Exploring the chemical diversity of Capsicum chinense cultivars using NMR-based metabolomics and machine learning methods.

The habanero pepper (Capsicum chinense) is a prominent spicy fruit integral to the historical, social, cultural, and economic fabric of the Yucatan peninsula in Mexico. This study leverages the power of 1H NMR spectroscopy coupled with machine learning algorithms to dissect the metabolomic profile of eleven C. chinense cultivars, including those grown by INIFAP (Habanero-Jaguar, Antillano-HRA 1-1, Antillano-HRA 7-1, Habanero-HAm-18A, Habanero-HC-23C, and Jolokia-NJolokia-22) and commercial hybrids (Habanero-Rey Votán, Habanero-Kabal, Balam, USAPR10117, and Rey Pakal). A total of fifty metabolites, encompassing sugars, amino acids, short-chain organic acids, and nucleosides, were identified from the 1H NMR spectra. The optimized machine learning model proficiently predicted the similarity percentage between the INIFAP-grown cultivars and commercial hybrids, thereby facilitating a comprehensive comparison. Biomarkers unique to each cultivar were delineated, revealing that the Habanero-Rey Votán cultivar is characterized by the highest concentration of sugars. In contrast, the Balam cultivar is rich in amino acids and short-chain organic acids, sharing a similar metabolomic profile with the Jolokia-NJolokia-22 cultivar. The findings of this study underscore the efficacy and reliability of NMR-based metabolomics as a robust tool for differentiating C. chinense cultivars based on their intricate chemical profiles. This approach not only contributes to the scientific understanding of the metabolomic diversity among habanero peppers but also holds potential implications for food science, agriculture, and the culinary arts.

Structural Features of Diacyldodecaheterocycles with Pseudo-C2-Symmetry: Promising Stereoinductors for Divergent Synthesis of Chiral Alcohols.

Pseudo-C2-symmetric dodecaheterocyclic structures, which possess two acyl/aroyl groups disposed on either a cis- or trans-relative configuration, were prepared from the naturally occurring (-)-(1R)-myrtenal. Addition of Grignard reagents (RMgX) to the diastereoisomeric mixture of these compounds unexpectedly showed that nucleophilic additions to the two prochiral carbonyl centers gave the same stereochemical result in both cis/trans diastereoisomers, making unnecessary the separation of this mixture. Noticeably, both carbonyl groups showed different reactivity because one of them is attached to an acetalic carbon and the other to a thioacetalic carbon. Furthermore, addition of RMgX to the carbonyl attached to the former carbon takes place through the re face, while addition to the second one proceeds through the si face, thus affording the corresponding carbinols in a highly diastereoselective process. This structural feature allowed the sequential hydrolysis of both carbinols, yielding separately (R)- and (S)-1,2-diols after reduction with NaBH4. The mechanism of the asymmetric Grignard addition was explained by density functional theory calculations. This approach contributes to the development of the divergent synthesis of structurally and/or configurationally different chiral molecules.

NMR-based metabolomics to determine the fluctuation of metabolites in hydroponic purslane crops at different harvesting times.

Purslane (Portulaca oleracea L.) has a high content of nutrients and medicinal effects that depend on the genotype, harvesting time, and production system. The objective of the present research work was to elucidate the NMR-based metabolomics profiling of three native purslane cultivars from Mexico (Xochimilco, Mixquic, and Cuautla) grown under hydroponic conditions and harvested in three different times (32, 39, and 46 days after emergence). Thirty-nine metabolites identified in the 1H NMR spectra of aerial parts of purslane, 5 sugars, 15 amino acids, 8 organic acids, 3 caffeoylquinic acids, as well as 2 alcohols and 3 nucleosides, choline, O-phosphocholine and trigonelline were also detected. A total of 37 compounds were detected in native purslane from Xochimilco and Cuautla, whereas 39 compounds were detected in purslane from Mixquic. Principal component analysis (PCA) and orthogonal partial least squares discriminant analysis (OPLS-DA) separated the cultivars into three clusters. Mixquic cultivar had the highest number of differential compounds (amino acids and carbohydrates), followed by Xochimilco and Cuautla cultivars, respectively. Changes in the metabolome were observed in latest times of harvest for all the cultivars studied. The differential compounds were glucose, fructose, galactose, pyruvate, choline, and 2-hydroxysobutyrate. The results obtained in this investigation may contribute to selecting the best cultivar of purslane and the best time in which the levels of nutrients are optimal.

