Charles L. Burandt

The American mayapple revisited : Podophyllum peltatum-still a potential cash crop?

Podophyllum peltatum, was reexamined for its potential use in the commercial production of podophyllotoxin, a lignan used in the semisynthesis of important anticancer drugs. A survey of the natural population of the American mayapple, Podophyllum peltatum, was conducted in order to identify high-yielding genotypes. Plants were collected from the eastern and central United States. The lignan content of leaf blades and rhizome material of the collected specimens was characterized by aqueous extraction followed by HPLC analysis. Podophyllotoxin and α-peltatin appeared most prominently among the lignans obtained. Leaf blades were generally richer in podophyllotoxin than rhizomes. Several high-yielding accessions were identified, the blades of which contained 4.0–5.6% podophyllotoxin. A negative correlation was observed between podophyllotoxin and peltatin content in the blades. The combination of high biosynthetic capacity and preferential accumulation of podophyllotoxin in leaves of mayapple makesthis plant an excellent candidate for agricultural production of podophyllotoxin.RésuméO potencial de utilização do Podophyllum peltatum foi rexaminado para a produção comercial de podofilotoxina, urn composto usado na semisìntese de importantes drogas anticancerìgenas. Urn levantamento da população norte-americana da mayapple, Podophyllum peltatum, foi conduzido com a finalidade de identificar genótipos de alta produtividade. As coletas foram feitas no centroeste dos Estados Unidos e o conteúdo de lignanas do limbo foliar e dos rizomas foi caracterizado por extração aquosa seguida da análise por HPLC. Podofilotoxina e a peltatin apareceram mais proemintes do que as demais lignanas. Geralmente, o limbo foliar apresentou um conteúdo de podofilotoxina mais rico do que os rizomas. Muitas accessões com alta produtividade foram identificadas e cujo o conteúdo de podophyllotoxina no limbo foliar variou entre 4.0–5.6%. Observou-se ainda uma correlação negativaentre apodofilotoxina e o conteúdo de peltatin no limbo foliar. Nas folhas, a combinaú ão entre a capacidade biosintética e o acúmulo preferencial da podofilotoxina, faz com que essa espécie seja considerada uma excelente candidata para a produção agrícola desta lignana.

Labdane Diterpenoids from Leonurus sibiricus

Six new labdane diterpenoids, preleosibirone A (1), 13-epi-preleosibirone A (2), isopreleosibirone A (3), leosibirone A (4), leosibirone B (5), and 15-epi-leosibirone B (6), were isolated from the leaves of Leonurus sibiricus. The absolute configurations of 1, 2, 5, and 6 were established by X-ray crystallographic analyses, and leosibirone A (4) was shown to be an artifact of the isolation process.

Labdane diterpenoids from Leonotis leonurus.

Three known (leoleorins A-C) and eight hitherto unknown (leoleorins D-J and 16-epi-leoleorin F) labdane diterpenoids, were isolated from leaves of Leonotis leonurus. The absolute configurations of leoleorins A and D were established by X-ray crystallographic analyses. In a competitive binding assay, all isolated compounds showed inhibition in excess of 50% at various CNS receptors. Leoleorin C showed moderate binding affinity (Ki=2.9 μM) for the Sigma 1 receptor.

Davidiol D, first naturally occurring resveratrol pentamer isolated from Sophora davidii

Abstract Davidiol D isolated from the roots of Sophora davidii was the first natural instance of a resveratrol pentamer. The structure and relative configuration were established by means of 2D-NMR spectroscopy.

Antileishmanial Germacranolides from Calea zacatechichi

Phytochemical study of the leaves and stems of Calea zacatechichi Schl. (Asteraceae) led to the isolation of a series of six germacranolides (1-6) with significant antileishmanial activity. The structure of a new compound named by us as calealactone D (1) was determined by NMR and MS, and its absolute configuration by X-ray crystallography. In addition, calealactone E (5) was discovered as a new naturally occurring compound, and the absolute configuration of calealactone C (2) was also determined by X-ray crystallography. All compounds were biologically evaluated in antimicrobial and antiprotozoal assays.

Bis-spirolabdane Diterpenoids from Leonotis nepetaefolia

Ten new bis-spirolabdane diterpenoids, leonepetaefolins A-E (1, 3, 5, 7, 9) and 15-epi-leonepetaefolins A-E (2, 4, 6, 8, 10), together with eight known labdane diterpenoids (11-18) as well as two known flavonoids, apigenin and cirsiliol, were isolated from the leaves of Leonotis nepetaefolia. The structures of the new compounds were determined on the basis of 1D- and 2D-NMR experiments including (1)H, (13)C, DEPT, (1)H-(1)H COSY, HSQC, HMBC, and NOESY. The absolute configuration of an epimeric mixture of 1 and 2 was determined by X-ray crystallographic analysis. The compounds isolated were evaluated for their binding propensity in several CNS G-protein-coupled receptor assays in vitro.

Qualitative and Quantitative High Performance Liquid Chromatographic Analysis of Quassinoids in Simaroubaceae Plants

A convenient and reliable reversed phase high performance liquid chromatography method was developed using a phenyl column and gradient elution for the determination of eight important quassinoids including glaucarubolone, chaparrinone, holacanthone, glaucarubinone, picrasin B, paraine, neoquassin and quassin, in diverse tissues of species of the Simaroubaceae. The method gave well resolved peaks for these compounds with good response and linearity in the range of 25–1000 ng. Incorporation of an internal standard provided easy quantitation of the quassinoids.

Two new benzofuran derivatives from the roots of Zanthoxylum flavum

Two new benzofuran derivatives (1 and 2) have been isolated from the roots of Zanthoxylum flavum Vahi. The structures of the new compounds 1 and 2 were characterised as 6-methoxybenzofuran-5-propionylmethylester (1) and 6,7-dimethoxybenzofuran-5-propionyl-methylester (2) based on one- and two-dimensional NMR spectroscopy and high-resolution mass spectrometry.