Two studies by researchers at Charles Darwin University in Australia's Northern Territory looked at the healing properties of two native plants, Calophyllum inophyllum and Tinospora smilacina, as alternative sources of medicine.
C. inophyllum is commonly known in northern Australia as beauty leaf. In addition to being a hardy tree that attracts birds and resists cyclones, it produces a fruit (ballnut) from which oil can be extracted. First Nations peoples ground the fruit’s kernel and mixed it with water to ease body pain. Meanwhile, T. smilacina, or snake vine, is native to central Australia and Indigenous communities crushed sections of the vine to treat headaches, rheumatoid arthritis, and other inflammatory conditions. The sap and leaves were sometimes used to treat wounds.
“These plants represent a rich source of bioactive compounds that have not been fully explored regarding their potential therapeutic applications,” said Elnaz Saki, the lead author of both studies.
Wound healing is a complex process requiring different cell types to work together. To be effective, substances used to penetrate the skin barrier and repair it are generally restricted to small molecular weight compounds or nanosystems. Nanosystems can be designed to interact with the outermost layer of the skin, which acts as a barrier to many substances. Nanosystems include nanoemulsions, the dispersion of droplets of one liquid (less than 200 nanometers) in another.
The researchers’ first study was concerned with creating an effective, cold-pressed nanoemulsion using seed oil from C. inophyllum (CSO). The researchers tested its wound-healing capabilities using a scratch assay, a laboratory technique whereby a layer of cells is sliced, and cell-to-cell interaction is examined over time.
They found that cells treated with a nanoemulsion containing CSO in a concentration as low as 0.4% resulted in 100% wound closure after 48 hours, compared to untreated cells, which only achieved 39% closure over the same period. The nanoemulsion was also found to be physically stable when stored and had antimicrobial and antioxidant effects.
They followed up on their initial experiment using T. smilacina. The plant’s leaves were dried and ground to a fine powder, mixed with water and filtered. Nano-sized droplets of CSO were then added. Again, the researchers used the scratch assay to test the nanoemulsion’s wound-healing abilities.
The combination of T. smilacina and CSO was found to have improved antioxidant and wound-healing activities compared to CSO or T. smilacina alone. The combination produced wound closure of approximately 90% after 24 hours, with complete closure after 48 hours. Untreated cells achieved 70% closure at 48 hours.
“Both nanoemulsions demonstrated an improvement or equivalent activity for biomedical applications such as wound healing, antimicrobial, and antioxidant effects,” said Saki.
According to the researchers, the study’s findings pave the way for the use of sustainable, environmentally friendly treatment solutions. They plan to explore the potential of these healing plants further.
“With the increasing demand for sustainable and eco-friendly solutions in the pharmaceutical industry, I recognized an opportunity to contribute to this field by investigating the bioactive properties of plant extracts,” Saki said. “I am also interested in exploring the potential of these compounds to be included in novel therapies for various diseases, including anti-cancer, anti-inflammation, multi-drug resistant and infectious diseases.”