Nanoencapsulation of Rhodiola rosea extract into 2-hydroxypropyl-β-cyclodextrin: enhanced antibacterial and anticancer activities

Abstract

The methanolic extract of Rhodiola rosea (RRME) exhibits multifaceted biological functions, notably antioxidant, anti-inflammatory, and neuroprotective potential. These properties are primarily associated with its rich therapeutic phytochemicals such as salidroside, rosavin, and tyrosol, which contribute to its potential therapeutic applications in managing stress-related disorders and neurodegenerative conditions. In this study, RRME was extracted using the Soxhlet method and subsequently encapsulated in (2-hydroxypropyl)-beta-cyclodextrin (HPβCD) using the freeze-drying technique, forming inclusion complexes (RRME-ICs). RRME-ICs were spherical morphologies with a size range of 87.36 to 166.5 nm. The ICs had a polydispersity index of 0.283 ± 0.01 and %EE of 78.88 ± 1.55%. FT-IR, ¹H NMR, 2D NMR NOESY, and TGA demonstrated the effective incorporation of RRME into HPβCD and enhanced integrity with a high thermal stability up to 350 °C. RRME-ICs demonstrated strong antibacterial effects compared to the extract. The MIC90 of RRME exceeded 20 mg mL⁻¹ against Escherichia coli, Pseudomonas putida, and Staphylococcus aureus, indicating limited antibacterial potency. Release kinetics analysis confirmed that the Korsmeyer–Peppas model provided the best fit for RRME-ICs across both pH conditions. RRME-ICs demonstrated remarkable antibacterial activity, with IC₉₀ of 2.38, 3.95, and 1.92 mg mL⁻¹ against E. coli, P. putida, and S. aureus, respectively. Additionally, RRME-ICs preserved antioxidant activity in the DPPH scavenging assay, demonstrating 92.6% scavenging efficiency with an IC₅₀ value of 0.0657 mg mL⁻¹. RRME-ICs also exhibited notable anticancer potential against melanoma (A375) cells with IC₅₀ of 48.14 µg mL⁻¹, compared to RRME (IC50 = 131.24 µg mL⁻¹). In conclusion, encapsulation through HPβCD inclusion complex formation improved its antibacterial and anticancer activities while preserving its antioxidant activity.