Chemical composition and biological activities of Cucurbita okeechobeensis extracts from its aerial parts, seeds, and fruit shells.

The Cucurbita genus has been widely used in traditional medicinal systems across different countries. In this study, we aimed to investigate the chemical composition, antioxidant properties, enzyme inhibitory, and cytotoxic effects of methanol and aqueous extracts obtained from the aerial parts, seeds, and fruit shells of Cucurbita okeechobeensis. Antioxidant properties were assessed using various chemical methods, including radical quenching (DPPH and ABTS), reducing power (CUPRAC and FRAP), metal chelation, and phosphomolybdenum assays. The extracts' enzyme inhibitory effects were tested against cholinesterase, amylase, glucosidase, and tyrosinase, whereas different cancer cell lines were used for the cytotoxicity study. The chemical composition, evaluated by HPLC-ESI-MSn, showed that the most abundant compounds were flavonoids (mainly quercetin glycosides) followed by phenolic acids (mostly caffeic acid derivatives). The aerial parts displayed stronger antioxidant ability than the seed and fruit shells, in agreement with the highest content in phytochemicals. In addition, the methanol extracts presented the highest bioactivity and content in phytochemicals; among them, the extract of the aerial part exhibited significant cytotoxic effects on cancer cell lines and induced apoptosis. Overall, our results suggest that C. okeechobeensis is a valuable source of bioactive compounds for the pharmaceutical and nutraceutical industries.

Luminescent Probe Based on Terbium-Carbon Quantum Dots for the Quantification of Imidacloprid in Caneberries.

We propose a modification of terbium-sensitized luminescence (TSL) by means of the introduction of nanoparticles to improve the sensitivity and selectivity of the analytical methods. TSL detection is usually based on the complexation between fluorescent organic compounds (the analytes) and terbium. The organic compound is then excited, and, after an energy transfer towards terbium, the latter emits the luminescence signal. Here, the modification consists of the introduction of nanoparticles (carbon quantum dots, CQDs) into the system. The carboxylic groups of CQDs react with terbium, providing an interesting time-resolved luminescence probe. We applied this system for the determination of the neonicotinoid imidacloprid (IMID). When IMID was introduced in the terbium-CQDs system, the luminescent signal (λexc/λem of 256/545 nm) was quenched, proportionally to IMID concentration in the range of 100-2500 ng·mL-1, obtaining a limit of detection of 30 ng·mL-1. A method detection limit of 0.9 mg·kg-1 was reached in caneberries, thus complying with the maximum residue level of 5 mg·kg-1 established by Codex Alimentarius. We performed recovery experiments in caneberries (blackberries, blueberries, raspberries, and mulberries), obtaining recovery yields close to 100% in all cases. These results show that the use of terbium ions-nanoparticles luminescence probes can be useful for screening purposes in quality control laboratories.

Understanding the Chemical Composition and Biological Activities of Different Extracts of Secamone afzelii Leaves: A Potential Source of Bioactive Compounds for the Food Industry.

Secamone afzelii (Roem. & Schult.) K. Schum (family Asclepiadaceae) is a creeping woody climber used to treat ailments in many traditional medicine systems. The present study aims to examine the antioxidant and enzyme inhibition activities of S. afzelii leaf using different compositions of methanol-water mixture as an extraction solvent. The extracts were characterized by HPLC-ESI-MSn in terms of chemical compounds. The in silico results show that compound 23 (quercitrin) has the higher docking scores among the selected substances and the MD simulation revealed that the interactions with the enzymatic pocket are stable over the simulation time and strongly involve the tyrosinase catalytic Cu atoms. All together the results showed that both 80% and 100% methanolic extracts contained significantly (p < 0.05) the highest total phenolics content while the highest content of total flavonoids was significantly (p < 0.05) extracted by 100% methanol. About 26 compounds were tentatively identified by HPLC-ESI-MSn and 6 of them were quantified using standards. Results showed that the extracts were rich in flavonoids with a relatively high abundance of two kaempferol glycosides comprising 60% of quantified compounds. The 100% and 80% methanol extracts recorded significantly (p < 0.05) the highest total antioxidant, DPPH and ABTS activity as well as tyrosinase and ⍺-amylase inhibitory activities. The best significant (p < 0.05) cholinesterase inhibitory activity and reducing capacity of Fe+++ and Cu++ was recorded from the 80% methanolic extract while 100% ethanolic extract gave the highest significant (p < 0.05) butyrylcholinesterase inhibitory activity. The best glucosidase activity was observed in the 50% and 80% methanolic extracts. Although the water extract displayed the least total phenolics and flavonoids content and consequently the lowest antioxidant and enzyme inhibition activity, it displayed significantly (p < 0.05) the highest chelating power. In conclusion, these results demonstrated the richness of S. afzelii leaf as a potential source of bioactive compounds for the food industry, for the preparation of food supplements and functional foods.

