Per M. Boll

Phytochemistry of the genus Piper

Abstract The secondary metabolites isolated from Piper species for the period 1907 to June 1996 have been reviewed. Nearly six hundred chemical constituents belonging to different classes of bioactive compounds are listed together with their source(s) and references.

Polyacetylenes in Araliaceae: their chemistry, biosynthesis and biological significance

Abstract Polyacetylenes are characteristic natural products of Araliaceae as they are of the closely related Umbelliferae. This review highlights recent findings on their distribution, chemistry, biosynthesis and biological activities.

Naturally occuring lactones and lactames—V: Halogenated β-keto esters as starting materials for the synthesis of tetronic acids

Abstract In an effort to improve and simplify the synthetic route to tetronic acids 15 differently substituted β-keto esters were investigated as potential starting materials. The β-keto esters were brominated and cyclised with 2·5 N KOH as cyclising agent. Tetronic acid and seven derivatives including the naturally occuring carolinic acid were obtained. In a number of cases products arising from a Favorskii rearrangment were isolated. The NMR spectroscopic data are discussed.

Lignans and neolignans from Piper schmidtii

Abstract The unknown enantiomeric lignan (−)-machilin G and the known lignans (+)-calopiptin, (−)-zuionin A as well as a new neolignan kadsurin A and known neolignans futoquinol, isodihydrofutoquinol A, isodihydrofutoquinol B, along with parsley apiole, have been isolated from the leaves and stem of Piper schmidtii . The unpublished 13 C NMR data of the above known neolignans and the reassignment of the 1 H NMR spectrum of isodihydrofutoquinol B are also reported.

Allergic contact dermatitis from falcarinol isolated from Schefflera arboricola

From the plant Seheffera arboricola, which has been reported in cause allergic contact dermatitis. we have isolated and determined the elicitor of allergic contact dermatitis as falcarinol. Heptadeca‐1,9(Z)‐diene‐4,6‐diyne‐3‐ol. Three polyacetylenes closely related in falcarinol, namely falcarindiol, falcarinone and dehydrofalcarinone were tested simultaneously. Falcarinol, but not faicarindiol, falcarinone and dehydrofalcarinone, elicited allergic contact dermatitis in a 38–year‐old female plant‐nursery worker.

Lignans and neolignans from piperaceae

Abstract During the past decade many new lignans and neolignans have been isolated from the Piperaceae. Lignans and neolignans are known to possess biological activity. This review summarizes the structures of lignans and neolignans presently known in the Piperaceae.

The polyacetylenic falcarinol as the major allergen in schefflera arboricola

Abstract Schefflera arboricola has been reported to cause allergic contact dermatitis. The major allergen is now isolated and identified as falcarinol, heptadeca-1,9(Z)dien-4,6-diyn-3-ol. The isolation of (E)-β-farnesene, phytol and 24β-ethylcholesta-5,22(E)-diene-3β-ol (poriferasterol) is also reported.

An aristolactam from Piper acutisleginum and revision of the structures of piperolactam B and D

Abstract A new aristolactam, 10-amino-4-hydroxy-2,3-dimethoxyphenanthrene-1-carboxylic acid lactam, was isolated from the stem of Piper acutisleginum . The structures of two related alkaloids, piperolactam B and D, have been revised.

Regiospecific alkylation of tetronic acids : Formation of 4-alkoxy-5H-furan-2-ones and 2-alkoxy-5H-furan-4-ones

Abstract 2-Alkoxy-5 H -furan-4-ones ( 7,8 ) and 4-alkoxy-5 H -furan-2-ones ( 4,5 ) were prepared regiospecifically and in high yields from tetronic acids (4-hydroxy-5 H -furan-2-ones) ( 2 ) in the first case by acetylating the 4-OH group and then reacting with trialkyloxonium tetrafluoroborate, and in the second case by alkylating tetrabutylammonium tetronates with dialkyl sulfate, respectively. Direct alkylation of tetronic acids with trialkyloxonium tetrafluoroborate gave in four cases regiospecific 2-O-alkylation, in one case 4-O-alkylation and in two other cases mixtures of 2- and 4-alkoxy derivatives.

Highly oxygenated bioactive flavones from Tamarix

Abstract Two new flavones, 5,7,2′-trihydroxy-6,4′-dimethoxyflavone (tamaridone) and 5,2′,4′-trihydroxy-6,7,8-trimethoxyflavone (tamadone) have been isolated from the aerial parts of Tamarix dioica, along with hexacosyl-p-coumarate, gardenins A, B, C and E, nevadensin A and apigenin. Gardenin B exhibited antiviral activity and anti-invasive activity against solid tumours.