Structural Analysis of the Michael-Michael Ring Closure (MIMIRC) Reaction Products.

A representative number of decalin and hydrindane derivatives 2a-l were prepared in 11-91% yield by means of a cascade reaction of cyclohexanone/cyclopentanone enolates and methyl acrylate through a Michael-Michael ring closure (MIMIRC) process. The relative stereochemistry of the four stereogenic centers formed in all products was determined by analyzing the vicinal coupling constants from the 1H NMR and X-ray crystallography. Such a stereochemical outcome was corroborated by conformational analysis supported by DFT calculations and simulating the 1H NMR spectra of representative products. All products showed the same relative stereochemistry at C-1 and C-8a, while at C-3 and bridgehead carbon C-4a, configurational changes were observed. The present results provide some insights about the scope and limitations of the triple cascade reaction between cycloalkanone enolates with methyl acrylate. This synthetic protocol is still a simple and very practical alternative to generate decalin and hydrindane derivatives with great structural diversity.

A semi-targeted NMR-based chemical profiling of retail samples of Mexican gordolobo.

Mexican gordolobo (MG) is one of the most important medicinal plants in Mexico and an important source of specialized metabolites with biological activities. The species employed in Mexican traditional medicine identified with this name are very different and difficult to identify according to existent criteria. In order to contribute to the identification of these species, a semi-targeted 1H NMR-based chemometric method was developed to characterize the chemical profiling of retail samples of MG. Thus, 17 retail samples of MG flowers were successively extracted with a gradient of water:chloroform (1:4, 1:2 and 0:1) in an ultrasonic bath for 15 min each. The organic phase of the three extracts was pooled, evaporated and analyzed by 1H NMR. The NMR data were subjected to multivariate statistical analysis, revealing that flavones gnaphaliin A (1), gnaphaliin B (2), araneol (3), 3,5,7-Tri-O-methylgalangin (4) and diterpenes sclareol (5) and kaur-16-en-18-oic acid (6) can be effectively used as chemotaxonomical markers for the correct identification of the Gnaphalium spp that compose MG. The aforementioned chemotaxonomic markers may be useful in establishing therapeutic criteria.

Bean cultivars (Phaseolus vulgaris L.) under the spotlight of NMR metabolomics.

The seeds of Phaseolus vulgaris are a rich source of protein consumed around the world and are considered as the most important source of proteins and antioxidants in the Mexican diet. This work reports on the 1H NMR metabolomics profiling of the cultivars Peruano (FPe), Pinto (FPi), Flor de mayo (FM), Negro (FN) and Flor de junio (FJ). Total phenolics, total flavonoids and total protein contents were determined to complement the nutritional facts in seeds and leaves. According to our results, the metabolomics fingerprint of beans seeds and leaves were very similar, showing the presence of 52 metabolites, 46 in seeds and 48 in leaves, including 8 sugars, 17 amino acids, 15 organic acids, 5 nucleosides and 7 miscellaneous compounds. In seeds, free amino acids were detected in higher concentrations than in the leaves, whereas organic acids were more abundant in leaves than in seeds. With multivariate and cluster analysis it was possible to rank the cultivars according to their nutritional properties according to NMR profiling, then a machine learning algorithm was used to reveal the most important differential metabolites which are the key for correct classification. The results coincide in highlighting the FN seeds and FPe leaves for the best nutritional facts. Finally, in terms of cultivars, FN and FM present the best nutritional properties, with high protein and flavonoids content, as well as, a high concentration of amino acids and nucleosides.

Experimental races of Capsicum annuum cv. jalapeño: Chemical characterization and classification by 1H NMR/machine learning.

