Essential Oil Extraction, Chemical Analysis and Anti-Candida Activity of Calamintha nepeta (L.) Savi subsp. glandulosa (Req.) Ball—New Approaches

Abstract

A comprehensive study on essential oils extracted from different Calamintha nepeta (L.) Savi subsp. glandulosa (Req.) Ball samples from Tarquinia (Italy) is reported. In this study, the 24-h steam distillation procedure for essential oil preparation, in terms of different harvesting and extraction times, was applied. The Gas chromatography–mass spectrometry (GC/MS) analysis showed that C. nepeta (L.) Savi subsp. glandulosa (Req.) Ball essential oils from Tarquinia belong to the pulegone-rich chemotype. The analysis of 44 samples revealed that along with pulegone, some other chemicals may participate in exerting the related antifungal activity. The results indicated that for higher activity, the essential oils should be produced with at least a 6-h steam distillation process. Even though it is not so dependent on the period of harvesting, it could be recommended not to harvest the plant in the fruiting stage, since no significant antifungal effect was shown. The maximum essential oil yield was obtained in August, with the highest pulegone percentage. To obtain the oil with a higher content of menthone, September and October should be considered as the optimal periods. Regarding the extraction duration, vegetative stage material gives the oil in the first 3 h, while material from the reproductive phase should be extracted at least at 6 or even 12 h.

Antimicrobial and Antibiofilm Activity and Machine Learning Classification Analysis of Essential Oils from Different Mediterranean Plants against Pseudomonas aeruginosa

“…As previously described, fresh aerial parts of CG [19], FV [21], and RS were collected in a wild area about 15 km from Tarquinia city (Province of Viterbo, Italy), in the archaeological zone near the Etruscan temple Ara della Regina (42°15′31.8″ N, 11°48′08.7″ E). The material was collected in summer and early autumn periods of the year 2015 and monitored for four (CG) and three (FV) months, from July to October, thus covering pre-, during-, and post-flowering periods.…”

“…EOs have been isolated, as previously reported, by direct steam distillation using a 62 L steel distillator apparatus (Albrigi Luigi E0131, Verona, Italy) [19,20,22]. Briefly, plant materials (about 1.5 kg) were subjected to fractioned steam distillation [20], collecting EOs at six interval times of 1, 2, 3, 6, 12, and 24 h, in case of RS a seventh fraction was collected after 30 h.…”

“…The gas chromatographic/mass spectrometric (GC/MS) EOs analyses were carried out with a GC-MS and GC-FID similarly as previously described [19,22]. …”

“…Taking into consideration the same plant variety, EO composition can differ according to geographical region, seasonality, and extraction methodology [19,20,21]. …”

“…glandulosa (Req.) Ball (CG) [19], Foeniculum vulgare Miller (FV) [21], and Ridolfia segetum Moris (RS). Furthermore, quantitative activity–composition relationships (QCAR) were developed through machine learning classification approaches with objective of discovery the chemical components mainly responsible for the anti-biofilm activity.…”