Carrier-free cryptotanshinone-peptide conjugates self-assembled nanoparticles: An efficient and low-risk strategy for acne vulgaris

Acne vulgaris ranks as the second most prevalent dermatological condition worldwide, and there are still insufficient safe and reliable drugs to treat it. Cryptotanshinone (CTS), a bioactive compound derived from traditional Chinese medicine Salvia miltiorrhiza, has shown promise for treating acne vulgaris due to its broad-spectrum antimicrobial and significant anti-inflammatory properties. Nevertheless, its local application is hindered by its low solubility and poor skin permeability. To overcome these challenges, a carrier-free pure drug self-assembled nanosystem is employed, which can specifically modify drug molecules based on the disease type and microenvironment, offering a potential for more effective treatment. We designed and synthesized three distinct structures of cationic CTS-peptide conjugates, creating self-assembled nanoparticles. This study has explored their self-assembly behavior, skin permeation, cellular uptake, and both in vitro and in vivo anti-acne effects. Molecular dynamics simulations revealed these nanoparticles form through intermolecular hydrogen bonding and π-π stacking interactions. Notably, self-assembled nanoparticles demonstrated enhanced bioavailability with higher skin permeation and cellular uptake rates. Furthermore, the nanoparticles exhibited superior anti-acne effects compared to the parent drug, attributed to heightened antimicrobial activity and significant downregulation of the MAPK/NF-κB pathway, leading to reduced expression of pro-inflammatory factors including TNF-α, IL-1β and IL-8. In summary, the carrier-free self-assembled nanoparticles based on CTS-peptide conjugate effectively address the issue of poor skin bioavailability, offering a promising new approach for acne treatment.