Akemi Umeyama

Triterpenoid glycosides from Anagallis arvensis

From the herb of Anagallis arvensis, we have isolated four novel oleanane glycosides, anagallosaponins VI-IX, and two artifact saponins, apoanagallosaponins III and IV, formed from anagallosaponins III and IV. The structures were elucidated by chemical and spectral methods, 2D NMR techniques being particularly helpful. The structures of anagallosaponins VI and VII were characterized as priverogenin B 3-O-beta-D-xylopyranosyl (1-->2)-beta-D-glucopyranosyl (1-->4)-alpha-L-arabinopyranoside and 3-O-(beta-D-glucopyranosyl (1-->4)-[beta-D-xylopyranosyl (1-->2)]beta-D-glucopyranosyl (1-->4)-alpha-L-arabinopyranoside), respectively. The structures of anagallosaponins VIII and IX were characterized as 23-hydroxypriverogenin B 22-acetate 3-O-(beta-D-xylopyranosyl (1-->2)-O-beta-D-glucopyranosyl (1-->4)[beta-D-glucopyranosyl (1-->2)]-alpha-L-arabinopyranoside), 3-O-(beta-D-glucopyranosyl (1-->4)-[beta-D-xylopyranosyl (1-->2)]beta-D-glucopyranosyl (1-->4)[beta-D-glucopyranosyl (1-->2)]- alpha-L-arabinopyranoside), respectively. The structures of apoanagallosaponins III and IV were characterized as camelliagenin A 16-acetate 3-O-beta-D-xylopyranosyl (1-->2)-beta-D-glucopyranosyl (1-->4)-alpha-L-arabnopyranoside, 3-O-(beta-D-xylopyranosyl (1-->2)-O-beta-D-glucopyranosyl (1-->4)[beta-D-glucopyranosyl (1-->2)]-alpha-L-arabinopyranoside), respectively.

Baccharane glycosides from seeds of Impatiens balsamina

From the seeds of Impatiens balsamina have been isolated four rare baccharane glycosides, hosenkosides L-O. The structures of all isolates were secured by the use of 2D NMR techniques (1H-1H COSY, HMQC, HMBC, ROESY) and chemical derivatization. Hosenkosides L and M are hosenkol A 3-O-sambubiosyl-28-O-glucoside and 3-O-sambubiosyl-26-O-glucosyl-28-O-glucoside, respectively. Hosenkoside N is hosenkol C 3-O-glucosyl-28-O-glucoside. Hosenkoside O is hosenkol D 3-O-sophorosyl-28-O-glucoside.

Hosenkosides A, B, C, D, and E, novel baccharane glycosides from the seeds of Impatiens balsamina

Abstract From the seeds of Impatiens balsamina has been isolated five novel baccharane glycosides, hosenkosides A-E. The structures of all isolates were secured by the use of 2D NMR techniques (1H-1H COSY, HMQC, HMBC, ROESY, TOCSY), CD spectroscopy and chemical derivatization.

Mechanism of inhibition of IgE-dependent histamine release from rat mast cells by xestobergsterol A from the Okinawan marine spongeXestospongia bergquistia

Histamine release from rat peritoneal mast cells induced by anti-IgE was essentially complete within 4–5 min. Xestobergsterol A and B, which are constituents of the Okinawan marine spongeXestospongia bergquistia Fromont, dose-dependently inhibited anti-IgE-induced histamine release from rat mast cells. The IC50 values of xestobergsterol A and B for histamine release in mast cells activated by anti-IgE were 0.07 and 0.11 μM, respectively. Anti-IgE stimulated PI-PLC activity in a mast cell membrane preparation. Xestobergsterol A dose-dependently inhibited the generation of IP3 and membrane-bound PI-PLC activity. Moreover, xestobergsterol A inhibited Ca2+-mobilization from intracellular Ca2+-stores as well as histamine release in mast cells activated by anti-IgE. On the other hand, xestobergsterol B did not inhibit the membrane-bound and cytosolic PI-PLC activity, IP3 generation or the initial rise in [Ca2+]i in mast cells activated by anti-IgE. These results suggest that the mechanism of inhibition by xestobergsterol A of the initial rise in [Ca2+]i, of the generation of IP3, and of histamine release induced by anti-IgE, was through the inhibition of PI-PLC activity.

