Laser frequency stabilization by modulation transfer spectroscopy and balanced detection of molecular iodine for laser cooling of 174Yb.

We report laser frequency stabilization by the combination of modulation transfer spectroscopy and balanced detection of a relatively weak hyperfine transition of the R(158)25-0 line of molecular iodine (127I2), which is used as a new frequency reference for laser trapping and cooling of 174Yb on the 1S0 - 3P1 transition. The atomic cloud is characterized by time-of-flight measurements, and an on-resonance optical depth of up to 47 is obtained. We show laser noise reduction and characterize the short-term laser frequency instability by the Allan deviation of the laser fractional frequency. The minimum measured value is 3.9 ×10-13 at 0.17 s of averaging time.

Loss of CDX2 and high COX2 (PTGS2) expression in metastatic colorectal cancer.

Lack of expression of the tumour suppressor gene caudal-type homeobox 2 (CDX2) associates with poor outcomes in early stage colorectal cancer (CRC). Yet its prognostic value in the context of other prognostic biomarkers in metastatic CRC (mCRC) is unknown. Overexpressed cyclooxygenase-2 (COX2) has been reported in advanced CRC. However, CDX2 and COX2 relationship in mCRC remains undetermined. We aimed to assess their expression in mCRC tumours from a clinically characterised cohort and their influence on overall survival (OS) and progression-free survival (PFS) in first line. Among 720 consecutive mCRC patients, 346 had tumour samples appropriate for tissue microarray assembly and immunohistochemistry analyses. Clinical and survival data were retrospectively assessed. Loss of CDX2 expression was detected in 27 (7.8%) samples, enriched in poorly differentiated tumours (20%; p < 0.01) and in those with the BRAF p.V600E variant (40%; p < 0.01). Most tumours (93.4%) expressed COX2. COX2-negative samples were enriched in poorly differentiated mCRC. In unadjusted analyses, median OS (p < 0.001) and median PFS (p < 0.05) were inferior for patients with CDX2-negative versus CDX2-positive tumours. In conclusion, loss of CDX2 was significantly associated with poorly differentiated mCRC and BRAF p.V600E allele and a prognostic marker of worse OS.

Enrichable consortia of microbial symbionts degrade macroalgal polysaccharides in Kyphosus fish.

Coastal herbivorous fishes consume macroalgae, which is then degraded by microbes along their digestive tract. However, there is scarce genomic information about the microbiota that perform this degradation. This study explores the potential of Kyphosus gastrointestinal microbial symbionts to collaboratively degrade and ferment polysaccharides from red, green, and brown macroalgae through in silico study of carbohydrate-active enzyme and sulfatase sequences. Recovery of metagenome-assembled genomes (MAGs) from previously described Kyphosus gut metagenomes and newly sequenced bioreactor enrichments reveals differences in enzymatic capabilities between the major microbial taxa in Kyphosus guts. The most versatile of the recovered MAGs were from the Bacteroidota phylum, whose MAGs house enzyme collections able to decompose a variety of algal polysaccharides. Unique enzymes and predicted degradative capacities of genomes from the Bacillota (genus Vallitalea) and Verrucomicrobiota (order Kiritimatiellales) highlight the importance of metabolic contributions from multiple phyla to broaden polysaccharide degradation capabilities. Few genomes contain the required enzymes to fully degrade any complex sulfated algal polysaccharide alone. The distribution of suitable enzymes between MAGs originating from different taxa, along with the widespread detection of signal peptides in candidate enzymes, is consistent with cooperative extracellular degradation of these carbohydrates. This study leverages genomic evidence to reveal an untapped diversity at the enzyme and strain level among Kyphosus symbionts and their contributions to macroalgae decomposition. Bioreactor enrichments provide a genomic foundation for degradative and fermentative processes central to translating the knowledge gained from this system to the aquaculture and bioenergy sectors.IMPORTANCESeaweed has long been considered a promising source of sustainable biomass for bioenergy and aquaculture feed, but scalable industrial methods for decomposing terrestrial compounds can struggle to break down seaweed polysaccharides efficiently due to their unique sulfated structures. Fish of the genus Kyphosus feed on seaweed by leveraging gastrointestinal bacteria to degrade algal polysaccharides into simple sugars. This study reconstructs metagenome-assembled genomes for these gastrointestinal bacteria to enhance our understanding of herbivorous fish digestion and fermentation of algal sugars. Investigations at the gene level identify Kyphosus guts as an untapped source of seaweed-degrading enzymes ripe for further characterization. These discoveries set the stage for future work incorporating marine enzymes and microbial communities in the industrial degradation of algal polysaccharides.

