Formulation and Biomedical Activity of Oil-in-Water Nanoemulsion Combining Tinospora smilacina Water Extract and Calophyllum inophyllum Seeds Oil

Abstract

Introduction

Tinospora smilacina is a native plant used in traditional medicine by First Nations peoples in Australia to treat inflammation. In our previous study, an optimised Calophyllum inophyllum seed oil (CSO) nanoemulsion (NE) showed improved biomedical activities such as antimicrobial, antioxidant activity, cell viability and in vitro wound healing efficacy compared to CSO.

Methods

In this study, a stable NE formulation combining T. smilacina water extract (TSWE) and CSO in a nanoemulsion (CTNE) was prepared to integrate the bioactive compounds in both native plants and improve wound healing efficacy. D-optimal mixture design was used to optimise the physicochemical characteristics of the CTNE, including droplet size and polydispersity index (PDI). Cell viability and in vitro wound healing studies were done in the presence of CTNE, TSWE and CSO against a clone of baby hamster kidney fibroblasts (BHK-21 cell clone BSR-T7/5).

Results

The optimised CTNE had a 24 ± 5 nm particle size and 0.21± 0.02 PDI value and was stable after four weeks each at 4 °C and room temperature. According to the results, incorporating TSWE into CTNE improved its antioxidant activity, cell viability, and ability to promote wound healing. The study also revealed that TSWE has >6% higher antioxidant activity than CSO. While CTNE did not significantly impact mammalian cell viability, it exhibited wound-healing properties in the BSR cell line during in vitro testing. These findings suggest that adding TSWE may enhance CTNE’s potential as a wound-healing treatment.

Conclusion

This is the first study demonstrating NE formulation in which two different plant extracts were used in the aqueous and oil phases with improved biomedical activities.

Keywords:

• medicinal plants
• nanoemulsion
• RSM
• wound healing
• in vitro

Data Sharing Statement

The datasets used and/or analysed during the current study are available from the corresponding author upon reasonable request.

Acknowledgments

The authors are grateful to the staff of the Berrimah Veterinary Laboratory for their assistance in cell culturing and to the Central Analytical Research Facility at Queensland University of Technology (QUT CARF) for the transmission electron microscopy imaging. The assistance provided by Jeremy Garnett of Top End Editing was greatly appreciated.

Disclosure

The authors report no conflicts of interest in this work.

Additional information

Funding

The authors would like to acknowledge Charles Darwin University for its financial support. Charles Darwin University had no role in the design of the study and collection, analysis, and interpretation of data and in writing this manuscript.