The antioxidant potentials of a total ethanolic extract of Hypericum perforatum (TE) and fractions were evaluated and correlated with their phenolic contents. The extracts were fully characterised by HPLC-DAD-MS-MS. Kaempferol 3-rutinoside and rutinacetyl were identified for the first time in TE extracts. The free radical-scavenging properties of TE (EC 50 ¼ 21 lg dwb/ml) and fractions were studied using DPPH. Fractions containing flavonoids and/or caffeoylquinic acids were found to be the main contributors to the free radical-scavenging activity of the TE. Lipid peroxidation, induced with ascorbate/Fe 2þ , was significantly reduced in the presence of the TE (EC 50 ¼ 26 lg dwb/ml) and fractions containing flavonoids and/or caffeoylquinic acids. The fraction containing flavonoid aglycones was found to be responsible for a major part of the TE protection against lipid peroxidation. Hypericins and hyperforins made no significant contributions to the antioxidant properties of TE. Human consumption of H. perforatum extract or fractions could be beneficial.

Xanthone production in Hypericum perforatum (HP) suspension cultures in response to elicitation by Agrobacterium tumefaciens co-cultivation has been studied. RNA blot analyses of HP cells co-cultivated with A. tumefaciens have shown a rapid up-regulation of genes encoding important enzymes of the general phenylpropanoid pathway (PAL, phenylalanine ammonia lyase and 4CL, 4-coumarate:CoA ligase) and xanthone biosynthesis (BPS, benzophenone synthase). Analyses of HPLC chromatograms of methanolic extracts of control and elicited cells (HP cells that were co-cultivated for 24h with A. tumefaciens) have revealed a 12-fold increase in total xanthone concentration and also the emergence of many xanthones after elicitation. Methanolic extract of elicited cells exhibited significantly higher antioxidant and antimicrobial competence than the equivalent extract of control HP cells indicating that these properties have been significantly increased in HP cells after elicitation. Four major de novo synthesized xanthones have been identified as 1,3,6,7-tetrahydroxy-8-prenyl xanthone, 1,3,6,7-tetrahydroxy-2-prenyl xanthone, 1,3,7-trihydroxy-6-methoxy-8-prenyl xanthone and paxanthone. Antioxidant and antimicrobial characterization of these de novo xanthones have revealed that xanthones play dual function in plant cells during biotic stress: (1) as antioxidants to protect the cells from oxidative damage and (2) as phytoalexins to impair the pathogen growth.

Twenty three samples of 18 Portuguese olive leaf cultivars were analysed by a reversed-phase HPLC/DAD procedure and eight flavonoidic compounds were identified and quantified (luteolin 7,4'-O-diglucoside, luteolin 7-O-glucoside, rutin, apigenin 7-O-rutinoside, luteolin 4'-O-glucoside, luteolin, apigenin and diosmetin). Luteolin 7,4'-O-diglucoside and luteolin 4'-O-glucoside were identified by HPLC/DAD/MS/MS - ESI. The studied olive leaf samples showed a common phenolic pattern, in which luteolin 4'-O-glucoside was almost always the major compound.

No abstract

Changes in phenolic metabolism after elicitation with Colletotrichum gloeosporioides (CG) has been studied in Hypericum perforatum L. (HP) cell suspension cultures. Soluble phenolics were analysed by HPLC-DAD and HPLC-DAD-MS/MS. HP cultures elicited with the CG elicitor showed a significant increase in xanthone accumulation. Xanthone accumulation increased twelve fold when the cells were primed with methyl-jasmonate (MeJ) or salicylic acid (SA), before elicitation. HP cultures exposed only to MeJ produced a set of flavonoids, the flavones which represent a substantial part (approx. 40%) of the total flavonoids accumulated in these cells. The possible importance of xanthones as a component of defence mechanism of HP against biotic stress is discussed.

In the present study we investigated the effects of phenolic compounds present in Hypericum perforatum against neuronal excitotoxicity and mitochondrial dysfunction. Quercetin, kaempferol and biapigenin significantly reduced neuronal death caused by 100 microM kainate plus 100 microM N-methyl-D-aspartate. The observed neuroprotection was correlated with prevention of delayed calcium deregulation and with the maintenance of mitochondrial transmembrane electric potential. The three compounds were able to reduce mitochondrial lipid peroxidation and loss of mitochondrial transmembrane electric potential caused by oxidative stress induced by ADP plus iron. Moreover, biapigenin was also able to significantly affect mitochondrial bioenergetics and decrease the capacity of mitochondria to accumulate calcium. Taken together, the results suggest that the neuroprotective action induced by quercetin and kaempferol are mainly mediated by antioxidant effects, whereas biapigenin mainly affects mitochondrial bioenergetics and calcium uptake.

Esca is a destructive disease that affects vineyards leading to important losses in wine production. Information about the response of Vitis vinifera plants to this disease is scarce, particularly concerning changes in plant metabolism. In order to study the metabolic changes in Vitis plants affected by esca, leaves from both infected and non-affected cordons of V. vinifera cv. Alvarinho (collected in the Vinho Verde region, Portugal) were analysed. The metabolite composition of leaves from infected cordons with visible symptoms [diseased leaves (dl)] and from asymptomatic cordons [healthy leaves (hl)] was evaluated by 1D and 2D (1)H-nuclear magnetic resonance (NMR) spectroscopy. Principal component analysis (PCA) of the NMR spectra showed a clear separation between dl and hl leaves, indicating differential compound production due to the esca disease. NMR/PCA analysis allowed the identification of specific compounds characterizing each group, and the corresponding metabolic pathways are discussed. Altogether, the study revealed a significant increase of phenolic compounds in dl, compared with hl, accompanied by a decrease in carbohydrates, suggesting that dl are rerouting carbon and energy from primary to secondary metabolism. Other metabolic alterations detected comprised increased levels of methanol, alanine, and gamma-aminobutyric acid in dl, which might be the result of the activation of other defence mechanisms.

The regulatory issues for registration of herbal products are complicated among the countries and regions worldwide. The information summarised in the text is for reference only. Some regulations which are presented in this review are still in legislation process and may change in due course. Before taking any regulatory action, readers are advised to consult current official legislation and guidance and/or to seek appropriate professional advice. The lessons learnt from global regulation of TCM will provide valuable insights for regulation of other traditional medicine such as Ayurveda and Unani medicine, as well as other forms of indigenous medicine. The WHO is well placed to co-ordinate a consultation process with the aim of putting forward suggestions for harmonisation to key regulatory agencies.