What is patchouli

Patchouli (Pogostemon cablin) is commonly known as “guanghuoxiang” in Chinese, is a bushy herb that is a member of the mint family (Lamiaceae), with erect stems, reaching around 75 centimetres (2.5 ft) in height and bearing small, pale pink-white flowers ¹⁾. A strong-smelling oil taken from the patchouli leaves is used in perfumes, incense, detergents, insect repellents and hair conditioners. It has been used in some cultures as alternative medicines to prevent disease.

Patchouli (Pogostemon cablin) is traditionally used in China to treat various illnesses, including fever, common cold, diarrhea and nausea ²⁾. Previous studies have demonstrated that Patchouli also exerts numerous bioactivities, including radical-scavenging, anti-microbial, analgesic and anti-inflammatory activities ³⁾. Several studies have been carried out on the composition of Patchouli (Pogostemon cablin) and the presence of patchouli alcohol, pogostone, eugenol, α-bulnesene, rosmarinic acid, etc. has been revealed ⁴⁾. Patchouli essential oils constitute about 1.5% of Patchouli and among them >50% is patchouli alcohol ⁵⁾. Patchouli alcohol (see Figure 2), which is a tricyclic sesquiterpene, is the main active ingredient of Patchouli ⁶⁾. Oral administration of Patchouli alcohol has been demonstrated to offer protection against influenza virus infection in mice via the enhancement of host immune responses, and the attenuation of systemic and pulmonary inflammatory responses ⁷⁾. In addition, it has been reported that pretreatment with Patchouli alcohol attenuates reactive oxygen species (ROS) generation following Aβ25–35-induced toxicity ⁸⁾. These findings indicated that Patchouli alcohol possesses anti-inflammatory and antioxidative activities ⁹⁾. Patchouli alcohol has an oral median lethal dose value of 4,693 mg/kg in mice ¹⁰⁾.

Figure 1. Patchouli

Patchouli alcohol

Patchouli alcohol (C15H26O), a naturally occurring tricyclic sesquiterpene, is the critically biological active constituent among the patchouli oil extracted from Patchouli and usually used as a pivotal chemical marker compound for the assessments in quality control of Pogostemonis Herba and patchouli oil in China ¹¹⁾. However, the practices of using Patchouli alcohol are blank in medical field, despite Patchouli alcohol has been demonstrated in test tube studies to possess multibeneficial pharmacological properties, such as immunomodulatory, anti-inflammatory, antioxidative, antitumor, antimicrobial, insecticidal, antiatherogenic, antiemetic, whitening, and sedative activities ¹²⁾.

In nature, Patchouli alcohol primarily exists in volatile oil of Patchouli and its contents are about 48.8% ¹³⁾. In general, Patchouli alcohol contents were higher in the leaves than that in the root and/or stem and altered in different collection parts as well as harvest times. Patchouli alcohol is also detected within volatile oil from other plants, such as Herba Lysimachia paridiformis (22.54%) ¹⁴⁾, Rhizoma Valeriana jatamansi jones (5.88%) ¹⁵⁾, Rhizoma Nardostachys chinensis (4.5%) ¹⁶⁾, Radix Mallotus apelta (4.48%) ¹⁷⁾, Foliage Ficus microcarpa (4.05%) ¹⁸⁾, Herba Pholidota cantonensis (3.60%) ¹⁹⁾, Herba Asarum sieboldii (2.75%) ²⁰⁾, Herba Gendarussa vulgaris (2.68%) ²¹⁾, Radix Helleborus thibetanus (0.811%) ²²⁾, Herba Sedum sarmentosum (0.53%) ²³⁾, Aquilaria agallocha (0.392%) ²⁴⁾, Pericardium Citri reticulatae (China: Xinhui, 0.178%; Guangxi, 0.162%; and Fujian, 0.086%) ²⁵⁾, Fructus Periploca forrestii Schltr. (MAE, 0.12%; and SDE, 6012%) ²⁶⁾, and Foliage Microtoena patchouli ²⁷⁾.

Figure 2. Patchouli alcohol chemical structure

[Source ²⁸⁾]

Figure 3. Possible mechanisms of bioactivities of Patchouli alcohol in immunomodulation, antitumor, anti-inflammation, and antioxidation

Note: Arrow up denotes activation or increase; arrow down denotes suppression or decrease. Inflammation and oxidation interact with each other.

