Menthane-type monoterpenes from branches and leaves of Illicium micranthum / 中草药

ABSTRACT

Objective: To study the chemical constituents from the branches and leaves of Illicium micranthum and insecticidal activitives on larvae of Bradysia odoriphaga. Methods: The chemical constituents were isolated and purified by silica gel, and Sephadex LH-20 column chromatography. Their structures were elucidated by physicochemical properties and spectroscopic analyses. The standard contact and stomach bioassay method was used to assess the effects of median lethal dose (LD50) of compound 2 on the demographic parameters of larvae of B. odoriphaga. Results: Five monoterpenoids were isolated from the ethyl acetate layer of methanol extract from the branches and leaves of I. micranthum. Compound 1, (-)-(1R*, 4S*)-1-(hydroxymethyl)-4-isopropylcyclohex-2-ene-1, 4-diol, was a new monoterpenoid and named as illicmicrene A, and the other compounds were identified as (1R, 2R, 4R)-1-methyl-4-(1-methylethyl)-1, 2, 4-cyclohexanetriol (2), 4-hydroxypiperitone (3), olibanumol C (4) and α, α-dimethyl-4-hydroxymethylbenzyl alcohol (5), respectively. Conclusion: Compound 1 is isolated as a new compound and compounds 2-5 are obtained from I. micranthum for the first time. Furthermore, compound 2 shows the insecticidal effects on larvae of B. odoriphaga with LD50 values at 30.4 mg/L after 48 h, at 22.5 mg/L after 72 h.