3-O-Methylquercetin from Achyrocline satureioides-cytotoxic activity against A375-derived human melanoma cell lines and its incorporation into cyclodextrins-hydrogels for topical administration.

3-O-Methylquercetin (3OMQ), a natural 3-O-methylflavonoid, was isolated from Achyrocline satureioides and purified using the high-performance counter current chromatography (HPCCC) on a semi-preparative scale. High-purity 3OMQ (98%) was obtained with excellent recovery (81.8% (w/w)) and good yield (190 mg/100 g of plant). Isolated 3OMQ was evaluated against the A375 human amelanotic melanoma cancer cell line and A375-derived with different degrees of aggressiveness (A375-A7, A375-G10, and A375-PCDNA3). The results showed that 3OMQ reduced the cell viability of all strains, demonstrating time- and dose-dependent responses. 3OMQ was used to obtain hydrogels for the topical treatment of melanoma. Thus, 3OMQ was incorporated into hypromellose hydrogels with/without different cyclodextrins (CDs). The 3OMQ formulations showed permeation/retention in all skin layers, namely stratum corneum, epidermis, and dermis. A significant amount of 3OMQ was found in the replication site of the melanoma cells (epidermis and dermis). Altogether, these results demonstrate that 3OMQ can be isolated from Achyrocline satureioides by HPCCC on a semi-preparative scale and exhibit cytotoxic activity against melanoma cells. Its incorporation into an HPMC hydrogel containing HP-β-CD yielded a formulation with excellent technological and biopharmaceutical characteristics for evaluating the topical management of melanoma.