Preliminary Phytochemical Screening and Antioxidant Activity of Commercial Moringa oleifera Food Supplements.

Moringa oleifera has been reported to possess a high number of bioactive compounds; hence, several food supplements are commercially available based on it. This work aimed to analyze the phytochemical composition and antioxidant activity of commercial food supplements. The phenolic composition of methanolic extracts was determined by using high-performance liquid chromatography with diode-array and electrospray ionization mass spectrometric detection (HPLC-DAD-ESI-MSn), and the antioxidant activity was assessed by ABTS·+ and DPPH assays. Thirty-three compounds were identified, and all the main compounds were quantified, observing that the main contribution to the phenolic profile was due to kaempferol and quercetin glucosides. The antioxidant activity in both assays agreed with the phenolic content: the higher the phenolic levels, the higher the antioxidant activity. The obtained results were compared with those previously published regarding Moringa oleifera leaves to establish the potential benefits of food supplement consumption in the diet.

New Biological and Chemical Evidences of Two Lamiaceae Species (Thymbra capitata and Thymus sipyleus subsp. rosulans): In Vitro, In Silico and Ex Vivo Approaches.

In this study, the methanolic and infusion extracts of two species, Thymbra capitata and Thymus sipyleus subsp. rosulans, were tested for their chemical composition and biological abilities (antioxidant, enzyme inhibitory and anti-inflammatory effects). The extracts yielded total phenolic and flavonoid contents in the range of 83.43-127.52 mg GAE/g and 9.41-46.34 mg RE/g, respectively. HPLC analysis revealed rosmarinic acid to be a major component of the studied extracts (15.85-26.43%). The best ABTS radical scavenging ability was observed in the methanol extract of T. capitata with 379.11 mg TE/g, followed by in the methanol extract of T. sipylus (360.93 mg TE/g). In the CUPRAC assay, the highest reducing ability was also found in the methanol extract of T. capitata with 802.22 mg TE/g. The phosphomolybdenum ability ranged from 2.39 to 3.61 mmol TE/g. In terms of tyrosinase inhibitory effects, the tested methanol extracts (83.18-89.66 mg KAE/g) were higher than the tested water extracts (18.74-19.11 mg KAE/g). Regarding the BChE inhibitory effects, the methanol extracts were active on the enzyme while the water extracts showed no inhibitory effect on it. Overall, the methanolic extracts showed better enzyme inhibition compared to the infusion extracts. Molecular docking also showed the selected exhibited potential binding affinities with all enzymes, with a preference for cholinesterases. Additionally, the extracts were effective in attenuating the LPS-induced increase in COX-2 and IL-6 gene expression in isolated colon, thus indicating promising anti-inflammatory effects. The preliminary results of this study suggest that these species are good natural sources of antioxidants and also provide some scope as enzyme inhibitors, most likely due to their bioactive contents such as phenolic acids, and thus can be exploited for different applications related to health promotion and disease prevention.

Effect of Ripening on the Phenolic Composition and Mineral Content of Three Varieties of Olive Fruits.

The phenolic composition and mineral content of Cornezuelo, Cornicabra and Picual olive fruit varieties were investigated during olive ripening in two different harvesting seasons (2017/2018 and 2018/2019). Phytochemical profiles were evaluated by high-performance liquid chromatography (HPLC) with diode-array and mass spectrometry detection. Mineral contents were determined by inductively coupled plasma-mass spectrometry (ICP-MS). Twenty-five compounds were characterized and the main ones quantified. These compounds corresponded mostly to secoiridoids, the main ones being oleuropein, oleoside/secologanoside, oleoside-11-methylester, and oleuropein and comselogoside isomers. Total phenolic contents reached the highest values between December and January, coinciding with the usual harvesting date. This trend was observed in both harvesting seasons, although higher phenolic contents were recorded in season 2018/2019. This was due to the different weather conditions, which caused a lower olive production in season 2017/2018. No clear tendency was observed between mineral content and harvest time in any of the studied seasons. The highest concentration of total phenolics was obtained in Cornezuelo variety (840 mg/100 g) in January 2019 (season 2018/2019). Picual and Cornicabra varieties reached concentrations of 670 mg/100 g and 530 mg/100 g, respectively, also in the last harvesting dates of season 2018/2019.

