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Humulene, also known as α-humulene or α-caryophyllene, is a naturally occurring monocyclic sesquiterpene with the chemical formula C15H24. It is characterized by its unique structure, which contains an 11-membered ring and consists of three isoprene units, each containing nonconjugated C=C double bonds. Among these double bonds, two are triply substituted, and one is doubly substituted.

Natural Source: Humulene was first discovered in the essential oils of Humulus lupulus, commonly known as hops. Its name is derived from this plant.

Isomer of β-Caryophyllene: Humulene is an isomer of β-caryophyllene, another sesquiterpene, and the two are often found together as a mixture in various aromatic plants.

Occurrence in Hops: In the hops plant, Humulus lupulus, humulene can account for up to 40% of the essential oil. It plays a significant role in giving certain beers their characteristic "hoppy" aroma.

Brewing Process: Humulene and its reaction products are involved in the brewing process of beer. The hydrolysis products of humulene epoxide II, in particular, contribute to the hoppy aroma in beer.

Aromatic Plants: α-Humulene is found in various aromatic plants on all continents. It is often present alongside β-caryophyllene. Some of the plants that contain α-humulene include pine trees, orange orchards, marsh elders, tobacco, sunflowers, Salvia officinalis (common sage), Lindera strychnifolia, ginseng species, Mentha spicata, ginger family plants, Litsea mushaensis, Cordia verbenacea, Persicaria odorata (Vietnamese coriander), and Cannabis.

Humulene's presence in these plants contributes to their characteristic aromas and flavors. It is also of interest in the brewing industry for its role in shaping the aroma of certain beers.

GHS Hazard Statements

• H304 (36.23%): May be fatal if swallowed and enters airways [Danger Aspiration hazard]

• H315 (81.16%): Causes skin irritation [Warning Skin corrosion/irritation]

• H319 (81.16%): Causes serious eye irritation [Warning Serious eye damage/eye irritation]

• H335 (100%): May cause respiratory irritation [Warning Specific target organ toxicity, single exposure; Respiratory tract irritation]

Chemical and Physical Properties

Computed Properties

Source: PubChem