Essential oils (EOs)
Essential oils (EOs) are a concentrated, hydrophobic fraction derived from aromatic plants that contain multiple chemical constituents that may have biologic activity. EOs are used in perfumery, as flavoring agents, and in aromatherapy for their therapeutic or relaxing properties. The chemical composition for an individual EO varies based on growing conditions of the plant and from which part of the plant the fraction was derived.
Numerous in vitro studies and some animal studies suggest that many different chemical constituents of EOs have anticancer properties. In-human studies have evaluated the use of EOs in a supportive role, and though EOs appear to have some efficacy in this setting, larger studies are needed to confirm their effects.
Essential oils are secondary metabolites with a key-role in plants protection, consisting primarily of terpenes with a volatile nature and a diverse array of chemical structures. Essential oils exhibit a wide range of bioactivities, especially antimicrobial activity, and have long been utilized for treating various human ailments and diseases. Cancer cell prevention and cytotoxicity are exhibited through a wide range of mechanisms of action, with more recent research focusing on synergistic and antagonistic activity between specific essential oils major and minor components.
Humans use medicinal plants for disease treatment for a long time. Such a traditional method possesses more than thousands of years of history, as noted by ancient Persian, Indian, Chinese, Arabic, and Greek manuscripts. Among natural phytochemicals, EOs have attracted human attention due to their pleasant aroma. They have been ethnotraditionally used for the treatment and prevention of various diseases by different human cultures. The application of EOs against neoplasia is a very promising field. In 2005, Warnke and coauthors reported that the application of tea tree and eucalyptus oils has reduced tumor smell and inflammation in cancer patients. Rosa x damascena has a long history of use in traditional medicine: its EO could increase cell proliferation on SW742 when higher concentrations were used, i.e. 10 μg/mL with 48 h of incubation time. Moreover, the same work showed that similar effects were perceived in human normal fibroblasts, thus inducing the authors to suggest that the EO of Rosa x damascene could stimulate cell growth. EOs extracted from 6 sand-dune plants of Portugal region (Seseli tortuosum L., Otanthus maritimus (L.) Hoffmanns. & Link, Eryngium maritimum L., Crithmum maritimum L., Artemisia campestris subsp. maritima (DC.) Arcang., Juniperus phoenicea var. turbinate (Guss.) Parl.,) reported promising cytotoxic properties. In 1997, Gould has postulated that the naturally occurring monoterpenes are a potential new class of potential anticancer agents. For example, D-limonene showed anticancer activity against many rodent solid tumor types by carcinogen detoxification and inhibition of the posttranslational isoprenylation of growth-controlling small G proteins (p21ras)