Eugenol uses, from clove oil by Ray Sahelian, M.D.
February 27 2015

Eugenol is a clear to pale yellow oily liquid extracted from certain essential oils especially from clove oil, nutmeg, cinnamon, and bay leaf. Eugenol has a pleasant, spicy, clove-like aroma.

Cholesterol lowering
Evid Based Complement Alternat Med. 2014. Antihypercholesterolemic and Antioxidative Potential of an Extract of the Plant, Piper betle, and Its Active Constituent, Eugenol, in Triton WR-1339-Induced Hypercholesterolemia in Experimental Rats. Results suggest that eugenol, an active constituent of the Piper betle extract, possesses antihypercholesterolemic and other activities in experimental hypercholesterolemic Wistar rats.

Eugenol as analgesic in dentistry
A natural congener of capsaicin, it is a routine analgesic agent in dentistry. Eugenol is a major component of root canal sealers and retrograde filling materials. Zinc-oxide powder mixed with eugenol or cariofillorum oil and sterilized cotton is frequently used in dental practice as surgical bandage for eliminating or dry socket. Osteonecrosis of alveolar bone caused by free eugenol is rare but a possible complication.

Immune system, protection from infection
Sci Rep. 2015. Phytonutrient diet supplementation promotes beneficial Clostridia species and intestinal mucus secretion resulting in protection against enteric infection. Plant extracts, or phytonutrients, are used in traditional medicine practices as supplements to enhance the immune system and gain resistance to various infectious diseases and are used in animal production as health promoting feed additives. To date, there are no studies that have assessed their mechanism of action and ability to alter mucosal immune responses in the intestine. We characterized the immunomodulatory function of six phytonutrients: anethol, carvacrol, cinnamaldehyde, eugenol, capsicum oleoresin and garlic extract. Mice were treated with each phytonutrient to assess changes to colonic gene expression and mucus production. All six phytonutrients showed variable changes in expression of innate immune genes in the colon. However only eugenol stimulated production of the inner mucus layer, a key mucosal barrier to microbes. The mechanism by which eugenol causes mucus layer thickening likely involves microbial stimulation as analysis of the intestinal microbiota composition showed eugenol treatment led to an increase in abundance of specific families within the Clostridiales order. Further, eugenol treatment confers colonization resistance to the enteric pathogen Citrobacter rodentium. These results suggest that eugenol acts to strengthen the mucosal barrier by increasing the thickness of the inner mucus layer, which protects against invading pathogens and disease.

Eugenol inhibits the antimicrobial functions of neutrophils.
J Endod. 2008.
Eugenol containing restorative materials are commonly used for vital pulp therapy. A well-regulated host defense response is pivotal for the success of vital pulp therapy. The present study was to assess the effects of eugenol on the antimicrobial functions of polymorphonuclear leukocytes (neutrophils). Treatment for 30 minutes did not significantly affect the viability of neutrophils. However, preincubation of neutrophils with eugenol abolished their bactericidal activity against oral pathogens Streptococcus mutans and Actinobacillus actinomycetemcomitans. In addition, through the suppression of the extracellular release of myeloperoxidase and the intracellular production of reactive oxygen species, eugenol at sufficient concentrations impaired the activation of neutrophils by cytochalasin B and fMet-Leu-Phe. These results suggested that the antimicrobial functions of neutrophils were interfered by eugenol, and the inhibitory effects of eugenol were not due to direct killing of neutrophils.

J Tradit Chin Med. 2013. Effects of combined acupuncture and eugenol on learning-memory ability and antioxidation system of hippocampus in Alzheimer disease rats via olfactory system stimulation. Both Xiu three-needle and eugenol can increase learning-memory ability, decrease MDA content, and increase SOD and GSH-Px activities in the hippocampus in AD rats. The combination of acupuncture with eugenol has stronger effects, and the effects depend on the olfactory pathway.