were oxidized by thermal processing. The magnitude of oxidation is: MS > SS > DS. Different thermal processing methods can exert great influence on color texture and nutrition to Penaeus vannamei, which can provide a theoretical knowledge for consumers to choose the appropriate processing method.

Dynamic and Assembly Characteristics of Deep-Cavity Basket Acting as a Host for Inclusion Complexation of Mitoxantrone in Biotic and Abiotic Systems.

We describe the preparation, dynamic, assembly characteristics of vase-shaped basket 13- along with its ability to form an inclusion complex with anticancer drug mitoxantrone in abiotic and biotic systems. This novel cavitand has a deep nonpolar pocket consisting of three naphthalimide sides fused to a bicyclic platform at the bottom while carrying polar glycines at the top. The results of 1 H Nuclear Magnetic Resonance (NMR), 1 H NMR Chemical Exchange Saturation Transfer (CEST), Calorimetry, Hybrid Replica Exchange Molecular Dynamics (REMD), and Microcrystal Electron Diffraction (MicroED) measurements are in line with 1 forming dimer [12 ]6- , to be in equilibrium with monomers 1(R) 3- (relaxed) and 1(S) 3- (squeezed). Through simultaneous line-shape analysis of 1 H NMR data, kinetic and thermodynamic parameters characterizing these equilibria were quantified. Basket 1(R) 3- includes anticancer drug mitoxantrone (MTO2+ ) in its pocket to give stable binary complex [MTO⊂1]- (Kd =2.1 μM) that can be precipitated in vitro with UV light or pH as stimuli. Both in vitro and in vivo studies showed that the basket is nontoxic, while at a higher proportion with respect to MTO it reduced its cytotoxicity in vitro. With well-characterized internal dynamics and dimerization, the ability to include mitoxantrone, and biocompatibility, the stage is set to develop sequestering agents from deep-cavity baskets.

Efficient NMR measurement and data analysis supported by the Bayesian inference: The case of the heavy fermion compound YbCo[formula omitted]Zn20

We propose a data-driven technique to infer microscopic physical quantities from nuclear magnetic resonance (NMR) spectra, in which the data size and quality required for the Bayesian inference are investigated. The 59Co-NMR measurement of YbCo2Zn20 single crystal generates complex spectra with 28 peaks. By exploiting the site symmetry in the crystal structure, the isotropic Knight shift Kiso and nuclear quadrupole resonance (NQR) frequency νQ were respectively estimated to be Kiso=0.7822±0.0090% and νQ=2.008±0.016 MHz (T=20 K and H≃10.2 T) by analyzing only 30 data points from one spectrum. The estimated νQ is consistent with the precise value obtained in the NQR experiment. Our method can significantly reduce the measurement time and the computational cost of data analysis in NMR experiments.

An Evaluation Method of Gas-Bearing Properties Based on Gaussian Bimodal Function Pore Structure Characterization: A Case Study of Tight Sandstone in the East China Sea Basin

The Xihu Sag in the East China Sea Basin is located at the edge of the eastern Chinese continent and has great exploration potential. In recent years, the development of low-permeability and tight sandstone gas has become an important area of exploration and development in the Huagang Formation (E3h) of the Xihu Sag. The tight sandstone reservoir in the Xihu Sag is characterized by serious heterogeneity, high water saturation, low resistivity, and a complex gas–water relationship. Because of these characteristics of tight sandstone reservoirs, it is difficult to perform an evaluation of them. In this work, a bimodal Gaussian density function was constructed using the data of high-pressure mercury intrusion (HPMI) and nuclear magnetic resonance (NMR); this approach was used to analyze the pore structure parameters. The reservoirs were divided into four types using the fitting parameter η, and the rock electric parameters that correspond to different pore structures were quite different. When combined with the log response equation of η with acoustic interval transit time (AC), density (DEN), and natural gamma (GR) logging curves, an evaluation method of gas-bearing properties that was based on the characteristics of the pore structure was established. Compared with the water saturation test of the sealing core, it was found that the water saturation calculated by the classification of the pore structure was more accurate than that obtained by the conventional method, and the error was less than 8.35%, which proves that this method is feasible and effective. The findings of this study can help provide a better understanding of the distribution characteristics of gas and water in tight sandstone and provide help for tight gas exploration and development.

