Hops
Humulus lupulus L.
Synonyms:
Lupulus humulus Mill.; and others. Sometimes incorrectly referred to as H. lupus L.
Family:
Cannabaceae
Other common names:
Common hop(s); hop
Drug name:
Lupuli flos; Lupuli strobilus. ‘Lupulin’ is the powder composed of the glandular trichomes separated from the strobiles (conical flowers).
Botanical drug used:
Dried female inflorescence
Main chemical compounds:
More than 1000 chemical constituents have been identified from hops. The most significant include the volatile constituents, which include humulene, myrcene, β-caryophyllene and 2-methly-3-buten-2-ol, the α- and β-bitter acids (di- and tri-prenylated phloroglucinol derivatives respectively), the prenylated flavonoids, and the polyphenols (e.g. gallocatechin).The main α-bitter acids are humulone, cohumulone and adhumulone, and the main β-acids are lupulone, colupulone and adlupulone. These isomerise naturally and on heating to produce isohumulones and isolupulones. The most important prenylated flavonoids include 8-prenylnaringenin, xanthohumol, isoxanthohumol, 6-isopentenylnaringenin. Other flavonoids present include astragalin, kaempferol, quercetin, quercitrin and rutin (Chadwick et al. 2006; Pharmaceutical Press Editorial Team 2013; Zanoli and Zavatti 2008).
Clinical evidence:
Sedative effects:
Human studies supporting the traditional uses of hops are limited. Clinical trials have investigated the sedative effects of hops only in combination with other botanical drugs, mainly valerian. A randomised, double-blind controlled trial in subjects suffering from sleep disorders showed equivalent efficacy and tolerability between a hop-valerian preparation and a benzodiazepine (Zanoli and Zavatti 2008). Another study found that addition of hops to a valerian formula reduced sleep latency (time required to fall asleep), compared to valerian on its own (Koetter and Biendl 2010).
Antidiabetic effects:
Isohumulones derived from hops have been shown to have beneficial effects in diabetes and obesity. In a study in subjects with mild type 2 diabetes, 100 mg of an isohumulone extract administered twice daily was shown to significantly reduce blood glucose, haemoglobin A1C and systolic blood pressure after 8 weeks. In a follow-up study in subjects with pre-diabetes, body mass index was significantly reduced after administration of 48 mg of isohumulones for 12 weeks (Koetter and Biendl 2010).
Pre-clinical evidence and mechanisms of action:
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