Analytica, Volume 7, Issue 2 (June 2026) – 10 articles

Comparative interpretation of antioxidant activity across complex natural-product extracts and multi-component formulations is often limited by heterogeneous endpoints, assay-specific reporting, and incompatible units. In this study, we establish a dimensionless Effect Factor (EF) framework as a standardized comparative indexing system for matched-condition comparison of antioxidant-related readouts. EF maps four widely used antioxidant-related readouts—ABTS, DPPH, total phenolic content (TPC), and total flavonoid content (TFC)—into a common dimensionless index space while preserving endpoint meaning through two complementary tracks: potency-type EF and content-type EF. Using a standardized extraction and assay pipeline, we generated EF indices for 586 extracts prepared under water and 30% ethanol conditions and organized them into EF-indexed databases. EF is not intended as a predictive or biologically validated efficacy metric, but as a standardized comparative indexing framework that enables reproducible benchmarking, database-level referencing, and structured interpretation of heterogeneous antioxidant-related data under harmonized experimental conditions. These results establish the EF-indexed resource as a scalable and expandable comparative infrastructure for natural-product research. Full article

Arachidonate 5-lipoxygenase (ALOX5) is a key enzyme implicated in several inflammatory disorders, including asthma and allergic rhinitis. Despite its therapeutic importance, only one compound is currently approved as an ALOX5 inhibitor in the United States, highlighting the urgent need for new drug candidates. Progress in this area is often hindered by conventional bioassays, which can be labor-intensive, costly, and unsuitable for complex mixtures. To overcome these challenges, we developed a simple thin-layer chromatography (TLC) bioautographic assay for the rapid detection of ALOX5 inhibitors in natural extracts, a rich source of pharmacologically active compounds. The method exploits the oxidative coupling of 3-methyl-2-benzothiazolinone hydrazone (MBTH) with 3-(dimethylamino)benzoic acid (DMAB) during the ALOX5-catalyzed conversion of arachidonic acid, producing a colored indamine dye. Experimental parameters influencing chromogenic reaction were investigated and optimized to minimize reagent consumption while ensuring accuracy and sensitivity of the method. The assay was then applied to a panel of natural products and to crude mushroom extracts, enabling the rapid identification of several active compounds within complex extracts, including the dual COX2/ALOX5 inhibitor 3α-acetylpolyporenic acid A. Easy to implement, cost-efficient, and well suited for screening and bioguided fractionation, this TLC bioassay provides a powerful tool to accelerate the discovery of novel anti-inflammatory compounds. Full article

This paper describes a simple and sensitive method for determining the content of five bisphenols at the µg L⁻¹ level in tea infusion samples. The procedure uses a polypropylene hollow fiber filled with a deep eutectic solvent as the acceptor phase and 1-octanol as the supported liquid membrane, and the optimal conditions for the three-phase stir bar microextraction method were established as follows: a menthol–octanoic acid mixture (1:1 molar ratio) as the hollow-fiber filling, an extraction time of 1 h, and 80 µL of methanol for analyte desorption. The method demonstrated good linearity over the ranges of 1.5–30.0 µg L⁻¹ (BPF, BPA, BPAF, and BADGE) and 6.0–120.0 µg L⁻¹ (BPZ), with limits of detection between 0.28 and 1.01 µg L⁻¹, and the relative recovery values were satisfactory (99–120%) with acceptable precision (RSD < 17%). Thus, the method was successfully applied to quantitatively analyze twenty commercial tea infusions, in which BPF was detected at concentrations above the LOQ, and the greenness and overall applicability of the approach were confirmed using the AGREEprep and BAGI assessment tools. Full article

We studied experimentally and computationally the structures and optical properties of sulfur (S), selenium (Se) and tellurium (Te) ring clusters. We encapsulated S, Se and Te into AFI, MOR, CHA and LTA zeolites via vapor adsorption or high-pressure injection from melt and studied Raman and optical absorption spectra (RS and OAS, respectively) of zeolite single crystals with incorporated S, Se and Te ring clusters. Importantly, strict orientation of the rings in zeolite crystals allowed us to study the polarization/orientation dependency of ring RS and OAS. The obtained experimental spectra are found to be in agreement with density functional theory results (DFT using the PBE0 functional and def2-TZVP basis sets) for S₈, Se₆, Se₈, Se₁₂, Te₆ and Te₈ ring molecules. The agreement is especially good for Te rings, while for S and Se rings harmonic frequency scaling factors are required. The S and Se rings display light-induced effects, which we attribute to the presence of conical intersections between their ground and excited electronic states, resulting in isomerization and subsequent fragmentation. We consider this effect using the Se₆ ring example. This phenomenon is important for understanding photostructural changes not only in chalcogen clusters but also in bulk materials such as amorphous selenium. Full article

