Researchers from the Institute of Chemistry of São Carlos (IQSC) and the National Institute of Science and Technology in Bioanalysis (INCTBio) developed a method for the production of hypericin-loaded nanoemulsions by ultrasonication according to an article published in August in the Journal of Photochemistry and Photobiology B: Biology. The new way to solubilize hypericin provides an increase in its cellular uptake, potentializing the hypericin (Hy) photodynamic therapy – a cancer treatment in potential.
The study financed by the Foundation of Support to Research of the State of São Paulo (FAPESP) consisted primarily on the production of hypericin-loaded nanoemulsion (NE), optimizing the process parameters – components proportions and time of ultrasonication – to generate the smallest possible nanodroplets. The stability tests of the NEs demonstrated a good stability during the 180 days of storage in which they were analyzed.
Posteriorly, the Hy-loaded nanoemulsions were combined with photodynamic therapy (PDT) in breast cancer cells. The tests indicated a six times greater anticancer potential of the PDT with hypericin NEs in comparison to free Hy. This is because of the increased absorption of the substance by the cells when loaded in NEs than when in their free state. The preclinical development of the Hy-PDT can be assisted by the data obtained from this research.
The production process of the nanoemulsions with nanodroplets of Hy began with the solubilization of hypericin in oil and surfactant. The solution was then mixed with water by ultrasonication, generating a homogeneous solution with nanodroplets of Hy, as illustrated by the image below.
Hypericin is a photosensitizer with great potential for use in photodynamic therapy due to its capacity of, when absorbs visible light, react and generate oxygen reactive species, which oxidate tumor cells components, leading them to death. In previous studies, Hy-PDT demonstrated minimal side effects and high selectivity when compared to conventional chemotherapies, moreover its efficiency against several types of cancer. However, hypericin is poorly soluble in water, making its clinical administration and absorption by the cells difficult.
Nanoemulsions are systems with droplets of the order of nanometers of a hydrophobic substance – that is, not soluble in water, like oil – stabilized in aqueous medium by a surfactant. In this way, the action of the surfactant makes the oil droplets stay dispersed in water and, therefore, solubilized.
The NEs are widely used in the pharmaceutical field aiming to load drugs that are poorly soluble in aqueous medium in the hydrophobic nucleus of the droplets stabilized by the surfactant, increasing its capacity to mix with water. Moreover, nanoemulsions furnish an extended contact area, increasing the absorption of the drug by the cells and hence minimizing dosage and possible side effects when existing.
* Republished from Journal of Photochemistry and Photobiology B: Biology, 223, H. L. Ma et al., Hypericin-loaded oil-in-water nanoemulsion synthesized by ultrasonication process enhances photodynamic therapy efficiency, Copyright (2021), with permission from Elsevier.
More informations
https://doi.org/10.1016/j.jphotobiol.2021.112303
Dr. Emanuel Carrilho
Address: Instituto de Química de São Carlos, Universidade de São Paulo, USP, Av. Trabalhador São-carlense, 400, 13566-590 São Carlos, SP, Brasil.
E-mail: emanuel@iqsc.usp.br