In vitro analysis of a local polymeric device as an alternative for systemic antibiotics in Dentistry

Abstract The development of a biodegradable material with antimicrobial properties for local applications is required in the prevention and treatment of infectious diseases. The objective of this study was to produce blends of poly-L-lactide acid (PLLA) synthetic polymer associated with several antimicrobials, as an alternative in the prevention and treatment of infections, as well as to evaluate its cytotoxicity, release of antimicrobials and inhibit bacteria growth. Blends of PLLA added with 20% Amoxicillin, Metronidazole, Clindamycin or Azithromicyn were used to produce Films (F) or Meshs (M) by casting and electrospinning methods, respectively. Standardized discs of the films and meshs were stored in buffer solutions (pH 5 or 7.4) and aliquots were analyzed by high performance chromatography (HPLC) during 168 hours. Cytotoxicity on human gingival fibroblasts was tested after 24, 48 and 72h by MTT reaction. The antimicrobial capacity was determined against P. gingivalis and S. pyogenes. The specimens were weighed after 3 and 6 months of storage for degradation analysis. SEM was performed to control interfaces and degradation. Antimicrobials presented a continuous and exponential drug release. Analysis showed that both M and F were able to inhibit S. pyogenes and P. gingivalis growth, indicating the release of active antimicrobial agents. The products were not toxic to the fibroblasts. Amoxicillin-film showed more degradation than PLLA at both pHs (p < 0.05), whereas Azithromycin-meshes were more degraded than PLLA at pH 7.4 (p < 0.05). PLLA association with antimicrobials is biocompatible and may represent a potential tool for the local delivery of antimicrobials.

Lycopene entrapped in human albumin protects: 2'-deoxyguanosine against singlet oxygen damage

La generación de singletes de oxígeno molecular (O²) ha sido mostrada en sistemas biológicos, tales como en la fotooxidación de una variedad de compuestos biológicos y xenobióticos ("acción fotodinámica") y también en reacciones enzimáticas. La alta reactividad que presenta el O² con compuestos no saturados, sulfuros y grupos aminos es debido a su electrofilicidad y tiempos de vida relativamente altos. Así, compuestos biológicos que contengan estos grupos funcionales que incluyan ácidos grasos, proteínas, enzimas y DNA interactuan con singletes de oxígeno. Es interesante hacer notar el rol de la nutrición en la prevención y patogénesis del cáncer. Estudios epidemiológicos en humanos han sugerido que hay un importante rol de los carotenoides en la prevención del cáncer. Compuestos como lipoproteínas y oxicarotenoides están presentes en niveles significantes en las células y el plasma. Biomoléculas que presentan dobles enlaces conjugados extensos como los carotenoides, actúan eficientemente como inhibidores físicos del O² y son mucho menos eficientes químicamente. En este estudio hemos observado el efecto proteico del ß-caroteno y licopeno, "atrapados" en albúmina humana (HSA), al ataque oxidativo de O² a 2'-deoxiguanosina (dGuo). Para generar singletes de oxígeno hemos usado la fotosensibilización con azul de metileno asociado con resina Chelex o bien, rosa de bengala-polímero (Sensitox) y la termodescomposición del endoperóxido soluble en agua 3,3'-(1,4-naftilideno) dipropionato. Se registró la detección de 8-oxo-7,8-dihidro-2'-deoxiguanosina (8-oxidGuo) y 4-hidroxi-8-oxo-7,8-dihidro-2'-deoxiguanosine (4-OH-8-oxodGuo) por medio de cromatografía HPLC en fase reversa, con detección UV electroquímica y "electrospray ionization mass spectrometry". Los resultados muestran una significante reducción de la cantidad de 8-oxodGuo en presencia de licopeno. Los porcentajes de 4-OH-8-oxodGuo y 8-oxodGuo fueron 50 por ciento y 70 por ciento menores que los controles, respectivamente. Estos datos indican que los carotenoides "atrapados" en albúmina pueden ser eficientes inhibidores del O², y de esta manera ejercer un efeto de protección frente al deterioro capaz de producir esta molécula en estado excitado

Singlet molecular oxygen: generation, reactivity, identification and biological effects

Electronically excited singlet molecular oxygen ((1)O2)) is of great importance in chemical and biological systems due to its high reactivity and involvement in physiological and pathological processes. It is a simple and useful reagent in organic synthesis of peroxides, endoperoxides, hydroperoxides, and dioxetanes. In biological systems, (1)O2 has been implicated in: i) Defense mechanisms of living organisms such as phagocytosis; ii) degradative oxidation of endogenous hallucinogens; iii) hormonal activity of prostaglandins; iv) photochemotherapy utilizing the photodynamic action of synthetic dyes; v) photosensitivity to drugs like chlorpromazine and vi) inborn errors of metabolism exemplified by erythropoietic porphyria. The high reactivity of (1)O2 with unsaturated compounds, sulfides and amines arises from its high electrophilicity and relatively long lifetime (2-4 ms in H2O and ~700 ms in CCI4). Thus, biological targets for (1)O2 having the above functional groups include unsaturated fatty acids, proteins, and DNA. Extensively conjugated biomolecules such as carotenoids act as chemical and physical quenchers of (1)O2 and hence provide protective mechanisms against the deleterious effects of this excited state of molecular oxygen. However, due to the difficulties involved in obtaining (1)O2 free from other reactive contaminants, there is a paucity of detailed studies on the mentioned aspects of (1)O2 biochemistry. Chemical and dye-sensitized photophysical methods are available to prepare (1)O2. The aim of this work is to give a general view on (1)O2 with regard to its chemical generation, reactivity with biologically important compounds, detection and its role in biological systems.

Enolizable carbonyl and imino metabolites may act as endogenous sources of reactive oxygen species

Highly reactive oxyradicals and electronically excited triplet carbonyls can be generated in vitro by iron complexes and heme enzyme-catalyzed aerobic oxidation of synthetic or naturally occurring substances capable of enolization in aqueous medium. Monoenols and enamines, obtained by (alpha-methyne-carbonyl and -imine enolization, undergo dioxygen insertion and ultimately originate triplet species; e.g., isobutanal, 3-methylacetoacetone, Schiff bases. In turn, (alpha-hydroxy- and (alpha-aminocarbonyls (e.g., carbohydrates, 5-aminolevulinic acid) tautomerize to enediols and enolamines and yield oxyradicals, initiated by electron transfer to dioxygen, as polyphenols (e.g., 6-hydroxydopamine) and polyphenolamines do. Free radicals and excited species have been implicated in several normal and pathological processes. We here briefly review our contributions to this research area, emphasizing a possible in vivo prooxidant role for 5-aminolevulinic acid, the heme precursor accumulated in several porphyric disorders (e.g., lead poisoning, acut intermittent porphyria, tyrosinosis).