Entada saponin-III,a saponin isolated from the bark of Entada phaseoloides

The structure of Entada saponin (ES)-III, one of the main saponins of Entada phaseoloides bark, was established to be 3-O-[β-d-xylopyranosyl (1 → 2)-α-l-arabinopyranosyl (1 → 6)] [β-l-glucopyranosyl (1 → 4)]-2-acetamido-2-deoxy-β-l-glucopyranosyl-28-O-[β-l-apiofuranosyl (1 → 3)-β-d-xylopyranosyl (1 → 2)] [(2-O-acetoxyl)-β-d-glucopyranosyl-(1 → 4)] (6 − O(R) (−)2,6-dimethyl-2-trans-2,7-octadienoyl)-β-d-glucopyranosyl echinocystic acid.     

Antioxidant phenolic compounds from the stems of Entada phaseoloides

The EtOH extract of the stems of Entada phaseoloides displayed potent antioxidant activity when assessed by the 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical-scavenging, reducing power, β-carotene-bleaching, and superoxide radical-scavenging analyses. Fractionation of the EtOH extracts showed that the AcOEt fraction is the most active, followed by the H(2) O fraction, while BuOH fraction was least active. Further activity-guided fractionation studies on the active fractions resulted in the isolation of 22 compounds. The identities of these compounds were established based on extensive spectroscopic studies. Furthermore, the antioxidant activities of the isolated compounds were evaluated by using the above-mentioned five assays. The results demonstrated that the EtOH extract of E. phaseoloides stems exhibits an excellent antioxidant activity and thus presents a great potential as a source of natural antioxidants.     

Rheediinosides A and B,two antiproliferative and antioxidant triterpene saponins from Entada rheedii

Two triterpenoid saponins have been isolated from the seed kernels of Entada rheedii. Their structures have been established using 1D- and 2D-NMR and mass spectrometry as 3-O-β-d-xylopyranosyl-(1 → 3)-O-α-l-arabinopyranosyl-(1 → 6)-2-acetylamino-2-deoxy-β-d-glucopyranosylentagenic acid 28-O-β-apiofuranosyl-(1 → 3)-β-d-xylopyranosyl-(1 → 2)-β-d-glucopyranoside (Rheediinoside A, 1) and 3-O-β-d-glucopyranosyl-(1 → 3)-O-[β-d-xylopyranosyl-(1 → 3)-α-l-arabinopyranosyl-(1 → 6)]-2-acetylamino-2-deoxy-β-d-glucopyranosylentagenic acid 28-O-β-apiofuranosyl-(1 → 3)-β-d-xylopyranosyl-(1 → 2)-β-d-glucopyranoside (Rheediinoside B, 2). Compounds 1 and 2 were tested for their antiproliferative activity against T98G, A431, PC3 and B16-F1 cell lines, and further for their antioxidant properties. Moderate cytotoxic potency and antioxidant properties were found for these compounds whereas Rheediinoside B was in all assays more active than Rheediinoside A.     

Isotachin A and isotachin B,two sulphur-containing acrylates from the liverwort isotachis japonica

Isotachin A and isotachin B, two new sulphur-containing acrylates, were isolated from the liverwort Isotachis japonica. Their structures were established to be benzyl trans-β-methylthioacrylate and β-phenylethyl trans-β-methylthioacrylate by chemical and spectral methods. This is the first report of sulphur-containing substances from bryophytes. Some previously known benzoates and cinnamates as well as 2-methoxy-4-hydroxyphenyl 1β-glucoside and stigmasteryl 3β-glucoside were also isolated.     

Methoxybrassenins A and B, sulphur-containing stress metabolites from Brassica oleracea var. Capitata

Two methoxybrassinin-related stress metabolites, named methoxybrassenins A and B, were isolated from Brassica oleracea var. capitata inoculated with Pseudomonas cichorii. Their structures have been elucidated by spectroscopic and chemical methods. The unusual NMR spectrum of methoxybrassenin B is also discussed in connection with its structure.     

Kojic acid-tripeptide amide as a new tyrosinase inhibitor

Twenty two kojic acid-tripeptide amides were prepared using a solid-phase Fmoc/tBu strategy with Rink Amide SURE(R) resin. To effectively obtain kojic acid-tripeptide amide conjugates, the coupling conditions of kojic acid to the tripeptide on the resin were optimized. The tyrosinase inhibitory activity of kojic acid-tripeptide amides and the effect of the amino acid sequence on the activity were compared with those of kojic acid-tripeptide acids. The stability of kojic acid-tripeptide amides were then compared with those of kojic acid and kojic acid-tripeptides acids. As a consequence, kojic acid-FWY-NH(2) proved to be the best compound, with the highest inhibitory activity, which was maintained over different storage times under various temperatures and pHs.     

B5, a new B cell-restricted activation antigen

The characterization of a new human B cell-restricted activation antigen (B5) is described in this report. With the use of a monoclonal antibody to B5, we show that B5 can be detected on peripheral blood or splenic B cells after 1 day of stimulation with either anti-immunoglobulin, protein A, Epstein Barr virus, or pokeweed mitogen. In contrast, B5 was not expressed on resting B, T, or myeloid cells. More important, B5 could not be detected on activated T cells or monocytes. The B5 antigen was expressed on some lymphoblastoid B cell lines and B cell neoplasms but was not expressed on leukemias or lymphomas of T or myeloid origin. The B5 antigen is distinct from previously reported B cell activation antigens by its m.w. and pattern of cellular expression. These studies suggest that B5 is a novel B cell-restricted activation antigen, which may be useful to study the events of early human B cell activation.     

