Chemical characterization and biological activity of Macfadyena unguis-cati (Bignoniaceae).

Macfadyena unguis-cati (L.) has been widely used in folk medicine as an anti-inflammatory, antimalarial and antivenereal. The purpose of this study was to chemically characterize the main plant components, and to evaluate the biological properties of some of the fractions derived from leaves (MACb) and liana (MACa) of this plant. Chemical characterization allowed the identification of the compounds corymboside, vicenin-2, quercitrin, chlorogenic acid, isochlorogenic acid, lupeol, beta-sitosterol, beta-sitosterylglucoside, allantoin and lapachol. The biological screening of fractions and/or purified substances derived from fractions revealed antitumoral and antitrypanosomal activities in fractions MACa/lapachol and MACb/MACb21, respectively. The anti-lipoxygenase and anti-cyclooxygenase effect seen in fractions MACa and MACb showed a partial correlation with the anti-inflammatory property attributed to this plant.

New acetylenes isolated from the bark of Heisteria acuminata.

Five new linear acetylenic compounds, namely, pentadeca-6,8,10-triynoic acid (1), octadeca-8,10,12-triynoic acid (2), trans-pentadec-10-en-6,8-diynoic acid (3), cis-hexadec-11-en-7,9-diynoic acid (4), and cis-octadec-12-en-7,9-diynoic acid (5), were isolated from the bark of Heisteria acuminata by bioassay-guided fractionation, using cyclooxygenase (COX) and 5-lipoxygenase (5-LO) assays as models for antiinflammatory activity. The structures of compounds 1-5 were established by NMR, MS, IR, and Raman spectroscopy. These isolated compounds were found to be potent inhibitors of COX. Compounds 4 and 5 were the most potent inhibitors of 5-LO, whereas the other compounds only showed a weak inhibition at the same concentration.

Inhibitory effects of baeomycesic acid from the lichen Thamnolia subuliformis on 5-lipoxygenase in vitro.

Baeomycesic acid (1), a ß-orcinol depside isolated from the lichen Thamnolia subuliformis (Ehrh.) W. Culb. was tested for in vitro inhibitory effects on arachidonate metabolism. Results showed that baeomycesic acid has potent dose-dependent inhibitory effects on 5-lipoxygenase isolated from porcine leucocytes, with an IC(50) value of 8.3 µM. Structure-activity relationships are discussed in comparison to other phenolic lichen constituents. Baeomycesic was inactive when tested for in vitro inhibitory effects against cyclooxygenase isolated from sheep seminal vesicle microsomes.

Biologically active alkamide from the lichen Stereocaulon alpinum.

The presence of an alkamide in lichens is reported for the first time. The alkamide was isolated from Stereocaulon alpinum Laur. and identified through spectroscopic analysis as 9-cis-octa-decenamide (1). With reference to previously known activity of alkamides from both the plant and animal kingdoms on inflammatory processes, 1 was tested for in vitro inhibitory activity against the key enzymes of the major pathways involved in arachidonate metabolism. The compound was shown to exhibit moderate dose-dependent inhibitory activity against cyclooxygenase from sheep seminal vesicle microsomes (IC(50) = 64.3 µM) whilst showing only slight activity against 5-lipoxygenase from porcine leucocytes.

Effect of marchantins and related compounds on 5-lipoxygenase and cyclooxygenase and their antioxidant properties: a structure activity relationship study.

Marchantins and related compounds, isolated from different species of liverworts, were investigated for their inhibitory potential on cyclooxygenase (COX) and 5-lipoxygenase 5-(LOX), the key enzymes of the arachidonic acid cascade, and additionally in a cell-free lipid-peroxidation system. The results were compared with rate constants obtained in pulse-radiolytic studies. All substances tested showed significant inhibitory COX and 5-LOX-activity. Marchantin B with two catechol moieties, as in NDGA, exerted an enhanced inhibitory effect in all test systems. The most active compound in the 5-LOX-test was Perrottetin D (IC(50) = 0.66 µM), which was also effective in the COX and lipid-peroxidation assay. While the rate constant determined by pulse radiolysis was rather low, EPR studies at elevated temperatures demonstrated for perrottetin D the presence of a pyrogallol-type radical, generated by a furan-ring opening reaction. In conclusion, all compounds from liverworts investigated possess significant antiinflammatory activities. The results let us suggest that all these phenolic compounds can be considered as promising leads due to their strong radical scavenger potential.