A Data Deposition Platform for Sharing Nuclear Magnetic Resonance Data.

Nuclear magnetic resonance (NMR) data are rarely deposited in open databases, leading to loss of critical scientific knowledge. Existing data reporting methods (images, tables, lists of values) contain less information than raw data and are poorly standardized. Together, these issues limit FAIR (findable, accessible, interoperable, reusable) access to these data, which in turn creates barriers for compound dereplication and the development of new data-driven discovery tools. Existing NMR databases either are not designed for natural products data or employ complex deposition interfaces that disincentivize deposition. Journals, including the Journal of Natural Products (JNP), are now requiring data submission as part of the publication process, creating the need for a streamlined, user-friendly mechanism to deposit and distribute NMR data.

Non-targeted chemical analysis of consumer botanical products labeled as blue cohosh (Caulophyllum thalictroides), goldenseal (Hydrastis canadensis), or yohimbe bark (Pausinystalia yohimbe) by NMR and MS.

Consumers have unprecedented access to botanical dietary supplements through online retailers, making it difficult to ensure product quality and authenticity. Therefore, methods to survey and compare chemical compositions across botanical products are needed. Nuclear magnetic resonance (NMR) spectroscopy and non-targeted mass spectrometry (MS) were used to chemically analyze commercial products labeled as containing one of three botanicals: blue cohosh, goldenseal, and yohimbe bark. Aqueous and organic phase extracts were prepared and analyzed in tandem with NMR followed by MS. We processed the non-targeted data using multivariate statistics to analyze the compositional similarity across extracts. In each case, there were several product outliers that were identified using principal component analysis (PCA). Evaluation of select known constituents proved useful to contextualize PCA subgroups, which in some cases supported or refuted product authenticity. The NMR and MS data reached similar conclusions independently but were also complementary.

Thirteen new peptaibols with antimicrobial activities from Trichoderma sp.

From the fungus Trichoderma sp., we isolated seven novel 18-residue peptaibols, neoatroviridins E-K (1−7), and six new 14-residue peptaibols, harzianins NPDG J-O (8−13). Additionally, four previously characterized 18-residue peptaibols neoatroviridins A-D (14−17) were also identified. The structural configurations of the newly identified peptaibols (1−13) were determined by comprehensive nuclear magnetic resonance (NMR) and high-resolution electrospray ionization tandem mass spectrometry (HR-ESI-MS/MS) data. Their absolute configurations were further determined using Marfey’s method. Notably, compounds 12 and 13 represent the first 14-residue peptaibols containing an acidic amino acid residue. In antimicrobial assessments, all 18-residue peptaibols (1−7, 14−17) exhibited moderate inhibitory activities against Staphylococcus aureus 209P, with minimum inhibitory concentration (MIC) values ranging from 8−32 μg·mL−1. Moreover, compound 9 exhibited moderate inhibitory effect on Candida albicans FIM709, with a MIC value of 16 μg·mL−1.

3site Multisubstrate-Bound State of Cytochrome P450cam.

