## 3 Results
### EOs Rich in Alpha-Phellandrene and Their Main Biological Activities
#### 3.4.1 Antimicrobial Activity
[78] studied the effects of the EO from _S. arena_ against _S. aureus_. This research studied the antimicrobial properties of different varieties of the plant finding that the leaf EO which contained the highest amount of alpha-phellandrene (30.9%) had optimal MIC against _S. aureus_, but was not the best when compared with varieties also containing higher concentrations of limonene, suggesting that the synergistic effect of these two molecules could be even stronger than the separate effects. [PERSON] et al., [79], compared six different EOs in their activity against _Legionella pneumophila_. They found that the EO from _Juniperus phoenica_, containing the highest concentration of alpha-phellandrene, presented the lowest MIC against the different pathogen strains tested (MIC \(<\) 30.0 \(\upmu\)g/mL). Another study, [80], proved the potential of this molecule used both as an antimicrobial and as a food preservative. [PERSON] et al. tested the EO of _Alchorea cardiolia_, in which alpha-phellandrene was one of the major components, finding strong activity against _S. aureus_ (MIC = 78.0 \(\upmu\)g/mL) and _A. niger_ (MIC = 156.0 \(\upmu\)g/mL). Another EO studied for its activity against _S. aureus_ was extracted from _Tussilago farfara_ (alpha-phellandrene 26%) and showed an MIC\({}_{50}\) of 368.0 \(\upmu\)g/mL. This group, headed by [PERSON] [81], also studied its activity against _E. coli_ with a MIC\({}_{50}\) of 468.0 \(\upmu\)g/mL. [PERSON] et al. [21] focused, likewise, on these two specific and common pathogens, finding that the EO from _Canarium ovatum_, with 64.9% of alpha-phellandrene, had an MIC\({}_{50}\) of 180.0 and 310.0 \(\upmu\)g/mL against _E. coli_ and _S. aureus_, respectively. Further proof of the antimicrobial potential of this molecule was given by [PERSON] et al. [82], testing _Nigella sativa_ seed EO against different bacterial strains, and obtaining promising results against _Acinetobacter baumannii_. [PERSON] et al. [41] tested the EO extracted from _S. molle_ and it showed an MIC against _Staphylococcus aureus_ of 0.25 mg/mL. Finally, [PERSON] et al. [83] found that the EO from _Rosnarrinus officinalis_ (alpha-phellandrene 11.1%) could be considered as a potential treatment against endometriis-causing microorganisms in mares. [PERSON] et al. [84] evaluated the antifungal effects of the EOs extracted from _Senecio amplexicaulis_, which had alpha-phellandrene as its main compound (48.6%). The experiment showed that the EO had strong antifungal activity in a concentration that ranged between 157.0 to 199.3 \(\upmu\)g/mL against different fungal species (_Macrophomina phaseulina_, _Riliactonia solani_, _Sclerotin volfsii_, _Fusarium oxysporum_ and _Pythium debaryanum_). Likewise, [PERSON] et al. [85] tested the EO from _E. camaldulensis_, with an alpha-phellandrene concentration of 10%, on different species from the _Fusarium_ genus showed that the EO, at a concentration of 7.0-8.0 \(\upmu\)L/mL after five days of incubation, completely inhibited mycelial growth in all the tested pathogens, and had an MIC in the same range of concentration. Another antifungal activity study of this molecule was led by [PERSON] et al. [86], focusing on the EO extracted from _Foeniculum vulgare_ which displayed its effects against _Cryptococcus neoformans_ and _C. albicans_ (MIC of 0.32 and 0.64 \(\upmu\)L/mL, respectively) and inhibited the filamentation of _C. albicans_ with a concentration of 0.08 \(\upmu\)L/mL.