This work reports on the metabolic fingerprinting of ten new races of Capsicum annuum cv. jalapeño using 1H NMR based metabolomics coupled to machine learning projections. Ten races were classified and evaluated according to their differential metabolites, variables of commercial interest and by multivariate data analysis/machine learning algorithm. According to our results, experimental races of jalapeño peppers exhibited differences in carbohydrate, amino acid, nucleotide and organic acid contents. Forty-eight metabolites were identified by 1D and 2D NMR and the differential metabolites were quantified by qNMR. Principal component analysis (PCA) and orthogonal partial least squares discriminant analysis (OPLS-DA) separated the studied races into two groups. The group A included the races Colosus, Emperador, Fundador and Rayo whereas the group B included the races Don Benito, SMJ 1416, SMJ 1417, SMJ 1423, SMJ 145 and STAM J0904. OPLS-DA revealed that levels of citric acid in group A were higher than in group B, while the levels of asparagine, fumaric acid, GABA, glucose, malic acid, pyruvic, quinic acid, sucrose and tryptophan were higher in the group B. Remarkably, ascorbic acid was exclusively found in the race Colosus. Random forest model revealed the diversity of the experimental races and the similarity rate with the well-established races. The most relevant variables used to generate a model were length, weight, yield, width, xylose content and organic acids content.

Revealing the 1H NMR metabolome of mirasol chili peppers (Capsicum annuum) infected by Candidatus Phytoplasma trifolii.

The infection of Capsicum annuum cv. mirasol by Candidatus Phytoplasma trifolii (16SrVI) causes devastating crop losses in northern Mexico. This study addresses the metabolomics profiling of mirasol chili peppers (Capsicum annuum cv. mirasol) infected by Candidatus Phytoplasma trifolii. For this study, 25 diseased fruits and 25 healthy fruits were used. Principal component analysis (PCA) and orthogonal projections to latent structures discriminant analysis (OPLS-DA) revealed dramatic changes in the content of 42 metabolites which were identified in diseased and healthy mirasol chili peppers. The endogenous levels of fructose, glucose and formic acid were substantially decreased in the diseased chili peppers. In the same group of samples, high concentrations of alanine, asparagine, fumaric acid, sucrose and threonine were observed. The content of Choline didnt present a significant difference. This evidence supports the fact that Candidatus Phytoplasma trifolii infection reduces de CO2 fixation into carbohydrates, decreases invertase activity, and inhibits glycolysis in the diseased plant tissues. The levels of ascorbic acid, capsaicin and dihydrocapsaicinin in diseased fruits were dramatically decreased, suggesting that Candidatus Phytoplasma trifolii can reduce the pungency and the nutraceutical value of mirasol chili peppers.

Identity Profiling of Complex Mixtures of Peptide Products by Structural and Mass Mobility Orthogonal Analysis.

Identity is a critical quality attribute that must be determined before releasing batches of medicinal and dietary products. However, the identities of peptide-derived products composed of a large number of diverse molecules is challenging since most analytical techniques cannot analyze multiple molecules simultaneously. Here, we proposed the determination of the weight-average molecular weight (Mw) and polydispersity index (PDI) by mass spectrometry for control quality for the batch release of complex products, namely, glatiramer acetate (Copaxone), collagen hydrolysate (Colagenart), and a human dialyzable leucocyte extract (Transferon). The Mw and PDI values were orthogonally determined by PFG-STE-H2O(presaturation)-DOSY-NMR analysis. To the best of our knowledge, this is the first time that MS and NMR spectra have been combined to determine the PDI of complex products derived from protein hydrolysis that are not monodisperse. The performance of each method was evaluated by comparing the obtained results to those reported for glatiramer acetate using MALLS, the technique commonly employed to determine PDI. This combined approach demonstrates the ability of these techniques to separate peptide populations from complex mixtures to establish their identity through their mass distribution profiles.

Role of dose-dependent Lactobacillus farciminis on ruminal microflora biogases and fermentation activities of three silage-based rations.

