Extracts from the Andean lichens Protousnea poeppigii and Usnea florida displayed antimicrobial activity against the pathogenic fungi Microsporum gypseum, Trichophyton mentagrophytes and T. rubrum with MIC values between 50 and 100 microg/mL. From the active extracts, four main metabolites were isolated and identified as the new depside, isodivaricatic acid, and the known metabolites 5-propylresorcinol, divaricatinic acid and usnic acid. Isodivaricatic acid and divaricatinic acid presented antifungal effect towards M. gypseum with a MIC of 50 microg/mL and against T. mentagrophytes and T. rubrum and with MIC values of 50 and 100 microg/mL, respectively. The new isodivaricatic acid was active towards Leishmania amazonensis, Leishmania brasiliensis and Leishmania infantum promastigotes with 100% lysis at 100 microg/mL.The activity of the new compound decreased on acetylation of the hydroxy groups as well as on methylation of the acid function. The structures were elucidated by spectroscopic means. The spectroscopic data of isodivaricatic acid are presented here for the first time.

Carnosic acid (1) has been shown to possess gastroprotective activity in vitro and in vivo. However, little is known of the gastroprotective effect or cytotoxicity of carnosic acid gamma-lactone (3). To determine structure-activity relationships, a series of 17 esters of 3 were prepared including aliphatic, aromatic, and heterocyclic derivatives. Also, two units of 3 were coupled with succinic and phthalic acid as linkers. The compounds were assessed for their gastroprotective effect in the HCl/EtOH-induced gastric lesions model in mice and for cytotoxicity in human lung fibroblasts, human adenocarcinoma AGS cells, and Hep G2 hepatocellular carcinoma cells. At a single oral dose of 40 mg/kg, the gastroprotective effect increased moderately with the length of the alkyl chain. The best effects were observed for the butyrate (9) and chloroacetate (6) derivatives. Activity of fatty acid esters increased with chain length but decreased with unsaturation. The best gastroprotective effect, with lowest cytotoxicity, was found for the palmitate (11) and oleate (12) derivatives.

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Abstract:The aim of the study was to assess changes in the activity of anti-inflammatory terpenes from Chilean medicinal plants after the formation of derivatives incorporating synthetic anti-inflammatory agents. Ten new hybrid molecules were synthesized combining terpenes (ferruginol (1), imbricatolic acid (2) and oleanolic acid (3)) with ibuprofen (4) or naproxen (5). The topical anti-inflammatory activity of the compounds was assessed in mice by the arachidonic acid (AA) and 12-O-tetradecanoyl phorbol 13-acetate (TPA) induced ear edema assays. Basal cytotoxicity was determined towards human lung fibroblasts, gastric epithelial cells and hepatocytes. At 1.4 µmol/mouse, a strong anti-inflammatory effect in the TPA assay was observed for oleanoyl ibuprofenate 12 (79.9%) and oleanoyl ibuprofenate methyl ester 15 (80.0%). In the AA assay, the best activity was observed for 12 at 3.2 µmol/mouse, with 56.8% reduction of inflammation, in the same range as nimesulide (48.9%). All the OPEN ACCESSMolecules 2015, 20 11220 terpenyl-synthetic anti-inflammatory hybrids showed better effects in the TPA assay, with best activity for 6, 12 and 15. The cytotoxicity of the compounds 8 and 10 with a free COOH, was higher than that of 2. The derivatives from 3 were less toxic than the triterpene. Several of the new compounds presented better anti-inflammatory effect and lower cytotoxicity than the parent terpenes.

The gastroprotective effect of the diterpenes jatropholone A, jatropholone B and 16 semisynthetic derivatives was assessed in the HCl/ethanol-induced gastric lesion model in mice and the cytotoxicity was determined towards fibroblasts and AGS cells. In a dose-response study, jatropholone B reduced gastric lesions by 65% at 6 mg/kg and jatropholone A by 54% at 100 mg/kg. The jatropholone B derivatives 9 - 14 and the compounds 15 - 18 were compared at a single oral dose of 25 mg/kg while the jatropholone A derivatives 2 - 7 were assessed at 100 mg/kg. A decrease in gastroprotective activity was observed for the ether as well as for the ester derivatives of jatropholone B. The methyl and propyl ethers of jatropholone A were more gastroprotective than the natural product. The placement of an additional methyl group at C-2 in the jatropholone B derivatives led to a loss of selectivity, the methyl and propyl ethers lack a gastroprotective effect. Jatropholone B was not toxic towards AGS cells and fibroblasts. Jatropholone A was active only against AGS cells. The gastroprotective effect of the epimeric jatropholones was selective showing a higher effect for jatropholone B. These results further support that the stereochemistry of the methyl group at C-2 in the jatropholones plays a relevant role in preventing the gastric lesions in mice. The compounds 3, 5 - 7, 10 and 12 - 18 are described for the first time.