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Long term infection of Helicobacter pylori (Hp) virulent strains is a key factor in the genesis of human gastric cancer, and so are certain dietary proinflammatory and genotoxic compounds. Carcinogenic bracken fern (Pteridium spp.) is one of these. Toxins from this plant are consumed as bracken culinary preparations, through milk and meat of bracken-exposed livestock, and drain waters from bracken swards. Bracken toxin ptaquiloside (PtQ), a suspected human carcinogen, elicits complex responses in animals leading to death. PtQ and Hp might cooperate in gastric pathologies. This paper presents an hypothesis on PtQ-Hp association leading to the enhancement of carcinogenesis in the human gastric environment that might explain the high gastric cancer incidence and death rates among Hp-infected people living in bracken zones at two levels: (1) The macroscopic scale comprising the flow of PtQ in the human diet. (2) the microscopic scale encompassing (A) gastric luminal medium; (B) gastric mucus structure and mucin degradation elicited by Hp; (C) bacterial pH gradient modification of the gastric mucosa that favors PtQ survival and its penetration into epithelial tissue; (D) combined PtQ/Hp effects on gastric immune and inflammatory responses; (E) PtQ-Hp complementary activity at selected cell signaling cascades and genome disturbance.

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Blakiella bartsiifolia (S.F. Blake), an endemic and rare high altitude plant of the northern Andes, appears well adapted to the prevailing harsh environment owing in part to a thick glandular trichome cover. From foliar exudates, two new clerodanes, 15,16-epoxy-2-hydroxy-3,13(16),14-clerodatrien-20-oic acid (bartsiifolic acid) (2) and Z-15,16-dihydroxy-3,13-clerodien-20-oic acid (barthydrolic acid) (3), were isolated in addition to the known junceic acid (1). In addition, three new alicyclic furanoditerpenes: 1,20-epoxy-1,3(20),6(E),10(E),14-phytapentaen-18-methyl-19-oic acid (blakielic acid) (4), 1,20-epoxy- 1,3(20),10(E),14-phytapentaen-18-methyl-19-oic acid (blakifolic acid) (5) and 1,20-epoxy-1,3(20),6,14-phytatetraen-19-methyl-18-oic acid (dihydrocentipedic acid) (6) were obtained in minor quantity. Seed germination and plantlet growth bioassays on Allium cepa and Lactuca sativa to monitor bioactivity during isolation procedures revealed compounds 1-3 with substantial inhibition comparable with synthetic linuron.

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INTRODUCTION: Bracken (Pteridium spp) illudane glycosidess are labile biologically active terpenoids that undergo decomposition in mild alkali or acid, heat and enzymatic reactions. Hypothetically, quantitation of these weakly chromophoric carcinogens may be challenged by plant sample preparation procedures that may alter the yield of isolates. OBJECTIVE: To study the influence of common plant sample pre-treatments on the recovery of Pteridium caudatum illudane glycoside carcinogens, ptaquiloside (1a), caudatoside (1c) and ptaquiloside Z (1d), and associated pterosins A, B and Z (2a, b, c) using HPLC-DAD. METHOD: Bracken fronds were divided in equal left/right sections. One section was subjected to high vacuum desiccation (VD) and the other to freeze-drying (FD), air drying at room temperature (AD) for 7 days, air drying at 70 °C for 72 h (HD), or no treatment (fresh frond, FF). Quantitation was achieved by brief hot-water extraction, base-acid transformation of 1a, 1c and 1d to 2a, b, c and HPLC-DAD analysis against standards. RESULTS: Substantial differences in extraction yields were found for all illudane glycosides in the order FF > FD ≈ VD > AD > HD. Illudane instability to HD was 1c > 1d > 1a. Significant losses also were recorded in yields of Pterosins A, B and Z. CONCLUSION: Glycoside extraction suffers from substantial yield loss of all illudane glycosides and indigenous pterosins in all sample pre-treatments studied relative to fresh frond material.

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El cáncer gástrico (CG) es el segundo en importancia entre varones en Venezuela y el tercero para hembras, con tasas muy variables según la región. Los cuatro estados del occidente venezolano presentan TAES (tasa de mortalidad ajustada para edad y sexo) estratificadas para la población de 35+ años de edad en el orden 13,3 (Zulia), 32,9 (Barinas) a 45,6 (Mérida) y 53,6 (Táchira), lo cual sugiere factores de propensión asociables al entorno montañoso. La proporción de CG frente al de otros órganos digestivos es más del doble en el territorio andino, (CG/colo-rectal en varones de 1,23; 3,91; 4,99 y 5,37 en esos estados, respectivamente). La distribución geográfica de TAES por distrito sanitario en el estado Mérida continuó siendo mayor en la zona andina que en el llano lacustre. El análisis de casos a nivel de localidad entre 1986 y 1999 permitió descubrir un conglomerado de CG en la zona suroeste del estado Mérida, limítrofe con Táchira, concentrado en la zona de Tovar y pueblos aledaños. Se sugieren posibles causales para investigación futura.

Gastric cancer (GC) is second in importance among males and third among females in Venezuela, with variable regional rates. Stratified GC age-sex standardized mortality (ASSM) rates truncated above 35 years age in the four western States were found to be 13.3 (Zulia), 32.9 (Barinas) a 45.6 (Merida) and 53.6 (Tachira), which suggests the occurrence of propensity factors associated to the mountain environment. The ratio of GC to other digestive organ tumors in the Andean states doubles the values of the lower territories. The GC/colo-rectal cancer ratio in males was 1.23; 3.91; 4.99 and 5.37, respectively. The geographical GC ASSM distribution per sanitary district in Mérida was also significantly greater for the mountain areas than for the lakeside plains. GC rate analysis at community levels (1995-1999) revealed a GC cluster limited to the south west portion of Merida State near the border with Tachira, around the town of Tovar and nearby villages. Some possible causes are suggested for further research.

