Paparan sinar matahari secara berlebih dapat menimbulkan dampak negatif seperti kemerahan dan rasa terbakar pada kulit. Tabir surya merupakan sediaan kosmetika yang digunakan untuk melindungi kulit dari sinar UV. Pengembangan tabir surya dari bahan alam dapat digunaan sebagai pengganti senyawa sintetis pada tabir surya. Salah satu tanaman yang berpotensi sebagai tabir surya adalah tanaman bunga kenop (Gomphrena globosa L.) yang memiliki kandungan senyawa flavonoid, tanin dan antioksidan. Penelitian ini bertujuan untuk mengetahui mutu fisik dan aktivitas tabir surya pada formulasi krim ekstrak bunga kenop (Gomphrena globosa L.). Uji mutu fisik yang dilakukan pada krim ekstrak bunga kenop meliputi uji organolepstis, homogenitas, pH, dan daya sebar. Uji aktivitas tabir surya dilakukan secara in vitro menggunakan spektrofotometri UV-Vis dan uji aktivitas tabir surya secara in vivo dilakukan menggunakan tikus putih yang disinari lampu exotera selama 12-24 jam. Hasil penelitian menunjukkan krim ekstrak bunga kenop memiliki mutu fisik yang baik. Pada pengujian secara in vitro nilai SPF krim ekstrak bunga kenop konsentrasi 0,5%, 1% dan 2% yaitu 15,53 (proteksi ultra); 21,12 (proteksi ultra); 30,84 (proteksi ultra). Pada uji in vivo seluruh konsentrasi krim dapat melindungi kulit tikus dari paparan sinar lampu exotera UV B dengan skor eritema 0. Krim ekstrak bunga kenop (Gomphrena globosa L.) memiliki mutu fisik yang baik dan memiliki aktivitas tabir surya secara in vitro dan in vivo. Kata kunci: tabir surya, SPF, bunga kenop, krim, in vitro, in vivo

Background. Excessive exposure to sunlight can cause negative effects such as redness and burning of the skin. Sunscreen is a cosmetic preparation used to protect the skin from UV rays. The development of sunscreen from natural ingredients can be used as a substitute for synthetic compounds in sunscreen. A plant that has potential as a sunscreen is the globe amaranth flower plant (Gomphrena globosa L.), which contains flavonoid compounds, tannins, and antioxidants. The purpose of this study was to determine the physical quality and sunscreen activity of a cream formulation of the globe amaranth flower extract cream (Gomphrena globosa L.). Method. This study employed physical quality tests conducted on the globe amaranth flower extract cream, including organoleptic tests, homogeneity, pH, and spreadability. Sunscreen activity tests were carried out in vitro using UV-Vis's spectrophotometry, and sunscreen activity tests in vivo were conducted using white mice exposed to an exo-terra lamp for 12-24 hours. Results. Findings indicated that the globe amaranth flower extract cream had good physical quality. In the in-vitro testing, the SPF value of globe amaranth flower extract cream at concentrations of 0.5%, 1%, and 2% was 15.53 (ultra-protection), 21.12 (ultraprotection), 30.84 (ultra-protection), respectively. In the in-vivo test, all concentrations of the cream could protect the white mice's skin from exposure to a UV-B exo-terra lamp with an erythema score of 0. Conclusion. Globe amaranth flower extract cream (Gomphrena globosa L.) has good physical quality and has sunscreen activity both in-vitro and in-vivo. Keywords: Sunscreen, SPF, Globe Amaranth, Cream, In-Vitro, In-Vivo