Phytochemical Composition and Antioxidant Activity of Portulaca oleracea: Influence of the Steaming Cooking Process.

In this work, we compared the phenolic composition and antioxidant capacity of methanolic extracts of raw and steamed aerial parts of Portulaca oleracea L. Two new cyclo-dopa amides were identified, named oleraceins X and Y, along with six known ones (oleraceins A, B, C, N, J, and U). Compounds identification and quantification were done by high-performance liquid chromatography with diode array and mass spectrometry detections. The most abundant compounds were phenolic alkaloids (oleraceins), and the main quantified compounds were isocitric and citric acids, with concentrations of 500-550 and 440-600 mg/100 g dried extract, respectively. The study of both the influence of the steaming process in Portulaca oleracea L. and total phenolic content and radical scavenging assays (ABTS·+ and DPPH) were also carried out. The total individual phenolic content of raw Portulaca decreased from 1380 mg/100 g DE to 1140 mg/100 g DE after the steaming process. The antioxidant capacity in ABTS and DPPH assays decreased approximately 50 and 40%, respectively, after samples were cooked by steaming. The raw extracts presented the highest concentration of bioactive compounds, as well as higher antioxidant and radical scavenging values.

Study on Three Sarcocapnos Species as Potential Sources of Bioactive Compounds: Relation between Phenolic Content and Bioactivity by Multivariate Analysis.

In this work, we report the phenolic composition and bioactivity of the aerial parts of three species of Sarcocapnos (S. enneaphylla, S. pulcherrima, and S. saetabensis) to study their potential as sources of bioactive compounds to revalorize them and contribute to the conservation of these plant species. Samples were collected in different locations in the province of Jaén (southeast of Spain), and qualitative and quantitative analyses of phenolic compounds were performed by high-performance liquid chromatography with diode array and mass spectrometry detection. S. enneaphylla presented the highest concentration of phenolic compounds (58 mg/g DE). The most abundant compound in S. enneaphylla and S. saetabensis was rutin (35 mg/g DE and 11.7 mg/g DE, respectively), whereas isorhamnetin-O-rutinoside was dominant in S. pulcherrima (11.5 mg/g DE). Several assays were performed to evaluate the potential bioactivity of the three species of Sarcocapnos. These assays included antioxidant and radical scavenging (ABTS and DPPH), reducing power (CUPRAC and FRAP), phosphomolybdenum and metal chelating, and enzyme inhibitory activity (acetylcholinesterase, amylase, butyrylcholinesterase, glucosidase, and tyrosinase). In general, all methanolic extracts presented the highest phenolic and flavonoid contents, as well as the highest radical scavenging, antioxidant, and enzyme inhibitory properties. This relationship between phenolics and bioactivity was confirmed by multivariate analysis.

Phenolic Characterization, Antioxidant Activity, and Enzyme Inhibitory Properties of Berberis thunbergii DC. Leaves: A Valuable Source of Phenolic Acids.

: Berberis species are known for their use in traditional medicine. Here, we report the phenolic composition and bioactivity of methanolic and aqueous extracts of Berberis thunbergii DC. leaves. The phenolic profiling and the quantitation of the main compounds were performed by high-performance liquid chromatography with diode array and mass spectrometry detections. The most abundant compounds in both extracts were caffeoylquinic acids (chlorogenic acid, particularly, with a concentration of 90.1-101.3 mg g-1 dried extract), followed by caffeoylglucaric acids and quercetin glycosides. Antioxidant and radical scavenging assays (phosphomolybdenum, DPPH, ABTS, CUPRAC, FRAP, metal chelating activity), as well as enzyme inhibitory assays (acetylcholinesterase, butyrylcholinesterase, tyrosinase, amylase, glucosidase, and lipase), were carried out to evaluate the potential bioactivity of B. thunbergii. The methanolic extract presented the highest antioxidant and radical scavenging values, in agreement with its higher phenolic content. Regarding enzyme inhibitory potential, the methanolic extract was also more potent than the aqueous one. Hence, B. thunbergii leaves represent a suitable candidate for the preparation of pharmaceutical or nutraceutical products.

