Allium macrostemon

Abstract: During the screening programme for new agrochemicals from Chinese medicinal herbs and local wild plants, the essential oil of dried bulbs of Allium macrostemon Bunge (Liliaceae) was found to possess larvicidal activity against mosquitoes. The aim of this research was to determine the larvicidal activity of the essential oil and its major constituent compounds against the larvae of the Culicidae mosquito, Aedes albopictus. Essential oil of A. macrostemon was obtained by hydrodistillation and analyzed by gas chromatography (GC) and gas chromaotography-mass spectrometry (GC-MS). The activity of the essential oil and its two major constituents were evaluated, using World Health Organization (WHO) procedures, against the fourth instar larvae of Ae. albopictus for 24 h and larval mortalities were recorded at various essential oil/compound concentrations ranging from 9.0 - 150 μg/ml. The essential oil of A. macrostemon exhibited larvicidal activity against the early fourth instar larvae of Ae. albopictus with an LC50 value of 72.86 μg/ml. The two constituent compounds, dimethyl trisulfide and methyl propyl disulfide possessed strong larvicidal activity against the early fourth instar larvae of Ae. albopictus with LC50 values of 36.36 μg/ml and 86.16 μg/ml, respectively. The results indicated that the essential oil of A. macrostemon and its major constituents have good potential as a source for natural larvicides.

Abstract: Two new steroidal saponins (1 and 2) were isolated from the dried bulbs of Allium macrostemon Bunge. Their structures were elucidated by the spectral data as 26-O-beta-D-glucopyranosyl-5alpha-furost-25 (27)-ene-3beta, 12beta, 22, 26-tetraol-3-O-beta-D-glucopyranosyl (1-->2) [beta-D-glucopyranosyl (1-->3)]-beta-D-glucopyranosyl (1-->4)-beta-D-galactopyranoside (1) and 26-O-beta-D-glucopyranosyl-5beta-furost-20 (22)-25 (27)-dien-3beta, 12beta, 26-triol-3-O-beta-D-glucopyranosyl (1-->2)-beta-D-galactopyranoside (2), respectively. Their cytotoxic activities on several cancer cell lines (MCF-7, NCI-H460, SF-268 and HepG2) were tested. 1 showed special cytotoxity on SF-268, while 2 showed cytotoxity on NCI-H460 and SF-268 cell lines, respectively.