J. C. Mitchell

Biological activities of sesquiterpene lactones

Abstract Sesquiterpene lactones are characteristic constituents of the Compositae but also occur sporadically in other angiosperm families and even in some liverworts. These bitter substances often contain as a major structural feature an α,β-unsaturated-γ-lactone, which in recent studies has been shown to be associated with anti-tumor, cytotoxic, anti-microbial and phytotoxic activity. They are known to poison livestock, to act as insect feeding deterrents and to cause allergic contact dermatitis in humans. This review highlights the present state of knowledge on the biological activities and mechanism of action of some sesquiterpene lactones.

Ultraviolet-mediated antibiotic activity of thiophene compounds of Tagetes

Abstract Two intensely mauve UV fluorescent compounds isolated from Tagetes root were found to be phototoxic to Candida albicans . By chromatography on alumina followed by gel filtration on Sephadex LH-20, the compounds were identified as 5-(3-buten-1-ynyl)-2,2′-bithienyl and α-terthienyl.

Multiple concomitant positive patch test reactions

Thirty‐five patients who showed 90 one plus (+) patch test reactions to 28 patch test chemicals at Day 2 (D2) were retested to the chemicals at D7. On retesting, 60 % (54/90) reactions were positive but 42 % (38/90) were negative at D9, suggesting that false positive patch test reactions were common when more than one positive reaction was obtained by concomitant patch testing. On retesting, the total % positivity was reduced from 344 to 241 suggesting that the true index of sensitivity was falsely exaggerated by concomitant testing.

Comparison of phenotype in uniparental disomy and deletion Prader-Willi syndrome: Sex specific differences

Prader-Willi syndrome (PWS) results primarily from either a paternal deletion of 15q11-q13 or maternal uniparental disomy (UPD) 15. Birth parameters and clinical presentation of 79 confirmed UPD cases and 43 deletion patients were compared in order to test whether any manifestations differ between the two groups. There were no major clinical differences between the two classes analyzed as a whole, other than the presence of hypopigmentation predominantly in the deletion group. However, there was a significant bias in sex-ratio (P < .001) limited to the UPD group with a predominance (68%) of males. An equal number of males and females was observed in the deletion group. When analyzed by sex, several significant differences between the UPD and deletion groups were observed. Female UPD patients were found to be less severely affected than female deletion patients in terms of length of gavage feeding and a later onset of hyperphagia. Although these traits are likely to be influenced by external factors, they may reflect a milder presentation of female UPD patients which could explain the observed sex bias by causing under-ascertainment of female UPD. Alternatively, there may be an effect of sex on either early trisomy 15 survival or the probability of somatic loss of a chromosome from a trisomic conceptus.

UV-mediated antibiotic activity of some compositae species

Abstract Roots, leaves, and flowers of 80 species of Compositae were tested for phototoxic activity against Candida albicans . Many genera showed activity, especially in the roots. No active genera were found in the tribe Cichorieae. Phototoxic compounds were isolated from Chrysanthemum leucanthemum florets and Cirsium arvense roots. Chemotaxonomic evidence plus preliminary chemical data suggests that the compounds are polyacetylenic in nature. Unlike other phototoxic compounds, these are inactive against human skin.

Allergic contact dermatitis from the radish, Raphanus sativus.

A waitress, aged 38 years, developed acute contact dermatitis of her hands after chopping salad plants. Patch tests to radish (Raphanus) and to allyl wothiocyanate and benzyl wothiocyanate produced positive reactions. Sinigrin, the thioglucoside of allyl isothiocyanate, was mixed in petrolatum with the enzyme myrosinase; the mixture produced a positive patch test reaction. Based on these preliminary findings, the immunochemical requisites of isothiocyanates (mustard oils) are discussed. A tabulation has been made of exposure risk to plants of the mustard family (Cruciferae) which yield these compounds; the plants include some commonly used culinary vegetables, salad plants, condiments and also horticultural plants.

Phototoxic polyacetylenes and their thiophene derivatives [Effects on human skin]

Polyacetylenes and their thiophene derivatives were tested for their effects on human skin. Topically applied α‐terthienyl evoked bi‐phasic phototoxic dermatitis and the appearance of ‘sunburn’ cells in human epidermis. None of 11 polyacetylenes had the same effect although they mimicked α‐terthienyl in their phototoxic effects on Candida albicans and certain pathogenic microorganisms. The UV‐mediated antibiotic activity of the compounds and their apparent lack of phototoxicity towards the skin suggest a potential topical therapeutic role for them in yeast, fungal and bacterial infections and light‐responsive dermatoses. Their topical sensitizing capacity, however, has not yet been studied.

Day 7 (D7) patch test reading - valuable or not?

Day 7 (D7) reading of 15,469 patch tests was carried out in 499 patients. In one fifth of them, positive reactions were observed at D7 having been judged negative at D2. The significance of the findings is discussed.

Contact hypersensitivity to sesquiterpene lactones inChrysanthemumdermatitis

In six persons with contact allergy to chrysanthemum of florists, patch tests were performed with 25 sesquiterpene hurt ones. Positive responses were observed to 15 lactones. The most frequently encountered positive responses were to alantolactone (positive in all cases) and to arbusculin A, 8‐deoxycumambrin, ambrosin, damsin and psilostachynin. The findings corroborate the assumption that an α‐methylene group attached to the γ‐lactone ring is an essential prerequisite for allergenic activity of sesquiterpene lactones. Pyrethrum produced a positive reaction in one of the patients, pyrethrins gave negative reactions in all. Some of the chrysanthemum patients were also hypersensitive to turpentine and colophony and to garlic, primin and tars.

Allergic contact dermatitis from pyrethrum (Chrysanthemum spp.). The roles of pyrethrosin, a sesquiterpene lactone, and of pyrethrin II.

Summary.— In a patient with allergic contact dermatitis from pyrethrum (Chrysanthemum spp., family Compositae), pyrethrosin produced strong, and pyrethrin II weak, positive patch test responses.