Enrichable consortia of microbial symbionts degrade macroalgal polysaccharides in Kyphosus fish.

Coastal herbivorous fishes consume macroalgae, which is then degraded by microbes along their digestive tract. However, there is scarce foundational genomic work on the microbiota that perform this degradation. This study explores the potential of Kyphosus gastrointestinal microbial symbionts to collaboratively degrade and ferment polysaccharides from red, green, and brown macroalgae through in silico study of carbohydrate-active enzyme and sulfatase sequences. Recovery of metagenome-assembled genomes (MAGs) reveals differences in enzymatic capabilities between the major microbial taxa in Kyphosus guts. The most versatile of the recovered MAGs were from the Bacteroidota phylum, whose MAGs house enzymes able to decompose a variety of algal polysaccharides. Unique enzymes and predicted degradative capacities of genomes from the Bacillota (genus Vallitalea) and Verrucomicrobiota (order Kiritimatiellales) suggest the potential for microbial transfer between marine sediment and Kyphosus digestive tracts. Few genomes contain the required enzymes to fully degrade any complex sulfated algal polysaccharide alone. The distribution of suitable enzymes between MAGs originating from different taxa, along with the widespread detection of signal peptides in candidate enzymes, is consistent with cooperative extracellular degradation of these carbohydrates. This study leverages genomic evidence to reveal an untapped diversity at the enzyme and strain level among Kyphosus symbionts and their contributions to macroalgae decomposition. Bioreactor enrichments provide a genomic foundation for degradative and fermentative processes central to translating the knowledge gained from this system to the aquaculture and bioenergy sectors.

Evaluating the Electromagnetic Shielding of Continuous Carbon Fiber Parts Produced by Additive Manufacturing.

Electronic devices are sensitive to electromagnetic (EM) emissions, and require electromagnetic shielding protection to ensure good operation, and prevent noise, malfunctioning, or even burning. To ensure protection, it is important to develop suitable material and design solutions for electronic enclosures. Most common enclosures are made with metal alloys using traditional manufacturing methods. However, using thermoplastic composites combined with additive manufacturing (AM) technologies emerges as an alternative that enables the fabrication of complex parts that are lightweight, consolidated, and oxidation- and corrosion-resistant. In this research, an AM technique based on material extrusion was used to print 2 mm-thick specimens with a multi-material made of micro-carbon fiber (CF)-filled polyamide that was reinforced at specific layers using continuous carbon fibers stacked with a 90° rotation to each other. The specimens' electromagnetic shielding effectiveness (EMSE) was evaluated in the frequency band of 0.03-3 GHz using the coaxial transmission line method. Depending on the number of CF layers, the EM shielding obtained can be up to 70 dB, with a specific shielding up to 60 dB.cm3/g, predominantly by the absorption mechanism, being 22 times higher than without the CF layers. These findings promote this innovative approach to lightweight customizable solutions for EM shielding applications.

Differential Protein and Glycan Packaging into Extracellular Vesicles in Response to 3D Gastric Cancer Cellular Organization.

