Phytochemical Study of Safflower Roots (Carthamus tinctorius) on the Induction of Parasitic Plant Germination and Weed Control.

Weeds have been a major threat in agriculture for several generations as they lead to decreases in productivity and cause significant economic losses. Parasitic plants are a specific type of weed causing losses in crops of great relevance. A new strategy has emerged in the fight against parasitic plants, which is called 'suicidal germination' or the 'honey-pot strategy'. Regarding the problem of weed control from an ecological point of view, it is interesting to investigate new natural compounds with allelopathic activity with the aim of developing new natural herbicides that can inhibit the growth of weeds without damaging the environment. Safflower crops have been affected by parasitic plants and weeds and, as a consequence, the secondary metabolites exuded by safflower roots have been studied. The sesquiterpene lactone dehydrocostuslactone was isolated and characterised, and the structurally related costunolide was identified by UHPLC-MS/MS in safflower root exudates. These sesquiterpene lactones have been shown to stimulate germination of Phelipanche ramosa and Orobanche cumana seeds. In addition, these compounds were phytotoxic on three important weeds in agriculture, namely Lolium perenne, Lolium rigidum and Echinochloa crus-galli. The exudation of the strigolactones solanacol and fabacyl acetate have also been confirmed by UHPLC-MS/MS. The study reported here contributes to our knowledge of the ecological role played by some secondary metabolites. Moreover, this knowledge could help identify new models for the development of future agrochemicals based on natural products.

Biological properties and pharmacological potential of plant exudates.

Exudates released from plants, consist of complex mixtures of organic and inorganic molecules that have been used in traditional medicine from several years. They may vary among genera, species or within a genus and mainly include latex, sap, gums, resins, seed or root exudates. Plant exudates are known to possess several biological activities including, antimicrobial, anti-inflammatory, antioxidant, wound healing and anti-nociceptive. Exudates oozed out from plants have also been used as ingredients in medicines, food, perfumes and cosmetics. The present review provides brief overview about the exudates released from plants, their biological properties and beneficial effects for human beings. Due to the presence of various compounds, different methodologies and procedures have been employed for their collection and analyses. Literature studies suggest that plant exudates have extensive therapeutic potential for curing diseases with minimal toxic effects. This aspect could be taken into account in prospective studies regarding the search of new products derived from plant exudates with pharmaceutical value.

Phytotoxic allelochemicals from roots and root exudates of Trifolium pratense.

Trifolium pratense, a widespread legume forage plant, is reported to exhibit phytotoxic activity on other plants, but the active metabolites have not been clarified so far. A bioassay-guided fractionation of the root extracts led to the isolation of five isoflavonoids, which were elucidated by spectroscopic analysis. All of the purified compounds observably showed phytotoxic activities against Arabidopsis thaliana . Moreover, the inhibitory effects were concentration-dependent. The furan ring linked at C-4 and C-2' positions by an oxygen atom and a 1,3-dioxolane at C-4' and C-5' positions are considered to be critical factors for the phytotoxic activity. The concentrations of (6aR,11aR)-maackiain and (6aR,11aR)-trifolirhizin, concluded to be allelochemicals from soil around plants of T. pratense, were determined by HPLC and LC-MS to be 4.12 and 2.37 µg/g, respectively. These allelochemicals, which showed remarkable activities against the weed Poa annua may play an important role in assisting the widespread occurrence of T. pratense in nature.

Cytotoxic and anti-angiogenic properties of minor 3,4-seco-cycloartanes from Gardenia sootepensis exudate.

Gardenia plants have long been used as traditional medicines in various countries including Thailand. In this study, two new 3,4-seco-cycloartane triterpenes, sootependial (1) and sootepenoic acid (2), were isolated from bud exudate of G. sootepensis, together with five known compounds. Their structures were elucidated on the basis of spectroscopic data. Sootependial (1) showed potent cytotoxicity selective to Hep-G2 cell lines and anti-angiogenic activity in ex vivo model (a rat aortic ring sprouting) assay. Furthermore, its angiogenic effect was found to occur mainly by suppressing endothelial cell proliferation and tubule formation, suggesting the potential of 1 as a lead compound for cancer treatment.

Discovery of a new source of resistance to Fusarium oxysporum, cause of Fusarium wilt in Allium fistulosum, located on chromosome 2 of Allium cepa Aggregatum group.

