Terpenes with antimicrobial activity from Cretan propolis.

Five terpenes, the diterpenes: 14,15-dinor-13-oxo-8(17)-labden-19-oic acid and a mixture of labda-8(17),13E-dien-19-carboxy-15-yl oleate and palmitate as well as the triterpenes, 3,4-seco-cycloart-12-hydroxy-4(28),24-dien-3-oic acid and cycloart-3,7-dihydroxy-24-en-28-oic acid were isolated from Cretan propolis. Moreover, 18 known compounds were also isolated, seven of them for the first time as propolis components. All structures were established on the basis of spectroscopic analysis and chemical evidence. All isolated compounds were tested for antimicrobial activity against some Gram-positive and Gram-negative bacteria as well as against some human pathogenic fungi showing a broad spectrum of antimicrobial activity.

Biologically active triterpenoids from Cephalaria ambrosioides.

The roots of Cephalaria ambrosioides yielded a new triterpene, 6alpha-hydroxyhederagenic acid ( 1), in addition to the known triterpene hederagenic acid ( 2) and four corresponding saponins, leontoside A (or akeboside Stb) ( 3), kalopanax saponin A (or alpha-hederin) ( 4), saponin PG (or sapindoside B) ( 5), and dipsacoside B ( 6). Their structures have been elucidated on the basis of their spectral data (MS, 1 D and 2 D NMR) and by some chemical transformations. The extract and all isolated compounds were evaluated for their antimicrobial, molluscicidal and IN VITRO cytotoxic activities. All compounds showed strong antimicrobial activity (MIC values 1.80 - 2.50 microg/mL), with 5 and 6 exhibiting activities comparable to those of standard antibiotics. Moreover, compounds 3 - 5 were active against all assayed cancer cell lines, whereas compounds 3 and 4 exhibited higher activities against Biomphalaria Glabrata snails, with minimum inhibitory concentrations of 5.4 and 6.2 microg/mL, respectively.

Chemical constituents of Lavatera trimestris L.--antioxidant and antimicrobial activities.

Nine phenolic compounds, such as cis-/trans-p-coumaric acid, cis-/trans-p-coumaric acid methyl ester, glucose ester of cis-/trans-p-coumaric acid, caffeic acid methyl ester, kaempferol 7-O-beta-D-glucoside and kaempferol 3-O-beta-D-glucoside, were isolated from Lavatera trimestris flowers by chromatographic techniques and their structures were elucidated by spectral means (NMR). All compounds were tested for their antioxidant activity, while the methanolic extract was tested also for its antimicrobial activity. Also several non-polar constituents have been identified using GC and GC/MS methods. This is the first time that phenolic esters and non-polar constituents were identified in the flowers of L. trimestris L.

Chemical composition and in vitro antimicrobial activity of the essential oils of two Helichrysum species from Tanzania.

The chemical composition of the essential oils obtained from the aerial parts of Helichrysum cymosum and H. fulgidum, from Tanzania, were analyzed by GC and GC/MS. A total of sixty-five compounds, representing 92.4% and 88.2% of the two oils, respectively, were identified. trans-Caryophyllene, caryophyllene oxide, beta-pinene, p-cymene, spathulenol and beta-bourbonene were found to be the main components. Furthermore, the oils were tested against six gram (+/-) bacteria and three pathogenic fungi. It was found that the oil of H. fulgidum exhibited significant antimicrobial activity, while the oil of H. cymosum was not active at all.

A new lignan glycoside and other constituents from Cephalaria ambrosioides.

A new lignan glycoside, 1,5-dihydroxy-2-(4"-beta-D-glucopyranosyloxy-3"-methoxyphenyl)-6-(4'-hydroxy-3'-methoxyphenyl)-3,7-dioxabicyclo[3.3.0]octane, named ambrosidine ([structure: see text]), along with seven known compounds (four iridoids and three hydroxycinnamic esters) were isolated from the roots of Cephalaria ambrosioides. The structures of these compounds were determined by use of NMR and MS techniques and by chemical transformations. The cytotoxic activity of the novel compound [structure: see text] was evaluated against five human solid tumour cell lines.

Cantleyoside-dimethyl-acetal and other iridoid glucosides from Pterocephalus perennis--antimicrobial activities.

Cantleyoside-dimethyl-acetal (6), was isolated from the endemic Greek plant Pterocephalus perennis subsp. perennis in addition to five other known iridoid glucosides, loganin, loganic acid, cantleyoside, secologanin, and secologanin-dimethyl-acetal. The structure of these compounds was determined by all spectroscopic means mainly by NMR and MS techniques. The above compounds as well as their acetyl derivatives were tested against six Gram positive and negative bacteria and three pathogenic fungi.