AIMS: The influence of Lactobacillus farciminis on ruminal fermentation characteristics was elucidated in this study. METHODS AND RESULTS: Ruminal fermentation was conducted using maize silage ration (R) and concentrate (C) as 75R:25C, 50R:50C and 25R:75C, supplemented with lactic acid bacteria (LB) at 0, 20 and 30 mg g-1 dry matter substrate and their interaction (1st experiment). The same LB product was used at 0, 20, 40 and 60 mg g-1 dry matter of the mixture (1 : 1) of oat straw and concentrate for 48 h of incubation (2nd experiment). At 24 and 48 h of incubation, LB0 produced the highest biogas and LB20 produced the lowest, whereas at 48 h of incubation LB40 produced the lowest. In ration x LB, LB40 resulted in the highest biogas production, while LB0 had the lowest (P < 0·001) at 8, 10 and 12 h of incubation. Inclusions of LB0, 20, 40 and 60 mg g-1 dry matter resulted in a linear increase (P < 0·003) in the asymptotic biogas production and fermentation parameters in a dose-dependent manner, except in pH which decreased (P = 0·029). CONCLUSIONS: The use of L. farciminis in diet with high level of concentrate without any adverse effect on the pH of rumen fluid to the point of acidosis. Furthermore, in high forage diet, the use of L. farciminis would help to improve the ruminal fermentation digestibility and mitigate ruminal biogas production. SIGNIFICANCE AND IMPACT OF THE STUDY: Using Lactobacillus as a feed additive can improve ruminal fermentation activities by maintaining the stability of pH in the rumen and improving the feed utilization through manipulation of the microbial ecosystem.

1H NMR-based fingerprinting of eleven Mexican Capsicum annuum cultivars.

Approximately 90% of the chili peppers consumed in the world are harvested in Mexico. The present article describes the untargeted 1H NMR-based metabolomic profiling of 11 cultivars of Capsicum annuum species which are routinely consumed worldwide. The metabolomic fingerprinting detected via 1H NMR contained 44 metabolites including sugars, amino acids, organic acids, polyphenolic acids and alcohols which were identified by comparison with the literature data, with Chenomx database and by 2D NMR. Statistical approaches based on principal component analysis (PCA) and linear discriminant analysis (LDA) were used to classify the Capsicum annuum cultivars according to their metabolite profile. LDA revealed metabolomic differences and similarities among Capsicum annuum cultivars, whereas hierarchical cluster analysis (HCA) significantly separated the cultivars according to the phylogenetic trees obtained. Substantial endogenous levels of free amino acids and carbohydrates were detected in all the studied cultivars but interestingly, Capsicum annuum cv. mirasol and C. annuum cv. chilaca contained almost three-fold more endogenous levels of vitamin C than the other cultivars. Considering that this antioxidant was found in crude aqueous extracts, its abundance could be directly proportional to its bioavailability for human nutrition. The results suggest that 1H NMR is an effective method to determine differences among cultivars of the Capsicum annuum species.

1H NMR-based metabolomics profiling of ten new races from Capsicum annuum cv. serrano produced in Mexico.

Herein we report on the 1H NMR-based metabolomics profiling of ten new races of Capsicum annuum cv. serrano, cultivated in Mexico. Forty eight metabolites (including sugars, amino acids, organic acids, polyphenolic acids and alcohols) were identified and quantified by 2D NMR and qNMR, respectively. Principal component analysis (PCA) and partial least squares discriminant analysis (PLS-DA) separated the ten races into two clusters, from which citric acid, formic acid, fumaric acid, malic acid, glucose, fructose, sucrose and galactose were found as differential metabolites. This is the first study describing the chemical profiling of ten new races of Capsicum annuum cv. serrano and the spectrometric method used presently is characterized by great simplicity, robustness and reproducibility. Thus, this technique can be used for establishing reliable metabolomic fingerprints of different races of Capsicum annuum cv. serrano.

1 H-NMR Based Metabolomics Profiling of Citrus Juices Produced in Veracruz, México.

This study describes the 1 H-NMR-based metabolomics profiling of juices from citrus fruits harvested in the state of Veracruz, México. The hydrophilic profile of commercial lemons (Agrio and Persian), tangerines (Fremont and Mónica), oranges (Valencia and Washington Navel), and grapefruits (Red Ruby and Rio Red) was determined. According to our results, 35 metabolites were identified in the 1 H-NMR profiling. The statistical differences obtained by PCA and OPLS-DA revealed that specific amino acids, sugars, and organic acids were differential metabolites in the species and cultivars studied. High endogenous levels of sucrose (10-190 mM), α-glucose, ß-glucose (α- and ß-isomers, 40-205 mm), and fructose (36-170 mm) were detected in the juices of grapefruits, oranges, and tangerines, whereas citric acid (40-530 mm) was the principal organic acid in the juices of lemons. To calculate the specific amounts of metabolites from these species and their cultivars, the results were finely analyzed using the qNMR method. According to these calculations, Valencia oranges had the highest concentration of ascorbic acid (>2 mm). The described 1 H-NMR method is highly reproducible, inexpensive, and highly robust in comparison to other analytical methods used to determine the hydrophilic profile of citrus juices.

