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The chemical composition of the leaf oils of five Malaysian Piper species ( P . aduncum L., P. lanatum Roxb., P. pedicellosum Wall., P. penangense C.DC. and P. betle L.) was determined by co-chromatography with authentic samples on two columns of different polarity, GC-MS and KovAts retention indices. Dillapiole at 64.5% was the most abundant component in the oil of P. aduncum. Chavibetol constituted 69.0% and 42.7% of the oils of P. betle and P. lanatum respectively. The major components of the oil of P . pedicellosum were P-phellandrene (21.9%) and eugenol (17.2%. )E)-Nerolidol (17.5%) and cedrol (14.8%) were found to be the major constituents of P. penangense.

The rhizome oils of Boesenbergia pandurata (Roxb.) Schlecht, water-distilled from samples obtained from two different sites in Malaysia, Medan in Indonesia and Bangkok in Thailand, were analysed by gas chromatography on two columns of different polarity, retention indices and GC-MS. The oils were found to possess some compositional differences and considerable variation in the levels of some individual constituents, suggesting the existence of chemical varieties, which could be distinguished according to their ocimene contents. (E)-ˇ-Ocimene and (Z)-ˇ-ocimene, which were present in appreciable amounts in three samples, were conspicuously absent in one sample. The major constituents of the oils were camphor (16. Experimental Plant MaterialThe rhizomes of B. pandurata were collected from Johore and Selangor in Malaysia, Medan in Indonesia, and Bangkok in Thailand. The voucher specimens were deposited at the Percentages were obtained by peak-area normalization on column DB 5, all relative-response factors being taken as one; the retention index of compounds on the SE 30 was also determined; RI D retention index; t D tentative identification for all compounds, except for c; a D mass fragmentation; b D retention index; c D co-chromatography with authentic sample;(1) D Johore; (2) D Selangor; (3) D Medan; (4) D Bangkok.

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