Chenoalbicin, a novel cinnamic acid amide alkaloid from Chenopodium album

The roots of Chenopodium album were infused in MeOH, and the extract was partitioned between AcOEt and H2O. AcOEt-Soluble material was subjected to different silica-gel column chromatographies and then purified by reverse-phase HPLC to afford a new cinnamic acid amide alkaloid as a racemic mixture. The new compound, named chenoalbicin (1), was characterized by extensive spectroscopic investigation, especially 1D and 2D NMR spectroscopy. Its effects on the germination and growth of Lactuca sativa L. has been studied. The results are reported as percentage differences of germination, root elongation, and shoot elongation from the control at concentrations ranging from 10(-4) to 10(-7) M.     

Immunological and biological characteristics of a new TRF analogue, L-pyroglutamyl-L-histidyl-L-pipecolic acid amide.

The immunological and biological potencies of a new synthetic TRF analogue, L-pyroglutamyl-L-histidyl-L-pipecolic acid amide, were compared with those of TRF. In a radioimmunoassay system for TRF, parallel inhibition curves were obtained with TRF and the analogue, the immunological potency of the latter being approximately 50 per cent of the former. In vitro and in vivo TSH-releasing activities of the analogue were almost equal to those of TRF. As was observed with TRF, the in vitro TSH-releasing effect of the analogue was reduced in the presence of T4, and the analogue was inactivated by incubation with rat serum. The data suggest that the pyrrolidine ring of TRF can be replaced with piperidine ring without significant loss of the biological activity.     

Purification and biochemical properties of a Kunitz-type trypsin inhibitor from Entada acaciifolia (Benth.) seeds

A new trypsin inhibitor (EATI) was isolated from Entada acaciifolia (Benth.) seeds. EATI is a competitive inhibitor with a molecular mass of 20 kDa and an inhibition stoichiometry of 1:1 for bovine trypsin. The dissociation constant (K_i) calculated was 1.75 nmol/L, displaying a high affinity between enzyme and inhibitor. Both Native PAGE and RP-HPLC revealed that EATI is composed of four isoinhibitors that share the amino acid composition and the amino-terminal sequence homolog to Kunitz-type inhibitors. EATI is stable to denaturation by heat (up to 70 °C), pH (2–10), urea (8 mol/L) and its inhibitory activity was unaltered in different concentrations of DTT (up to 100 mmol/L). CD analysis revealed that EATI in reduced form underwent structural modifications associated with a decrease in thermal and pH stabilities, suggesting that their disulfide bonds are not involved in the structuring of its reactive site, but are important for maintenance of its conformational stability. This behavior makes EATI one of the few inhibitors described in the literature with high DTT resistance.     

Emericella astellata, a new producer of aflatoxin B, B and sterigmatocystin

AIMS: To report on aflatoxin B(1) and B(2) production from a species of Emericella. METHODS AND RESULTS: Aflatoxins and sterigmatocystin were determined by high-pressure liquid chromatography (HPLC) with diode array detection and confirmed by HPLC with mass spectrometry detection. Among 30 known species of Emericella only one species produced aflatoxin. Strains originating from the same geographical source material had different patterns of aflatoxin and sterigmatocystin production on different media, indicating that epigenetic factors may be involved in the regulation of aflatoxin production. However, two cultures from the same original genet were very similar. CONCLUSIONS: Emericella astellata can produce small amounts of sterigmatocystin and aflatoxin B(1) and B(2). SIGNIFICANCE AND IMPACT OF THE STUDY: Emericella has been used extensively in genetic studies and therefore the isolates producing aflatoxin can be used to elucidate the genetic, evolutionary and maybe ecological role of aflatoxins using molecular genetic methods.     

Cespitulactones A and B, new diterpenoids from Cespitularia taeniata

Two new diterpenoids, designated cespitulactones A (1) and B (2), were isolated from a sample of the soft coral Cespitularia taeniata collected in Taiwan. Compound 1 possesses a novel structure with a bond cleavage between C-10 and C-11, and having a 14-membered lactone ring junction between C-10 and C-12. Their structures were elucidated on the basis of extensive spectroscopic analysis and chemical derivatization. The isolated compounds were also evaluated for cytotoxicity toward human cancer cell lines.     

Schizonellin A and B,new glycolipids from Schizonella melanogramma

Two new glycolipids, schizonellin A and B, were isolated from cultures of the smut fungus Schizonella melanogramma. Their structures were elucidated by chemical degradation and spectroscopic methods. The schizonellins are active against Gram-positive bacteria, as well as against some Gram-negative bacteria and some fungi. DNA-, RNA- and protein-syntheses in Ehrlich carcinoma ascitic cells are inhibited simultaneously after addition of the schizonellins. Strong haemolytic action on bovine erythrocytes was observed.