Essential Oils in Plants

Properties and Extraction

Essential oils are volatile compounds formed in plants as metabolic byproducts. They accumulate in glandular hairs, epidermal scales, specialized oil cells, or larger oil ducts, and are present in various plant organs. Some plants contain essential oils throughout, while others have them in specific parts. All essential oils are highly volatile, evaporating with a distinct, species-specific odor. They are insoluble in water but dissolve well in fats, oils, alcohol, and other organic solvents. Unlike fatty oils, essential oils are typically lighter than water, floating on its surface, and are usually colorless or slightly yellowish. Exposure to oxygen and light can alter their properties, so they should be stored in dark, tightly sealed containers.

For plants rich in essential oils, proper harvesting, careful and rapid drying, and storage in sealed containers are crucial. Essential oils are characterized by their unique odor and taste, detectable by humans even in high dilutions. The primary extraction method is steam distillation, where essential oils evaporate with water vapor, condense upon cooling, and separate from water. For oils sensitive to high temperatures or present in small quantities, extraction is used. Essential oils from citrus peels, such as orange, are obtained by pressing, followed by distillation, filtration, or centrifugation to isolate pure oil from the emulsion.

Health Benefits and Uses

Essential oils applied to the skin, in forms like ointments, compresses, or massage oils, enhance blood circulation, causing redness and a warming sensation. This irritation triggers the release of mediators and boosts adrenal hormone production, aiding conditions such as rheumatism, muscle and nerve issues, poor circulation, sports injuries, contusions, and bruises. Anti-inflammatory essential oils inhibit histamine and prostaglandin formation while stimulating corticoid hormone production by the adrenal glands.

Antimicrobial essential oils, used both externally and internally, combat microorganisms and are employed in food preservation, gargling, and urinary tract disinfection. Oils that promote expectoration thin secretions and enhance respiratory motility, acting partly through stomach nerve irritation and partly when exhaled through the lungs. Oils that stimulate fluid excretion target renal epithelium, improving kidney blood flow and urinary output, though overdosing or prolonged use may cause side effects.

Essential oils that relax smooth muscles benefit the intestines, gallbladder, bronchi, and blood vessels. Those acting on the digestive system regulate gastric juice secretion, motility, and intestinal bacteria, preventing improper fermentation and reducing bloating. They also enhance bile secretion and drainage. Soothing essential oils are typically used internally or in baths, while those invigorating the heart and bloodstream act directly through the central nervous system or reflexively via smell. Oils targeting intestinal parasites aid in their elimination but require professional consultation due to potential side effects.

Precautions

Improper use, particularly in large quantities, prolonged use, or with impure oils, can lead to side effects or poisoning. Oils containing asarone or safrole in high amounts are carcinogenic, those with thujone or apiol may cause miscarriage, and oils from celandine, laurel, citrus, or turpentine can trigger allergies. Some oils may damage the kidneys or liver, and those with furanocoumarins are photosensitive, requiring cautious handling.