Alterations of the glycosylation machinery are common events in cancer, leading to the synthesis of aberrant glycan structures by tumor cells. Extracellular vesicles (EVs) play a modulatory role in cancer communication and progression, and interestingly, several tumor-associated glycans have already been identified in cancer EVs. Nevertheless, the impact of 3D tumor architecture in the selective packaging of cellular glycans into EVs has never been addressed. In this work, the capacity of gastric cancer cell lines with differential glycosylation is evaluated in producing and releasing EVs when cultured under conventional 2D monolayer or in 3D culture conditions. Furthermore, the proteomic content is identified and specific glycans are studied in the EVs produced by these cells, upon differential spatial organization. Here, it is observed that although the proteome of the analyzed EVs is mostly conserved, an EV differential packaging of specific proteins and glycans is found. In addition, protein-protein interaction and pathway analysis reveal individual signatures on the EVs released by 2D- and 3D-cultured cells, suggesting distinct biological functions. These protein signatures also show a correlation with clinical data. Overall, this data highlight the importance of tumor cellular architecture when assessing the cancer-EV cargo and its biological role.

Herbivorous Fish Microbiome Adaptations to Sulfated Dietary Polysaccharides.

Marine herbivorous fish that feed primarily on macroalgae, such as those from the genus Kyphosus, are essential for maintaining coral health and abundance on tropical reefs. Here, deep metagenomic sequencing and assembly of gut compartment-specific samples from three sympatric, macroalgivorous Hawaiian kyphosid species have been used to connect host gut microbial taxa with predicted protein functional capacities likely to contribute to efficient macroalgal digestion. Bacterial community compositions, algal dietary sources, and predicted enzyme functionalities were analyzed in parallel for 16 metagenomes spanning the mid- and hindgut digestive regions of wild-caught fishes. Gene colocalization patterns of expanded carbohydrate (CAZy) and sulfatase (SulfAtlas) digestive enzyme families on assembled contigs were used to identify likely polysaccharide utilization locus associations and to visualize potential cooperative networks of extracellularly exported proteins targeting complex sulfated polysaccharides. These insights into the gut microbiota of herbivorous marine fish and their functional capabilities improve our understanding of the enzymes and microorganisms involved in digesting complex macroalgal sulfated polysaccharides. IMPORTANCE This work connects specific uncultured bacterial taxa with distinct polysaccharide digestion capabilities lacking in their marine vertebrate hosts, providing fresh insights into poorly understood processes for deconstructing complex sulfated polysaccharides and potential evolutionary mechanisms for microbial acquisition of expanded macroalgal utilization gene functions. Several thousand new marine-specific candidate enzyme sequences for polysaccharide utilization have been identified. These data provide foundational resources for future investigations into suppression of coral reef macroalgal overgrowth, fish host physiology, the use of macroalgal feedstocks in terrestrial and aquaculture animal feeds, and the bioconversion of macroalgae biomass into value-added commercial fuel and chemical products.

Microbial communities in freshwater used for hydraulic fracturing are unable to withstand the high temperatures and pressures characteristic of fractured shales.

Natural gas is recovered from shale formations by hydraulic fracturing, a process known to create microbial ecosystems in the deep subsurface. Microbial communities that emerge in fractured shales include organisms known to degrade fracturing fluid additives and contribute to corrosion of well infrastructure. In order to limit these negative microbial processes, it is essential to constrain the source of the responsible micro-organisms. Previous studies have identified a number of potential sources, including fracturing fluids and drilling muds, yet these sources remain largely untested. Here, we apply high-pressure experimental approaches to assess whether the microbial community in synthetic fracturing fluid made from freshwater reservoir water can withstand the temperature and pressure conditions of hydraulic fracturing and the fractured shale environment. Using cell enumerations, DNA extraction and culturing, we show that the community can withstand high pressure or high temperature alone, but the combination of both is fatal. These results suggest that initial freshwater-based fracturing fluids are an unlikely source of micro-organisms in fractured shales. These findings indicate that potentially problematic lineages, such as sulfidogenic strains of Halanaerobium that have been found to dominate fractured shale microbial communities, likely derive from other input sources into the downwell environment, such as drilling muds.

