**4. Antifungal activities of essential oils**

Considering the case of fungi (eukaryotes), they have similarities with their guests both at a cellular and molecular level. Therefore, fungi are a difficult target to attack [22]. Currently there is evidence of the emergence of drug-resistant strains, infections associated with biofilms and the side effects of prescription drugs present difficulties for the prevention and treatment of fungal infections.

Therefore, invasive fungal infections are associated with very high morbidity and mortality rates [23]. Studies have been reported where various fungal pathogens of plants and humans, including yeasts, have been found to be susceptible to EOs [24]. There is evidence that pathogenic yeasts sensitive to drugs, as well as resistant ones, including the main pathogen of humans, *C. albicans*, were inhibited using terpenoid-rich EOs [25].

The efficiency using EOs and their components against the biofilms of *C. albicans* resistant to drugs is important. These activities can be mediated through the inhibition of the ergosterol membrane and the signaling pathways involved in the morphogenesis of the hyphae [26].

### **5. Cancer preventive properties using essential oils**

The treatment in malignant cells represents a challenge for current medicine; In this sense, many plants with phytotherapeutic properties (such as taxol) have shown their efficiency as an alternative method in combating and proliferating malignant cells that can lead to cancer such as: colon cancer, gastric cancer, human liver tumor, lung tumors, breast cancer and leukemia, which have reported a decrease after treatment with OEs [27].

For example, there is evidence that *Cymbopogon martini* geraniol (i.e., palmarosa oil) manages to interfere with membrane functions, ionic homeostasis, and cell signaling events in cancer cell lines, which inhibits synthesis of DNA and a subsequent reduction in the size of the colon tumor [28].

In the case of terpenoids and constituent polyphenols, obtained from plant EOs, they can prevent the proliferation of tumor cells by necrosis or induction of apoptosis [29].

Citral present in lemongrass oil is found useful against the early phase hepatocarcinogenesis [30]. Another example, well known for its anticancer properties is the use of EO from *Allium sativum* (garlic). The preventive activity of chemotherapy is limited to the ability of garlic to suppress detoxifying enzymes of drugs [31]. Additionally the use of EO of lemon balm (*M. officinalis*) inhibits the growth of a series of human cancer cell lines [32].

In this way, it is well established that OEs exhibit a capacity to act as antioxidants and interfere with the mitochondrial functions of cells, decreasing metabolic events (for example, increased cellular metabolism, mitochondrial overproduction and permanent oxidative stress) characteristic of the development of malignant tumors [33].

#### **6. Antiviral efficacy of essential oils**

In addition to the aforementioned antimicrobial activities, there are plants that have significant antiviral properties, for example: *Origanum vulgare* anti-viral inactivation of enteric virus [34]; *Eucalyptus globulus* (Eucalyptus oil) activity against respiratory viruses [35]; *Salvia fruticosa*, antiviral activities [36], among

**73**

**Figure 1.**

*Essential Oils in the Development of New Medicinal Products*

(cytomegalovirus) and thus prevent viral activation [41].

cloves > cinnamon > nutmeg > basil > oregano > thyme [46].

other. It is believed that the inhibition of viral replication is attributed to the presence of the monoterpene, sesquiterpene and phenylpropanoid components of

EOs of eucalyptus and thyme possess inhibitory activity against the herpes virus [38]. Evidence has been found that OEs of *Melaleuca alternifolia* showed significant efficacy in the treatment of herpes virus [39]. The way in which the adsorption or entry of virus into host cells is prevented is associated with the ability to interfere with the viral envelope structures. For example, oregano oil causes dissolution of the HSV envelope to attenuate its infectious capacity [40]. There is evidence that the components of EOs specifically inhibit the early expression of the gene in CMV

A cause of damage suffered by macromolecules is due to the oxidative stress that is associated with the generation of free radicals and reactive oxygen species (ROS) [42]. Published works show that oxidative damage is related to several health problems such as aging, arteriosclerosis, cancer, Alzheimer's disease, Parkinson's

Cellular balance of free radicals is maintained by different antioxidants. Flavonoids, terpenoids and phenolic constituents of EOs exhibit significant antioxidant effects [44]. There is evidence that species, such as: *Origanum majorana*, *Tagetes filifolia*, *Bacopa monnieri* and *C. longa* oils have pronounced antioxidant capacities [45]. In general, efficiency among the essential oils with good radical and antioxidant removal properties are made to order. We can mention species such as:

Essential oils can be obtained from plant material by three main methods [47]

*Obtaining essential oils by entrainment with steam (external source of steam, e.g., boiler); distillation with water vapor (wet steam obtained by heating the water to its vigorous boiling); and hydrodistillation (heating of* 

*the water with the submerged plant material, generally very delicate, for example, flowers).*

*DOI: http://dx.doi.org/10.5772/intechopen.86572*

**7. Essential oils as antioxidants**

disease, diabetes and asthma [43].

