Per-N-methylated analogues of an antitumor bicyclic hexapeptide RA-VII.

Penta-N-methyl and hexa-N-methyl analogues of RA-VII, an antitumor bicyclic hexapeptide of plant origin, were prepared. In the former, the nitrogens of d-Ala-1 and Ala-4 and in the latter, those of d-Ala-1, Ala-2, and Ala-4 were methylated under the phase-transfer catalysis conditions. Their solution structures were established by NOESY experiments and the crystal structures by X-ray crystallography.

A novel bicyclic hexapeptide, RA-XVIII, from Rubia cordifolia: structure, semi-synthesis, and cytotoxicity.

A new bicyclic peptide of RA-series, RA-XVIII (3), was isolated from the roots of Rubia cordifolia L. Its structure was established to be a hydroxylated derivative of RA-VII by the semi-synthesis of 3 from deoxybouvardin, and its cytotoxicity against P-388 cells was 0.012 microg/mL.

Authentication and chemical study of isodonis herba and isodonis extracts.

Isodonis Herba is used as a Japanese dietary supplement and folk medicine. The extract of the herb (Isodonis extract) is also used as a food additive whose major compound is enmein (1). Here we compared internal transcribed spacer sequences of nuclear ribosomal DNA from Isodonis Herba available on the Japanese and Chinese crude drug markets, and found that the former derived from Isodon japonicus and Isodon trichocarpus, while the latter derived from distinct species such as Isodon eriocalyx.

HPLC separation of naringin, neohesperidin and their C-2 epimers in commercial samples and herbal medicines.

Flavanone glycosides, such as naringin and neohesperidin, are distributed in some Citrus species and have a chiral center in the C-2 position of the flavanone moiety. Naringin and neohesperidin (2S-form) were separated from the corresponding C-2 epimers (2R-epi-form) by normal-phase HPLC using a polysaccaride-derived chiral stationary phases (CSPs), CHIRALPAK IB. The analyses of commercial samples of naringin revealed that the relative ratios of naringin to the C-2 epimer were 29-89%.

Iridoid glycosides and cucurbitacin glycoside from Neopicrorhiza scrophulariiflora.

Three iridoid glycosides, picrorosides A (1), B (2) and C (3), and a cucurbitacin glycoside, scrophoside A (4), were isolated from the rhizomes of Neopicrorhiza scrophulariiflora (Scrophulariaceae), along with two known iridoid glycosides, picrosides I (5) and II (6), and three known cucurbitacin glycosides (7-9). Their structures were elucidated on the basis of both chemical and spectroscopic data.

Two phenylpropanoid glycosides from Neopicrorhiza scrophulariiflora.

Two new phenylpropanoid glycosides, scrophulosides A (1) and B (2), were isolated from the rhizomes of Neopicrorhiza scrophulariiflora (Scrophulariaceae), along with two known compounds, androsin (3) and picroside I. Their structures were elucidated on the basis of both chemical and spectroscopic data.

HPLC separation of hesperidin and the C-2 epimer in commercial hesperidin samples and herbal medicines.

Hesperidin (2S-form), the flavanone 7-O-glycoside, is the main constituent of some Citrus species. The peels of two Citrus species are used as a crude drug, Aurantii nobilis pericarpium, in the Japanese Pharmacopoeia and as components in Kampo formulae. Thus, HPLC analysis of hesperidin as a marker compound is needed for quality control of medicines.

Quassinoid glucosides from seeds of Brucea amarissima.

Quassinoid glucosides, javanicosides I, J, K and L, were isolated from the seeds of Brucea amarissima (Lour.) Desv. ex B.

New quassinoids, javanicolides C and D and javanicosides B--F, from seeds of Brucea javanica.

Two new quassinoids, javanicolides C and D, and five new quassinoid glucosides, javanicosides B-F, were isolated from the seeds of Brucea javanica, along with eight known quassinoids, i.e., yadanziolides A, C, D, and S, bruceins D and E, brusatol, and the aglycone of yadanzioside D, and 19 known quassinoid glucosides, i.