Optical Investigation of Essential Oils Using Absorbance and Photoluminescence.

Essential oils are complex mixtures of organic substances with large commercial importance in the pharmaceutical, food, fragrance, and cosmetic industries due to their organoleptic and biological properties. Also, these materials are also luminescent what has taken several studies about its potential uses for the detection and quality control of essential oils, imaging, and for the investigation of the synergies of their constituents. Concerning this, the present work is dedicated to studying the optical properties of selected essential oils: citronella (Cymbopogon winterianus), Japanese mint (Mentha arvensis), clove bud (Syzygium aromaticum), and bergamot (Citrus bergamia). We carried out a comparative study of the photoluminescence and the ultraviolet-visible optical absorption (abs-UV-Vis) of these essential oils with their typical constituents. To inspect the effects of the intermolecular interactions on the optical response of these systems, mixtures between the essential oils constituents following the expected average percent mass fraction were also studied. From these experiments, the main results were bathochromic effects in the abs-UV-Vis spectra; excimer formation in citral, isopulegol, isomenthone, eugenol, and eugenyl acetate; excimer emission enhancing and specific solvent effect in the essential oils photoluminescence spectra. These results contribute to the knowledge of essential oils' applications, especially in the evaluation of components' interactions through a simple abs-UV-Vis assay.

Optimisation of Bjerkandera adusta culture conditions for the production of α-α-trehalose.

Several factors affect the vegetative growth of fungi, such as temperature, pH, and culture medium. In addition to mycelial growth, these factors affect metabolite production. There are limited studies that have identified the metabolites produced by the fungus Bjerkandera adusta, which have potential biotechnological applications. Here, we evaluated the effects of temperature, culture medium, and incubation time on the production of mycelial mass and metabolites of B. adusta isolated from Pinus taeda. The highest mycelial mass was obtained at 24 °C, in the potato dextrose and malt extract media, upon incubation for 28 and 35 days. The disaccharide α-α-trehalose was for the first time isolated and identified by X-ray diffraction in this fungal genus.

Lactones and quinones from the tubers of Sinningia aggregata.

Three new aromatic epsilon-lactones, aggregatins A (1), B (2), and C (3), a new naphthoquinone derivative, aggregatin D (4), and three known anthraquinones, 2-methylanthraquinone, 7-methoxy-2-methylanthraquinone, and 7-hydroxy-2-methylanthraquinone, were isolated from the tubers of Sinningia aggregata (Gesneriaceae). Compounds 1 and 4 and the anthraquinones showed marginal antimicrobial activity.