A compendium of bacterial and archaeal single-cell amplified genomes from oxygen deficient marine waters.

Oxygen-deficient marine waters referred to as oxygen minimum zones (OMZs) or anoxic marine zones (AMZs) are common oceanographic features. They host both cosmopolitan and endemic microorganisms adapted to low oxygen conditions. Microbial metabolic interactions within OMZs and AMZs drive coupled biogeochemical cycles resulting in nitrogen loss and climate active trace gas production and consumption. Global warming is causing oxygen-deficient waters to expand and intensify. Therefore, studies focused on microbial communities inhabiting oxygen-deficient regions are necessary to both monitor and model the impacts of climate change on marine ecosystem functions and services. Here we present a compendium of 5,129 single-cell amplified genomes (SAGs) from marine environments encompassing representative OMZ and AMZ geochemical profiles. Of these, 3,570 SAGs have been sequenced to different levels of completion, providing a strain-resolved perspective on the genomic content and potential metabolic interactions within OMZ and AMZ microbiomes. Hierarchical clustering confirmed that samples from similar oxygen concentrations and geographic regions also had analogous taxonomic compositions, providing a coherent framework for comparative community analysis.

Adiposity, hepatic steatosis, and metabolic health transitions in people with obesity: Influences of age and sex.

BACKGROUND AND AIMS: Metabolically healthy (MHO) and unhealthy obesity (MUO) may be transient conditions. This study aimed to quantify and identify predictive factors of metabolic transitions in obesity, exploring influences of age and sex. METHODS AND RESULTS: We retrospectively evaluated adults with obesity who underwent routine health evaluation. In a cross-sectional analysis of 12,118 individuals (80% male, age 44.3 ± 9.9 years), 16.8% had MHO. In a longitudinal evaluation of 4483 participants, 45.2% of individuals with MHO at baseline had dysmetabolism after a median follow-up of 3.0 (IQR 1.8-5.2) years, whereas 13.3% MUO participants became metabolically healthy (MH). Development of hepatic steatosis (HS, ultrasound) was an independent predictor of MHO conversion to dysmetabolism (OR 2.36; 95% CI 1.43, 3.91; p < 0.001), while HS persistence was inversely associated with transition from MUO to MH status (OR 0.63; 95% CI 0.47, 0.83; p = 0.001). Female sex and older age were associated with a lower chance of MUO regression. A 5% increment in body mass index (BMI) over time increased the likelihood of metabolic deterioration by 33% (p = 0.002) in females and 16% (p = 0.018) in males with MHO. A 5% reduction in BMI was associated with a 39% and 66% higher chance of MUO resolution in females and males, respectively (both p < 0.001). CONCLUSION: The findings support a pathophysiological role of ectopic fat depots in metabolic transitions in obesity and identify female sex as an aggravating factor for adiposity-induced dysmetabolism, which has implications for personalized medicine.

Fuerza de prensión débil y su asociación con la dependencia funcional y el rendimiento físico alterado en adultos mayores de 80 años

Introducción: La fuerza de prensión débil suele ser un marcador de dependencia funcional y pobre rendimiento físico, sin embargo, esta asociación es controversial en adultos mayores de 80 años. Objetivo: Determinar la asociación entre la fuerza de prensión y la dependencia funcional y rendimiento físico entre adultos mayores de 80 años. Métodos: El presente estudio es de tipo analítico transversal, fue realizado en 147 sujetos pertenecientes a la Marina de Guerra del Perú. Evaluamos la fuerza muscular, el rendimiento físico, la funcionalidad, las medidas antropométricas y la valoración nutricional. Resultados: Encontramos una asociación significativa entre la fuerza de prensión débil y la dependencia para actividades básicas de la vida diaria (ORa: 2,81, IC95%: 1,32 a 10,11), así como el rendimiento físico alterado (ORa: 4,32, IC95%: 1,97 a 9,59), dichas asociaciones fueron independientes de la edad, número de comorbilidades, síndromes geriátricos, hemoglobina, ferritina, glucosa, colesterol total, linfocitos, vitamina b12, triglicéridos, albúmina sérica, puntaje de MMSE, circunferencia de pantorrilla, circunferencia braquial, IMC, grado de instrucción, estado civil, sexo y índice cintura/cadera. Conclusiones: En los participantes mayores de 80 años, tener una fuerza de prensión débil estuvo asociada con tener fuerza muscular débil y pobre rendimiento físico. Nuestros resultados podrían ser útiles para la inclusión de estas medidas dentro de protocolos de atención hacia poblaciones de edad avanzada y alta comorbilidad. Con ello, se busca mejorar la integridad y atención de los pacientes geriátricos.

