Search

Since its first isolation in 1934, hyaluronic acid (HA) has been studied across a variety of research areas. This unbranched glycosaminoglycan consisting of repeating disaccharide units of N-acetyl-D-glucosamine and D-glucuronic acid is almost ubiquitary in humans and in other vertebrates. HA is involved in many key processes -including cell signaling, wound reparation, tissue regeneration, morphogenesis, matrix organization and pathobiology-, and has unique physico-chemical properties -such as biocompatibility, biodegradability, mucoadhesivity, hygroscopicity and viscoelasticity. For these reasons, exogenous HA has been investigated as drug delivery system and treatment in cancer, ophthalmology, arthrology, pneumology, rhinology, urology, aesthetic medicine and cosmetic. To improve and customize its properties and applications, HA can be subjected to chemical modifications: conjugation and crosslinking. The present review gives an overview regarding HA, describing its history, physico-chemical, structural and hydrodynamic properties, and biology –occurrence, biosynthesis (by hyaluronan synthases), degradation (by hyaluronidases and oxidative stress), roles, mechanisms of action and receptors. Furthermore, both conventional and recently emerging methods developed for the industrial production of HA and its chemical derivatization are presented. Finally, the medical, pharmaceutical and cosmetic applications of HA and its derivatives are reviewed, reporting examples of HA-based products which currently are on the market or are undergoing further investigations.

Piper pubinervulum C. DC., es una planta medicinal utilizada por los indígenas amazónicos del sur del Ecuador, las hojas poseen características aromáticas. El objetivo de la presente investigación es la de extraer y analizar las propiedades químicas y de actividad biológica del aceite esencial proveniente de las hojas.El estudio de composición química a través de GC-EM y RMN 1H arrojó la detección de 44 constituyentes dentro de los cuales b cariofileno, isoeugenol-metil éter, asarona y el nerolidol fueron los mayoritarios. La Actividad antioxidante del aceite fue evaluada por los métodos DPPH (1,1-diphenyl-2-picrylhydrazyl), ABTS (2,2’-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt) y la fotoquimioluminiscencia (PCL). Adicionalmente se realizaron estudios de actividad empleando (HP)TLC-DPPH bioautográficos. La actividad antimicrobiana fue evaluada por el método de difusión de disco en dos bacterias Gram+, dos bacterias Gram- y dos levaduras. Los resultados más interesantes se producen con las dos levaduras Candida tropicalis (MIC 0,77mg/ml) y Candida albicans (MIC0,33mg/ml) donde la actividad fue similar al aceite esencial de Thymus vulgaris el estándar natural de referencia. Los buenos resultados con respecto a la actividad antifúngica nos llevan a concluir que el aceite esencial podría ser usado con esta finalidad. // Piper puvinervulum C. DC. is a medicinal plant used by Amazon Indians in southern Ecuador, the leaves possess aromatic characteristics. The objective of this research is to extract and analyze the chemical properties and biological activity of the essential oil from the leaves. The study of the chemical composition based on analysis GC-MS and 1H RMN data resulted in the identification of 44 compounds including the main components: b-caryophyllene (1), isoeugenol methyl ether (2), asarona (3), and nerolidol (4). The antioxidant potential of the oils was assessed with the DPPH (1,1-diphenyl-2-picrylhydrazyl), ABTS (2,2’-Azinobis(3- ethylbenzothiazoline-6-sulfonic acid) diammonium salt), Photochemiluminescence and bioautographic HPTLC-DPPH methods. The antimicrobial activity was evaluated by means of disc diffusion method while the antimicrobial effect was evaluated in two Gram+ bacteria, two Gram- bacteria, and two yeasts. The essential oil was found effective against Candida tropicalis (MIC0,77 mg/ml) and Candida albicans (MIC0,33mg/ml) yeasts in a manner similar to the reference essential oil of Thymus vulgaris. The positive results in terms of antifungal activity suggest that the essential oil could be used for this purpose.

Following the recent output of scientific publications in the matter of synergic activity between different antioxidants, we have undertaken the present study with the aim to synthesize new molecules with radical-scavengers activity based on the conjugation of bioactive portions (i.e. phenols, cysteine, methionine or tyrosine), characterized by different structures and mechanisms of action, to promote the simultaneous quenching of different radical species in the site of the oxidative damage. In this context, derivatives of phenolic acid, aminoacids and dopamine have been also prepared. The newly synthesized compounds were evaluated in vitro applying specific and complementary antioxidant test such as DPPH assay and ORAC test. As emerged from the evaluation, prerequisites for the activity of the synthesized molecules were: i) the maintenance of at least two hydroxylic groups on the aromatic moiety of phenolic portion, ii) the presence of a spacer between the aromatic moiety and the carbonilic group.