Dendritic Cells Promoted by Ginseng Saponins Drive a Potent Th1 Polarization

Dendritic cells (DC) play a pivotal role in the initiation of T-cell-mediated immune responses, making them an attractive cellular adjuvant for use in cancer vaccines. The interaction of T cells with DC is crucial for directing T cell differentiation towards the Th1, Th2 or Th17 type, and several factors determining the direction of the T cell polarization. IL-12 plays a central role in the immune system, not only by augmenting the cytotoxic activity of T cells and NK cells and regulating IFN-γ production, but also by the capacity of IL-12 to promote the development of Th1 cells. Therefore, it is important to identify factors that might affect the differentiation, maturation and function of DC. Ginseng is a medicinal herb widely used in Asian countries, and many of its pharmacological actions are attributed to the ginsenosides. Moreover, T-cadinol and calamenene are sesquterpenes isolated from the heartwood of Cryptomeria japonica being pharmacologically active substances. We investigated whether M1 and M4, end products of steroidal ginseng saponins metabolized in digestive tracts, as well as T-cadinol and calamenene can drive DC maturation from human monocytes in vitro. Human monocytes were cultured with GM-CSF and IL-4 for 6 days under standard conditions, followed by another 2 days in the presence of M1, M4, T-cadinol or calamenene. The expression levels of CD1a, CD80, CD83, CD86 and HLA-DR on M1-primed DC, M4-primed DC, T-cadinol-primed DC and calamenene-primed DC were enhanced with a concomitant decrease in endocytic activity. M1-primed DC, M4-primed DC, T-cadinol-primed DC or calamenene-primed DC enhanced the T cell stimulatory capacity in an allo MLR (allogeneic mixed lymphocyte reaction). Naïve T cells co-cultured with allogeneic M1-primed DC, M4-primed DC, T-cadinol-primed DC or calamenene-primed DC turned into typical Th1 cells, which produced large quantities of IFN-γ and released small amounts of IL-4 depending on IL-12 secretion. In the CTL assay (cytotoxic T-lymphocyte assay), the production of IFN-γ and 51Cr release on M4-primed DC was more augmented than of immature DC or TNF-α-primed DC. These results suggest that M1, M4, T-cadinol and calamenene appear to be a good factor to induce DC maturation, or even better in some respect, for the use in clinical DC therapy to induce strong Th1 type immune responses.

Diterpene, 16-phyllocladanol enhances Th1 polarization induced by LPS-primed DC, but not TNF-α-primed DC

16-Phyllocladanol is diterpene isolated form the heartwood of Cryptomeria japonica. We demonstrate that the effect of 16-phyllocladanol on the phenotypic and functional maturation of human monocytes-derived DC in vitro. Human monocytes were exposed to 16-phyllocladanol alone, or in combination with LPS and thereafter co-cultured with naïve T cells. The expression levels of CD83 and HLA-DR on LPS-primed DC were enhanced by 16-phyllocladanol. 16-Phyllocladanol dose-dependently augmented the T cell stimulatory capacity in an allo MLR to LPS-primed DC and the production of IL-12p70 by LPS-primed DC. The cytokine production by 16-phyllocladanol-primed DC was not inhibited by anti-TLR2 and 4 mAbs. IFN-gamma secretion from naïve T cells co-cultured with DC differentiated with LPS was also augmented by 16-phyllocladanol. These results suggest that the enhancement of Th1 cells polarization to LPS-primed DC induced by 16-phyllocladanol via the activation of IL-12p70 and independent on TLR2 or TLR4.

In vitro antitrypanosomal activity of the cyclodepsipeptides, cardinalisamides A–C, from the insect pathogenic fungus Cordyceps cardinalis NBRC 103832

During the search for new antitrypanosomal drug leads, three new antitrypanosomal compounds, cardinalisamides A–C (1–3), were isolated from cultures of the insect pathogenic fungus Cordyceps cardinalis NBRC 103832. Their structures were elucidated using MS analyses and extensive 2D-heteronuclear NMR. The absolute configurations of 1–3 were addressed by chemical degradation and Marfey’s analysis. 1–3 showed in vitro antitrypanosomal activity against Trypanosoma brucei brucei with IC50 values of 8.56, 8.65 and 8.63 μg ml−1, respectively.