Selective luminescence determination of cysteine by using terbium-modified silver nanoparticles or terbium-modified graphene quantum dots.

Two methods for the luminescence determination of cysteine (Cys) are presented. They make use of either silver nanoparticles (Ag NPs) or graphene quantum dots (GQDs), both doped with terbium(III). The methods are based on the finding that Cys quenches the green luminescence of Tb(III)-Ag NPs and Tb(III)-GQDs. The excitation/emission maxima are at 306/545 and 257/545 nm, for both nanoprobes, respectively. Response is linear in the 0.28-5.0 µg mL-1 Cys concentration range for the Tb(III)-Ag NP system, and from 0.05-3.0 µg mL-1 for the Tb(III)-GQD system. The respective limits of detection are 0.09 and 0.015 µg mL-1. The probes were applied to the time-resolved luminometric determination of Cys in (spiked) food supplements and gave satisfactory results. Graphical abstractSchematic representation of the quenching by cysteine (Cys) of the time-resolved luminescence (TSL) of terbium-graphene quantum dots [Tb(III)-GQD] and of terbium-silver nanoparticles [Tb(III)-Ag NP].

Direct determination of graphene quantum dots based on terbium-sensitized luminescence.

Graphene quantum dots (GQD) were determined in water samples using terbium-sensitized luminescence (TSL). Terbium ions complex with GQD due to the carboxylic groups that are usually present in these nanomaterials, increasing the luminescence signal of terbium. In Tb(III)-GQD complexes, GQD absorb energy at their characteristic excitation wavelength and transfer it to terbium ion, which emits at its particular emission wavelength. The analytical signal, measured at λexc=257nm and λem=545nm, increases proportionally to GQD concentration between 50 and 500µgL-1. Under optimum conditions, the proposed method presents a detection limit of 15µgL-1 and is selective to GQD in the presence of other nanomaterials of similar size. As GQD are highly water-soluble, they are potential contaminants in environmental or drinking waters water samples, and hence the method was applied to the analysis of different drinking waters which were the target samples for the application of the developed method.

A photochemically induced fluorescence based flow-through optosensor for screening of nitenpyram residues in cruciferous vegetables.

One of the most used agrochemicals in agricultural production, nitenpyram (NTP), has been determined by using a flow-through optosensing device based on Photochemically Induced Fluorescence detection. The combination of both methodologies allows, on one hand, a quick on-line photodegradation of NTP and, on the other hand, the preconcentration, quantification and desorption of the fluorescent photoproduct generated when retained on Sephadex QAE-A25 as solid support, which was monitored at 295 and 362 nm for excitation and emission, respectively. The proposed analytical method presents a detection limit of 500 pg mL-1 by using Multicommutated Flow Injection Analysis. Recovery experiments were carried out in different kinds of cruciferous vegetables at or below the MRL established in Japan, demonstrating that this method combines advantages of simplicity, high sensibility and high selectivity, fulfilling the requirements for its application in quality control. Results obtained in the analysis of real samples were in good agreement with those provided by a reference HPLC method.

Graphene quantum dots-terbium ions as novel sensitive and selective time-resolved luminescent probes.

We propose an alternative approach for the development of analytical methods based on terbium-sensitized luminescence (TSL). TSL is based on the complexation between Tb(III) ions and fluorescent organic compounds that have appropriate functional groups to complex with Tb(III). We report the use of graphene quantum dot (GQDs) nanoparticles to improve the sensitivity and selectivity of TSL detection. GQDs can react with terbium ions through the carboxylic groups present in their structure. These Tb(III)-GQD complexes, formed in situ in aqueous solution, can be used as time-resolved luminescent probes. Ascorbic acid was selected as a target analyte to demonstrate the suitability of the proposed method. The selectivity of the TSL method was highly improved for most of the interferences tested. Under the optimum conditions [Tb(III) concentration 5 × 10-4 mol L-1, GQD concentration 4 mg L-1], a minimum 100% increase in selectivity was observed for several vitamins and common cations that may be present in the samples to be analyzed. In addition, the analytical signal showed a 30% enhancement with the use of GQDs compared with the use of merely Tb(III) ions, with a detection limit of 0.12 µg mL-1. The repeatability and intermediate precision were lower than 3% and 5%, respectively. From the results obtained, the implementation of GQDs in TSL can lead to the development of novel time-resolved luminescent probes with high analytical potential. Graphical abstract Quenching of Tb(III)-graphene quantum dot (GQD) luminescence by ascorbic acid (AA). TBL terbium-sensitized luminescence.