O câncer gástrico (CG) é a segundo em importância entre os homens ea terceiro entre mulheres em Venezuela. Os quatro estados ocidentais mostram valores TAES (Tasas de mortalidade estandarizadas pra edade e sexo) de 13,3 (Zulia), 32,9 (Barinas), 45,6 (Mérida) e 53,6 (Táchira), sugerindo a existência de fatores de risco associados ao ambiente de montanha. O rácio de GC, em comparação com outros órgãos digestivos é mais do dobro nos Andes, ( CG / colo-retal em pacientes do sexo masculino de 1,23; 3,91; 4,99 e 5,37, respectivamente). A distribuição geográfica das TAES por Distrito Sanitário em Mérida manteve o padrão de mortalidade devido ao câncer gástrico mais elevadas na região andina em comparação com na planicie. A análise de casos nas aldeias entre 1986 e 1999 revelou um aglomerado de câncer gástrico em Tovar e suas aldeias circundantes, no sudoeste do estado de Mérida, adjacente ao Táchira. Algumas causas possíveis são sugeridas para futuras pesquisas.

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Three labdane diterpenes 15,16-epoxy-6-hydroxylabda-5,8,13(16),14-tretraen-7-one (leojaponin), (9alpha,13S);15,16-diepoxy-7beta-hydroxylabd-14-en-6-one (13-epi-preleoheterin), and (9alpha,13R);15,16-diepoxy-6beta-hydroxylabd-14-en-7-one (iso-preleoheterin) were isolated from the leaves of Leonurus japonicus, in addition to the previously reported preleoheterin. The structure elucidations were made based on analysis of their spectroscopic data.

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The time-dependent natural release of hydrogen cyanide (HCN) was studied quantitatively using young croziers of the neotropical bracken fern Pteridium arachnoideum. HCN production was quantified in crushed tissue using a flow reactor at 30.0 +/- 0.1 degrees C. Released HCN was carried into appropriate traps with a moist air flow. Aliquots were drawn from the traps at fixed time intervals, and the HCN concentration was evaluated spectroscopically. All available prunasin (Pru), the only cyanogenic glycoside present, underwent decomposition into HCN in less than 1200 min. Fiddleheads (N = 76) contained 1.84-107.70 mg Pru g(1) dw in a continuous fashion suggesting genetic polymorphism. Acyanogenic morphs were rare (1/77). From the kinetics of the samples with Pru content near the median histographic distribution (N = 46), accumulated HCN formation as a function of time, initial velocities, average HCN production rate, and corresponding rate equations were obtained. Initial and average velocities correlated well with total Pru content. The yield of cyanide liberation varied widely between 0.51 and 47.86 microg HCN min(-1) g(-1) dw and was a linear function of [Pru]t. However, the beta-glucosidase enzyme involved in this reaction was not rate limiting and occurs in excess in the natural system. Enzyme activity was found to be independent of [Pru]t. The contribution of HCN as an allomone-upon-request against herbivores was assessed quantitatively. Bracken fiddleheads produced a pulse of HCN soon after tissue injury that waned rapidly, leaving a large portion of intact prunasin to decompose more slowly in the herbivore's lumen. The balance between the external and internal courses was found to depend on the concentration of prunasin in the plant, the amount of crozier eaten, and the time used to consume it.

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The phagodepression activity of five furanocoumarins (FC), bergapten, xanthotoxin, psoralen, imperatorin, and angelicin, has been studied against larvae of Egyptian cotton leafworm Spodoptera littoralis (Boisduval) (Lepidoptera: Noctuidae) using a leaf-disk choice bioassay. The dose range used was 0-10 microg/cm2 for linear furocoumarins and 0-30 microg/cm2 for angelicin, the angular furanocoumarin. Dose-feeding deterrency activity correlations were governed by various sigmoidal functions, except in the case of imperatorin and bergapten, which had dose-response curves showing irregular traces with two maxima. All five FCs induced various degrees of phagodepression in S. littoralis; at 3 microg/cm2, the relative feeding deterrence was bergapten = xanthotoxin > psoralen = imperatorin = angelicin. Structure-activity correlations indicated that a methoxy group on C-5 or C-8 enhanced the activity. Comparison of experimental feeding deterrence of binary mixtures of imperatorin with xanthotoxin, bergapten, or psoralen at various relative concentrations with the calculated additive activity of each combination indicated that a proportion of 40% or more of imperatorin may exert a greater antifeedant effect on S. littoralis than the sum of individual compounds. The effect of angelicin also was examined in combination with psoralen, both of which are present in Psoralea plants. Their mixtures yielded a clear synergistic effect in the 20-80% angelicin range (coactivity coefficient = 124-133). By contrast, the effect of angelicin on xanthotoxin was only additive. In the dose-response curves of imperatorin/bergapten combinations, synergism was found at >60% imperatorin relative concentration and 1 microg/cm2, whereas lower proportions led to antagonism. The threshold between the two opposing effects was found to depend on the total FC concentration employed. Some natural systems contain FCs in the range of synergistic proportions recorded here and, thus, may have been produced by the host to increase its defensive effect at a lower metabolic cost.

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