Trixis angustifolia hexanic extract displays synergistic antibacterial activity against M. tuberculosis.

A phytochemical and antibacterial study of Trixis angustifolia, a species endemic to Mexico, was performed allowing the isolation of six flavones. The minimal inhibitory concentration (MIC) of the hexanic extract, against Mycobacterium tuberculosis H37Rv was 25 µg/mL. The hexanic extract caused a significant inhibition of intracellular mycobacterial growth at 12.5 µg/mL. The biodirected assay of hexane extract enabled the detection of an active fraction (AF) against M. tuberculosis (MIC = 12.5 µg/mL), and a major flavone 1 (pebrellin) with no antimycobacterial activity (MIC > 200 µg/mL). A subsequent combination antimicrobial assay showed a synergistic antimycobacterial effect of AF in combination with pebrellin; the results of the synergistic activity suggest that the antimycobacterial activity found in T. angustifolia is due to the combined action of diverse metabolites present in the plant.

NMR-based metabonomic approach reveals changes in the urinary and fecal metabolome caused by resveratrol.

An untargeted NMR-based metabonomics approach was used to evaluate the effects of pure resveratrol (RSV, 50 and 250 mg/kg per os) on the urinary and faecal metabolome of normal female Wistar rats. Multivariate data analysis on both the endogenous and xenobiotic metabotype of RSV provided an insight into its metabolic fate and influence on endogenous metabolites. The xenobiotic trajectory shows that RSV is highly metabolized within the first 12 h, the period of the most significant variation of endogenous metabolites. The results reveal alterations in gut microbiota co-metabolites, mainly at the high dose of RSV, such as hippurate, phenylacetyl glycine (PAG), p-cresyl glucuronide (p-CG), p-cresyl sulfate (p-CS) and 3-indoxylsulfate (3IS), as well as in osmolytes (creatine, creatinine, taurine and proline betaine). This metabolic variation could mean that RSV modulates the composition and/or function of the gut microbiota as well as its interaction with the host through the gut-microbiome-liver-kidney axis. For instance, RSV may interact with conjugating enzymes present in the intestine and liver. There were also modifications in metabolites of the tricarboxylic acid (TCA) cycle and energy metabolism (2-oxoglutarate, lactate and alanine), and diet-derived metabolites (pantothenate and trans-aconitate). These effects of RSV are perhaps related to its capacity to control energy homeostasis, provide renal protection, and downregulate some biomarkers of oxidative stress (e.g., glycoproteins). Such changes contribute to reduced oxidative stress and inflammation, which are associated with RSV-induced biological activity to improve various conditions, including metabolic disorders, obesity, and chronic and cardiovascular diseases.

1H NMR-based metabolomic profiling for identification of metabolites in Capsicum annuum cv. mirasol infected by beet mild curly top virus (BMCTV).

Beet mild curly top virus (BMCTV) is associated with an outbreak of curly top in chili pepper, tomato and other Solanaceae species, which can cause severe crop losses. The aim of this work was to obtain the 1H NMR metabolomic profiling of both healthy chili peppers (cv. mirasol) and infected chili peppers with BMCTV in order to find chemical markers associated to the infection process. Significant differences were found between the two groups, according to principal component analysis and orthogonal projections to latent structure discriminant analysis. Compared to the asymptomatic peppers, the symptomatic fruits had higher relative abundance of fructose, isoleucine, histidine, phenylalanine and tryptophan. Contrarily, the asymptomatic samples showed greater amounts of malonate and isobutyrate. These results suggest that in diseased chili peppers there are metabolic changes related to the viral acquisition of energy for replication and capsid assembly. This is the first study describing the chemical profiling of a polar extract obtained from Capsicum annuum infected by BMCTV under open field conditions.

Etapa de diagnóstico del Cáncer de Próstata ¿Estamos llegando a tiempo? / Prostate cancer stage at diagnosis. Are we running late?

