Chemical reactions in perfume ageing

Evaluation of selected quality parameters to monitor essential oil alteration during storage

Several analytical methods including high-performance liquid chromatography (HPLC) were applied on essential oils to establish a set of suitable quality parameters for monitoring changes during storage. For this purpose, 7 essential oils derived from various plant families were exposed to possible worst-case conditions for up to 3 mo at 38 °C under cool white light in the presence of atmospheric oxygen. After storage and immediate freezing at -80 °C to stop further alterations until analysis, individual physicochemical parameters were assessed and are discussed with regard to the precision of the respective method as well as suitability to monitor aging processes. To determine conductivity and pH values, a work-up of essential oils by water extraction was established. Conductivity, peroxide value as well as pH turned out to be suitable parameters to picture alterations. Additionally, HPLC fingerprints were monitored by diode array detection to track underlying chemical changes in essential oil composition.

PRACTICAL APPLICATION

This study evaluates a set of analytical parameters to track changes during essential oil storage. On this basis, quality alterations can be monitored.

Determination of Teloschistes flavicans (sw) norm anti-inflammatory activity

BACKGROUND

Lichens produce a variety of substances that possesses pharmacological actions. However, rare products are submitted to rigorous scientific tests or have the risk potential or side effects evaluated. The lack of medical and sanitary control, absence of accurate botanical identification or purity certification, founded in diverse natural products, may represent great danger to population health. This work aimed to evaluate toxic effects and anti-inflammatory action in vivo of Teloschistes flavicans (Sw.) Norm. (TFN) unrefined extracts, as well as determinate its main constituents.

METHODS

The carrageenan induced paw edema and cotton pellet implant induced granuloma methods were utilized, besides a classic acute toxicity test. TFN acetone extract inhibited carrageenan paw edema on 60, 120, and 180 min (inhibition percentiles of 45.03%, 60.59% and 41.72%).

RESULTS

TFN ethereal (inhibition percentiles of 23.95% and 29.01%) and chloroform (inhibition percentiles of 28.8% and 22.04%) extracts inhibited edema on 120 and 180 min. None of the extract inhibited the granuloma development. None of the extract caused death or other acute toxicity signs. Vicanicine (60.26% in ethereal extract and 51.17% in acetone extract), parietine (9.60% in ethereal extract and 15.38% on second), falacinol (0.78% in ether and 14.95% in acetone) and very low concentration of falacinal (0.15% in ethereal extract and 3.32% in acetone extract) were detected in the medicine.

CONCLUSIONS

The tested extracts have antiedematogenic activity, but are not effective on subchronic inflammation. The extracts do not present toxic effects in administered doses.

Contact Allergens Formed on Air Exposure of Linalool. Identification and Quantification of Primary and Secondary Oxidation Products and the Effect on Skin Sensitization

Linalool (3,7-dimethyl-1,6-octadien-3-ol) is an important fragrance chemical, frequently used in scented products because of its fresh, flowery odor. Linalool is an unsaturated hydrocarbon and is therefore susceptible to oxidation in the presence of air. The primary oxidation products, that is, hydroperoxides, formed in the autoxidation process, are reactive compounds that can be suspected to act as sensitizers. In the present investigation, we studied the autoxidation of linalool with emphasis on the formation of hydroperoxides. The oxidation products were isolated using flash chromatography and preparative HPLC and were identified with NMR and GC/MS, using synthesized reference compounds. Two hydroperoxides and several different secondary oxidation products were identified, among which some contain structural features that make them potential allergens. The amounts of linalool and the major oxidation products were quantified over time, using GC and an HPLC-method, suitable for the analysis of thermolabile primary oxidation products. The hydroperoxide 7-hydroperoxy-3,7-dimethylocta-1,5-diene-3-ol was found to be present in 15% in an oxidized sample. The local lymph node assay (LLNA) was used to investigate the sensitizing potential of pure linalool, two samples of air-exposed linalool, and oxidation products of linalool (an alpha,beta-unsaturated aldehyde, a mixture of two hydroperoxides, and an alcohol). Pure linalool showed no sensitizing potential. The air-exposed samples of linalool produced clearly positive responses, and the hydroperoxides were the strongest allergens of the tested oxidation products. The study demonstrates the importance of autoxidation on the sensitizing potential of linalool. We also conclude that the sensitizing potential differs with the composition of the oxidation mixture and thus with the air exposure time.