Bengaluru: In the 2002 Hollywood thriller Insomnia, the character played by Al Pacino suffers from acute sleeplessness after perpetual daylight in Alaska and the guilt of killing his colleague catches up with him. At the movie’s end, the dazed and wounded protagonist breathes his last, saying he only wanted to sleep.
For millions of people suffering from insomnia, there could be a ray of light, thanks to the humble marine cone snail, found at the coast of south-east India and Sri Lanka.
In a research paper published in the Toxicon medical journal, scientists Jayaseelan Benjamin Franklin and Rajaiah Pushpabai Rajesh said they discovered the sleep-inducing properties of the venom of conus araneosus, while trying to identify various compounds in it.
The intrigued researchers named the sleep-inducing part of the venom sandman peptide, inspired by the European mythical character who sprinkles magical sand in people’s eyes to put them to sleep to bring good dreams. A peptide is a kind of small proteins found in living beings. Their studies have been proven on mice.
“The marine cone snails seem to have taken on the sandman’s role in the world of molluscs. The primary initiative of the study was to isolate and identify various components of the highly complex mix of poisons in this marine snail’s venom. Now that we have seen mice responding well, we will elaborate the study on other animals and also try and understand the mechanism of how it works,” said Franklin, a project scientist at the Andaman and Nicobar Centre for Ocean Science and Technology.
The two scientists dissected venom glands of marine snails, which are not endangered, picked up from the Gulf of Mannar in Tamil Nadu. The venom was then purified and 14 peptides were isolated. These peptides were classified according to the class they belong to.
Five of the peptides were checked for biological effects on mice. When the pure solution of these five peptides was injected in mice, only one showed activity. Within just four minutes of injecting, the peptide called ‘ar3J’ put the mice to sleep for two hours. When the dosage was doubled, the mice slept for five hours.
“The mice also took longer to regain their activity to normal behavioural levels after this treatment, exhibiting that the peptide could induce variable periods of sleep at variable dosages,” said Rajesh, a DST (department of biotechnology and science) Young Scientist at the Molecular Biophysics unit of Indian Institute of Science, Bangalore.
The scientists, in collaboration with the National Centre for Biological Sciences, would further study why and how the peptide induces sleep in mice and whether it can be developed into a therapeutic drug for treatment of sleep disorders. Currently, there are several drugs obtained from Conus toxins that are either in use or in clinical trials as non-addictive painkillers in cancer and neuroscience research.
According to them, the results of the discovery open up various prospects in terms of drug-based therapy for sleep disorders such as insomnia and sleep apnoea.
“Future experiments may prove to be useful in humans,” Franklin said.