INTRODUCCIÓN: El cáncer de próstata es el segundo cáncer más diagnosticado en hombres en Chile y el mundo. El tamizaje modificó la etapa de diagnóstico, siendo actualmente en EE.UU. un 80 por cinto localizada, 12 por cinto compromiso regional y 4 por ciento metastásico. Tamizaje con APE no está considerado dentro de un programa nacional en Chile. El objetivo de este estudio es caracterizar a la población diagnosticada de cáncer de próstata en un Hospital público en Chile. MATERIALES Y MÉTODO: Estudio descriptivo, retrospectivo. Se revisaron todas las fichas de los pacientes ingresados al GES por Cáncer de Próstata en el Hospital Carlos Van Buren de Valparaíso desde el año 2014 a 2016. RESULTADOS: Se revisaron 259 fichas y se analizaron 226. Edad promedio fue 70,5 años. 46 por ciento presentó APE sobre 20 ng/dL. 31 por ciento presentó metástasis. 42 por ciento recibió tratamiento paliativo. 57 por ciento se realizó tratamiento curativo, con edad promedio 67,4 años. De estos, 31,8 por ciento a cirugía, 68 por ciento índice Gleason <6 y 90 por ciento APE <20. 68 por ciento a RDT con o sin HT, 44 por ciento índice Gleason <6, 75 por ciento APE <20. DISCUSIÓN: El tamizaje del cáncer de próstata es un tema en discusión. En Chile no hay un programa nacional para realizar APE. Centros de atención primaria con acceso a APE tienen mayor tasa de tamizaje. La etapa al diagnóstico en nuestro centro difiere a las series de países desarrollados, siendo considerablemente superior la etapa metastásica. Esto podría deberse a la poca cobertura para detección temprana. Parece ser necesario implementar un programa nacional con cobertura de tamizaje para cáncer de próstata.(AU)

INTRODUCTION: Prostate cancer is the second most diagnosed cáncer in Chile and the world. Screening modified the stage at diagnosis, beeing now in the US 80 pertcent localized, 12 pertcent with regional compromised and 4 pertcent metastatic. Screening with PSA isn't considerd within a national program in Chile. The objetive of this study is to caracterize men diagnosed with prostate cancer at a public hospital in Chile. MATERIALS AND METHODS: Retrospective and descriptive study. Every patient who entered GES because of prostate cancer at the Carlos Van Buren Hospital from Valparaiso between 2014 and 2016 was review. RESULTS: 259 clinical records were review and 226 analized. Mean age was 70,5 years. 46 pertcent had PSA above 20 ng/dL. 31 % had metástasis. 42 % received paliative treatment. 57 % had curative treatment with a mean age of 67,4 years.From this group 31,8 pertcent surgery with a Gleason index <6 and 90 pertcent PSA <20. 68 pertcent had EBRT with or without HT, 44 pertcent of this group had Gleason index <6 and 75 pertcent PSA <20. DISCUSSION: Prostate cancer screening it's a debated topic. In Chile there's no national program to do a PSA. Primary care centers with acces to PSA have more rate of screening. Stage at diagnosis in our center difers from developed countries series, beeing metastatic stage considerably superior. This could be because of the low screening rate for early diagnosis. It seems necesary to implement a national program for prostate cancer screening.(AU)

1H NMR-based metabolomic fingerprinting to determine metabolite levels in serrano peppers (Capsicum annum L.) grown in two different regions.

Chili pepper (Capsicum annuum) is the most important and emblematic condiment in Mexican food. Serrano pepper is a variety of C. annuum that is traditionally cultivated in Mexico and commercialized in local markets. The aim of this study was to describe the 1H NMR metabolomic profiling of the aqueous phase of serrano peppers harvested from two distinct regions, in the states of Veracruz and Oaxaca, Mexico. According to the current results, aspartate citrate, lactate, leucine and sucrose were found at higher amount in the serrano peppers from Veracruz. On the other hand, acetate, formate, fumarate, malonate, phosphocholine, pyruvate and succinate showed the highest abundance in this product from Oaxaca. These are the main metabolites that distinguish one group from the other. The spectrometric method reported presently is characterized by great simplicity, robustness and reproducibility. Thus, this technique can be used for establishing reliable metabolomic fingerprints of serrano peppers grown under different environmental conditions.

