## 2 Materials and Methods
### Gas Chromatography Working Conditions  
For qualitative analysis, a GC-MS system (Thermo Electron Corporation, Austin, TX, USA) was used that consisted of a capillary gas chromatograph (Thermo-Quest CE Instruments Trace GC 2000 series) and an MS detector (Finnigan Trace). For analysis, a Quadrex 5 MS fused silica capillary column (column length (\(l\)) = 30 m, inner diameter (i.d.) = 0.32 mm, stationary phase film thickness (\(d_{j}\)) = 0.5 \(\upmu\)m; Quadrex Corporation, Woodbridge, CT, USA) and on-column injection (2 \(\upmu\)L) were used. The flow rate of the helium (He) carrier gas was 5 mL min\({}^{-1}\). The temperature gradient was as follows: 2 min at 50 \({}^{\circ}\)C; temperature rise to 200 \({}^{\circ}\)C at a rate of 5 \({}^{\circ}\)C min\({}^{-1}\); 2 min at 200 \({}^{\circ}\)C; temperature rise to 220 \({}^{\circ}\)C at a rate of 15 \({}^{\circ}\)C min\({}^{-1}\); and 10 min at 220 \({}^{\circ}\)C. The temperature of the injector was 220 \({}^{\circ}\)C. Identification of the separated analytes was performed using the NIST mass spectral library (National Institute of Standards and Technology, Gaithersburg, MD, USA). A capillary gas chromatograph (Fisons Instruments GC 8000 Series) with a flame ionisation detector (FID) (Fisons Instruments, Milan, Italy), on-column injection (5 \(\upmu\)L), and a Chromapack CP-Sil 8 CB capillary column (column length (\(l\)) = 50 m, inner diameter (i.d.) = 0.53 mm, stationary phase film thickness (\(d_{f}\)) = 1 \(\upmu\)m; Agilent, Santa Clara, CA, USA) were used for quantitative analysis. Helium (He) was used as the carrier gas at the flow rate of 4 mL min\({}^{-1}\). The injector temperature was set at 250 \({}^{\circ}\)C. The temperature gradient was as follows: 5 min at 50 \({}^{\circ}\)C; temperature rise to 150 \({}^{\circ}\)C at a rate of 15 \({}^{\circ}\)C min\({}^{-1}\); temperature rise to 220 \({}^{\circ}\)C at a rate of 15 \({}^{\circ}\)C min\({}^{-1}\); 5 min at 200 \({}^{\circ}\)C; temperature rise to 250 \({}^{\circ}\)C at a rate of 20 \({}^{\circ}\)C min\({}^{-1}\); and 20 min at 250 \({}^{\circ}\)C. Calibration curves for the eight compounds were constructed using the commercial standards by injection of 1, 2, 3, 4, and 5 \(\upmu\)L aliquots of 5 mg mL\({}^{-1}\)\(n\)-hexane solutions into the GC-FID system in triplicate (n = 3). The respective limits of detection (LOD) and limits of quantification (LOQ) were determined based on the standard deviation of the peak height taken as the noise measure (SD) and the slope (a) of the corresponding calibration curve (y = ax + b). The used equations were as follows: LOD = 3.3 \(\times\) SD/a and LOQ = 10 \(\times\) SD/a. For identification of the bioactive compounds, prior to SPME-GC-MS analysis, the HPTLC zones of interest were eluted with ethanol into vials sealed with a silicon/PTFE septum (20 mL headspace) with the use of the TLC-MS Interface (CAMAG) [43]. A CTC Combi PAL (CTC Analytics AG, Zwingen, Switzerland) automatic multipurpose sampler with a 65 \(\upmu\)m StableFlex carboxen/polydimethylsiloxane/divinylbenzene (CAR/PDMS/DVB) SPME fibre (Supelco, Bellefonte, PA, USA) was used for static headspace-solid phase microextraction (sHS-SPME). A 5 min incubation at 100 \({}^{\circ}\)C was followed by a 10 min extraction at 100 \({}^{\circ}\)C exposing the fibre to the headspace. Then, the fibre was transferred immediately to the GC-MS injector port and desorbed for 1 min at 250 \({}^{\circ}\)C. A Fibre Bakeout Station was applied to clean and condition the SPME fibre in a pure nitrogen atmosphere at 250 \({}^{\circ}\)C for 15 min. Analyses were performed using an Agilent 6890N/5973N GC-MSD (Santa Clara, CA, USA) system equipped with a capillary column (Agilent SLB-5 MS, 30 m \(\times\) 250 \(\upmu\)m \(\times\) 0.25 \(\upmu\)m).