In this study, we prepared and characterized a callus extract from Citrus junos and assessed its utility as a source of topical anti-aging ingredients. Callus extract was produced by aqueous extraction from Citrus junos grown on Murashige and Skoog medium with picloram as a growth regulator. After measuring the total phenolic and flavonoid contents, the major phenolic compound in calli was identified as p-hydroxycinnamoylmalic acid (1) by spectroscopic analysis. The total phenol content in the extract was determined to be 24.50 ± 0.43 mg/g of gallic acid equivalents; however, the total flavonoid content of the extract was not determined. The biological activities of the callus extract, in terms of skin anti-aging, were assessed by measuring the anti-tyrosinase activity in, and melanogenesis by, melanoma cells; and proliferation of, and procollagen synthesis by, human fibroblasts. The callus extract was incorporated into nanoliposomes (NLs) to improve its percutaneous absorption. Addition of the callus extract resulted in a 1.85-fold decrease in the melanin content of melanocytes compared with that with arbutin. The extract (500 μg/mL) significantly promoted the proliferation of, and procollagen synthesis by, fibroblasts (by 154% and 176%, respectively). In addition, the flux through the human epidermis of Citrus junos callus extract incorporated into NLs was 17.67-fold higher than that of the callus extract alone. These findings suggest that Citrus junos callus extract-loaded NLs have promise as an anti-aging cosmetic, as well as having a skin-lightening effect.
Keywords: Citrus junos; anti-aging; callus extract; cosmetic ingredients; plant cell culture; skin lightening.