Evaluación del efecto citotóxico de una resina dental a base de siloranos sobre fibroblastos L929 / Evaluation of the cytotoxic effect of a silorane-based dental resin on fibroblasts L929

Introducción: Las resinas dentales basadas en siloranos, son el resultado de la unión química de siloxanos y oxiranos. Dentro del proceso de evolución de las resinas, se han modificado sus formulaciones para optimizar sus propiedades físicas, mecánicas y estéticas. Sin embargo, aún presentan problemas como la contracción de polimerización, problemas alérgicos y toxicológicos. Objetivo: Determinar el potencial efecto citotóxico de las resinas a base de siloranos sobre la viabilidad celular en un cultivo de fibroblastos de la línea L929. Metodología: Se estudió la exposición de fibroblastos de ratón L929 a resinas dentales a base de siloranos Filtek p90 y metacrilatos Filtek p60 en tres tiempos de fotocurado durante 6 días. Se evaluó el efecto sobre la viabilidad celular mediante pruebas de exclusión vital, micrografías electrónicas y composición elemental de superficie (Mg, Na, K y Ca) por ESEM/EDAX. Resultados: La resina Filtek p90 mostró un mayor efecto citotóxico a tiempos de fotocurado prolongados (20 segundos o más) respecto a la resina Filtek p60. El efecto resultó más marcado para 20 segundos de fotocurado, ya que las concentraciones de Ca y K en la superficie celular fueron las más afectadas. Conclusiones: La resina dental Filtek p90 ejerce un efecto citotóxico relativamente bajo sobre las células de fibroblastos L929 (p <0.01). Su uso en la práctica odontológica se puede considerar bioseguro, pero un tiempo de fotocurado prolongado con la resina dental a base de siloranos puede afectar significativamente la viabilidad de los tejidos dentales.

Introduction: The resins dental based on siloranes, are the result of chemical bonding between siloxanes and oxiranes. In the process of evolution of the resins, they have changed their formulations to optimize their physical, mechanical and aesthetic properties. However have problems as polymerization shrinkage, allergic and toxicological problems. Objective: determine the potential cytotoxic effect of siloranes based resins on cell viability in cultured fibroblast line L929. Methodology: The exposure of mouse L929 fibroblasts to commercial dental resins based on either, methacrylate Filtek P60 or silorane Filtek P90 for three curing times was assessed throughout 6 days. Its effect on the cell viability was determined by vital exclusion tests, electron micrographs and ionic composition (Mg, Na, K and Ca) by ESEM/EDAX. Results: The dental resin Filtek p90 displayed a higher cytotoxic effect for prolonged curing times (20 seconds or more) than the resin Filtek P60. Moreover, such an effect was stronger at 20 seconds of curing, as long as the concentration of Ca and K on the cell's surface were the more affected. Conclusions: The dental resin Filtek p90 exerts a relatively low cytotoxic effect on L929 fibroblast cells (p < 0.01), and then, its use can be considered biologically safe in practical dentistry but a prolonged curing time of the silorane-based resin could significantly affect the viability of dental tissues.

Oligomerization of 10,16-dihydroxyhexadecanoic acid and methyl 10,16-dihydroxyhexadecanoate catalyzed by lipases.

The main monomer of tomato cuticle, 10,16-dihydroxyhexadecanoic acid (10,16-DHPA) and its methyl ester derivative (methyl-10,16-dihydroxyhexadecanote; methyl-10,16-DHHD), were used to study their oligomerization reactions catalyzed by five lipases: Candida antarctica lipase B (CAL-B), Rhizomucor miehei lipase (RM), Thermomyces lanuginosus lipase (TL), Pseudomonas cepacia lipase (PCL) and porcine pancreatic lipase (PPL). For 10,16-DHPA, optimum yields were obtained at 60 °C using toluene and 2-methyl-2-butanol (2M2B) as solvent, while for methyl-10,16-DHHD the bests yields were obtained in toluene and acetonitrile. Both reactions leaded to linear polyesters according to the NMR and FT-IR analysis, and there was no data indicating the presence of branched polymers. Using optimized conditions, poly(10,16-DHPA) and poly(methyl-10,16-DHHD) with Mw = 814 and Mn = 1,206 Da, and Mw = 982 and Mn = 860 Da, respectively, were formed according to their MALDI-TOF MS and ESI-MS data. The self-assembly of the polyesters obtained were analyzed by AFM.