Highly Aromatic Flavan-3-ol Derivatives from Palaeotropical <i>Artocarpus lacucha</i> Buch.-Ham Possess Radical Scavenging and Antiproliferative Properties

Phytochemical investigation of leaves and stembark of Artocarpus lacucha collected in Thailand resulted in three yet undescribed isomeric flavan-3-ol derivatives (1–3), the four known compounds gambircatechol (4), (+)-catechin (5), (+)-afzelechin (6) and the stilbene oxyresveratrol (7). Compounds 1 to 3 feature 6/6/5/6/5/6 core structures. All structures were deduced by NMR and MS, while density functional theory (DFT) calculations on B3LYP theory level were performed of compounds 1 to 3 to support the stereochemistry in positions 2 and 3 in the C-ring. Possible biosynthetic pathways leading to 4 are discussed. The DPPH assay revealed high radical scavenging activities for 1 (EC50 = 9.4 ± 1.0 µmol mL−1), 2 (12.2 ± 1.1), 3 (10.0 ± 1.5) and 4 (19.0 ± 2.6), remarkably lower than ascorbic acid (EC50 = 34.9) and α-tocopherol (EC50 = 48.6). A cytotoxicity assay revealed moderate but consistent antiproliferative properties of 1 in CH1/PA-1 (ovarian teratocarcinoma) and SW480 (colon carcinoma) cells, with IC50 values of 25 ± 6 and 34 ± 4 µM, respectively, whereas effects in A549 (non-small cell lung cancer) cells were rather negligible. The performed DCFH-DA assay of 1 in the former cell lines confirmed potent antioxidative effects even in the cellular environment

Bioavailable DDT residues in sediments: Laboratory assessment of ageing effects using semi-permeable membrane devices

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Yellow Twig (<i>Nauclea</i> <i>orientalis</i>) from Thailand: Strictosamide as the Key Alkaloid of This Plant Species

Comprehensive phytochemical examination from different perspectives using preparative and analytical chromatographic techniques combined with spectroscopic/spectrometric methods of the so-called “yellow twig” Nauclea orientalis (L.) L. (Rubiaceae) led to the identification of 13 tryptamine-derived (=monoterpene-indole) alkaloids. The identified alkaloids comprise strictosamide and four of its glucosidic derivatives, three oxindole derivatives, and five yellow-colored angustine-type aglycones. Qualitative and quantitative HPLC analyses showed the enrichment of strictosamide in all studied organs. Based on these results, we performed metabolomic analyses of monoterpene-indole alkaloids and made a 1H NMR in vitro monitoring of enzymatic deglucosylation of strictosamide. A comparison of the stability of strictosamide and its enantiomer vincoside lactam by theoretical calculations was also performed revealing a slightly higher stability of vincoside lactam. Additionally, we conducted two different anti-feedant assays of strictosamide using larvae of the polyphageous moth Spodoptera littoralis Boisduval. The obtained results indicate that generally two different biosynthetic pathways are most likely responsible for the overall alkaloid composition in this plant. Strictosamide is the key compound in the broader pathway and most likely the source of the identified angustine-type aglycones, which may contribute significantly to the yellow color of the wood. Its cross-organ accumulation makes it likely that strictosamide is not only important as a reservoir for the further biosynthesis, but also acts in the plants’ defense strategy

Insight into the Molecular Mechanisms of AuNP-Based Aptasensor for Colorimetric Detection: A Molecular Dynamics Approach

Colorimetric aptasensor based on assembly of salt-induced gold nanoparticles (AuNPs) is a promising biosensor. However, the molecular mechanism of the aptasensor is far from being fully understood. Herein, molecular dynamics (MD) simulation was used to investigate molecular interactions in the detection of ochratoxin A (OTA) including the following: (i) the molecular recognition of the anti-OTA aptamer, (ii) OTA–aptamer interactions in monovalent (Na⁺) and divalent (Mg²⁺) electrolytes, (iii) the binding mode of citrate on the AuNP surface, (iv) interactions of the aptamer with citrate-capped AuNPs, and (v) a detailed mechanism of the aptasensor. Our MD simulations revealed a specific binding of the OTA–aptamer complex, compared with OTB and warfarin. Compared with Na⁺, Mg²⁺ ions exerted a more effective attractive force between OTA and anti-OTA aptamer. Three different binding modes of citrate on AuNP surfaces were found. The kinetics of the adsorption of unfolded aptamers onto the citrate-capped AuNP was also elucidated. Most importantly, our MD simulation revealed an insightful analysis of the molecular mechanisms in the AuNP-based aptasensor and paved the way for the design of a novel colorimetric aptasensor for other target molecules, which is not limited to OTA detection

Proteomic Analysis and Molecular Dynamics Simulation of Riboflavin-Coated Superparamagnetic Iron Oxide Nanoparticles Reveal Human Serum-Derived Protein Coronas: Implications as Magnetic Resonance Imaging Contrast Agents

Superparamagnetic iron oxide nanoparticles (SPIONs) have been increasingly used as nanomedicine platforms due to their exceptional magnetic properties, which emerged from their nanoscopic sizes. Recently, SPIONs with a riboflavin (Rf)-citrate ligand were developed and showed increased internalization in breast cancer cells, with exceptional properties as T2 contrast agents for magnetic resonance imaging (MRI). The interactions of the Rf-coated SPIONs with proteins from fetal bovine serum (FBS) were previously characterized to understand how the nanoparticles will interact with biomolecules. To closer mimic the human biological environments, human serum (HS) has been suggested as a better model. Therefore, in this work, protein coronas of bare, citrate-coated, and Rf-coated SPIONs formed with HS were studied by proteomic analysis to identify and quantify the nanoparticle-protein interaction. The results were compared with the FBS-derived coronas to understand the differences in the protein corona formation from different serum origins. Furthermore, the interactions of the SPIONs with riboflavin carrier protein (RCP), which is a target protein for the Rf-SPIONs, were also studied. The overall physical properties of the corona proteins were similar between the FBS and HS groups, but some specific homologous proteins interacted differently. The RCP was found to bind more to the citrate-coated SPIONs than the Rf-coated one. The outcome could be explained by molecular dynamics simulation, where the orientation of the Rf ligand did not favor the binding with RCP. The simulation results also showed the influence of surface hydrophilicity of the SPIONs on the RCP interaction. The combined data from proteomic and simulation analyses suggested a way to improve the Rf ligand to enhance the interaction with RCP and reduce the interactions with the serum proteins, which could enhance the specific cellular interactions and improve the Rf-SPIONs as MRI contrast agents for breast cancer.This project was funded by the National Research Council of Thailand (NRCT) with Mahidol University: N42A650357. This research project was supported by Mahidol University (MU’s Strategic Research Fund): 2023. Partial support was also provided by the CIF and CNI grant, Faculty of Science, Mahidol University. W.M. was supported by the Science Achievement Scholarship of Thailand. The authors thank Prof. Dr. Chutima Kuhakarn for the support of the facilities for the synthesis of the Rf-citrate ligand.With funding from the Spanish government through the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000917-S).Peer reviewe