2-methoxy-6-pentyl-1,4-dihydroxybenzene (miconidin) from Primula obconica: a possible allergen?

Formation of toxic 2-nonyl-p-benzoquinones from α-tertiary 4-nonylphenol isomers during microbial metabolism of technical nonylphenol

In many environmental compartments, microbial degradation of α-quaternary nonylphenols proceeds along an ipso-substitution pathway. It has been reported that technical nonylphenol contains, besides α-quaternary nonylphenols, minor amounts of various α-H, α-methyl substituted tertiary isomers. Here, we show that potentially toxic metabolites of such minor components are formed during ipso-degradation of technical nonylphenol by Sphingobium xenophagum Bayram, a strain isolated from activated sewage sludge. Small but significant amounts of nonylphenols were converted to the corresponding nonylhydroquinones, which in the presence of air oxygen oxidized to the corresponding nonyl-p-benzoquinones-yielding a complex mixture of potentially toxic metabolites. Through reduction with ascorbic acid and subsequent analysis by gas chromatography-mass spectrometry, we were able to characterize this unique metabolic fingerprint and to show that its components originated for the most part from α-tertiary nonylphenol isomers. Furthermore, our results indicate that the metabolites mixture also contained several α, β-dehydrogenated derivatives of nonyl-p-benzoquinones that originated by hydroxylation induced rearrangement, and subsequent ring and side chain oxidation from α-tertiary nonylphenol isomers. We predict that in nonylphenol polluted natural systems, in which microbial ipso-degradation is prominent, 2-alkylquinone metabolites will be produced and will contribute to the overall toxicity of the remaining material.

Allergic contact dermatitis to plants: understanding the chemistry will help our diagnostic approach

Allergic contact dermatitis due to plants is common. Potentially allergenic plants and plant products are found in many everyday environments, such as the home, the garden, the workplace, and recreational settings. By improving our knowledge of allergenic plant-derived chemical compounds, we will be better positioned to identify novel allergens. We review the most relevant chemical allergens that contribute to plant allergic contact dermatitis and propose a clinical classification system based on 5 major families of chemical sensitizers: α-methylene-γ-butyrolactones, quinones, phenol derivatives, terpenes, and miscellaneous structures (disulfides, isothiocyanates, and polyacetylenic derivates). We also describe the different clinical pictures of plant allergic contact dermatitis and review currently available patch test materials. A better understanding of the specific allergens involved in plant allergic contact dermatitis will help to predict cross-reactivity between different plant species or families.

Plants used as remedies antirheumatic and antineuralgic in the traditional medicine of Lebanon

AIM OF THE STUDY

In the present investigation, ethnobotanical and ethnopharmacological research of the traditional use of plants to cure antirheumatic and antineuralgic diseases was carried out in Lebanon.

MATERIALS AND METHODS

The information was collected from different cities and villages of the twenty-six districts "aqdya or qadaa" of the six governorates "mohaafazah" of Lebanon. The knowledge on the medicinal use of plants has been recorded directly on the basis of a detailed survey on herbalists "Attarin or dabbous", folk healers, on older experienced people and midwives "daye". This research was carried out for 5 years (2002-2007).

RESULTS AND CONCLUSIONS

In this survey, 231 species of which 5 are endemic, distributed in 79 botanical families, currently used as antirheumatic herbal remedies, were collected and identified. Among them 53.3% are indigenous, 19.2% are cultivated and 17.5% are imported. Their latin names, local names, local medicinal uses, the used parts of the plant and the preparations and the ways of administration are described. The anti-inflammatory properties due to the plant compounds have been demonstrated and discussed.

Miconidin and miconidin methyl ether from Primula obconica Hance: new allergens in an old sensitizer

Several chemical and clinical observations have suggested the presence of at least one more allergen in addition to primin in Primula obconica. The aim of this study was to investigate the allergenicity of the primin precursor miconidin and the related miconidin methyl ether, both isolated from P. obconica. 12 primin-positive persons were patch tested with miconidin 0.01% petrolatum (pet.), miconidin in 96% ethanol incorporated into 0.01% pet., and miconidin methyl ether 1.0% pet. All persons were positive to miconidin 0.01% pet., with the strength of reactions very similar to those of the individual primin reactions, and remained inexplicably negative while testing with miconidin in 96% ethanol and pet., while miconidin methyl ether elicited 7 positive reactions. Although both miconidin and miconidin methyl ether may be allergenic only due to their conversion to primin in the skin, the presence of these substances nevertheless has to be taken into account when assessing the allergenicity of new P. obconica cultivars.

Primula obconica- is contact allergy on the decline?

Primula obconica, a member of the Primulaceae family, was introduced to Britain from China in 1880. P. obconica cultivars, which are reputed to contain less primin, have been developed over the past number of years in an attempt to reduce the incidence of allergic contact dermatitis. Primin (2-methoxy-6-pentyl-1,4-benzoquinone) is the main sensitizer, although other allergens have been postulated. We believe the incidence of primula allergic contact dermatitis has fallen since the introduction of primin-free P. obconica into the European market and thus the aims of this study were twofold. First, to determine whether the incidence of primula allergic contact dermatitis was truly on the decline and, second, to confirm the presence of primin-free P. obconica in the UK. We surveyed the incidence of primula allergic contact dermatitis in the UK and compared the incidence in the period between 1995 and 2000 with a subsequent follow-up study looking at the incidence for 2002. The results showed a significant fall in primin-positive patch tests from 1995 to 2000. The follow-up results for 2002 showed a further reduction in the number of primin-positive patch tests. The yearly incidence of contact allergy to primin has fallen from 0.785% in 1995/1996 to 0.429% in 2002. This downward trend was statistically significant (P = 0.001). A telephone survey of UK seed suppliers and selected plant retailers was also undertaken to clarify what types of P. obconica were available for sale and to assess suppliers' and retailers' knowledge of the primin-free varieties. This survey showed that 50% of suppliers were selling primin-free varieties but that the majority of surveyed retailers were not currently selling any variety of P. obconica. Our study suggests that although the yearly incidence of contact allergy to primin has fallen significantly over the past 8 years, it is still an important allergen, and thus its inclusion in the standard series remains justified for the foreseeable future.

Contact dermatitis due to hardy Primula species and their cultivars

For more than 100 years, it has been widely held that of all the Primula species to cause allergic contact dermatitis, P. obconica is the most likely culprit, particularly in Northern Europe. The main sensitizer is primin, but other sensitizers are reported. Other species are rarely implicated, but we suspect from our discussions with Primula growers that this is probably a consequence of under-reporting. Moreover, cutaneous reactions to other hardy Primula species and cultivars would appear to be milder and may sometimes be associated with a state of tolerance after repeated handling. With the co-operation of members of the Midland and West Section of the National Auricula and Primula Society of the UK, 462 questionnaires were sent out to members and 316 replies were returned (response rate 68.4%) with data on 320 growers. 84 out of a total of 320 (26.25%) attributed a cutaneous reaction to Primula species, whereas 236 (73.75%) reported no reaction. Of the 84 who reported reactions, 48 suspected P. auricula, 34 P. obconica, 10 P. vulgaris, 5 P. allionii, 3 P. marginata and 2 P. forrestii 19 believed that they had reacted to 2 or more species of Primula. Our study suggests that Primula species other than P. obconica may elicit dermatitis more frequently than previously recorded.