Accumulation of the labdane diterpene Marrubiin in glandular trichome cells along the ontogeny of Marrubium vulgare plants

The content of the diterpene Marrubiin was assessed by GC-FID in leaves of Marrubium vulgare plants along their ontogeny. Maximum accumulation occurred just before flowering time and in fully expanded leaves. After feeding the plants with radio labeled [³H]-geranyl geranyl diphosphate, up to 70% of the radioactivity was recovered in HPLC-Rt coincidental with authentic Marrubiin, which was also characterized by GC-EIMS, thus confirming that the biosynthesis of Marrubiin proceeds through the 1-deoxy-D-xylulose-5-phosphate pathway. The major accumulation of radioactivity occurred in glandular trichome cells, and the product remained stable throughout.     

Minor labdane diterpenes from Marrubium thessalum

Five new labdane diterpenes, thessalines A, B, and D, 14β-hydroxythessaline A, and 14β-hydroxythessaline B (1-5, resp.) were isolated from the aerial parts of Marrubium thessalum, along with the known labdane diterpene deacetylvitexilactone (6) and the methoxylated flavones 4',7-dimethylapigenin and salvigenin. (3S,5R)-Loliolide was also found in the same source. Their structures were established by 1D- and 2D-NMR (COSY, HSQC, HMBC, NOESY, and ROESY) and MS analyses. The plant produces a great variety of labdane-type diterpenes, with variations in functionalities, particularly in the side chain. Their structures could be of chemotaxonomic significance for the genus Marrubium.     

Acylated flavonoid and phenylethanoid glycosides from Marrubium velutinum

From the aerial parts of Marrubium velutinum, one acylated flavonoid glycoside, chrysoeriol 7-O-(3",6"-di-O-E-p-coumaroyl)-beta-D-glucopyranoside, and two tetrasaccharidic phenylethanoid glycosides, velutinosides I-II, have been isolated together with ten known flavonoids and seven known phenylethanoid glycosides. The structures of the isolated compounds were established by means of NMR, MS, and UV spectral analyses.     

Labdane diterpenes from Marrubium velutinum and Marrubium cylleneum

From the aerial parts of Marrubium velutinum and Marrubium cylleneum, seven labdane diterpenes, velutine A, 15-epi-velutine A, velutine B, 15-epi-velutine B, velutine C, cyllenine A and 15-epi-cyllenine A, have been isolated together with five known diterpenes and four known flavones. The structures of the isolated compounds were established by means of NMR [(1)H-(1)H-COSY, (1)H-(13)C-HMQC, HMBC, HMQC-TOCSY, NOESY] and MS spectral analyses. Complete NMR assignments are reported for known compounds.     

Potential for Integrated Control of Horehound Marrubium vulgare L. by the Plume Moth Wheeleria spilodactylus (Curtis) and 2,4-D

Marrubium vulgare is an introduced perennial herbaceous weed of pastures and natural ecosystems in southern Australia. The moth Wheeleria spilodactylus has recently been established as a biocontrol agent and is spreading widely; its larvae feed on shoots and later leaves of M. vulgare. Glasshouse experiments were carried out to examine how eggs, larvae and adult W. spilodactylus might be affected by herbicide treatment of M. vulgare and thus to determine whether the two control techniques were compatible. Survival and development of larvae was generally little affected by herbicide treatments that were sufficient to damage the weed severely. Adult moths showed large reductions in longevity and fecundity in response to loss of M. vulgare flowers as a food source. Female moths offered a choice of treated or untreated plants as oviposition sites strongly avoided herbicide-treated M. vulgare. The results justify further investigation of the combined effects of herbicide and W. spilodactylus in the management of M. vulgare infestations.     

Biology and Host Specificity of Chamaesphecia mysiniformis (Lepidoptera: Sesiidae), a Potential Biological Control Agent of Marrubium vulgare (Lamiaceae) in Australia

The biology of the rhizophagous clearwing moth Chamaesphecia mysiniformis Rambur and its specificity to Marrubium vulgare L. (Lamiaceae) (horehound), a serious introduced weed in southern Australia, were studied in France. Adults emerged in late spring during the morning and began mating on the same day, usually in the mid to late afternoon. Eggs were laid among flower clusters, with females laying an average of 96 2.41 (range, 1-268) with an overall hatch success of 79%. In no-choice, host-specificity tests, first instar larvae attacked only four species of Marrubium, along with Ballota nigra L. and Stachys arvensis L. This high level of specificity and the high mortality of the target plant in its native range make this moth a promising biological control agent of horehound in Australia.     

Marrubium vulgare extract inhibits human-LDL oxidation and enhances HDL-mediated cholesterol efflux in THP-1 macrophage

The objective of the present study was to elucidate the beneficial properties of aqueous extracts of Marrubium vulgare (AEM) towards cardiovascular disease by protecting human-LDL against lipid peroxidation and promoting HDL-mediated cholesterol efflux. Human-LDL were oxidised by incubation with CuSO(4) in the presence of increased concentrations of AEM (0-100 microg/ml). LDL lipid peroxidation was evaluated by conjugated diene formation, vitamin E disappearance as well as LDL-electrophoretic mobility. HDL-mediated cholesterol efflux assay was carried out in human THP-1 macrophages. Incubation of LDL with AEM significantly prolonged the lag phase (P=0.014), lowered the progression rate of lipid peroxidation (P=0.004), reduced the disappearance of vitamin E and the electrophoretic mobility in a dose-dependent manner. Also, incubation of HDL with AEM significantly increased HDL-mediated cholesterol efflux from THP-1 macrophages implicating an independent ATP binding cassette A1 (ABCA1) pathways. Our findings suggest that M. vulgare provides a source of natural antioxidants, which inhibit LDL oxidation and enhance reverse cholesterol transport and thus can prevent cardiovascular diseases development. These antioxidant properties increase the anti-atherogenic potential of HDL.