We identified a multisubstrate-bound state, hereby referred as a 3site state, in cytochrome P450cam via integrating molecular dynamics simulation with nuclear magnetic resonance (NMR) pseudocontact shift measurements. The 3site state is a result of simultaneous binding of three camphor molecules in three locations around P450cam: (a) in a well-established "catalytic" site near heme, (b) in a kink-separated "waiting" site along channel-1, and (c) in a previously reported "allosteric" site at E, F, G, and H helical junctions. These three spatially distinct binding modes in the 3site state mutually communicate with each other via homotropic allostery and act cooperatively to render P450cam functional. The 3site state shows a significantly superior fit with NMR pseudo contact shift (PCS) data with a Q-score of 0.045 than previously known bound states and consists of D251 free of salt-bridges with K178 and R186, rendering the enzyme functionally primed. To date, none of the reported cocomplex of P450cam with its redox partner putidaredoxin (pdx) has been able to match solution NMR data and controversial pdx-induced opening of P450cam's channel-1 remains a matter of recurrent discourse. In this regard, inclusion of pdx to the 3site state is able to perfectly fit the NMR PCS measurement with a Q-score of 0.08 and disfavors the pdx-induced opening of channel-1, reconciling previously unexplained remarkably fast hydroxylation kinetics with a koff of 10.2 s-1. Together, our findings hint that previous experimental observations may have inadvertently captured the 3site state as an in vitro solution state, instead of the catalytic state alone, and provided a distinct departure from the conventional understanding of cytochrome P450.

Terpenoids from the endophytic fungus Microdiplodia sp. and their anti-inflammatory activities

Motivated by the potential anti-inflammatory effect of the crude extract of endophytic fungus Microdiplodia sp. CJ01 derived from Camellia sinensis, chemical investigation of the extract of Microdiplodia sp. CJ01 led to the isolation and identification of sixteen terpenoids, including five undescribed eremophilane sesquiterpenoids named microdiplodins A-E (1–5), one undescribed meroterpenoid 13-carboxymacrophorin A (13), seven known eremophilane sesquiterpenoids (6–12), and three known meroterpenoids (14–16). The structures of these compounds were elucidated based on extensive spectroscopic analysis, including nuclear magnetic resonance (NMR) and high-resolution mass spectrometry (HRMS) data. Their absolute configurations were determined by calculational and experimental electronic circular dichroism (ECD) data. Anti-inflammatory activity assays revealed that compounds 3, 4, 14–16 exhibited moderate inhibitory effects on the production of nitric oxide (NO) in the lipopolysaccharide (LPS)-induced RAW 264.7 macrophage cells.

Subplenones A-J: Dimeric Xanthones with Antibacterial Activity from the Endophytic Fungus Subplenodomus sp. CPCC 401465.

Subplenones A-J (1-10), 10 new xanthone dimers, have been isolated and characterized from the endophytic fungus Subplenodomus sp. CPCC 401465, which resides within the Chinese medicinal plant Gentiana straminea. The isolation process was guided by antibacterial assays and molecular-networking-based analyses. The chemical structures of these compounds were elucidated through the interpretation of nuclear magnetic resonance (NMR) and high-resolution electrospray ionization mass spectrometry (HRESIMS) data. Furthermore, the relative configuration of the compounds was determined using NMR and single-crystal X-ray diffraction analyses, and the absolute configuration was established using electronic circular dichroism calculations. All of the isolated compounds exhibited significant inhibitory activity against Gram-positive bacteria. Notably, compounds 1, 5, and 7 displayed remarkable inhibitory activity against methicillin-resistant Staphylococcus aureus (MRSA) ATCC 700698, with a minimum inhibitory concentration (MIC) of 0.25 μg/mL, and against vancomycin-resistant Enterococcus faecium (VRE) ATCC 700221, with MIC values ranging from 0.5 to 1.0 μg/mL.

Transfer learning enhanced graph neural network for aldehyde oxidase metabolism prediction and its experimental application