**8. Obtaining essential oils**

view **Figure 1**.

the EOs [37].

*Essential Oils in the Development of New Medicinal Products DOI: http://dx.doi.org/10.5772/intechopen.86572*

*Essential Oils - Oils of Nature*

using terpenoid-rich EOs [25].

the morphogenesis of the hyphae [26].

decrease after treatment with OEs [27].

apoptosis [29].

tumors [33].

reduction in the size of the colon tumor [28].

of a series of human cancer cell lines [32].

**6. Antiviral efficacy of essential oils**

**4. Antifungal activities of essential oils**

Considering the case of fungi (eukaryotes), they have similarities with their guests both at a cellular and molecular level. Therefore, fungi are a difficult target to attack [22]. Currently there is evidence of the emergence of drug-resistant strains, infections associated with biofilms and the side effects of prescription drugs present

Therefore, invasive fungal infections are associated with very high morbidity and mortality rates [23]. Studies have been reported where various fungal pathogens of plants and humans, including yeasts, have been found to be susceptible to EOs [24]. There is evidence that pathogenic yeasts sensitive to drugs, as well as resistant ones, including the main pathogen of humans, *C. albicans*, were inhibited

The efficiency using EOs and their components against the biofilms of *C. albicans* resistant to drugs is important. These activities can be mediated through the inhibition of the ergosterol membrane and the signaling pathways involved in

The treatment in malignant cells represents a challenge for current medicine; In this sense, many plants with phytotherapeutic properties (such as taxol) have shown their efficiency as an alternative method in combating and proliferating malignant cells that can lead to cancer such as: colon cancer, gastric cancer, human liver tumor, lung tumors, breast cancer and leukemia, which have reported a

For example, there is evidence that *Cymbopogon martini* geraniol (i.e., palmarosa oil) manages to interfere with membrane functions, ionic homeostasis, and cell signaling events in cancer cell lines, which inhibits synthesis of DNA and a subsequent

In the case of terpenoids and constituent polyphenols, obtained from plant EOs, they can prevent the proliferation of tumor cells by necrosis or induction of

Citral present in lemongrass oil is found useful against the early phase hepatocarcinogenesis [30]. Another example, well known for its anticancer properties is the use of EO from *Allium sativum* (garlic). The preventive activity of chemotherapy is limited to the ability of garlic to suppress detoxifying enzymes of drugs [31]. Additionally the use of EO of lemon balm (*M. officinalis*) inhibits the growth

In this way, it is well established that OEs exhibit a capacity to act as antioxidants and interfere with the mitochondrial functions of cells, decreasing metabolic events (for example, increased cellular metabolism, mitochondrial overproduction and permanent oxidative stress) characteristic of the development of malignant

In addition to the aforementioned antimicrobial activities, there are plants that have significant antiviral properties, for example: *Origanum vulgare* anti-viral inactivation of enteric virus [34]; *Eucalyptus globulus* (Eucalyptus oil) activity against respiratory viruses [35]; *Salvia fruticosa*, antiviral activities [36], among

difficulties for the prevention and treatment of fungal infections.

**5. Cancer preventive properties using essential oils**

**72**

other. It is believed that the inhibition of viral replication is attributed to the presence of the monoterpene, sesquiterpene and phenylpropanoid components of the EOs [37].

EOs of eucalyptus and thyme possess inhibitory activity against the herpes virus [38]. Evidence has been found that OEs of *Melaleuca alternifolia* showed significant efficacy in the treatment of herpes virus [39]. The way in which the adsorption or entry of virus into host cells is prevented is associated with the ability to interfere with the viral envelope structures. For example, oregano oil causes dissolution of the HSV envelope to attenuate its infectious capacity [40]. There is evidence that the components of EOs specifically inhibit the early expression of the gene in CMV (cytomegalovirus) and thus prevent viral activation [41].