Introduction: Weak grip strength is a well-known associated factor with disability and physical performance, but this association is controversial in older adults aged 80 years or more. Objective: To determine the association between prehensile strength and functional dependence and physical performance among adults older than 80 years. Methods: This research was an analytical, cross-sectional study, conducted in 147 older adults aged 80 years or more, from Naval Peruvian Service. We included assessments about muscle strength, physical performance, disability, anthropometric variables, and nutritional assessment. Results: We found a significant association between weak grip strength and dependence for basic activities of daily living (aOR: 2.81, 95% CI: 1.32 to 10.11), as well as altered physical performance (aOR: 4.32, 95% CI: 1.97 to 9.59), these associations were independent of age, number of comorbidities, geriatric syndromes, hemoglobin, ferritin, glucose, total cholesterol, lymphocytes, vitamin B12, triglycerides, serum albumin, MMSE score, calf circumference, brachial circumference, BMI, level of education, marital status, sex, and waist/hip ratio. Conclusions: In persons older than 80 years, having weak grip strength was associated with weak muscle strength and poor physical performance. Our results could be useful for the inclusion of these measures within care protocols for elderly and high comorbidity populations. With this, it seeks to improve the integrity and care of geriatric patients.

Validation of discriminant functions from the rib necks in two Portuguese adult identified populations.

Sexual dimorphism is the basis for sex estimation research in skeletal remains, helping the positive identification of individuals in forensic backgrounds. In this regard, it has been proved that the metrical analysis of the costal neck of the first four ribs in Spanish contemporary adult skeletons shows high sexual dimorphism, especially in the first rib. However, the validation of any method developed in identified skeletal collections must be compulsorily reproduced in other skeletonized sets to verify either its potential application in individuals from other locations, or the existence of possible biases associated with inter-population variation. Due to the geographical and socioeconomic proximity between Spain and Portugal, this paper aims to check the utility of the discriminant functions designed by Partido-Navadijo et al. (2021) in the two skeletal collections of the University of Coimbra (Portugal). Results show the utility of these discriminant functions in Portuguese population, with frequencies of cases correctly assigned reaching up to 93.6% in the Coimbra Identified Skeletal Collection (CISC); and up to 92.6% in the 21st Century Identified Skeletal Collection (CEI/XXI). However, two particularities between the Spanish and Portuguese osteological assemblages can be highlighted: the possible existence of secular changes in relation to the CISC collection (1904-1938); and a reversal in the degree of costal dimorphism, being the third and fourth ribs of the CEI/XXI collection more dimorphic than the first ones.

Respect versus resect approaches for mitral valve repair: A study-level meta-analysis.

Mitral valve repair (MVr) restores leaflets coaptation while preserving the patient's own valve. The two main techniques are: (a) chordal replacement ("respect approach"), whereby artificial neochordae are used to resuspend prolapsed segments of the affected leaflet - and (b) leaflet resection ("resect approach"), whereby diseased leaflet segment is resected, and the remaining segments are sutured together. Both techniques of MVr are associated with better long-term results, fewer valve-related complications and lower mortality when compared with mitral valve replacement (MVR). They also restore quality of life and improve survival to rates equivalent to those of the general population. We performed a meta-analysis to pool data of clinical studies that compared outcomes of MVr stratified by the surgical technique. Seventeen studies accounting for 6,046 patients fulfilled our eligibility criteria. The "respect approach" outperformed the "resect approach" with lower permanent pacemaker implantation rates and lower mean gradients. Despite any possible advantages of one technique over the other, which approach is best for each patient must be decided on a case-by-case basis and more long-term follow-up data are warranted.

