Low-energy nanoemulsions as carriers for red raspberry seed oil: Formulation approach based on Raman spectroscopy and textural analysis, physicochemical properties, stability and in vitro antioxidant/ biological activity

PLoS One. 2020 Apr 16;15(4):e0230993. doi: 10.1371/journal.pone.0230993. eCollection 2020.

Abstract

Considering a growing demand for medicinal/cosmetic products with natural actives, this study focuses on the low-energy nanoemulsions (LE-NEs) prepared via the Phase inversion composition (PIC) method at room temperature as potential carriers for natural oil. Four different red raspberry seed oils (ROs) were tested, as follows: cold-pressed vs. CO2-extracted, organic vs. non-organic, refined vs. unrefined. The oil phase was optimized with Tocopheryl acetate and Isostearyl isostearate, while water phase was adjusted with either glycerol or an antioxidant hydro-glycolic extract. This study has used a combined approach to formulation development, employing both conventional methods (pseudo-ternary phase diagram - PTPD, electrical conductivity, particle size measurements, microscopical analysis, and rheological measurements) and the methods novel to this area, such as textural analysis and Raman spectroscopy. Raman spectroscopy has detected fine differences in chemical composition among ROs, and it detected the interactions within nanoemulsions. It was shown that the cold-pressed, unrefined, organic grade oil (RO2) with 6.62% saturated fatty acids and 92.25% unsaturated fatty acids, was optimal for the LE-NEs. Textural analysis confirmed the existence of cubic gel-like phase as a crucial step in the formation of stable RO2-loaded LE-NEs, with droplets in the narrow nano-range (125 to 135 nm; PDI ≤ 0.1). The DPPH test in methanol and ABTS in aqueous medium have revealed a synergistic free radical scavenging effect between lipophilic and hydrophilic antioxidants in LE-NEs. The nanoemulsion carrier has improved the biological effect of raw materials on HeLa cervical adenocarcinoma cells, while exhibiting good safety profile, as confirmed on MRC-5 normal human lung fibroblasts. Overall, this study has shown that low-energy nanoemulsions present very promising carriers for topical delivery of natural bioactives. Raman spectroscopy and textural analysis have proven to be a useful addition to the arsenal of methods used in the formulation and characterization of nanoemulsion systems.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Administration, Topical
  • Antioxidants / chemistry
  • Antioxidants / pharmacology
  • Cell Line
  • Cell Survival
  • Drug Compounding
  • Drug Delivery Systems
  • Drug Stability
  • Electric Conductivity
  • Emulsions
  • Fatty Acids / chemistry
  • Fruit / chemistry
  • Humans
  • Microscopy, Atomic Force
  • Nanostructures
  • Plant Oils / chemistry
  • Plant Oils / pharmacology
  • Rheology
  • Rubus / chemistry*
  • Seeds / chemistry
  • Spectrum Analysis, Raman

Substances

  • Antioxidants
  • Emulsions
  • Fatty Acids
  • Plant Oils

Grants and funding

This research was funded by the Ministry of Education, Science and Technological Development, Republic of Serbia, through the research project TR34031 Development of Micro- and Nanosystems as Carriers for Drugs with Anti-inflammatory Effects and Methods for Their Characterization. This funder provided support in the form of salaries, materials, equipment, and facilities for authors [AG, JD, IN and SDS], but did not have any additional role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript. This work was also part of the project for which financial support was provided by the Ministry of Education, Science and Technological Development of Serbia (project OI172043 A.J.L, D.B.-B.). This funder provided Raman spectroscopy analysis but it did not play a role in study design, or preparation of the manuscript. Publication funding was provided by the London College of Fashion, University of the Arts London (S.T). DCP Hemigal [S.N.S] did not play a role in funding, study design, or preparation of the manuscript. The authors declare no conflict of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, or in the decision to publish the results.