The species Psychotria densicostata Müll.Arg. is a shrub belonging to the Rubiaceae family, endemic to Brazil. So far, there are reports neither of phytochemical work on nor of biological evaluation of it. This study investigated its alkaloid profile and evaluated the inhibitory effects of extracts, alkaloid-enriched fractions and one of its major constituents on human neutrophil elastase (HNE). The monoterpene indole alkaloids (MIAs) strictosidine (1), (3α,5α)-5-carboxystrictosidine (2), strictosidine lactam (3), lyaloside (4), lyalosidic acid (5), 5-carboxystrictosamide (6), 3,4-dehydrostrictosidinic acid (7), and N-glucopyranosyl vincosamide (8) were characterized in mixture, in its leaves, and/or stems by using an integrated approach combining nuclear magnetic resonance (NMR) techniques, high performance liquid chromatography coupled to a tandem mass spectrometer with an electrospray ionization source (HPLC-ESI-MS/MS), and molecular networks. The crude leaf extract and an alkaloid-enriched fraction derived from it showed inhibitory activity against HNE. These results contribute to the chemical knowledge of the species and suggest its potential biological property. Full article

The herbal tea industry has experienced substantial growth, particularly regarding green tea (Camellia sinensis). In the manufacturing of filter tea, fine herbal dust is generated as a residual by-product during grinding and sieving and is typically discarded as waste. This study aims to explore the application of ultrasound-assisted extraction (UAE) for secondary valorisation of green tea herbal dust by investigating the effects of various parameters on extraction efficiency. Antiradical activity of UAE extracts was determined using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay, and the total phenolic content (TPC) was measured using Folin–Ciocalteu’s assay. Furthermore, selected phenolics were quantified by HPLC and qualitatively characterised by liquid chromatography coupled with electrospray ionisation and quadrupole time-of-flight tandem mass spectrometry (LC-ESI-QToF-MS/MS). The results demonstrate that UAE parameters have a pronounced influence on the antioxidant activity, TPC, and individual polyphenolic profile of green tea herbal dust extracts. Ethanol–water mixtures at a ratio of around 40–60%, as well as moderate impulse regimes (around 60%) and extraction times (around 10 min), were the most suitable for extracting green tea polyphenols. Epigallocatechin gallate was the predominant phenolic component in most extracts, alongside epicatechin, epigallocatechin, catechin, and gallic acid. The findings highlight the UAE technique as a robust, green, and scalable method for valorising green tea by-products, thereby facilitating the development of high-value natural extracts for applications in the food, pharmaceutical, and cosmetic industries. Full article

C₁₃-Norisoprenoids are important contributors to the aroma of Riesling wine. Their quantification is analytically challenging due to their low concentrations, the lack of commercial standards and their pronounced sensitivity to analytical conditions, reflecting their chemical lability, as well as the dynamic nature of the wine matrix, leading to high reactivity and, consequently, remarkable structural diversity. Here, we developed an assay for the analysis of C₁₃-norisoprenoids in wine using headspace solid-phase microextraction coupled to gas chromatography–mass spectrometry (HS-SPME–GC-MS/MS). After evaluating different fiber materials, a statistical design of experiments (DoE) approach was employed to systematically optimize key HS-SPME parameters, including incubation, extraction and desorption conditions. Selected reaction monitoring (SRM) transitions were established for all targeted C₁₃-norisoprenoids, allowing the assay to provide relative quantification of more than 40 compounds using representative labeled and unlabeled standards to generate linear calibration curves. Following method validation, this approach was applied to a young German Riesling wine to investigate the effect of various acidic hydrolysis conditions on the norisoprenoid profile as well as on specific compounds. A central composite design (CCD) was used to systematically study the impact of pH, temperature, and hydrolysis time. Quantitative data were obtained for 22 C₁₃-norisoprenoids demonstrating that hydrolysis conditions strongly affected the norisoprenoid composition. pH and temperature showed a greater influence than reaction time. Response surface models (RSM) indicated that TDN, Vitispirane and TPB in particular are predominantly formed under strongly acidic and high-temperature conditions, whereas others such as Riesling acetal and actinidols are formed under milder conditions. The results indicate that hydrolysis conditions should be tailored to the specific norisoprenoid under investigation and the research question, particularly when simulating conditions of accelerated wine ageing for analytical purposes. Full article

