Three New Polyphenol Derivatives from the Fruits of Macaranga Monandra and their Antioxidant Potential.

Phytochemical investigation of the methanol extract from the fruits of Macaranga monandra (Euphorbiaceae Muell. et Arg.) afforded one new geranylated 1',2'-dihydrophenanthrene and two new flavonoid derivatives, named macamondrin (1), macamondrione A (2) and B (3) respectively. The structures of these compounds were elucidated mainly by NMR, mass spectral data and in comparison with data from the literature. Along with compounds 1-3, nine known compounds among which oleanolic acid (4); daucosterol (5); 3ß-acetoxy-11α,12α-epoxytaraxerol (6); 3,3',4-tri-O-methylellagic acid (7); 3,3',4,4'-tetra-O-methylellagic acid (8); 4'-O-methyl-6-isoprenylapigenin (9); 4'-O-methyl-8 isoprenylkaempférol (10); 4'-O-methyl-6-isoprénylkaempférol (11); 6-isoprénylkaempférol (12), were also isolated. Crude extracts as well as isolated compounds were evaluated for their antioxidant activity using the ABTS, DPPH and FRAP methods. It appears that the 50 % radical scavenging concentrations ranging from 6.26 to 11.7 µg/ml on the ABTS radical, from 1.77 to 48.22 µg/ml on the DPPH radical, and from 1.54 to 67.97 µg/ml with the FRAP method. For the compounds tested, very good antioxidant activities were observed, which clearly shows that these molecules can have an anti oxidative stress potentiel.

Two new secondary metabolites with antibacterial activities from Conyza aegyptiaca (Asteraceae).

The bio guided fractionation of the dichloromethane/methanol (1:1) crude extract of the air-dried whole plant of C. aegyptiaca led to the isolation of one new flavone derivative designated conyflavone (1) and one new clerodane diterpene type designated conyclerodane (2) along with five known compounds including two flavonoids Gardenin C (3), chrysosplenetin (4) and two steroids glucoside of ß-sitosterol (5), the mixture of stigmasterol (6) and ß-sitosterol (6') and ent-2b,18,19trihydroxycleroda-3,13-dien-16,15-olide (7). The structures were established by spectroscopic methods including IR, 1D and 2D NMR in conjunction with mass spectroscopy and by comparison to data of related compounds described in literature. The stereocentres in compound 2 were determined by SC-XRD analysis. Crude extract as well as fractions and pure compounds were evaluated in vitro for their antibacterial activities against four pathogenic and two clinical isolate strains using microdilution methods. Extracts and compounds displayed a moderate antibacterial activity with MIC values ranging from 125 to 500 µg/mL.

Constituents from Nauclea latifolia with Anti-Haemophilus influenzae Type b Inhibitory Activities.

Three previously undescribed indole alkaloids, named latifolianine A (1) and latifoliaindoles A and B (2 and 3), along with 10 known compounds (4-13), were isolated from the heartwood of Nauclea latifolia. Their structures were elucidated based on the analysis of their NMR and MS data. Latifolianine A (1) represents an unusual and unprecedented monoterpene indole alkaloid unit condensed with an ursane-type pentacyclic triterpenoid moiety. Plausible biogenetic routes toward latifolianine A (1) and latifoliaindoles A and B (2 and 3) were proposed. All the isolates were assessed in vitro for their inhibitory effects on Haemophilus influenzae. Naucleidinal (7) exhibited potent antibacterial activity (MIC value of 3.1 µg/mL) as compared to a reference drug, ciprofloxacin (MIC value of 1.6 µg/mL).