eng Oriental Scientific Publishing Company Biomedical and Pharmacology Journal 0974-6242 2024-12-30 17 4 2527 2534 10.13005/bpj/3045 62183 article Luh Putu Ratna Sundari 1 I Gusti Ayu Widianti 2 Made Alyashanti Radya Bulandari 3 I Ketut Tunas 4 Department of Physiology, Faculty of Medicine, Udayana University, Bali, Indonesia Department of Anatomy, Faculty of Medicine, Udayana University, Bali, Indonesia Bachelor of Medicine Study Program, Faculty of Medicine, Udayana University, Bali, Indonesia Department of Health Information Management, Faculty of Health Science, Bali International University, Bali, Indonesia The ethanol extract of Ulva lactuca cream was developed to assess its potential as an anti-hyperpigmentation agent by inhibiting tyrosinase enzyme expression and melanin formation. This study aims to evaluate the effectiveness of the cream in preventing hyperpigmentation by inhibiting tyrosinase enzyme activity. This study  uses a randomized post-test-only control group design. The subjects were 27 healthy male guinea pigs (Cavia porcellus), aged 3-4 months, weighing 300-350 grams, divided into three groups. The control group received a base cream, while treatment group 1 received a cream with 30% ethanol extract of Ulva lactuca. Treatment group 2 received a cream with 50% ethanol extract. All of the groups were exposed to UVB radiation, three times a week at a dose of 65 mJ/cm² for 65 seconds for two weeks. The cream was applied daily, 20 minutes before and 4 hours after UVB exposure. The levels of tyrosinase enzyme were measured and analyzed using an independent T-test. The average tyrosinase enzyme level in the control group was significantly higher, at 111.92 ng/ml ± 6.56, compared to Group 1 with 91.42 ng/ml ± 0.96, and Group 2 with 58.83 ng/ml ± 1.21. This indicates that tyrosinase enzyme was inhibited in the groups treated with 30% and 50% Ulva lactuca extract cream compared to the control group (p<0.001). It can be concluded that the ethanol extract Ulva lactuca creams have significant potential to inhibit the formation of tyrosinase enzyme, which plays a role in hyperpigmentation, in guinea pig skin exposed to UVB radiation. https://biomedpharmajournal.org/vol17no4/potential-of-ethanol-extract-ulva-lactuca-cream-in-inhibiting-tyrosinase-enzyme-activity-as-an-anti-hyperpigmentation-agent-in-guinea-pig-cavia-porcellus-skin-exposed-to-ultraviolet-radiation/ Ethanol extract cream Guinea Pig Hyperpigmentation Tyrosinase Enzym Ulva Lactuca