MOSCOW — An organ-failure-inducing, military-grade nerve agent may seem an unlikely source of inspiration for a product that is advertised as promoting “longevity.”

Not so for Alexei Yakushev, a farmer from a village in central Russia. This week, he launched “Novichok,” a sunflower oil named after the chemical agent the Kremlin is accused of using last month to poison the Russian former spy Sergei V. Skripal and his daughter, Yulia, in Salisbury, England.

The oil comes in a tall brown bottle with a black label decorated with the emblem of the Soviet-era secret police and the words, “Recommended by the K.G.B.” On Thursday, a beaming Mr. Yakushev posed for photos and a video promoting his new product at a trade fair in Ulyanovsk, a city 520 miles east of Moscow.

The 43-year-old farmer, who runs a family business called Yakushev, said in a telephone interview that he was seeking to inject an element of humor into an international spy scandal that has prompted Western nations to eject more than 150 Russian diplomats and the United States to impose a new round of economic sanctions, sending relations with the West to their lowest point since Russia’s military interventions in Crimea and eastern Ukraine.