Esential oils extraction: a 24-hour steam distillation systematic methodology

Microwave-assisted hydrodistillation (MAHD) is an advanced hydrodistillation (HD) technique utilizing a microwave oven in the extraction process. MAHD of essential oils from the aerial parts (tops) of Thymus vulgaris L. (common thyme) was studied and the results were compared with those of the conventional HD in terms of extraction time, extraction yield/efficiency, chemical composition, quality of the essential oils and cost of the operation. MAHD was superior in terms of saving energy and extraction time (75min, compared to 4h in HD). Scanning electron microscopy (SEM) of thyme leaves undergone HD and MAHD provided evidences as to a sudden rupture of essential oil glands with MAHD. Gas chromatography-mass spectrometry analysis of the extracted essential oils indicated that the use of microwave irradiation did not adversely influence the composition of the essential oils. MAHD was found to be a green technology.

Matricine and its transformation product chamazulene are constituents of chamomile extracts. Both have been demonstrated to exert anti-inflammatory activity in vivo. Since preparations from chamomile are used for the treatment of inflammatory skin and bowel diseases, we studied the effects of these compounds on the leukotriene production in neutrophilic granulocytes. Chamazulene inhibited the formation of leukotriene B4 in intact cells and in the 105,000 x g supernatant fraction in a concentration-dependent manner. The IC50 values were 15 and 10 microM, respectively. Matricine showed no effect up to 200 microM. Chamazulene (IC50: 2 microM), but not matricine, blocked the chemical peroxidation of arachidonic acid. Additionally, matricine (up to 200 microM) had no effects on the cyclooxygenase and 12-lipoxygenase activities in human platelets. Therefore, it is concluded that chamazulene, but not matricine, may contribute to the anti-inflammatory activity of chamomile extracts by inhibiting the leukotriene synthesis and additional antioxidative effects.