Premnafolioside, a New Phenylethanoid, and Other Phenolic Compounds from Stems of Premna corymbosa var. obtusifolia

Abstract

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

Solvent Derived Artifacts in Natural Products Chemistry

“…in glycoside-like structures for the determination of the connections. During the investigation of the n-BuOH soluble fraction of the methanolic extract of Premna corymbosa, Yuasa and co-workers isolated an artifact resulting from the caffeoyl migration on the structure of an acteosyde glycoside [28]. Although the authors do not report the exact method followed in the purification procedure, they refer to a similar phenomenon found by Nonaka and co-authors in which the caffeoyl acid moiety on a phenyl ethanoid structure migrated from position C-4 to C-6 of the glucose [29].…”

Ethnomedicinal uses, phytochemistry and pharmacological aspects of the genus Premna : a review

“…Lignans, a phenylpropanoid derivatives, were identified within 6 species of Premna and commonly found as furan lignans [ 199–202] (Rao & Rao 1981 ; Yuasa et al. 1993 ; Habtemariam et al. 1995 ) and furofuran lignans [ 203–209 ] (Yuasa et al.…”

“… 2013 ) in the genus Premna except for compounds 195–198 which are dibenzylbutane lignans (Yuasa et al. 1993 ; Habtemariam et al. 1995 ) ( Table 2 ).…”

New glyceroglycolipid and ceramide from Premna microphylla

“…Recent studies on the biological and chemical constituents of members of the genus Premna have resulted in the isolation of iridoids (1)(2)(3), sesquiterpenes (4,5), diterpenes (6)(7)(8)(9), and phenylethnoids (10,11), some of which have exhibited significant antibacterial (4,6,8) and cytotoxic activities (9). Premna microphylla Turez., distributed mainly in the southern part of China, is a shrub whose leaves are applied widely to treat skin cuts and infections, malaria, dysentery, headaches, and viper bites in Chinese traditional medicine (12).…”