[Source ²⁹⁾]

The present information exhibited remarkably therapeutic properties of Patchouli Alcohol in vivo (animal) and in vitro (test tube) studies, which could contribute to the prevention and treatment of many diseases, such as immune disorders, infections by microbes, mosquitoes or Trypanosoma cruzi, ALI, mastitis, gastric ulcer, skin photoaging, atherosclerosis, and tumor. However, further studies are required to investigate the safety and toxicity Patchouli alcohol in both animals and humans. And so far there has been no well designed human clinical trials to support the purported benefits of Patchouli, Patchouli alcohol or Patchouli essential oil. Finally, any medicinal benefit of Patchouli remains unclear.

Patchouli essential oil

The dry leaves of patchouli on steam distillation, requiring rupture of its cell walls by steam scalding, light fermentation, or drying to yield an essential oil called the patchouli oil. Patchouli essential oil is hence an important ingredient in many fine fragrance products such as perfumes, as well as in soaps and cosmetic products ³⁰⁾. Results of High Performance Thin Layer Chromatography studies indicated that the ethyl acetate extract of Patchouli leaves included triterpenes, as 10 and 14 peaks of ultra violet (UV) absorption were observed in 254 nm and 366 nm, respectively. Hence, triterpenes may be responsible for antidermatophytic activity of this plant ³¹⁾.

Moreover, patchouli oil in the plant is widely used in Traditional Chinese Medicine as it offers various types of pharmacological activities ³²⁾. It has also been reported to strengthen the immune activity and resistance to bacterial action ³³⁾. The composition of the patchouli oil is complex like many essential oils, which consist of the major components such as patchoulol alcohol and pogostone etc. The mechanism of action of major pharmacologic components in patchouli oil as an antibacterial agent has not been reported. However, in an in-vitro (test tube) study, the main compounds in patchouli essential oil seems to be patchouli alcohol and pogostone, whose composition exceeded 60% (g/g) in patchouli oil samples – all have good antibacterial activities ³⁴⁾.

Figure 4. 26 chemical compounds in Patchouli oil

[Source ³⁵⁾]

Patchouli oil uses

Perfume

Patchouli oil is an important essential oil in the perfume industry, keeping a base and lasting character to a fragrance. For characteristic pleasant and long lasting woody and camphoraceous odor, patchouli oil is appreciated and very suitable for the utilization of decorative cosmetics, fragrances, shampoo, toilet soaps, paper towels, air fresheners and other toiletries as well as noncosmetic products such as household cleaners and detergents ³⁶⁾.

Insect repellent

One study suggests that patchouli oil may serve as an all-purpose insect repellent ³⁷⁾. More specifically, the patchouli plant is claimed to be a potent repellent against the Formosan subterranean termite ³⁸⁾. The experiment on repellent and toxic effects of Patchouli alcohol on Coptotermes formosanus Shiraki (Isoptera: Rhinotermitidae) was carried out by Zhu et al. ³⁹⁾. The results uncovered that patchouli alcohol pretreatment resulted in elevation in mortality percentage and decline in termites feeding, contacting and tunneling behaviors, and particularly the internal tissue of termites was destructed inside the exoskeleton when patchouli alcohol was topically applied into the dorsum. Furthermore, patchouli alcohol was witnessed to have obvious repellency and toxicity towards mosquitoes. Patchouli alcohol, at 2 mg/cm2 concentration, was the most effective for repellent activity, providing 100% protection up to 280 min, against Ae aegypti, An. Stephensi, and Cx. quinquefasciatus, and for pupicidal activity at 100 mg/L concentration, providing 28.44, 26.28, and 25.36 against above vector mosquitoes tested ⁴⁰⁾. These findings provide experimental basis for the development of patchouli alcohol as an ideal eco-friendly pesticide for the control of termites and mosquitoes.

Incense

Patchouli is an important ingredient in East Asian incense. Both patchouli oil and incense underwent a surge in popularity in the 1960s and 1970s in the US and Europe, mainly as a result of the hippie movement of those decades ⁴¹⁾.

Culinary

Patchouli leaves have been used to make an herbal tea. In some cultures, patchouli leaves are eaten as a vegetable or used as a seasoning.