Mangosteen Gel Applied Before NB-UVB Exposure in Healthy Adults

This study examined whether a gel containing mangosteen (\*Garcinia mangostana\*) pericarp extract could reduce short-term skin redness caused by narrowband ultraviolet B (NB-UVB) exposure when applied before irradiation. Healthy adults aged 20-45 years with Fitzpatrick skin phototype III or IV participated. Six small test sites were marked on each participant's back. Each site was assigned to one of six conditions: mangosteen gel containing 5%, 10%, or 20% extract; gel base without extract; NB-UVB exposure without topical treatment; or no topical treatment and no NB-UVB exposure. Because all six conditions were evaluated in the same participant, each participant served as their own control. The active gels and gel base were applied 20 minutes before NB-UVB exposure. The ultraviolet dose was based on each participant's individual skin sensitivity. Skin redness and lightness were measured with a color-measuring instrument before exposure and at 12, 24, and 48 hours afterward. The investigator performing the skin-color measurements was not informed which condition had been assigned to each test site.

Inclusion Criteria: Adults aged 20-45 years. Fitzpatrick skin phototype III or IV. In good general health, without an acute or chronic medical condition. Clinically normal back skin without erythema or pathological lesions at the proposed test sites. Able and willing to provide written informed consent. Exclusion Criteria: History of atopic disease. Uneven pigmentation at the proposed test sites. Open wounds at the proposed test sites. Current use of topical or systemic corticosteroids or antihistamines. History of photosensitivity or polymorphic light eruption. History of malignancy within the previous 5 years. Pregnancy or breastfeeding. Sunbathing or use of a tanning bed within the previous 4 weeks. Known hypersensitivity to mangosteen or any component of the study gel.