Bergamot

Citrus bergamia (bergamot) is a fruit tree thought to originate in the Mediterranean area; its fruit has been a part of the diet in that region since the early 18th century.¹ Bergamot is known to confer antioxidant as well as anti-inflammatory activity, and yields proapoptotic effects in the sebaceous gland.^2,3 The plant contains the natural furocoumarin bergapten, which is also known as 5-methoxypsoralen.⁴

Antibacterial, anti-inflammatory, hypolipemic, and anticancer properties have been associated with bergapten, which is primarily found in bergamot essential oil and used effectively as a photosensitizing agent.⁵ In this capacity, bergamot oil has been used for photodynamic therapy of cutaneous conditions such as vitiligo.⁶ In fact, for several years 5-methoxypsoralen and 8-methoxypsoralen have been used to achieve acceptable clearance rates of psoriasis and vitiligo.⁷ This column focuses on bergapten, as well as the cutaneous conditions for which bergamot has been shown to have some benefits warranting application or further investigation.

Bergapten

In a 2021 literature review, Liang et al. cited the anti-inflammatory, antimicrobial, anticancer, and other salutary effects associated with bergapten. Based on numerous citations, they also cautioned about the phototoxicity of the compound combined with ultraviolet (UV) light while noting the photoactivation of bergapten for anticancer uses.⁴

The following year, Quetglas-Llabrés et al. acknowledged, in another literature review, the numerous preclinical and in vitro studies demonstrating the therapeutic activity of bergapten and highlighted clinical trials revealing notable lesion clearance rates of psoriasis or vitiligo imparted by oral or topical bergapten along with UV irradiation. Bergapten was also found to be effective as hypolipemic therapy.⁵

Anti-inflammatory topical uses

In a 2017 study by Han et al. of 10 essential oils, bergamot was among the investigated oils, all of which exhibited significant anti-proliferative activity in a preinflamed human dermal fibroblast system simulating chronic inflammation. Bergamot was among three essential oils that also suppressed protein molecules involved with inflammation, immune responses, and tissue remodeling, indicating anti-inflammatory and wound healing characteristics.⁸

More recently, Cristiano et al. reported that ultradeformable nanocarriers containing bergamot essential oil and ammonium glycyrrhizinate were demonstrated in healthy human volunteers to be characterized by the appropriate mean size, size distribution, surface charge, and long-term stability for topical administration. Topical administration on human volunteers also revealed greater activity of the combined agents as compared with a nanosystem loaded only with ammonium glycyrrhizinate. The researchers concluded that this combination of ingredients in ultradeformable vesicles shows potential as topical anti-inflammatory treatment.³

Acne

In a 2020 study using golden hamsters, Sun et al. assessed the effects of the juice and essential oils of bergamot and sweet orange on acne vulgaris engendered by excessive androgen secretion. Among 80 male hamsters randomly divided into 10 groups ranging from low to high doses, all results demonstrated improvement with treatment as seen by decreased growth rates of sebaceous glands, suppressed triglyceride accumulation, lowered inflammatory cytokine release, and apoptosis promotion in sebaceous glands. The authors noted that the essential oils yielded better dose-dependent effects than the juices.²