Oil obtained from plants is divided into two types : one is volatile oil (Essential Oil), the other non-volatile oil (Oil and Fat). The writers' intentions are to clarify the specific metabolism of essential oil, and at the same time to find out the different functions of essential oils in a living body. We human beings are leading our daily life in the world as a member of nature, unaware of the fact that we are enjoying the benefits of “aroma chemicals”. In recent years the effects of these “aroma chemicals” have been revealed by science, and they are gradually being applied to such fields as food products, nonessential luxuries and cosmetics. Our research goes beyond the functionality of aroma chemicals such as scents and stimulants. Our aim now is seek out new potentials of aroma chemicals to prevent or cure stress-related diseases in the modern society, focusing on their bioactive effects. Furthermore, we are trying to explain the inner mechanism through which various kinds of novel compounds are produced by metabolic reaction. This reaction is caused when aroma chemicals are absorbed into the body by cytochrome P450 enzymes, which mainly exists in liver.
The functions to prevent or cure modern diseases that we have discovered are as follows : (1) a “acetylcholinesterase inhibitory activity” which may improve dementia; (2) a “suppression effect of DNA mutation” from environmental mutagens expected to help prevent the onset of cancer; (3) a “cyclooxygenase-2 selective inhibitory activity” which is an anti-inflammatory target enzyme; and (4) a “P450 molecular species control involved in nicotine metabolization” which aims to help smokers with nicotine dependency to quit smoking.
It is shown that they have bioactive functions that are extremely effective and valuable to support our life. They are sure to provide a method of preventing or curing modern diseases and to play an important role in this era of self-medication. Aromas will come into the spotlight.

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Supercritical CO₂ (scCO₂) is non-polar and has weak van der Waals forces, hence it is not suitable for dissolving polar substances. This disadvantage has limited its application in chemical processes such as separation, reaction, and materials synthesis. One of the most promising approaches for enhancing solubility of polar substances in scCO is to form reversed micelles with high-polarity aqueous cores in the continuous scCO₂ phase, that is, a water-in-scCO₂ microemulsion (W/CO₂μE). Since such an organized fluid has the attractive characteristics of scCO₂ as well as the solvation properties of bulk water, it is expected to behave as a universal solvent. For example, a W/CO₂μE will hopefully be a volatile organic compound (VOC) -free and energy-saving solvent for nano-material synthesis, enzymatic reactions, dry-cleaning, dyeing, preparation of inorganic/organic hybrid materials, and so on. To be a viable green technology, the amount of surfactant used for those applications should be as small as possible, and one approach to decrease the amount is to develop surfactants with higher solubilizing powers.
This review is introducing (1) a good solubilizer for a W/CO₂μE, (2) phase behavior and nano-structure of the W/CO₂μE, and its industrial applications.

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