The Fungicidal Terpenoids and Essential Oil from Litsea cubeba in Tibet

Abstract

A new C9 monoterpenoid acid (litseacubebic acid, 1) and a known monoterpene lactone (6R)-3,7-dimethyl-7-hydroxy-2-octen-6-olide (2), along with three known compounds – vanillic acid (3), trans-3,4,5-trimethoxylcinnamyl alcohol (4), and oxonantenine (5) – were isolated with bioassay-guided purification from the fruit extract of Litsea cubeba collected in Tibet. The structure of 1 was elucidated by MS, 1H-NMR, 13C-NMR, COSY, HSQC, HMBC, NOE spectral data as 2,6-dimethyl-6-hydroxy-2E,4E-hepta-2,4-diene acid. Additionally 33 compounds were identified from the essential oil of L. cubeba. The preliminary bioassay results showed that 1 and 2 have good fungicidal activities against Sclerotinia sclerotiorum, Thanatephorus cucumeris, Pseudocer-cospora musae and Colletotrichum gloeosporioides at the concentration of 588 and 272 μM, and the essential oil has good fungicidal activities against T. cucumeris and S. sclerotiorum, with IC50 values of 115.58 and 151.25 μg/mL, repectively.

Keywords

• Litsea cubeba
• Lauraceae
• (6R)-3,7-dimethyl-7-hydroxy-2-octen-6-olide
• litseacubebic acid
• essential oil
• fungicidal activity