Methods for sex estimation of prepubertal individuals (< 12 years old): bibliographic review and future directions.

Sex estimation is essential in both bioarchaeological and forensic research. Based on bibliographical research, this study aims to systematize and compare the existing methods and glance at the future on this research topic. The survey in Web of Science and Google Scholar revealed 37 papers describing the generation of original procedures, and 25 validation studies. The results show that the pelvis, namely the ilium, is the most analyzed anatomical region, followed by the deciduous teeth, the cranium, the mandible, and the long bones. The morphometric approaches are addressed in greater proportion, both as original methods (n = 19) or validations (n = 24). Only one of the 19 approaches that require expensive equipment (conventional radiology, computer tomography, geometric morphometrics and 3D modelling) was tested. Most of them were generated during the 21st century; however, 24 have not been tested yet. Comparing all the methods tested, the percentages of correctly estimated cases are always lower in validation studies. It is suggested that the most promising ones be tested in documented samples by a group of researchers. Thus, the interobserver error would be evaluated and may also lead to new methodological proposals and refinements.

Effects of cataract surgery on blinking.

PURPOSE: To assess the effects of cataract surgery on the spontaneous blinking pattern and blinking kinematics. SETTING: FISABIO Oftalmología Médica Eye Hospital, Valencia, Spain. DESIGN: Observational descriptive clinical study. METHOD: Patients with senile cataract were evaluated before (visit 1) and at 1 month (visit 2) and 3 months (visit 3) after undergoing phacoemulsification cataract surgery. The blinking of patients was recorded for 90 seconds using an eye-tracking device. Blinks were analyzed by means of image analysis to obtain a noninvasive detailed description of blinking including blink rate, number of complete and incomplete blinks, percentage of incomplete blinks, and kinematic parameters, including amplitude, closing, contact, opening, and total durations and closing and opening speeds. RESULTS: 50 patients were included in this study. The blink rate was significantly smaller at visit 3 compared with baseline ( P = .03) and visit 2 ( P = .001). Likewise, the number of complete blinks was significantly smaller, and the percentage of incomplete blinks was significantly higher at 3 months postoperatively compared with baseline ( P = .02 and P = .01, respectively), although no differences were observed at 1 month postoperatively ( P > .05). Conversely, no differences in the number of incomplete blinks or any kinematic parameter were observed between visits ( P = .12). CONCLUSIONS: Cataract surgery significantly altered the blinking pattern at 3 months postoperatively, although kinematic parameters remained unvaried. Clinicians should be aware of potential alterations in blinking after phacoemulsification cataract surgery and the implications this may have on the ocular surface of patients.

Prospective analysis on carotid endarterectomy: intermediate-deep ultrasound-guided cervical blockade versus general anesthesia.

