2,2-Diphenyl-1-picrylhydrazyl radical (DPPH*) scavenging activity-guided fractionation of a leaf extract of Thymus vulgaris led to the isolation of the radical scavengers rosmarinic acid 1, eriodictyol, taxifolin, luteolin 7-glucuronide, p-cymene 2,3-diol, p-cymene 2,3-diol 6-6'-dimer, carvacrol, thymol, and a new compound, 2. The fractionation was considerably facilitated by using an on-line HPLC detector for radical scavenging activity. In this detector activity is monitored as the disappearance of the color of a postcolumn added stable radical after reacting with radical scavengers in a reaction coil. Compound 2, which consists of rosmarinic and caffeic acid moieties linked via a C-3'-C-8' ' ether bridge, was mainly elucidated by various NMR techniques and CD. Phenylpropanoid trimer 2 was a weaker and stronger radical scavenger than rosmarinic acid 1 in off-line TEAC and DPPH* assays, respectively.

A mutagenic compound, designated aquilide A, was isolated and identified from bracken fern (Pteridium aquilinum (L.) Kuhn). Aquilide A was found to be responsible for greater than 50% of the mutagenic activity observed after incubation of the methanol extract at alkaline conditions. This compound was found to be a potent genotoxic compound in mammalian cells in vitro and therefore, may be responsible for at least part of the carcinogenic activity of bracken. The instability of aquilide A under conditions normally encountered during analytical chemical procedures may explain why so many efforts to elucidate the carcinogenic factor(s) present in bracken have been unsuccessful.

A quantitative 'H NMR procedure for the determination of bilobalide and ginkgolides A, B, C and J in Ginkgo bilobu leaves and in phytopharmaceuticals without prior chromatographic separation of the mixture has been developed. The method is based on the comparison of the integral of each H-12 proton of the five ginkgo terpene trilactones with that of the olefinic protons of the internal standard (maleic acid). These protons are all well separated at 200 MHz and occur in a less crowded region of the NMR spectrum (6.15-6.50 ppm). The selectivity, reproducibility and sensitivity are comparable with high pressure liquid chromatography (HPLC) with refractive index (RI) detection. The minimum amount that can be quantified within 30min at 200MHz is approximately 0.1 mg for all four ginkgolides and bilobalide. Advantages, in comparison with HPLC-RI, are that no reference substances are needed and that for the occasional analysis of a limited number of samples a very significant time-gain can be achieved.

Gel-filtration and thin layer chromatography of low molecular weight carbohydrates from culture filtrates of Agrobacterium radiobacter, Isolate II, have shown, that next to the neutral beta-1,2-glucan fraction a major acidic fraction was present which was found to be glycerophosphorylated cyclic beta-1,2-glucans. Re-examination of cyclic beta-1,2-glucan preparations which had been obtained by extraction of Rhizobium cells with hot phenol-water also showed these acidic modified beta-1,2-glucans to be present. Cyclic beta-1,2-glucans from R. leguminosarum (9 strains) and of R. phaseoli (1 strain) had ring size distribution with degrees of polymerisation (DPs) of 19 and 20 as major ring sizes of which a minor part was glycerophosphorylated; beta-1,2-glucans of R. trifolii (3 strains) had ring sizes with DPs measuring 19-22 as prominent components which were largely unsubstituted, and R. meliloti (7 strains) had beta-1,2-glucans with ring size distributions extending to still higher DPs of 19-25 of which the major part appeared to be glycerophosphorylated.

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