Chikara Ichino

Acylated pregnane glycosides from Caralluma tuberculata and their antiparasitic activity.

Five pregnane glycosides were isolated from Caralluma tuberculata (1-5), in addition to a known one (russelioside E, 6). The structures of the isolated compounds were elucidated by the analysis of NMR data and FAB-MS experiments. All the isolated compounds were tested for their antimalarial and antitrypanosomal activities as well as their cytotoxicity against human diploid embryonic cell line (MRC5).

Antitrypanosomal activity of some pregnane glycosides isolated from Caralluma species

Pregnane glycosides previously isolated from genus Caralluma (C. Penicillata, C. tuberculata and C. russelliana) were tested for their antitrypanosomal activity. Penicilloside E showed the highest antitrypanosomal activity (IC(50) 1.01 microg/ml) followed by caratuberside C (IC(50) 1.85 microg/ml), which exhibited the highest selectivity index (SI 12.04). It was noticed that acylation is required for the antitrypanosomal activity while glycosylation at C-20 has no significant effect on the activity.

In vitro anti-influenza virus activity of a cardiotonic glycoside from Adenium obesum (Forssk.)

Methanolic extracts of six Saudi plants were screened for their in vitro antiviral activity using influenza virus A/PR/8/34 (H1N1) and MDCK cells in an MTT assay. The results indicated that the extracts of Adeniumobesum and Tephorosianubica possessed antiviral activity (99.3 and 93.3% inhibition at the concentration of 10 μg/ml, respectively). Based on these results A. obesum was selected for further study by applying bioactivity-guided fractionation to isolate its antiviral principle. The antiviral principle was isolated from the chloroform fraction through solvent fractionation, combined open liquid chromatography and HPLC. The isolated active compound A was identified as oleandrigenin-β-D-glucosyl (1→4)-β-D-digitalose, on the basis of its spectral analysis (MS, 1D and 2D NMR). The isolated glycoside showed reduction of virus titre by 69.3% inhibition at concentration of 1 μg/ml (IC(50)=0.86 μg/ml).

A new pterocarpan from Erythrina fusca

A new pterocarpan, 3-hydroxy-10-(3-hydroxy-3-methylbutyl)-9- methoxypterocarpan (1), together with seven known compounds, sandwicensin (2), erythrisenegalone (3), citflavanone (4), liquiritigenin (5), lonchocarpol A (6), lupinifolin (7) and 8-prenyldaidzein (8), were isolated from the stem bark of Erythrina fusca. The structure of 1 was determined on the basis of spectroscopic analyses. Among these compounds, lonchocarpol A (6) exhibited strongly antibacterial activities in vitro against Staphylococcus aureus, Bacillus subtilis and Enterococcus faecalis. Compounds (2, 3, 6 and 7) exhibited weakly antimycobacterial activity with minimum concentrations (MICs) of 100, 50, 50 and 25 µg/mL, respectively.