BACKGROUND: The best regional anesthesia plan with the best clinical results for Carotid endarterectomy (CEA) has not been defined yet. METHODS: Prospective multicentric observational study of two non-randomized matched cohorts including patients undergoing elective unilateral CEA (N.=100) between January-October 2021. Main outcomes were cerebral oximetry measurements, verbal numeric pain score assessment, peripheral nerve blockades and in-hospital stay. The main objective is to compare results achieved after carotid endarterectomy (CEA) performed under loco-regional blockade (LRB) versus general anesthesia (GA), in terms of intraoperative hemodynamic and neurologic variability. Patients undergoing LRB were performed under ultrasound (US) guidance and mild sedation. RESULTS: The LRB and GA groups showed no differences in comorbidities and risk factors. However, there was a significant difference in the intraoperative hemodynamic behavior due to the amount of vasoactive drugs used (0% vs. 16% for phenylephrine, P=0.006). The results showed neurological stability through the cerebral oximetry measurements during the procedure except for the left hemisphere de-clamp values, which were higher in the GA group (68.7±9.9 vs. 72.7±8.8; P=0.035). There were also significant differences in the verbal pain scale scores assessed 6 hours and 12 hours after the procedure; better pain control was evidenced in the LRB group (0[0-1] vs. 1[0-3], P=0.01; 1[0.5-2] vs. 0[0-2], P=0.01). An increased transient hypoglossal and laryngeal nerves blockade was observed in the LRB group (30% vs. 4%; P<0.001). The in-hospital length of stay was longer in the GA group (77.2±36.3 hours vs. 129.1±41.1 hours; P<0.001). CONCLUSIONS: Although the use of intermediate-deep cervical plexus blockade for CEA confers similar neurologic stability as GA does, there is a difference on the hemodynamic behaviour due to the differences in vasoactive drug consumption. Loco-regional techniques provide a better postoperative pain control and shorten in-hospital length of stay.

Flavonoid glycosides and ellagic acid cognates from defatted African mango (Irvingia gabonensis) seed kernel.

Seventeen compounds of diverse classes including four flavonoid glycosides, five ellagic acid derivatives, and eight other metabolites were isolated from the methanolic extract of the defatted seed kernel of Irvingia gabonensis. Among the isolates, quercetin 3-O-methyl-4'-[α-L-rhamnopyranosyl-(1→3)]-O-α-L-rhamnopyranoside (1) and 3,3'-di-O-methyl-4'-O-α-L-rhamnopyranosylellagic acid 4-sulfate ester (5) were found to be previously undescribed. Structure elucidation was mainly achieved by the interpretation of 1D and 2D NMR and HRESIMS spectral data. Though compound 6 was previously reported, its 13C NMR data is being reported herein for the first time. To the best of our literature search knowledge, this is the first phytochemical report on I. gabonensis seed kernels.

Bioautography-guided HPTLC-MS as a rapid hyphenated technique for the identification of antimicrobial compounds from selected South African Combretaceae species.

INTRODUCTION: Many species within Combretaceae are traditionally used for the treatment of bacterial infections. The similarity in chemistry and antimicrobial activities within the family pose a challenge in selecting suitable species for herbal drug development. OBJECTIVE: This study aimed at rapidly identifying antimicrobial compounds using bioautography-guided high-performance thin-layer chromatography coupled with mass spectrometry (HPTLC-MS). METHODS: Hierarchical cluster analysis of ultra-performance liquid chromatography-mass spectrometry data from the methanol extracts of 77 samples, representing four genera within Combretaceae, was carried out. Based on groupings on the dendrogram, 15 samples were selected for bioautography analysis against four pathogens (Staphylococcus aureus, Bacillus cereus, Escherichia coli and Salmonella typhimurium). Active compounds were identified using HPTLC-MS analysis of bands corresponding to the inhibition zones. RESULTS: Bioautography revealed 15 inhibition zones against the four pathogens, with the most prominent present for Combretum imberbe. Analysis of the active bands, using HPTLC-MS indicated that flavonoids, triterpenoids and combretastatin B5 contributed to the antibacterial activity. The compounds corresponding to molecular ions m/z 471 (Combretum imberbe) and 499 (Combretum elaeagnoides) inhibited all four pathogens, and were identified as imberbic acid and jessic acid, respectively. Chemotaxonomic analysis indicated that arjunic acid, ursolic acid and an unidentified triterpenoid (m/z 471) were ubiquitous in the Combretaceae species and could be responsible for their antibacterial activities. CONCLUSION: Application of HPTLC-MS enabled the rapid screening of extracts to identify active compounds within taxonomically related species. This approach allows for greater efficiency in the natural product research workflow to identify bioactive compounds in crude extracts.