The alkaloid vincamajine from the herb Vinca major is pharmacologically active. A method for its quantitative determination is proposed, which involves obtaining the vincamajine fraction, two-stage thin-layer chromatography (TLC) on silica gel LS 5/40 using solvent systems 1 (benzene-ethyl acetate-methanol, 1:1:1) and 2 (benzene-ethyl acetate-methanol, 2:2:0.5), and spectrometric determination of the alkaloid in the eluate. The procedure includes extraction of comminuted dry raw material with ethanol, treatment with hydrochloric acid, exhaustive chloroform extraction, fractionation with citrate-phosphate buffers (pH 6.0 and 3.0), TLC with a chromatographically pure vincamajine marker, elution of the target band, and measurement of optical density. The amount of vincamajine in the herbage of Vinca major during the phase of the second autumn flowering was found to be 0.0123% based on absolutely dry raw material. Additionally, a new alkaloid, haplaphine (I), was isolated from the epigeal part of Haplophyllum perforatum. The structure of haplaphine was identified as 4(γ,γ-dimethylallyloxy)-2-quinolone using mass spectrometry (molecular ion peak at m/z 229), infrared (IR) spectroscopy (absorption bands at 3160 cm⁻¹ and 1665 cm⁻¹ indicating an -NH-CO- group), ultraviolet (UV) spectroscopy (spectral features typical of 4-alkoxy-2-quinolone alkaloids, with no changes upon acidification or alkalinization), and proton magnetic resonance (PMR) spectroscopy. Haplaphine has a melting point of 159-160°C (acetone) and a yield of 15 mg.