Jun. 4, 2019
By Leonardo Gottems, reporter for AgroPages
The dye extracted from the Indian saffron (Curcuma longa L.), also called Curcumin, can eliminate the larvae of the mosquito that transmits dengue and other diseases, the Aedes aegypti, within 3 to 48 hours. This was concluded by a research conducted by Brazilian scientists of the Center for Research in Optics and Photonics (Cenop), linked to the University of São Paulo (USP).
"Curcumin, one of the substances that gives the orange color to the India saffron, has natural photodynamic properties that allow it to produce highly toxic reactive oxygen species through exposure to light," explained Vanderlei Bagnato, researcher at the University of São Paulo (USP) and coordinator of the project.
According to researcher, Dr. Natalia Inada, "After the larvae eat curcumin, in contact with the oxygen present in the environment and with illumination, a reaction occurs from the inside out, destroying these larvae." The researchers found that the extract has natural photodynamic properties capable of raising the vulnerability of larvae to light and eliminating them.
Bagnato explained that mosquito larvae are very sensitive to photodynamic effects and that the dye accumulates in the insect's intestine after being ingested with the water where the mosquito breeds. When the substance is activated by light, it induces the production of molecules that cause fatal damage to the tissues of the digestive tract of the mosquitoes.
Experiments to prove the efficacy of the extract in the fight against dengue have so far been confined to the laboratory. However, what has already been done proves the effect of photodynamic treatment with the use of sunlight, using common white light and LED lights.
Exposure to sunlight has so far been the most effective treatment since 100% of larvae raised in dyed water died after being exposed for two hours or more to sunlight when there were 15 micrograms of saffron for every milliliter of water.
The aim of the researchers is to determine the best concentration of the extract for the treatment and if its use does not have environmental impacts. So far, it has been proven that exposure to sunlight for 24 hours completely degrades the dye in smaller derivatives whose toxicity is still being analyzed to ensure minimal environmental effects.
"Before taking the research to the natural breeding grounds, we need to be absolutely sure that the substances resulting from the photochemical fragmentation are harmless to other living things, such as algae, fish, domestic animals and humans," the researcher added.
India's saffron or saffron is a widely used species in the Middle Eastern and South Asian gastronomy, where the spice is also known for its anti-inflammatory properties. The researchers also evaluated with PDT Pharma the effectiveness of curcumin dye in medical applications: in combating fungi that cause nail fungal infections, oral decontamination and treatment of venous ulcers.
The experiment was funded by the Ministry of Health and the São Paulo State Research Support Foundation (FAPESP). The government awaits completion to assess the possibility of releasing the substance for the control of dengue. The researchers are gathering documents to send, in the first semester for the National Agency of Sanitary Surveillance (Anvisa) the approval of the use of the substance in the public health system.