[Study on chemical constituents from Mastic (Pistacia lentiscus)].

Phytochemical investigation on the methanolic extract of Mastic by using various chromatographic techniques led to the isolation of 9 compounds. Based on the analysis of spectroscopic data(NMR and MS) and/or comparisons with the data reported in the literature, their structures were elucidated as 3β,8α,13-trihydroxypolypoda-14-methoxy-14-methyl-17,21-diene(1), 4-hydroxymyrtenal(2),3-methyl-6-(prop-1-en-2-yl)cyclohex-3-ene-1, 2-diol(3), 2-oxo-Δ~3-4,5,5-trimethylcyclopentynyl acidic acid(4),(1S,2R,3R,5R)-6,6-dimethyl-4-methylidenebicyclo[3.1.

3-(4-Carb-oxy-5-carboxyl-ato-1H-imidazol-2-yl)pyridin-1-ium monohydrate.

In the zwitterionic mol-ecule of the title compound, C(10)H(7)N(3)O(4)·H(2)O, one carboxyl group is deprotonated and the pyridine N atom is protonated. The pyridinium and imidazole rings form a dihedral angle of 5.23 (1)°.