Cynanchum is a genus of about 300 species including some swallowworts, belonging to the family Apocynaceae. Roots densely fibrous, fragrant. Stems slender, erect, to 1 m, glabrous or hispid below, rigid, unbranched or with few branches from upper parts. Leaves opposite; petiole ca. 3 mm; leaf blade lanceolate to linear, 5-13 × 0.5-1.5 cm, stiffly papery, glabrous or adaxially puberulent, ciliate, base and apex acute; lateral veins obscure. Inflorescences terminal and from upper nodes, laxly branched, to 7 cm; peduncle 2.5-4 cm.
Ten compounds were isolated from the 80% methanol extract of roots of Cynanchum paniculatum Kitagawa (Asclepiadaceae) and identified as paeonol (1), 4-acetylphenol (2), 2,5-dihydroxy-4-methoxyacetophenone (3), 2,3-dihydroxy-4-methoxyacetophenone (4), acetoveratrone (5), 2,5-dimethoxyhydroquinone (6), vanillic acid (7), resacetophenone (8), m-acetylphenol (9) and 3,5-dimethoxyhydroquinone (10). The protective effect of compounds 1-10 against glutamate-induced cytotoxicity in hippocampal HT22 cell line was evaluated.