David S. Rycroft

Molecular, morphological, and phytochemical evidence for a broad species concept of Plagiochila bifaria (Hepaticae)

Abstract Debate over the synonymy of the European Plagiochila killarniensis and the Neotropical P. bifaria of P. sect. Arrectae has focused on differences in secondary metabolite composition. The broad morphological species concept of P. bifaria proposed in recent papers has now been tested by comparing nrDNA ITS1 and ITS2 sequences of P. bifaria populations encompassing several different morpho- and chemotypes from the British Isles, Tenerife, Costa Rica, Brazil, Ecuador, and Bolivia, with sequences of other species of P. sects. Arrectae, Rutilantes, and Fuscoluteae. Phylogenetic analyses demonstrate that specimens of P. bifaria form a well supported clade within Plagiochila sect. Arrectae. Sequences of P. bifaria from the British Isles, Tenerife, and Ecuador, representing the “methyl everninate” chemotype, form a well supported subclade within the P. bifaria clade. Sequences of specimens from Costa Rica, Brazil, and Bolivia are placed in the basal part of the P. bifaria clade. The data support a broad species concept of P. bifaria. The different chemotypes do not warrant distinct taxonomic ranks. Plagiochila centrifuga and P. compressula are treated as new synonyms of P. bifaria.

Sesquiterpenoid phytoalexins from suspended callus cultures of Nicotiana tabacum

Abstract Treatment of suspended callus cultures of Nicotiana tabacum with commercial cellulase elicited four principal stress metabolites including the phytoalexin capsidiol and a second eremophilane-type diol, shown on the basis of chemical and spectroscopic evidence to be 4-epieremophil-9-ene-11 /gx, 12-diol (without assignment of absolute configuration). This diol appears to be structurally identical with debneyol isolated from N. debneyi (see accompanying paper). Among minor metabolites were an isomer and a dehydro-analogue of the diol. GC/MS of cyclic derivatives (boronates and di-t-butylsilylene derivatives) of vicinal diols was useful for their detection and characterisation. The remaining two major metabolites appeared to be phytuberol and phytuberin.

Formation of three new flavones by differentiating callus cultures of andrographis paniculata

Abstract Differentiating tissue cultures of Andrographis paniculata produce three new flavones, 5-hydroxy-7,8,2′-trimethoxy-, 5,2′-dihydroxy-7,8-dimethoxy- and 5-hydroxy-7,8-dimethoxy-flavones. Flavones are not synthesized by the de-differentiated callus. Closely related flavones have been isolated from intact plants of Andrographis species.

Triterpenoids from walsura piscidia

A series of tirucallane (piscidinol A and B) and apotirucallane (piscidinol C–E) derivatives has been isolated from the leaves of Walsura piscidia. The fruit yielded a new tetranortriterpenoid, piscidofuran. The structures were assigned on the basis of 1H NMR and 13C NMR evidence.

Anadensin, a new fusicoccane diterpenoid from the liverwort Anastrepta orcadensis. Crystal structure analysis.

Abstract Anadensin, a new diterpenoid from the liverwort Anastrepta orcadensis (Hook) Schiffn., has been shown by X-ray crystallographic analysis to have the fusicoccane structure (1).

Phytochemical, morphological, and molecular evidence for the occurrence of the neotropical liverwort Plagiochila stricta in the Canary Islands, new to Macaronesia

Abstract Plant material from the Canary Islands similar to Plagiochila spinulosa (Dicks.) Dumort. has been identified as the Neotropical liverwort P. stricta Lindenb. The secondary metabolite profiles of CDCl3 extracts of both Neotropical and Macaronesian specimens of P. stricta are distinct from those of P. spinulosa in containing alloocimene and neoalloocimene as the principal monoterpenes rather than β-phellandrene; the two species also show differences in the 9,10-dihydrophenanthrenes and other aromatic compounds present. Phylogenetic analyses of ITS nrDNA sequence variation place P. spinulosa sister to P. stricta. Morphologically, P. stricta from Tenerife is distinguished most easily from P. spinulosa by the scarcely decurrent antical leaf margin.

A phytochemical and morphological study of the liverwort Plagiochila retrorsa Gottsche, new to Europe

Abstract The Neotropical liverwort Plagiochila retrorsa Gottsche is conspecific with P. sharpii H.L.Blomq., known previously as a Southern Appalachian endemic, as well as P. tricarinata Carl and P. permista Spruce var. subintegerrima Herzog from Costa Rica. It has been discovered recently in the Azores and Madeira, new to Europe. Illustrations, SEM micrographs of spores and elaters, nuclear magnetic resonance (NMR) fingerprints and gas chromatography–mass spectrometry (GC-MS) data are presented, based on American and European material. Costa Rican material used for an earlier phytochemical study has now also been identified as P. retrorsa. Although NMR fingerprinting initiated the present discoveries, the NMR fingerprint of P. retrorsa is not unique and NMR fingerprinting alone is not sufficient to identify the species. P. retrorsa belongs to the 9,10-dihydrophenanthrene chemotype group and the two principal secondary metabolites are 3,5-dimethoxy-9,10-dihydrophenanthren-2-ol and methyl 4-hydroxy-4′-O-methyllunularate.

Sesquiterpenoids and diterpenoids from the liverwort Jungermannia truncata

Twelve ent-kaurane diterpenoids, nine of which are new, have been isolated from the liverwort Jungermannia truncata, collected in Malaysia. The extract also contained new gymnomitrane and nor-gymnomitrane sequiterpenoids together with known pimarane and halimane diterpenoids. The structures were established mainly by 1H and 13C NMR spectroscopy.

Plagiochila virginica A. Evans rather than P-dubia Lindenb. & Gottsche occurs in Macaronesia; placement in sect. Contiguae Carl is supported by ITS sequences of nuclear ribosomal DNA

Abstract. Plagiochila dubia Lindenb. & Gottsche is reduced to a synonym of the Neotropical P. patula (Sw.) Lindenb. Specimens from the Canary Islands and Madeira proved to belong to the eastern North American P. virginica A.Evans, new to Europe. Phylogenetic analyses of the internal transcribed spacer regions (ITS1-5.8S-ITS2) of nuclear ribosomal DNA of ten Plagiochila species produced four independent lineages that are well supported by all bootstrap analyses (maximum likelihood, maximum parsimony, and distance). These lineages correspond with the Plagiochila sections Arrectae, Contiguae, Cucullatae and Glaucescentes. Spruces “Ramiflorae” and “Cauliflorae” may no longer be regarded as monophyletic units of Plagiochila.

Cyclodextrins as chiral nuclear magnetic resonance shift reagents

Although chemical shift non-equivalence between enantiotopic groups in n.m.r. spectra has often been observed employing optically active solvents or chiral lanthanide shift reagents, or when a substrate is complexed to a chiral crown compound, such methods are normally critically dependent upon suitable substrate functionality. We now report that guest binding within the chiral cavity of β-cyclodextrin in D2O provides a method for inducing 19F n.m.r. chemical shifts between the prochiral CF3 groups of compounds 1 [1,1,1,3,3,3-hexafluoro-2-phenyl-2-propanol] and 2 [1,1,1,3,3,3-hexafluoro-2-(p-tolyl)propane], it being particularly noteworthy that the latter molecule lacks the type of functional group usually required for such chiral effects.