A quartz crystal microbalance-based biosensor for the specific detection of the first transgenic common bean (L.) cultivar (BRS FC401 RMD) with resistance to Bean golden mosaic virus (BGMV) was developed. The immobilization chemistry relies on the strong bond between the thiolated probe and the gold electrode surface. The probe sequence is internal to a region of the BGMV rep gene that was introduced into the common bean genome. The sensor’s analytical performance was determined using synthetic oligonucleotides. Real samples of transgenic and wild-type bean seeds were also tested. Sample pretreatment consisted only of enzymatic fragmentation, followed by a thermal denaturation step combined with blocking oligonucleotides. Different biosensor regeneration approaches were studied. Immobilization showed good reproducibility (CV% of 5.8%). The biosensor proved specific for both synthetic oligonucleotides and non-amplified genomic DNA. A linear detection range of 0–1.4 ng/µL was observed, with a detection limit of 0.18 ng/µL. Three sequential detections were performed without loss of surface activity. The results demonstrate the biosensor’s potential for direct, real-time, label-free detection of DNA samples for field screening of transgenic common bean cultivars. Full article

Secondary electrospray ionization mass spectrometry (SESI-MS) has emerged as a powerful technique for the real-time, non-invasive analysis of volatile organic compounds (VOCs) in complex matrices, such as exhaled breath and microbial volatilomes. However, its transition to routine application is hindered by significant challenges in absolute quantification, unambiguous identification, and standardization. This review provides a comprehensive overview of these limitations and the emerging solutions proposed to overcome them. Matrix effects, including gas-phase ion suppression and C-trap competition, are examined alongside mitigation strategies such as spectral stitching and standard addition. To enhance quantification stability, advanced standard delivery systems and dynamic quality control protocols are evaluated. The identification bottleneck—stemming from the absence of chromatographic separation—is addressed through the use of curated databases and advanced fragmentation techniques, such as incremental quadrupole acquisition to resolve overlapping spectra (IQAROS), to resolve isobaric interferences. Furthermore, the role of chemometrics in extracting biological fingerprints is discussed. Finally, the need for harmonized reporting standards and multicenter validation is emphasized to ensure cross-study reproducibility. Resolving these methodological gaps is essential for the clinical and industrial translation of SESI-MS. Full article

Natural deep eutectic solvents (NADES) offer sustainable alternatives to conventional solvents for plant extraction, yet their influence on extract composition and bioactivity preservation requires further study. Here, choline chloride-based NADES with lactic acid or propylene glycol were evaluated for ultrasound-assisted extraction (60 °C, 30 min, 1:20 w/v) of polyphenol-rich fractions from Sanguisorba officinalis and Symphytum officinale. Spectrophotometric analysis yielded total phenolic contents of 6.49–9.67 mg GAE g⁻¹ and total flavonoids of 0.08–0.52 mg g⁻¹, with values dependent on the plant matrix and the NADES formulation. Targeted HPLC-MS/MS enabled identification of representative phenolic acids (chlorogenic, caffeic, ferulic, rosmarinic) and flavonoid markers (rutin, quercetin derivatives), showing qualitative differences in the detected marker profiles between solvents and matrices. Functional assays demonstrated pronounced antioxidant-related effects, including DPPH radical scavenging at 0.5–25 µg mL⁻¹ (polyphenols), inhibition of lipid peroxidation in rat erythrocytes at 0.25–1.20 µg mL⁻¹, and modulation of mitochondrial respiration and permeability transition in isolated rat liver mitochondria. Overall, the results indicate that choline chloride-based NADES can be used to obtain polyphenol-rich plant extracts compatible with the applied analytical workflow while preserving redox-active fractions, supporting their utility in green analytical sample preparation. Full article