Opaliferin, a new polyketide from cultures of entomopathogenic fungus Cordyceps sp. NBRC 106954.

Opaliferin, a polyketide with a unique partial structure in which a cyclopentanone and tetrahydrofuran were connected with an external double bond, was isolated from the insect pathogenic fungus Cordyceps sp. NBRC 106954. The structure and relative configuration of opaliferin were determined by spectroscopic analysis and X-ray crystallography. The absolute configuration was established by anomalous dispersion effects in X-ray diffraction measurements on the crystal of di(p-bromobenzoyl) ester of opaliferin. A plausible biosynthetic pathway for opaliferin is proposed.

Polyacetylenediols regulate the function of human monocyte-derived dendritic cells.

Callyspongidiol and 14,15-dihydrosiphonodiol are Polyacetylenediols isolated from marine sponges and are pharmacologically active substances. Dendritic cells (DC) play an important role in the initiation and regulation of immune response. DC have a key influence in the differentiation of naïve T cells into Th1, Th2 or Th17 effector cells. We demonstrated that callyspongidiol and 14,15-dihydrosiphonodiol activate human DC as documented by phenotypic and functional maturation, and altered cytokine production. Up regulation of cell surface expression of CD1a, CD80, CD83, CD86, HLA-DR and CCR7 was observed following DC treatment with callyspongidiol and 14,15-dihydrosiphonodiol. The production of IL-10 by callyspongidiol-primed DC after stimulation with CD40-L was higher than that of LPS- or 14,15-dihydrosiphonodiol-primed DC. Naïve T cells co-cultured with allogeneic 14,15-dihydrosiphonodiol-primed DC at 1:5 DC/T cell ratio turned into typical Th1 cells depending on IL-12 secretion and independent on TLR2 or TLR4. In contrast, callyspongidiol-primed DC co-cultured with naïve T cells secreted IL-4 and IL-10, but had little effect on IFN-gamma. Callyspongidiol-primed DC induced the development of Th2 cells via the inhibition of IL-12p70 and the enhancement of IL-10. Polyacetylenediols-primed DC expressed the chemokine receptor CCR7 and had a high migration to CCL19. These results suggested that some Polyacetylenediols modulate human DC function in a fashion that favors Th1/Th2 cell polarization or IL-10 producing T cells, and might have implication in tumor or in autoimmune diseases.

Uncarinic Acid C Isolated from Uncaria rhynchophylla Induces Differentiation of Th1-Promoting Dendritic Cells Through TLR4 Signaling

Uncarinic acid C (URC) is triterpene isolated from Uncaria rhynchophylla and is a pharmacologically active substance. The induction of dendritic cells (DC) is critical for the induction of Ag-specific T lymphocyte responses and may be essential for the development of human vaccines relying on T cell immunity. DC might be a potential target for URC. We demonstrate that URC activates human DC as documented by phenotypic and functional maturation, and altered cytokine production. The expression of CD1a, CD38, CD40, CD54, CD80, CD83, CD86, HLA-DR and CCR7 on URC-primed DC was enhanced. The production of IL-12p70 by URC-primed DC was higher than that of lipopolysaccharide (LPS)-primed DC. The production of IL-12p70 by URC-primed DC was inhibited by the anti-Toll-like receptor 4 (TLR4) monoclonal antibody (mAb), but partially abolished by anti-TLR2 mAb. mRNA coding for TLR2 and TLR4 was expressed in URC-primed DC. URC-primed DC induced the NF-κB transcription factor. Naïve T cells co-cultured with URC-primed DC turned into typical Th1 cells that produced large quantities of IFN-γ depending on IL-12 secretion. URC enhanced the T cell stimulatory capacity in an allo MLR. In the cytotoxic T-lymphocyte assay (CTL) assay, DNA fragmentation assay and 51Cr release on URC-primed DC were more augmented than that of TNF-α-primed DC. DC matured with URC had an intermediate migratory capacity towards CCL19 and CCL21. These results suggest that URC modulates DC function in a fashion that favors Th1 polarization via the activation of IL-12p70 dependent on TLR4 signaling, and may be used on DC-based vaccine for cancer immunotherapy.