When broken down in the body, glucosinolates yield compounds including sulforaphane that help rid the body of carcinogens.
University of Illinois researchers found that spraying methyl jasmonate on five commercial field-grown varieties increased levels of three glucosinolate compounds.
But it also led to even greater boosts to four compounds to which glucosinolates give rise, including sulforaphane, suggesting the hormone assisted the hydrolysis process in the plant.
Weather was also found to affect compound levels, the researchers pointed out in their study, which was published in the American Chemical Society's Journal of Agricultural & Food Chemistry.
In a separate US study, another brassica compound - 3,3'-diindolylmethane (DIM) - was found to help recovery from radiation exposure. Researchers at the Georgetown University Medical Center in Washington DC found that well over half of rats treated with DIM remained alive 30 days after a lethal radiation dose, while untreated animals all died.
The compound could help protect normal tissues of cancer sufferers during radiation therapy, as well as preventing or mitigating sickness caused by radiation exposure, the researchers suggested.