Composition, antioxidant activity and safety of ecuadorian essential oils as natural resource for functional ingredients

Amazonian plants are particularly interesting since the Amazonian basin is one of the most important biodiversity hotspots, where the ecological conditions and high density and diversity of species per unit area drive the plant secondary metabolism to biosynthetic pathways which are particularly rich in different chemical structures [1]. Starting from this point of view, essential oils (EOs) from fresh crude drugs of Ecuadorian Curcuma longa (Zingiberaceae), Cymbopogon citratus (Poaceae), Ocimum micranthum (Lamiaceae), and Zingiber officinale (Zingiberaceae) were chemically characterized by HPTLC, GC-MS, HS-GC. Over eighty constituents were identified, and ar- and alpha-turmerone (23.35-22.81%), geraniol (39.43%), eugenol (50.97%) and alpha-zingiberene (15.45%), respectively, were found as major components. With the object to find possible functional applications, the EOs were tested for several bioactivities and compared to those achieved for Thymus vulgaris and Melaleuca alternifolia EOs considered as positive references. Antioxidant activity was checked through DPPH and ABTS+ assays performed both by spectrophotometric and TLC-bioautographic strategies, always evidencing O. micranthum phytocomplex as the most effective (IC50 values of 0,012mg/ml for DPPH and 0,0013mg/ml for ABTS+). For each EO the most bioactive compounds were isolated and characterized. Antimicrobial activity of the whole EOs and of their most volatile fraction was performed against a total of eight bacteria (4 Gram+ and 4 Gram-) and two yeasts [2]. All microorganisms showed similar sensitivity to the phytocomplexes with values sometimes comparable or more interesting than those of Thyme and Tea tree oils. Among the amazonian EOs, the best values of Minimum Inhibitory Concentration (MIC) has been expressed by Cymbopogon citratus with interesting values against all tested strains, while Curcuma longa EO expressed always poor values. TLC-bioautographic assay evidenced the most bioactive compounds in each phytocomplex and their different efficacy profile against different microorganisms [3]. Checked the citotoxicity and potential genotoxic activity, mutagen protective properties by means of Ames test and S. cerevisiae D7 strain were assayed. All the EOs displayed geno-protective values with particular reference to frame-shift and gene-point mutations. This findings suggest the possibility to employ these EOs as safe flavouring functional ingredients for foods, cosmetics or dietary supplements.