A new approach for automated liquid-liquid extraction in a sequential injection manifold.

A new approach for the implementation of liquid-liquid extraction in a sequential injection manifold is presented. The manifold consists of two syringe pumps and one multi-position valve. The use of a 30 % MeOH/H2O (v/v) solution as the carrier, with isobutanol as the extractant, made it possible to avoid the problems associated with the different affinities of the organic and aqueous phases for Teflon tubing, and the formation of bubbles. The suitability of the proposed method was demonstrated by the determination of thiamine in pharmaceutical preparations and dietary supplements. Detection and quantification limits were estimated as 9 and 30 µg L(-1), respectively. The repeatability was lower than 3 % and the intermediate precision (3 d) was lower than 7 %. The sample throughput was 14 samples per h. The results were in agreement with a high-performance liquid chromatography-electrospray/mass spectrometry reference method.

Analysis of Bisphenol A in milk by using a multicommuted fluorimetric sensor.

Bisphenol A (BPA) is a polyphenol widely used in industry as an intermediate in the production of polycarbonate plastics and epoxy resins, which are applied to produce plastic food containers, inner surface coating of food and beverage cans. Hence, BPA can migrate from these containers and cans with epoxy coating into foods. It is dangerous taking into account that BPA is considered as a potential endocrine disruptor, which mimics the action of the hormone estrogen. The method here proposed for the determination of BPA involves the implementation of solid-phase spectroscopy (SPS) in an automatic flow system. With this purpose, the measurement of the native fluorescence of BPA, retained on C(18) silica gel together with the implementation of multicommutation have been employed for its determination in different types of milk. The analytical measurements were made at 271/305nm (λ(ex)/λ(em)) obtaining a detection limit (LOD) of 0.06ngmL(-1). The pre-cleaning procedure and the posterior extraction with C(18) applied to the samples allowed the removal of proteins and the extraction of BPA from the matrix, respectively. The method showed an RSD lower than 6.0% (n=10). BPA was determined in powdered milk, infant formula and pure liquid milk samples, being found in five samples at levels lower than the maximum residue limit (MRL) established by the European Union. In addition, a recovery study has been carried out where values close to 100% were observed in all cases, so demonstrating that the proposed analytical method fulfills the requirements for its application in quality control analyses.

Indirect determination of aflatoxin B1 in beer via a multi-commuted optical sensor.

This paper reports the determination of aflatoxin B1 (AFB1), one of the most carcinogenic substances known. A multi-commuted flow injection-solid phase spectroscopy (FI-SPS) system combined with photochemically induced fluorescence (PIF) was developed, for the first time, for its quantitative determination. A strongly fluorescent degradation product was obtained on-line by irradiation with ultraviolet light. The determination was carried out by measuring the fluorescence intensity of the photo-product at 353/424 (λ (ex)/λ (em)), once retained on C18 silica-gel filling the flow-cell. A linear dynamic range of 0.09-12 µg l⁻¹, detection limit as sensitive as 29 ng l⁻¹ and a relative standard deviation (RSD) of 1.4% were obtained. The method proposed was satisfactorily applied to the determination of AFB1 in different types of beer (normal and non-alcoholic). Hydrophobic compounds were eliminated from beer samples and AFB1 was extracted with acetonitrile by solid-phase extraction on C18 sorbent. Recoveries of the target compound from spiked beers were between 94 and 106%. The results obtained in the analysis of real samples are in good agreement with those provided by a reference chromatographic method.

An automatic optosensing device for the simultaneous determination of resveratrol and piceid in wines.

For the first time, a spectrofluorimetric method is reported for the simultaneous determination of resveratrol (RVT) and piceid (PCD), two stilbenes showing diverse interesting physiological and biochemical attributes, as well as a wide range of health benefits ranging from cardioprotection to chemoprevention. The method makes use of a multicommutated flow-through optosensor in which the resolution of RVT and PCD is accomplished by means the sequential arrival of their photoproducts, on-line generated by UV-irradiation, to the detection area. This is possible due to the different kinetic behaviour of these latter on a solid support (C(18) silica gel) filling a minicolumn placed before the detector. The measurement in solid-phase of the photochemically induced fluorescence of the photoproducts (λ(ex): 257 nm/λ(em): 382 nm) is used as analytical signal for monitoring both compounds. The method has been applied to the analysis of RVT and PCD in wines and requires a previous solid-phase extraction (SPE) using Bakerbond C(18) cartridges. This pretreatment and the use of a solid-support in both the minicolumn and the flow-cell of the detector allow the determination of RVT and PCD by external calibration. Detection limits (DLs) are 9.3 and 12.6 ng mL(-1) for RVT and PCD, respectively. Commercial red and white wine samples have been analysed and the results obtained have been satisfactorily validated by high-performance liquid chromatography (HPLC).

