Scientists have begun examining tetrahydrocannabivarin, a little-known components of cannabis. Their preliminary findings suggest the chemical can inhibit some of the negative effects of cannabis’s main component.

Cannabis sativa produces more than 100 chemical compounds that act on cannabinoid receptors in the brain. Of these chemicals, which are known simply as cannabinoids, the most common are tetrahydrocannabinol (THC) and cannabidiol (CBD). Tetrahydrocannabivarin (THCV) also naturally occurs in cannabis, but typically in very low quantities.

In a double-blind study, researchers from King’s College London administered 10mg of THCV or placebo capsules to ten healthy male volunteers for four days before injecting them with 1mg of THC on the fifth day. After two weeks, the experiment was repeated but the volunteers who were administered THCV capsules received placebo capsules, and vis-versa.

The drug was “well tolerated among the participants,” many of whom could not distinguish the THCV capsules from the placebo capsules, the researchers reported. Four out of the ten volunteers incorrectly guessed which week they had been given the THCV capsules.

THC impaired the volunteer’s verbal memory recall, a well-known side effect of the drug. However, this impairment was only observed when the volunteers had been given a placebo beforehand. THCV appears to have prevented the impairment.

“THC produced impairments to delayed recall, although this effect was only present under placebo condition and absent in the presence of THCV,” the researchers explained. “This suggests a protective and antagonistic effect of THCV on THC-induced memory impairment.”

THCV also inhibited increases in heart rate caused by THC.

Previous research has found that other cannabinoids, such as CBD, inhibit some of the negative effects produced by THC.

Nine out of ten volunteers said the subjective effects of THC were weaker when it was combined with THVC, but they did not report it to be any less pleasurable.

The researchers cautioned that their study, which was published in the Journal of Psychopharmacology in November 2015, was only a small pilot study. “A larger study is needed to confirm the current findings,” they said.