This study was carried out to evaluate the antifungal effect of Allium cepa Aggregatum group (shallot) metabolites on Fusarium oxysporum and to determine the shallot chromosome(s) related to Fusarium wilt resistance using a complete set of eight Allium fistulosum - shallot monosomic addition lines. The antifungal effects of hexane, butanol, and water extraction fractions from bulbs of shallot on 35 isolates of F. oxysporum were examined using the disc diffusion method. Only hexane and butanol fractions showed high antifungal activity. Shallot showed no symptom of disease after inoculation with F. oxysporum f. sp. cepae. The phenolic content of the roots and the saponin content of root exudates of inoculated shallot increased to much higher levels than those of the control at 3 days after inoculation. Application of freeze-dried shallot root exudates to seeds of A. fistulosum soaked in a spore suspension of F. oxysporum resulted in protection of seedlings against infection. Among eight monosomic addition lines and A. fistulosum, FF+2A showed the highest resistance to Fusarium wilt. This monosomic addition line also showed a specific saponin band derived from shallot on the thin layer chromatography profile of saponins in the eight monosomic addition lines. The chromosome 2A of shallot might possess some of the genes related to Fusarium wilt resistance.

The ethanolic extract of Kaempferia parviflora reduces ischaemic injury in rat isolated hearts.

AIMS OF THE STUDY: The ethanolic extract of Kaempferia parviflora (KPE) has been reported to contain a range of flavonoids and to enhance endothelial synthesis of NO. We investigated the vascular relaxant, antioxidant and cardioprotective activities of KPE. MATERIALS AND METHODS: Vascular function was assessed in rat aortic rings and superoxide generation determined using lucigenin enhanced chemiluminescence. Ischaemia and reperfusion were induced in rat isolated, perfused hearts. RESULTS: KPE caused vasorelaxation (R(max) 102 ± 2%), which was partly inhibited by removal of the endothelium (R(max) 91 ± 1%) or by N(G)-nitro-l-arginine (L-NNA, R(max) 83 ± 3%) or 1H-[1,2,4] oxadiazolo[4,3-a]quinoxaline-1-one (ODQ, R(max) 80 ± 2%). In addition KPE caused concentration-dependent inhibition of the contractile response to exogenous Ca(2+). KPE (10(-3)M) also significantly inhibited superoxide radical generation induced by of xanthine/xanthine oxidase (2.3 ± 0.4% of control) to a similar extent to the xanthine oxidase inhibitor allopurinol (10(-4)M, 1.6 ± 0.5%) or by rat isolated aorta in the presence of NADPH (30.0 ± 6.3% of control) similarly to the NADPH oxidase inhibitor diphenyliodonium (5 × 10(-6)M, 23.1 ± 5.6%). In the presence of oxidant stress generated by pyrogallol endothelium-dependent relaxation of rat aortic rings was impaired (ACh R(max) control 99 ± 1%; pyrogallol 44 ± 5%), an effect that was significantly reduced by KPE (10(-4)M, ACh R(max) 82 ± 4%). In addition, KPE was found to attenuate the ventricular dysfunction caused by 20 min global ischaemia and 30 min reperfusion (I/R) in rat isolated hearts (dP/dt IR 1016 ± 242, IR+KPE 2238±233 mm Hg/s). CONCLUSION: KPE is an effective vasodilator and antioxidant that is able to prevent myocardial ischaemia-reperfusion injury. We suggest that KPE may be useful as an adjunct to thrombolytic therapy in the management of reperfusion injury.

Quantitation of chafurosides A and B in tea leaves and isolation of prechafurosides A and B from oolong tea leaves.

A procedure was developed for the quantitative determination of chafuroside A, a flavone C-glycoside with potent anti-inflammatory activity, and its regioisomer chafuroside B, as well as isovitexin and vitexin, by selected reaction monitoring liquid chromatography-tandem mass spectrometry (SRM LC-MS/MS) analysis. This method was successfully applied to commercial leaves of green tea, houji tea, oolong tea, and black tea. High levels of chafurosides A and B were found in oolong tea leaves that had been heated at >140 degrees C. Next, their precursors, prechafurosides A and B, were isolated from methanol extract of oolong tea leaves prepared from Shizu 7132, Camellia sinensis (L.) O. Kuntze, by partition with n-butanol and H2O and chromatography on Diaion SP-825, Sephadex LH-20, and ODS C-18, guided by assay of chafuroside formation. Prechafurosides A and B gave chafurosides A and B, respectively, in good yields when heated at 160 degrees C for 0.5 h. Solvolysis of prechafurosides A and B with pyridine and dioxane quantitatively afforded isovitexin and vitexin, respectively. On the basis of these results and physicochemical data (MS, UV, and NMR), prechafurosides A and B were concluded to be new flavone C-glycoside sulfates, isovitexin-2''-sulfate and vitexin-2''-sulfate, respectively.