Identification and Evaluation of New Potential Inhibitors of Human Neuraminidase 1 Extracted from Olyra latifolia L.: A Preliminary Study.

Sialidases, also called neuraminidases, are involved in several human pathologies such as neurodegenerative disorders, cancers, as well as infectious and cardiovascular diseases. Several studies have shown that neuraminidases, such as neuraminidase 1 (NEU-1), may be promising pharmacological targets. Therefore, the discovery of new selective inhibitors of NEU-1 are necessary to better understand the biological functions of this sialidase. In the present study, we describe the isolation and characterization of nine known compounds from Olyra latifolia L. leaves. This plant, known to have several therapeutic properties, belongs to the family of Poaceae and is found in the neotropics and in tropical Africa and Madagascar. Among the purified compounds, feddeiketone B, 2,3-dihydroxy-1-(4-hydroxy-3,5-diméthoxyphényl)-l-propanone, and syringylglycerol were shown to present structural analogy with DANA, and their effects on membrane NEU-1 sialidase activity were evaluated. Our results show that they possess inhibitory effects against NEU-1-mediated sialidase activity at the plasma membrane. In conclusion, we identified new natural bioactive molecules extracted from Olyra latifolia as inhibitors of human NEU-1 of strong interest to elucidate the biological functions of this sialidase and to target this protein involved in several pathophysiological contexts.

New Oleanane-type glycosides and secoiridoid glucoside from Aptandra zenkeri.

Four new saponins, camelliagenin A and B derivatives, and one new secoiridoid glucoside were isolated from the stem bark of Aptandra zenkeri Engl. (Aptandraceae) together with two known secoiridoid glucosides. Their structures were determined based on a combination of 1D- and 2D-NMR experiments techniques and HR-ESI-MS analysis. This is the first report on saponins in genus Aptandra.

Isolation and structure elucidation of cyclopeptide alkaloids from the leaves of Heisteria parvifolia.

Heisteria parvifolia Sm. is prescribed in traditional medecine against numerous diseases in Côte d'Ivoire. Due to the shortcoming in scientifical knowledge of use of this species, our investigations revealed five undescribed cyclopeptide alkaloids added to one known derivative namely anorldianine. These compounds were elucidated by 1D and 2D-NMR experiments and comparison with literature data, and confirmed by HR-ESI-MS. Cytotoxic activity evaluation of these compounds against the chronic myeloid leukemia (K565) cell line exhibited an antiproliferative activity with cell growth inhibition from 13% to 46%.

Triterpene saponins from the roots of Parkia bicolor A. Chev.

Five undescribed triterpene-type saponins, parkibicolorosides A-E, a cassane-type diterpene, and a known trimethoxy benzene glucoside were isolated from the roots of Parkia bicolor A. Chev. Their structures were elucidated by different spectroscopic methods including 1D- and 2D-NMR experiments as well as HR-ESI-MS analysis. Their cytotoxic activity against the chronic myeloid leukemia (K562) cell line was evaluated. The monosaccharides saponins exhibited a moderate antiproliferative activity with IC50 ranging from 48.49 ±â€¯0.16 to 81.66 ±â€¯0.17 µM.

Triterpene glycosides from the aerial parts of Gouania longipetala.

Six previously undescribed triterpenoid saponins, gouaniaside I-VI, were isolated from the aerial parts of Gouania longipetala Hemsl. (Rhamnaceae), in addition to four known triterpenes. The structure elucidation of these compounds was based on analyses of spectroscopic data including 1D- and 2D-NMR and HR-ESI-MS techniques. The inhibitory activity of isolated compounds against promyelocytic leukemia HL60 and human erythromyeloblastoid leukemia K562 cell lines was evaluated and jujuboside I exhibited moderate cytotoxicity, with IC50 values of 13.5 and 21.0 µM, respectively. Among the isolated triterpenes, alphitolic acid exhibited moderate antibacterial activity against Staphylococcus aureus, Enterococcus faecalis and Escherichia coli (MICs 32, 64 and 128 µg/mL, respectively).

Antibacterial and cytotoxic triterpenoids from the roots of Combretum racemosum.

A new pentacyclic triterpenoid glucoside, together with fourteen known compounds, was isolated from the roots of Combretum racemosum. Combretaceae). The structure of the new compound was established as 28-O-ß-d-glucopyranosyl-2α,3ß,21ß,23-tetrahydroxyolean-18-en-28-oate (1) on the basis of detailed spectroscopic data including MS, 1D, and 2D NMR. The inhibitory activity of compounds 1-15 against promyelocytic leukemia HL-60 and human erythromyeloblastoid leukemia K562 cell lines was evaluated. Compounds 11 (3-O-ß-acetyl-ursolic acid), 14 (betulinic acid), and 15 (quadranoside II) exhibited significant cytotoxicity, with IC50 values of 13 to 50 µM. Among the isolated triterpenes, compounds 1, 3 (arjungenin), 5 (terminolic acid), and 11 exhibited moderate antibacterial activity against Staphylococcus aureus, Escherichia coli and Enterococcus faecalis (MICs within a range of 64 and 256 µg/mL).