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The phytochemical investigation of the dichloromethane/methanol (1:1) extract of the stem bark of Scyphocephalium ochocoa, led to the isolation of one new dibenzofuran derivative, named scyphocephalione A (1), along with three other compounds, including epicatechin (2), gentisic acid (3) and myo-inositol (4). The structures of all the compounds were established with help of spectroscopic data including IR, UV, MS, 1 D- and 2 D-NMR, as well as by comparison with previously reported data in literature, and chemical modification. All the compounds were obtained from the genus Scyphocephalium for the first time. The anti-inflammatory activity (using chemiluminescence technique) of the crude extract and compound 1, together with NO inhibition (using ELISA), TNF-α (using ELISA) and MCF-7 cells cytotoxicity effects (using MTT assay) of compound 1 were assessed. From the results obtained, compound 1 could be considered as a promising chemotherapeutic agent for the treatment of inflammatory diseases.

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BACKGROUND: Malaria remains a major public health problem, especially in tropical and subtropical regions because of the emergence and widespread of antimalarial drug resistance. Traditional medicine represents one potential source of new treatments. Here, we investigated the in vitro antiplasmodial activity of bark extracts from two Fabaceae species (Tetrapleura tertaptera and Copaifera religiosa) traditionally used to treat malaria symptoms in Haut-Ogooué province, Gabon. FINDINGS: The antiplasmodial activity of dichloromethane and methanolic extracts was tested on P. falciparum strains FCB (chloroquine-resistant) and 3D7 (chloroquine-sensitive) and on fresh clinical isolates, using the DELI method. Host cell toxicity was analyzed on MRC-5 human diploid embryonic lung cells using the MTT test.The dichloromethane extracts of the two plants had interesting activity (IC50 between 8.5 ± 4.7 and 13.4 ± 3.6 µg/ml). The methanolic extract of Tetrapleura tetraptera was less active (IC50 around 30 µg/ml) and the methanolic extract of Copaifera religiosa was inactive. The selectivity index (toxicity/antiplasmodial activity) of the dichloromethane extract of Tetrapleura tetraptera was high (around 7), while the dichloromethane extract of Copaifera religiosa had the lowest selectivity (0.6). The mean IC50 values for field isolates were less than 1.5 µg/ml for dichloromethane extracts of both plants, while methanolic extracts of Tetrapleura tetraptera showed interesting activity (IC50 = 13.1 µg/ml). The methanolic extract of Copaifera religiosa was also inactive on field isolates. CONCLUSIONS: Dichloromethane extracts of Tetrapleura tetraptera and Copaifera religiosa, two plants used to treat malaria in Gabon, had interesting antiplasmodial activity in vitro. These data provide a scientific rationale for the traditional use of these plants against malaria symptoms. Bioactivity-guided phytochemical analyses are underway to identify the active compounds.

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AIM OF THE STUDY: As part of a project to identify new compounds active on malarial parasites, we tested the in vitro antiplasmodial activity of nine plants traditionally used to treat malaria symptoms in Haut-Ogooué Province, South-East Gabon. MATERIALS AND METHODS: Dichloromethane and methanolic extracts of each plant were tested for their antiplasmodial activity on two chloroquine-resistant strains of Plasmodium falciparum (FCB and W2), based on lactate dehydrogenase activity. Cytotoxicity was assessed with the MTT test on MRC-5 human diploid embryonic lung cells. RESULTS: The methanolic extract of Staudtia gabonensis and the dichloromethane extract of Adhatoda latibracteata showed high antiplasmodial activity (IC50<1 µg/ml) and low cytotoxicity, with selectivity indexes of about 58.25 and 16.43, respectively. The methanolic extract of Monodora myristica and the dichloromethane extract of Afromomum giganteum also showed promising activity (1