Aldehyde oxidase (AOX) is a molybdoenzyme that is primarily expressed in the liver and is involved in the metabolism of drugs and other xenobiotics. AOX-mediated metabolism can result in unexpected outcomes, such as the production of toxic metabolites and high metabolic clearance, which can lead to the clinical failure of novel therapeutic agents. Computational models can assist medicinal chemists in rapidly evaluating the AOX metabolic risk of compounds during the early phases of drug discovery and provide valuable clues for manipulating AOX-mediated metabolism liability. In this study, we developed a novel graph neural network called AOMP for predicting AOX-mediated metabolism. AOMP integrated the tasks of metabolic substrate/non-substrate classification and metabolic site prediction, while utilizing transfer learning from 13C nuclear magnetic resonance data to enhance its performance on both tasks. AOMP significantly outperformed the benchmark methods in both cross-validation and external testing. Using AOMP, we systematically assessed the AOX-mediated metabolism of common fragments in kinase inhibitors and successfully identified four new scaffolds with AOX metabolism liability, which were validated through in vitro experiments. Furthermore, for the convenience of the community, we established the first online service for AOX metabolism prediction based on AOMP, which is freely available at https://aomp.alphama.com.cn.

Molecular Networking and Bioassay-Guided Preparation and Separation of Active Extract and Constituents from Vicia tenuifolia Roth.

Molecular networking drove the selection of material from V. tenuifolia organs that targeted active flavonoid glycosides. To optimize the extraction process, the flowers of V. tenuifolia were used to produce an anti-inflammatory extract. The effects of variables-organic solvent ratio; extraction time; and temperature-were investigated by the response of anti-inflammatory activity. Bioactivities-guided experiments helped identify fractions with high total phenolic and flavonoid content as well as antioxidant potential. Furthermore, one new compound (1), 19 first isolated together, and two known compounds were obtained and identified from the active fraction of this plant. Among them, compounds (15 and 22) were first reported for nuclear magnetic resonance (NMR) data from this study. All the isolates were evaluated for their anti-inflammatory capacity throughout, modulating nitric oxide (NO), interleukin (IL)-1β, and IL-8 production. Active compounds were further investigated for their regulation and binding affinity to the inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) proteins by Western blot and in silico approaches, respectively. The findings of this study suggested that the developed extract method, active fraction, and pure components should be further investigated as promising candidates for treating inflammation and oxidation.

Mechanism of the pore and molecular structure evolution of coal exposed to acid mine drainage (AMD)

In the post-extraction epoch, wastewater from mining activities, particularly acid mine drainage (AMD) residing in sulfur-laden coal terrains, assumes a pivotal role in the safety stewardship of decommissioned coal mines. This research aims to investigate the mechanism behind coal characteristic deterioration from prolonged exposure to AMD. Immersion assays were performed on coal samples across pH 2 to 5 to assess the impact of acid mine drainage. Subsequently, the pore and molecular architecture was appraised using microscopic methodologies. Computed Tomography (CT) findings elucidate that post-immersion, the porosity, and fissures proliferated longitudinally along the coal strata, engendering a marked amplification in surface porosity contiguous to pre-existing pores. This escalation in surface porosity was further accentuated in correlation with the intensification of AMD acidity. Nuclear Magnetic Resonance (NMR) data indicated a marginal augmentation in the content of both micropores and macropores within a tepid AMD milieu. However, in a more virulent AMD context, the proportion of micropores diminished, whereas that of macropores and pore throat size (PTS) experienced an upswing, thereby transmuting adsorptive pores into permeable conduits and consequently enhancing coal permeability. Scanning Electron Microscopy (SEM) corroborated the NMR outcomes; as AMD acidity transitioned from mild to severe, the coal matrix manifested many erosive pores, matrix layer disintegration, and an expansion in cleat width. Therefore, the microscopic pore evolution can be succinctly encapsulated as follows: in a mild AMD environment, dissolution of minerals predominates, generating erosive pores, whereas, in a more acidic AMD milieu, the matrix undergoes partial contraction, thereby augmenting pore volume, enhancing permeability, and inducing structural degradation. Additionally, Fourier Transform Infrared Spectroscopy (FTIR) analysis substantiated that AMD compromised the pore architecture and catalyzed the disintegration of coal macromolecules into lower molecular weight constituents. Therefore, AMD degrades coal macromolecules into smaller compounds, heightening matrix layer porosity and impairing coal characteristics. This research yields vital insights for the security and efficient management of abandoned mine excavations.