Chemical Composition of Algerian Pinus halepensis Mill. Essential Oils Obtained by Hydrodistillation and Solvent-Free Microwave Extraction Methods and Their Biological Activities

Fresh cones of Pinus halepensis Mill., collected from Constantine (sample 1) and Jijel provinces (sample 2) in northeastern Algeria, were extracted by conventional hydrodistillation (HD) and by solvent-free microwave extraction (SFME). GC and GC/MS analyses showed that the HD essential oils of the two samples were characterized by the presence of respective higher contents of β-pinene (40.3%, 28.2%,), β-pinene (4.5%, 2.5%), β-myrcene (16.8%, 31.5%) and caryophyllene oxide (3.2%, 7.0%) than the SFME essential oils in respective percentages of β-pinene (27.4%, 12.1%), β-pinene (2.6%, 1.0%), β-myrcene (16.4%, 14.8%) and caryophyllene oxide (0.6%, 2.2.2). (E)-Caryophyllene (35.5%, 51.2%) and α-humulene (6.4%, 10.7%) were found in higher percentages in SFME than in HD essential oils where they occurred with the respective percentages of 18.1%, 20.1%, and 3.5%, 4.2%. Exclusively, HD and SFME essential oils of sample 1 were characterized by the main presence of limonene (5.3%, 2.6%, respectively). These oils were tested against acetyl- and butyrylcholisterase, a-amylase and urease. HD essential oil exhibited a higher acetylcholinesterase (97.46 ± 2.04%) and butyrylcholinesterase (85.39 ± 4.01%) inhibition than the SFME essential oil (77.24 ± 0.90% and 68.01 ± 5.04%, respectively) at a concentration of 200 mg/mL. Moreover, the inhibition of α-amylase by both HD and SFME essential oils (32.63 ± 2.75 and 33.76 ± 0.34%, respectively) at a concentration of 2000 μg/mL, was nearly close to Acarbose (37.21 ± 3.44%), used as a standard. However, HD and SFME essential oils showed a weak urease inhibition (17.78 ± 1.79 and 45.73 ± 0.04%, respectively), at a concentration of 400 mg/mL, compared to the standard.