A novel multicommuted fluorimetric optosensor for determination of resveratrol in beer.

Resveratrol (3,5,4'-trihydroxystilbene) is a phytoalexin that plays a central role in the human diet because of its antioxidant, anticarcinogenic and antimutagenic properties. This paper shows the development of a multicommuted optosensing device for the determination of resveratrol in beer. The method is based on the measurement of the fluorescence (277/382 nm, λ(ex)/λ(em)) of the photoproduct on-line generated by UV-irradiation of resveratrol. The fluorescent photoproduct is monitored once it is retained on a solid support (Sephadex QAE A-25) in the detection area, which improves both sensitivity and selectivity. The sample was delipidated with toluene and cyclohexane and resveratrol was extracted by solid-phase extraction (SPE) on C(18) cartridges, using methanol as eluent. This pre-treatment allowed recovering about an 82% resveratrol and removing its 3-O-ß-d-glycoside (piceid) and other interfering substances present in beer. The method provides a detection limit (DL) of 1.0 ng mL(-1) and a linear dynamic range (LDR) of 3.3-100 ng mL(-1). It was satisfactorily applied to the determination of resveratrol in top- and bottom-fermented beers by standard addition calibration. Resveratrol concentrations in the analysed samples varied from 4.1 to 14.1 ng mL(-1). This is the first proposed spectroscopic method for determination of resveratrol in beer.

Automatic optosensing device based on photo-induced fluorescence for determination of piceid in cocoa-containing products.

Piceid (3,4',5-trihydroxystilbene-3-ß-D: -glucoside) is a stilbene which occurs naturally in various families of plants and has been shown to protect lipoproteins from oxidative damage and to have cancer chemopreventive activity. This paper deals with the determination of piceid in cocoa-containing products by using photo-induced fluorescence and the aid of a multicommutated continuous-flow assembly which was provided with an on-line photoreactor. A strongly fluorescent photoproduct is generated from piceid when it is irradiated under UV light for 30 s, which is retained on Sephadex QAE A-25 and directly monitored on this active solid support at 257/382 nm (λ (exc)/λ (em), respectively). The pre-concentration of the photoproduct of piceid on the solid support greatly improves both sensitivity and selectivity. The influence of different experimental parameters, both chemical (pH, ionic strength) and hydrodynamic (irradiation time, flow rate, photoreactor length, sampling time), was tested. The sample pre-treatment included delipidation with toluene and cyclohexane, stilbene extraction with ethanol/water (80:20, v/v) and clean-up by solid-phase extraction on C(18) cartridges and methanol/water (40:20, v/v) as eluting solution. This procedure allowed the elimination of the aglycon of piceid, resveratrol and other potential interfering species and a recovery of about a 90% piceid. The method was applied to the analysis of piceid in cocoa powder, dark chocolate and milk chocolate. The quantification limits were 1.4, 1.1 and 0.09 mg kg(-1), respectively. Relative standard deviations ranged from 1.8% to 3.1%. This is the first reported non-chromatographic method for determination of piceid in these foods.

Sensitive determination of indomethacin in pharmaceuticals and urine by sequential injection analysis and optosensing.

A selective and sensitive method based on coupling of sequential injection analysis (SIA) and optosensing was developed and applied to the determination of indomethacin in pharmaceutical and urinary samples. After alkaline hydrolysis, the fluorescent product generated from indomethacin is inserted in the flow system, transitorily retained on an active solid support (Sephadex QAE A-25) filling the flowcell, and monitored at 283/371 nm (lamda ex / lamda em). The system was calibrated for two sample volumes, 100 and 1000 microL. It showed a linear dynamic range of 0.5-6.5 ng/mL, with an LOD of 0.15 ng/mL and an RSD of 3.9% (n=10) when the highest sample volume was used. The proposed fluorometric SIA optosensor was applied to the determination of indomethacin in both pharmaceuticals and urine samples, and satisfactory results were obtained.