Terpinen-4-ol is naturally found in various plant essential oils(table 1), ecologically safe with pleasant odor, and has a variety of biological activities.

Terpinen-4-ol, CAS: 562-74-3, formula C10H18O, has two optical isomers: D-Terpinen-4-ol and L-Terpinen-4-ol. It is pale yellow transparent liquid with unique pleasant odor, volatile and soluble in ether, acetone and other solvents with medium polarity. It can also be synthesized from Terpinolene 4, 8-epoxide or 1,4-Cineole.

Terpinen-4-ol itself or with the combined effect of other ingredients has a variety of biological activities, such as attracting activity, repellent activity, fumigant toxicity and growth inhibitory activity to insects, as well as antimicrobial activity, which bring broad prospects for its development and application in pesticides.

1. Attracting activity

The capture rate of Rhizophagus Grandis Gyll is increased to 21.6% by the attractant composed of equal amount of Terpinen-4-ol, fenchol, borneol, α-terpineol, verbenol, fenchone, camphor and pentane, higher than the rate attracted by its favorite foods. The male and female of Hylotrupes bajulus all show strong tropism to terpinen-4-ol.

2. Repellent activity

With unique odor, terpinen-4-ol has repellent activity for some insects.

3. Fumigant toxicity and growth inhibitory activity

It was found that terpinen-4-ol has high insecticidal activity to Tetranychus urticae Koch and other two types of the main pests, and the essential oil which contains terpinen-4-ol has high Fumigant toxicity to Rhyzopertha dominea. As well as many other oxygenated monoterpenes, terpinen-4-ol can also obstacle the development of insects and acari larvae.

4. Antimicrobial activity

Many essential oils containing abundant terpinen-4-ol, shows antimicrobial activity to yeast, lactobacillus, staphylococcus aureus, escheri chia cali, proteus miabilis, klebsirlla pneumaniae, pseudomonas aeruginosa, candida albicans and etc. Two essential oils containing terpinen-4-ol can lower 73.0%~75.8% the ratio of rot fruit as one research said.

As a natural material with abundant sources, aside from its insecticidal and antimicrobial effects, terpinen-4-ol is also widely used in daily chemicals, pharmaceuticals, foods and etc.

• With pleasant odor, no skin irritation, the antimicrobial activity and the insecticidal effect to human acari, terpinen-4-ol has already been widely used in daily chemicals like perfume, soap, toothpaste, shower gel and etc.
• In pharmaceuticals, A similar high antiulcer action has found in both optical isomers of terpinen-4-ol which presents its inhibitory activity to ulcers. In addition, Terpinen-4-ol also shows antimicrobial activity to Helicobacter pylori related to ulcers.
  Terpinen-4-ol is the most active ingredient in Tea Tree oil (TTO) to exert antibacterial and antifungal effects. Such a wide range of antimicrobial effects of Terpinen-4-ol have been shown against several microbes responsible for hospital-acquired infections and ocular surface infections. Additionally, Terpinen-4-ol also possesses anti-inflammatory properties by suppressing superoxide production and pro-inflammatory cytokines, Terpinen-4-ol as the most active pharmaceutical ingredient in future formulations to treat a number of ocular and cutaneous diseases caused by demodicosis that may be associated with or without concomitant bacterial or fungal infections.
• A study about the skin irritancy of the main monoterpenes compositions in Australian Tea tree oil concluded no participants showed irritancy to terpinen-4-ol, α-pinene, β-pinene, limonene, cineole, α-terpineol and etc.