More recently, Nelson et al. conducted a literature survey to evaluate the efficacy and morbidity of nonsurgical treatments for anal fissures from 1966 to August 2010. Clove oil was among 17 agents used in the 77 cited studies. While no medical therapies were found to display the efficacy of surgical sphincterotomy (or, fortunately, linked to the risk of incontinence), clove oil was identified as one of the “newer” agents demonstrating promise.9
Musculoskeletal pain
Clove oil is included among several herbal ingredients (i.e., eucalyptus oil, gaultheria oil, turpentine oil, menthol, and camphor) associated with analgesic and anti-inflammatory properties that are used in the topical spray Eezpain. Nawaz et al. showed in a prospective pilot study with 20 male and female subjects that the polyherbal formulation was efficacious in relieving mild to moderate knee and wrist joint pain.10
Laboratory studies
Just over a decade ago, Chaieb et al. assessed the antioxidant characteristics of the essential oil of clove, finding that it displayed a robust radical scavenging capacity against 2,2-diphenyl-1-picrylhydrazyl in comparison to the synthetic antioxidant tert-butylated hydroxytoluene. It also showed potent antifungal activity against 53 test strains of human pathogenic yeasts. The authors noted that clove oil is a readily available source of natural antioxidants and is a worthy ingredient in pharmaceutical products.11
Anti-inflammatory activity
In 2017, Han and Parker studied the biological activity of four concentrations of a commercially available clove essential oil product on 17 protein biomarkers important in inflammation in a model of human skin disease. They found that the 0.011% concentration of the oil enacted strong antiproliferative effects on human dermal skin fibroblasts, and significantly suppressed multiple proinflammatory biomarkers as well as tissue remodeling protein molecules. The investigators also observed that essential clove oil significantly influenced global gene expression and signaling pathways involved in inflammation, tissue remodeling, and cancer processes. They concluded that their results indicate anti-inflammatory, anticancer, and tissue-remodeling properties of clove essential oil, and its main active ingredient eugenol, in human dermal fibroblasts.1
UVB protection
Recently, Patwardhan and Bhatt assessed the capacity of flavonoids from clove buds to protect human dermal fibroblasts from UVB exposure. They found that the flavonoid-enriched fraction of clove demonstrated significant potential, as it mitigated the effects of UVB radiation, and delivered protection via the nuclear factor E2-related factor 2-antioxidant response pathway. The flavonoid-enriched clove fraction, they concluded, warrants consideration as a topically applied cutaneous protectant against the effects of UVB exposure.4
Antiviral and immunomodulatory activity
Based on their earlier work showing the antiviral activity of clove bud oil against Pseudomonas aeruginosa PAO1, Haripriyan et al. reported this year that clove bud oil affects pseudomonal proteases (elastase A, elastase B, protease IV, and alkaline protease), attenuating significant viral mechanisms of this noted human disease agent while bolstering host immunomodulatory functions. They concluded that their results suggest the viability of clove bud oil as a topical treatment for infections resistant to antibiotics.12
Acne
In 2017, Owen et al. developed a topical preparation incorporating clove bud, rosewood, and litsea essential oils that compared favorably with the topical antibiotics Dalacin T and Stiemycin in controlling acne vulgaris-linked bacteria. Specifically, the herbal formulation exhibited synergistic activity against Propionibacterium acnes, although not to Staphylococcus epidermidis, and its antimicrobial activity exceeded or equated to that of the tested antibiotics. The investigators suggested that the polyherbal preparation may serve as an option for treating acne-linked bacteria.13