Scientists at the university saiy they had previously documented that substances from the South African plant species Crinum and Cyrtanthus - akin to snowdrops and daffodils - have an effect on the mechanisms in the brain involved in depression. Their new research shows that many of these plants contain compounds that can pass the defensive blood-brain barrier that is a key challenge in all new drug development.

"Several of our plant compounds can probably be smuggled past the brain's effective barrier proteins. The biggest challenge in medical treatment of diseases of the brain is that the drug cannot pass through the blood-brain barrier. The blood vessels of the brain are impenetrable for most compounds, one reason being the very active transporter proteins. You could say that the proteins pump the drugs out of the cells just as quickly as they are pumped in.

"So it is of great interest to find compounds that manage to 'trick' this line of defence," Prof. Birger Brodin said in a statement.

The team says it wil be a long time before any possible new drug reaches our pharmacy shelves.

"This is the first stage of a lengthy process, so it will take some time before we can determine which of the plant compounds can be used in further drug development," says Brodin.

The group's results were published in the Journal of Pharmacy and Pharmacology.