# Anti-Breast Cancer Activity of Essential Oil:
## 3 Result
### Essential Oil
#### 3.2.1 Classification Based on the Method of Extraction
Over the past ten years, interest in ohmic hydrodistillation, which combines ohmic heating with hyrodistillation, has increased. In comparison to the traditional hydrodistillation procedure, ohmic-aided hydrodistillation (OAHD) has a shorter extraction time, uses less energy, and produces a greater yield. The extraction time for the OAHD method was 24.75 min, but the HD approach required 1 h to extract the thyme essential oil. In comparison to HD, there were no differences in the essential oil molecules derived by OAHD [54]. Classification Based on Contents  
Most essential oils are composed of secondary metabolite components of the terpenoid group (monoterpenoids, triterpenoids, and sesquiterpenoids) and phenylpropanoids. Other names for essential oils are culinary oil and ethereal oil. The oil can have a strong flavor, be volatile at ambient temperature without disintegrating, and frequently dissolve in organic solvents, while being insoluble in water, depending on the plant species [55]. Terpenes  
Terpenes are the main constituents of essential oils derived from various types of plants or flowers. They are naturally occurring, volatile, unsaturated or open-chain, or cyclic compounds. Terpenes can be classified according to the number of isoprene units, a 5-carbon compound that gives off a scent or taste as a defense mechanism [56]. Based on the isoprene, terpenes are divided into monoterpenes, sesquiterpenes, diterpenes, tritterpenes, tetraterpenes, and polyterpenes. Monoterpenes and sesquiterpenes are the largest components in essential oils [57]. Most types of terpenes, excluding clove oil, have a lower specific density than water and are soluble in organic solvents like ether and alcohol. It has a distinctive odor that characterizes the essential oils and high refractive index [57]. Terpenes play an important role in the taste, fragrance, and pigment of a plant. It has been reported that terpene possesses a variety of bioactivities, including anticancer, antibacterial, antihyperglycemic, antifungal, antiviral, analgesic, anti-inflammatory, and antiparasitic [56]. Monoterpenes  
Almost all essential oils are monoterpenes, a 10 carbons compound with at least one double bond. Monoterpenes have a basic structure consisting of two linked isoprene units. These compounds can undergo cyclization and oxidation in various ways [58]. The high hydrocarbon content and fast reaction to air and heat sources making it not durable [34; 59]. Due to their low molecular weight, many of these compounds exist in the form of essential oils. Examples of monoterpenes are geraniol, terpineol, limonene, myrcene, linalool and pinene [58]. It is reported that monoterpenes have antimicrobial, anti-inflammatory, antioxidant, antipurritic, hypotensive, and analgesic pharmacological properties [58]. Sesquiterpene  
Sesquiterpene consists of 15 carbon atoms and has complex pharmacological action, such as that of chamazulene, which is found in German chamomile. The most prevalent kind of functional group identified in essential oils is the oxygenated groups. Similar to terpen, it is vital to know the different classes of oxygenated compounds since each class has a distinct potential for health benefits [59; 60; 61]. Three linked isoprene units combine to form sesquiterpene lactones with one of the methanol groups oxidized to the lactone form. These sesquiterpenes are vital for plant defense since they are insecticides, antibacterial, antiviral, and antifungal agents. In addition, this compound can also provide biological activities, such as antibacterial, antiviral, antifungal, and anticancer [62].