Urticaceae pollen concentration in the atmosphere of North Western Spain. (1/12)

Plants of the Urticaceae family can develop into a pest on soils enriched with nitrogen. Urticaceae pollen is a biohazard because it elicits severe pollinosis. Pollen grains were sampled by using a Lanzoni seven-day-recording trap from February 1995-December 2000 in the atmosphere of the city of Ponferrada (Leon, North Western Spain). The Spearman test was used to analyse the statistical correlation between Urticaceae pollen and certain meteorological factors in different main pollination periods. Maximum values are reached in June and July, minimum levels are recorded in January and December. The parameters bearing the greatest positive influence on the occurrence of Urticaceae pollen grains are: temperature (maximum, minimum and mean), humidity (absolute, wet-bulb temperature, dew point and mixing ratio) and south western wind direction; negative parameters are: relative humidity, rainfall and period without wind. The highest correlation coefficients were obtained with temperature and wet-bulb. Absolute humidity and wet-bulb temperature yielded better correlation than relative humidity; hence, these two parameters must be included in this type of study. The use of one main pollination period or another in statistical analysis has an influence on the coefficient value. The behaviour of the pollen grains in the atmosphere during the year also influences the results.  (+info)

Identification of oxalic acid and tartaric acid as major persistent pain-inducing toxins in the stinging hairs of the nettle, Urtica thunbergiana. (2/12)

BACKGROUND AND AIMS: Once human skin contacts stinging hairs of Urtica spp. (stinging nettles), the irritant is released and produces pain, wheals or a stinging sensation which may last for >12 h. However, the existence of pain-inducing toxins in the stinging hairs of Urtica thunbergiana has never been systematically demonstrated. Experiments were therefore conducted to identify the persistent pain-inducing agents in the stinging hairs of U. thunbergiana. METHODS: The stinging hairs of U. thunbergiana were removed and immersed in deionized water. After centrifugation, the clear supernatants were then subjected to high-performance liquid chromatography (HPLC), enzymatic analysis and/or behavioural bioassays. KEY RESULTS: The HPLC results showed that the major constituents in the stinging hairs of U. thunbergiana were histamine, oxalic acid and tartaric acid. However, the well-recognized pain-inducing agents, serotonin and formic acid, existed at a low concentration as estimated by HPLC and/or enzymatic analyses. The behavioural tests showed that 2% oxalic acid and 10% tartaric acid dramatically elicited persistent pain sensations in rats. In contrast, 10% formic acid and 2% serotonin only elicited moderate pain sensation in the first 10 min. Moreover, no significant pain-related behavioural response was observed after injecting 10% acetylcholine and histamine in rats. CONCLUSIONS: Oxalic acid and tartaric acid were identified, for the first time, as major long-lasting pain-inducing toxins in the stinging hairs of U. thunbergiana. The general view that formic acid, histamine and serotonin are the pain-inducing agents in the stinging hairs of U. dioica may require updating, since their concentrations in U. thunbergiana were too low to induce significant pain sensation in behavioural bioassays.  (+info)

New chemical constituents of roots of Urtica triangularis HAND-MASS. (3/12)

Studies on the chemical constituents of roots of Urtica triangularis HAND-MASS have led to the isolation of four new compounds. The structures, including the absolute configurations, of these constituents have been elucidated through spectral studies including (1)H-NMR, (13)C-NMR, 2D-NMR experiments (heteronuclear single-quantum coherence, heteronuclear multiple bonding connectivity and nuclear Overhauser effect spectroscopy), high resolution mass spectroscopy (HR-MS) and circular dichroism as (-)-4-methoxy-8'-acetyl olivil, (-)-4-methoxy-8'-acetyl olivil-4-O-alpha-arabinopyronosyl-(1-->6)-beta-glucopyranoside, (-)-olivil-9-O-beta-glucopyranoside and cyclo-olivil-9-O-beta-glucopyranoside.  (+info)

Aroma-active compounds of Elatostema laetevirens and Elatostema umbellatum var. majus. (4/12)

The essential oils from aerial parts of Elatostema laetevirens and Elatostema umbellatum var. majus were investigated by capillary GC and GC-MS. The important aroma-active compounds were also detected in the oil using GC-MS/O and aroma extraction dilution analysis (AEDA). As a result, 79 compounds of E. laetevirens and 80 compounds of E. umbellatum var. majus, accounting for 95.41% and 98.37%, were identified, respectively. The major components of E. laetevirens oil were phytol (667.4 microg/100 g fresh samples), neophytadiene (335.2 microg) and gamma-himachalene (49.8 microg). On the other hand, E. umbellatum var. majus oil contained phytol (402.3 microg), linoleic acid (289.4 microg) and palmitic acid (241.4 microg) as the major components. GC-MS/O and AEDA showed that (2E)-hexenal and (2E, 4E)-nonadienal were most aroma compounds of E. laetevirens oil. It seems that these components make the green-floral odor. On the other hands, it seems that (2E)-hexenal, (3Z)-hexenol and 1-octen-3-ol make the green-oily odor of E. umbellatum var. majus oil.  (+info)

Alternative therapy for autosensitization dermatitis. (5/12)


Characterization and quantification of polyphenols in Amazon grape (Pourouma cecropiifolia Martius). (6/12)


Antioxidant rich flavonoids from Oreocnide integrifolia enhance glucose uptake and insulin secretion and protects pancreatic beta-cells from streptozotocin insult. (7/12)


Morphology and behavior of the early stages of the skipper, Urbanus esmeraldus, on Urera baccifera, an ant-visited host plant. (8/12)