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Condensation of 1-bromo-2-naphthalenecarboxylic acid (9) with 7-methoxy-2,2-dimethyl-2H-1-benzopyran-5-ylamine (13) followed by acid-mediated cyclization afforded 6-methoxy-3,3-dimethyl-3,14-dihydro-7H-benzo[c]pyrano[3,2-h]acridin-7-one (15), which was further methylated into 6-methoxy-3,3,14-trimethyl-3,14-dihydro-7H-benzo[c]pyrano[3,2-h]acridin-7-one (benzo[c]acronycine) (3) and 6,7-dimethoxy-3,3-dimethyl-3H-benzo[c]pyrano[3,2-h]acridine (4). Osmium tetroxide oxidation of 15 gave the (+/-)-cis-diol 16, which afforded the benzopyranoacridine and benzopyranoacridone esters 17-22 upon acylation. Condensation of 9 with suitable aminoquinolines 23-25 afforded the carboxylic naphthylquinolylamines 26-28. Cyclization gave the corresponding naphtho[1,2-b][1,10]-phenanthrolin-7(14H)-ones 29 and 30, and naphtho[1,2-b][1,7]-phenanthrolin-7(14H)-one 31, which were subsequently N-methylated to the desired 14-methylnaphtho[1,2-b][1,10] and [1,7]-phenanthrolinones 6, 7, and 8. Benzo[c]pyrano[3,2-h]acridin-7-one derivatives 3, 16, and 22 displayed cytotoxic activities within the same range of magnitude as acronycine itself, whereas 7-alkoxybenzo[c]pyrano[3,2-h]acridine and 7-acyloxybenzo[c]pyrano[3,2-h]acridine derivatives 4 and 17-21 were less active when tested against L1210 murine leukemia cells in vitro. Naphthophenanthrolinones 6-8 were devoid of significant antiproliferative activity, but compounds 29-31 bearing no substituent on the nitrogen atom at position 14 were more potent.

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The cell surface aminopeptidase N (APN/CD13), overexpressed in tumor cells, plays a critical role in angiogenesis. However, potent, selective, and, particularly, noncytotoxic inhibitors ot this protein are lacking, and the present work was undertaken with the aim of developing a new generation of noncytotoxic inhibitors that bind to APN/CD13. In this context, we have synthesized a series of novel flavone-8-acetic acid derivatives. Among the herein described and evaluated compounds, the 2',3-dinitroflavone-8-acetic acid (19b) proved to be the most efficient and exhibited an IC(50) of 25 microM which is 2.5 times higher than that of bestatin (1), the natural known inhibitor of APN/CD13. However, in contrast to bestatin (1), the dinitroflavone 19b did not induce any cytotoxicity to cultured human model cells. The presence of other substituents such as NO(2) or OCH(3) groups at the 3'- or 4'-position of the B phenyl group, or the existence of steric constraints (compounds 24 and 29), did not improve selectivity and potency. The flavone 19b affinity for APN/CD13 is not recovered with other proteases such as matrix metalloproteinase-9 (MMP-9), angiotensin converting enzyme (ACE/CD143), neutral endopeptidase (NEP/CD10), gamma-glutamyl transpeptidase (CD224), or the serine proteases dipeptidyl peptidase IV (DPPIV/CD26) or cathepsin G.

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The cytotoxic and antitumor activities of cis-1,2-diacyloxy-6-methoxy-3,3,14-trimethyl-1,2,3,14-tetrahydro-7H-benzo[b]pyrano[3,2-h]acridin-7-one derivatives 3, 6-9 were strongly correlated with their ability to give covalent adducts with purified, as well as genomic, DNA. Such adducts involve reaction between the exocyclic N-2 amino group of guanines exposed in the minor groove of double helical DNA and the leaving ester group at the benzylic position 1 of the drug. A transesterification process of the ester group from position 2 to position 1 in aqueous medium accounted for the intense activity of the cis-1-hydroxy-2-acyloxy-6-methoxy-3,3,14-trimethyl-1,2,3,14-tetrahydro-7H-benzo[b]pyrano[3,2-h]acridin-7-one derivatives 10-13. Compounds without acyloxy or hydroxy group at position 1, such as 15, 17, 18, and 22, were inert with respect to DNA and almost devoid of significant cytotoxic activity. Condensation of 5-amino-2,2-dimethyl-2H-chromene (26) with 3-bromo-2-naphthoic acid (27), followed by cyclization, gave access to 6-demethoxy analogues. Diacetate 32 and cyclic carbonate 33, both belonging to the latter series, were less reactive toward DNA and less cytotoxic than their 6-methoxy counterparts 3 and 34. DNA alkylation appears thus to play an important role in the antitumor properties of benzo[b]pyrano[3,2-h]acridin-7-one derivatives.

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