Tyrosinase plays a key role in the production of melanin. A variety of industrial fields have shown interest in the development of tyrosinase inhibitors from plants. In this study, compounds 1–5 derived from Leonurus japonicas were evaluated to determine their ability to inhibit tyrosinase. Of these, 10-methoxy-leonurine (1) and leonurine (2) exhibited IC₅₀ values of 7.4 ± 0.4 and 12.4 ± 0.8 μM, respectively, and acted as competitive inhibitors of tyrosinase, with Ki values in the micromolar range. In silico modeling revealed a guanidine group located in the inner cavity and a benzene ring docked within the active site of these compounds. These guanidine pseudoalkaloids show potential not only as tyrosinase inhibitors but also as lead compounds in new scaffolds for the development of novel inhibitors.

Background/Objectives: Degenerative arthritis is a chronic inflammatory disease marked by tissue degradation and vascular fibrosis. Macrophages play a central role in the inflammatory response by releasing mediators such as nitric oxide (NO), interleukin (IL)-6, tumor necrosis factor alpha (TNF-α), and prostaglandin E2 (PGE2). This study aimed to investigate the anti-inflammatory potential of BTEX-K, a formulation of dried red ginseng combined with alpha-galactosidase, in lipopolysaccharide (LPS)-stimulated cells. Methods: LPS-treated immune cells were used to assess the anti-inflammatory effects of BTEX-K. The levels of NO, IL-6, TNF-α, and PGE2 were measured following BTEX-K treatment. The protein expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) was evaluated. Cytotoxicity assays were conducted to determine whether the observed effects were due to cell viability loss. The involvement of MAPK signaling and NF-κB pathway modulation was examined by analyzing JNK phosphorylation, IκB degradation, and PPAR-γ expression. Results: BTEX-K significantly reduced the production of NO, IL-6, TNF-α, and PGE2 in LPS-treated cells without inducing cytotoxicity. The protein expression levels of iNOS and COX-2 were also suppressed. Furthermore, BTEX-K inhibited the LPS-induced phosphorylation of JNK in the MAPK pathway. It restored IκB levels and suppressed NF-κB activation by preventing the downregulation of PPAR-γ. Conclusions: BTEX-K demonstrates notable anti-inflammatory effects by inhibiting key inflammatory mediators and signaling pathways in immune cells. These findings support its therapeutic potential in mitigating inflammation-related symptoms, including pain, swelling, and redness, commonly seen in degenerative arthritis.