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The essential oils from the leaves and rhizomes of Alpinia pahangensis Ridl., collected from Pahang, Peninsular Malaysia, were obtained by hydrodistillation, and their chemical compositions were determined by GC and GC/MS analyses. The major components of the rhizome oil were γ-selinene (11.60%), β-pinene (10.87%), (E,E)-farnesyl acetate (8.65%), and α-terpineol (6.38%), while those of the leaf oil were β-pinene (39.61%), α-pinene (7.55%), and limonene (4.89%). The investigation of the antimicrobial activity of the essential oils using the broth microdilution technique revealed that the rhizome oil of A. pahangensis inhibited five Staphylococcus aureus strains with minimum inhibitory concentration (MIC) values between 0.08 and 0.31 μg/μl, and four selected fungi with MIC values between 1.25 and 2.50 μg/μl.

Key indicators: single-crystal X-ray study; T = 100 K; mean (C-C) = 0.003 Å; R factor = 0.037; wR factor = 0.090; data-to-parameter ratio = 10.2.The title compound, systematic name 9-isopropylidene-2,6-dimethyl-11-oxatricyclo[6.2.1.0 1,5 ]undec-6-en-8-ol, C 15 H 22 O 2 , which crystallizes with two molecules of similar conformation in the asymmetric unit, features three fused rings, two of which are five-membered and the third six-membered. Of the two five-membered rings, the one with an O atom has a distinct envelope shape (with the O atom representing the flap). The six-membered ring is also envelope-shaped as it shares a common O atom with the five-membered ring. In the crystal, the two independent molecules are linked by a pair of O-HÁ Á ÁO hydrogen bonds, generating a dimer. Related literatureFor the C2 modification isolated from Globba malaccensis Ridl, see: Muangsin et al. (2004). ExperimentalCrystal data Data collectionBruker SMART APEX diffractometer 13257 measured reflections 3298 independent reflections 2882 reflections with I > 2(I) R int = 0.046