Composition and Antimicrobial Activity of Essential Oils from Leaves and Twigs of Magnolia hookeri var. longirostrata DXLi & R. Z. Zhou and Magnolia insignis Wall. in Ha Giang Province of Vietnam

The essential oils from leaves and twigs of Magnolia hookeri var. longirostrata D.X.Li & R.Z.Zhou and Magnolia insignis Wall., growing wild in Ha Giang Province of Vietnam, were obtained by hydrodistillation and analyzed by gas chromatography-flame ionization detector (GC-FID) and gas chromatography-mass spectrometry (GC-MS). The respective yields of the M. hookeri var. longirostrata leaf and twig oils were 0.14% and 0.05% (v/w), and of the M. insignis leaf and twig oils were 0.16% and 0.05% (v/w), calculated on a dry weight basis. Major components of the oils of M. hookeri var. longirostrata were: Linalool (21.3%), (E)-nerolidol (12.2%) and neo-intermedeol (13.5%) (leaf oil); 1,8-cineole (13.3%) and linalool (17.1%) (twig oil). Major components of the oils of M. insignis were: Linalool (24.1%), geraniol (14.9%) and (E)-nerolidol (22.5%) (leaf oil); 1,8-cineole (9.5%) and linalool (26.9%) (twig oil). The essential oils from M. insignis showed stronger inhibitory effects on the seven test microorganisms than those from M. hookeri var. longirostrata. Candida albicans and Lactobacillus fermentum were more sensitive to the essential oils than the other tested microorganisms. This is the first time information on essential oils of M. hookeri var. longirostrata leaves and twigs and of M. insignis twigs are reported.