Optimasi Kombinasi Ekstrak Umbi Teki dan Daun Patikan Kebo dengan Rancangan Simplex-Lattice sebagai Inhibitor Tirosinase dan Antibakteri Propionibacterium acnes

Abstract

Penuaan kulit dan jerawat sama-sama dipicu oleh stres oksidatif dan peningkatan aktivitas tirosinase yang menyebabkan hiperpigmentasi, termasuk PIH pasca-jerawat. Adapun bahan sintetis seperti hidrokuinon dan antibiotik topikal berisiko menimbulkan efek samping, penelitian ini mengeksplorasi kombinasi ekstrak umbi rumput teki (Cyperus rotundus L.) dan daun patikan kebo (Euphorbia hirta L.) yang kaya fenolik dan flavonoid, meskipun aktivitas masing-masing ekstrak telah banyak dilaporkan secara terpisah, penelitian mengenai efek sinergis kombinasi keduanya masih sangat terbatas, danbelum ada literatur ilimiah yang menetukan rasio optimal campuran kedua ekstrak tersebut untuk aplikasi antijerawat dan percerah kulit. Oleh karena itu, penelitian ini mengeksplorasi kombinasi kedua ekstrak menggunakan {2,4} Simplex-Lattice Design (SLD) model kuartik untuk menentukan rasio optimal sebagai agen antitirosinase, antibakteri Propionibacterium acnes, dan penghambat peroksidasi lipid (MDA). Ekstrak diperoleh melalui maserasi dengan etanol 96%, kemudian dianalisis kadar fenolik total, flavonoid total, dan aktivitas antioksidan (DPPH, TBA-MDA). Lima belas kombinasi rasio dioptimasi menggunakan Design Expert 13.0, lalu formulasi terpilih diuji aktivitas inhibisi peroksidasi lipid TBA-MDA, inhibisi IC50 inhibisi tirosinase, aktivitas antibakteri (difusi cakram), dan profil senyawanya dianalisis dengan UHPLC-Q-Orbitrap-HRMS. Model kuartik SLD terbukti signifikan (R² 0,98–0,99) untuk seluruh respon. Formulasi optimum diperoleh pada rasio 20% umbi teki : 80% patikan kebo (desirability = 1), dengan hasil verifikasi laboratorium sangat mendekati prediksi model (selisih 0–3%). Formulasi ini menunjukkan efek sinergis nyata pada inhibisi tirosinase (IC50 = 15,96 ± 0,04 µg/mL, lebih kuat dari kedua ekstrak tunggal) dan inhibisi MDA (81,16 ± 0,64%, mendekati a-tokoferol). Namun pada uji antibakteri terhadap P. acnes, kombinasi (zona hambat 8,50 ± 0,6 mm, kategori kuat) tidak menunjukkan sinergi dibanding ekstrak tunggal, dan seluruh sampel tidak aktif terhadap S. aureus. Analisis LC-MS mengidentifikasi senyawa bioaktif pendukung seperti kuersetin, kaempferol, dan asam galat (patikan kebo), serta nootkatone dan alantolakton (umbi teki). Secara keseluruhan, kombinasi kedua ekstrak pada rasio 20:80 berpotensi sebagai bahan aktif kosmetik multifungsi untuk hiperpigmentasi dan jerawat, dengan pendekatan SLD terbukti efektif menentukan formulasi optimum.

Skin aging and acne are both triggered by oxidative stress and increased tyrosinase activity, which lead to hyperpigmentation, including post-acne PIH (post-inflammatory hyperpigmentation). Since synthetic agents such as hydroquinone and topical antibiotics carry a risk of side effects, nutgrass tuber (Cyperus rotundus L.) and asthma weed leaf (Euphorbia hirta L.) represent potential natural alternatives, being rich in phenolic and flavonoid compounds with antioxidant, antibacterial, and anti-tyrosinase activities. Although the activities of each extract have been widely reported individually, research on the synergistic effects of their combination remains very limited, and no scientific literature has yet established the optimal mixing ratio of the two extracts for anti-acne and skin-brightening applications. Therefore, this study explores the combination of both extracts using a {2,4} Simplex-Lattice Design (SLD) with a quartic model to determine the optimal ratio as a tyrosinase inhibitor, an antibacterial agent against Propionibacterium acnes, and a lipid peroxidation (MDA) inhibitor. Extracts were obtained through maceration with 96% ethanol, followed by analysis of total phenolic content, total flavonoid content, and antioxidant activity (DPPH and TBA-MDA methods). Fifteen extract ratio combinations were optimized using Design Expert 13.0, after which the selected formulation was evaluated for TBA-MDA lipid peroxidation inhibition, tyrosinase inhibition (IC50), antibacterial activity (disc diffusion method), and compound profiling using UHPLC-Q-Orbitrap-HRMS. The SLD quartic model proved significant (R² 0.98–0.99) for all measured responses. The optimum formulation was obtained at a ratio of 20% nutgrass extract to 80% asthma weed extract (desirability = 1), with laboratory verification results closely matching the model's predictions (0–3% deviation). This formulation exhibited a clear synergistic effect in tyrosinase inhibition (IC50 = 15,96 ± 0.04 µg/mL, stronger than either single extract) and MDA inhibition (81,16 ± 0.64%, approaching a-tocopherol's activity). However, in the antibacterial assay against P. acnes, the combination (inhibition zone of 8,50 ± 0,6 mm, classified as strong) showed no synergistic effect compared to the single extracts, and none of the samples showed activity against S. aureus. LC-MS analysis identified supporting bioactive compounds such as quercetin, kaempferol, and gallic acid (in asthma weed extract), as well as nootkatone and alantolactone (in nutgrass extract). Overall, the combination of both extracts at a 20:80 ratio shows potential as a multifunctional cosmetic active ingredient for addressing hyperpigmentation and acne, with the SLD approach proving effective in determining the optimum formulation.