From an MeOH extract of the stems of Premna corymbosa var. obtusifolia, thirteen compounds were isolated. The structure of a new compound 1 was determined to be 3hydroxy-4-methoxyphenethyl alcohol 3-D-(3'-0-ot-L-rhamnopyranosyl,-4'-0^-Dglucopyranosyl,-6' -O-feruloyl) glucopyranoside. Confirmation of the stereochemical structure of 4-^>/-gummadiol-4-0-P-D-glucopyranoside [6] was also performed in this study.From the leaves of Premna corymbosa (Burm. fil.) Rottb. et Willd. var. obtusifolia (R.Br.) Flecher (Verbenaceae), harvested on an Okinawan island, premcoryoside, a conjugate of verbascoside and mussaenosidic acid, was isolated (1). From the stems of the same plant, a new phenyl ethanoid, named premnafolioside [!}, and twelve known compounds have now been isolated from the zz-BuOH soluble fraction of the MeOH extract.Premnafolioside [1], [ot}D -35.8°, was obtained as an amorphous pale yellow powder whose elemental composition was determined to be C37H5002o by negative hrfabms. The uv max at 206, 289, and 326 nm, and ir absorption at 3399 (vOH), 1696 (a conjugated ester), 1632 (a double bond), and 1595 and 1516 (aromatic rings) cm 1 were very similar to those of verbascoside [2] and martynoside [3} (2), which co-exist in this plant. The JH nmr spectrum showed the presence of two units of aromatic protons coupled in an ABX system, a trans double bond [ 6.40 (d,J= 16 Hz) and 7.26 (d,J= 16 Hz)], anomeric protons for ß-glucopyranose [ 4.34 (d,J=8 Hz)} and for rhamnopyranose [ 5.35 (d,J=2 Hz)} and two MeO signals. The 13C-nmr spectrum indicated that, besides the presence of the above-mentioned moieties, there was one more molecule of non-substituted ß-glucopyranose [6H_r 4.32 (d, J=9 Hz), 6c_r 104.34} in the skeleton. These results indicated that premnafolioside [1} was a derivative of martynoside {3} (see Table 1), having one more glucopyranose unit.A phenylethanoid 4, which has an extra glucose unit at the 6 position of the glucopyranoside in martynoside [3], was isolated from other plant sources (3,4), but the 13C-nmr chemical shifts of 1 were not superimposable with those of 6'-0-ß-glucopyranosyl martynoside (see 1 and 4 in Table 1). Namely, significant differences in the chemical shifts of C-4' and C-6' between 4 ( 70.47 and 69.47, respectively) and premnafolioside {1} ( 76.2 and 63.7, respectively) suggested that the extra glucose and acyl moieties in 4 have been exchanged. This was supported by the fact that the 13C-nmr chemical shift of the C-6' position of isoacteoside [5] ( 64.6) (5-7) was close to that of
