Effects Of Secondary Metabolites Research Articles

The efficacy of polyherbal formulation of Moringa oleifera, Viola odorata, Allium sativum against microbes- synergistic effect

The purpose of our present study is to test antimicrobial and antifungal activity of polyherbal formulations. The testing of the antimicrobial activity on polyhernal formulation was done against gram positive (Staphylococcus aureus, Bacillus subtilis) and gram negative (Salmonella typhi, Escherichia coli,) bacteria. The testing of antifungal activity was done against Aspergillus niger and Candida albicans with different combinations of polyherbal formulation. The microorganism to be tested was grown in relevant nutritional media. The solvent used for the extraction of Moringa oleifera, Viola odorata, Allium sativum was methanol. These methanolic extracts of chosen plants were further used in specific proportions for the preparation of polyherbal formulation (PF-1, PF-2, and PF-3). The resultant compositions were further used to check the efficacy against selected experimental microorganisms. PF-3 showed the significant high zone of inhibition against all the experimental microorganisms as compared to the other two combinations PF-1 and PF-2. Thus, the result has revealed that the antimicrobial activity is due to the synergistic effect of secondary metabolites present in these selected plants.

Polyphenolic content and in vitro antioxidant evaluation of the stem bark extract of <i>Peltophorum africanum</i> sond (Fabaceae)

Background: Peltophorum africanum has been traditionally used to relief stress induced diseases. The study was aimed to evaluate the antioxidant activities of ethyl acetate extract.Material and methods: The in vitro antioxidant activities of Peltophorum africanum stem bark extract was examined in this study by means of +radical scavenging and ferric reducing power analysis using 2, 2-diphenyl-1-picrylhydrazyl (DPPH), 2, 2`-azino-bis (3-ethylbenzthiazoline-6- sulfonic acid (ABTS) kit, hydrogen peroxide (H2O2), iron (iii) chloride (Fe3+) and nitric oxide (NO). In assessing the likely effects of secondary metabolites on the activities observed; total proanthocyanidins, phenolics, flavonols, and flavonoids were determined using standard phytochemical methods. Data was analyzed by ANOVA test and the p-value < 0.05 was considered significant.Results: Extract scavenging activity of 88.73± 6.69 % (25 μg mL-1), 53.93±1.09 % (25 μg mL-1), 87.293±6.64 % (25 μg mL-1), 10.55±2.16 mM (0.42 mM) and 3.8115±0.06 (25 μg mL-1) were recorded for H2O2, NO, DPPH, ABTS and Fe3+ reducing power respectively. These values were comparable to the standard compounds; DBPC*BHT, L (+) - Ascorbic acid and Trolox™ (p < 0.05). Proanthocyanidins (92.18±4.68 mg/g) occurred more (p < 0.05) in the extract when compared to all other compounds tested: phenolics (60.53±1.46 mg/g) > flavonoids (18.37± 2.11 mg/g), > flavonols (11.20±3.90 mg/g). However the difference between flavonols and flavonoids was not significant (p > 0.05) at 95% confidence interval.Conclusion: The results of this study validated the folkloric use of P. africanum which could be exploited as an easily available and a cheaper source of natural antioxidants.Key words: Peltophorum africanum, antioxidant, phytochemicals, polyphenolics, radicals.

Efficiency assessment of the antifungal metabolites from Sclerotium cepivorum against onion white rot disease

The inhibitory effects of secondary metabolites of Sclerotium cepivorum against itself were studied both in vitro and in vivo. The highest inhibition of fungal growth and a 98.6 % reduction in the number of sclerotia was obtained with 50 % culture filtrate. No sclerotial germination was observed on media amended with culture filtrates at 10, 25 and 50 %. Methanol extract of mycelia and sclerotia, and ethyl acetate extract of culture filtrate both exhibited over 90 % inhibition of S. cepivorum growth at 1200 ppm. A chloroform extract of culture filtrate resulted in 71.1 % inhibition at 1200 ppm. All extracts completely suppressed the formation and germination of sclerotia at 400, 800 and 1200 ppm. In greenhouse experiments, no disease was observed with the ethyl acetate extract when onion seedlings were dipped in the extract for 4 or 8 h. The GC-MS analysis revealed 28 compounds in the methanol extract. The methanol extract contained mainly hexadecanoic acid methyl ester (31.16 %), whereas 5-hydroxymethylfurfural, HMF, (36.40 %) was the main constituent of the ethyl acetate extract. These results suggest that the secondary metabolites of S. cepivorum are potential and promising antifungal agents for the control of onion white rot. These results can be also applied to reduce the incidence and severity of other diseases in different crops.

In vitro antifungal activity and probable fungicidal mechanism of aqueous extract of Barleria grandiflora.

Barleria grandiflora Dalz. (Acanthaceae) is being used in India to treat different types of disorders including skin infections. Therefore, there are good possibilities to find antifungal compounds in its extracts with novel mechanism of action. The main objectives of the present study were to evaluate the antifungal activity of plant extracts and to study its effects on metabolic pathways of A. fumigatus. The microbroth dilution assay was used to explore antifungal activity and MIC of various extracts. Metabolic profiles of control and treated cultures were collected from Q-TOF-MS interfaced with HPLC. Affected metabolic pathways of A. fumigatus after the treatment were analyzed by discrimination analysis of mass data. Antifungal activities were observed in hot and cold water extracts of the plant. Hot water extract of B. grandiflora showed significant activity against tested fungi in the range 0.625-1.25 mg/mL. Partial least discrimination analysis revealed that the hot water plant extract downregulated amino acid, glyoxylate pathway, and methylcitrate pathways at the same time due to the synergistic effects of secondary metabolites. Hot water extract also downregulated several other metabolic pathways unique to fungi indicating its specific activity toward fungi. B. grandiflora showed promising antifungal activity which can further be exploited by identification of active compounds, to inhibit the specific fungal pathways and development of novel therapeutic antifungal drugs.

不同生境条件下核桃凋落叶次生代谢物质的差异及其分解初期对小白菜光合生理特性的影响

不同生境条件下核桃凋落叶次生代谢物质的差异及其分解初期对小白菜光合生理特性的影响

美洲黑杨凋落叶分解初期对小白菜生长的影响

A pot experiment was conducted to study the effects of secondary metabolites released by decomposing Populus deltoides leaf litter on the growth and physiology of Brassica chinensis.In the main test four leaf litter application levels was set as 0,30,60 and 90 g / pot(respectively denoted as CK,L30,L60 and L90).Meanwhile,in order to test whether the physical form of the leaf litter could obviously influence the soil aeration,water permeability and even the growth of B.chinensis,the parallel blank test was performed with the steamed leaf litter,and the design of the test was set as same as the main test,namely 0,30,60 and 90 g / pot steamed leaf litter treatments(denoted as Z30,Z60 and Z90).Each pot contained 7 kg soil mixed with P.deltoides leaf litter and then sowed the seeds of B.chinensis.The height and physiological indices of B.chinensis were determined on 50 th,80thd after sowing.The results showed that:1) The height and fresh weight of B.chinensis with high leaf litter addition(L90) of P.deltoides to the soil was significantly inhibited on 50 thd,afterwards,the growth gradually resumed to normal on 80 thd,while the height and fresh weight of B.chinensis in the other two treatments were markedly promoted consistently during the experimental period; 2) After 50 days of sowing,the net photosynthetic rate(Pn) of B.chinensis was largely improved under low(L30) and medium(L60) addition of leaf litterrelative to CK.As time went by,there were no obvious differences between all treatments and CK on 80 thd.The variation trends of pigment contents on 50 thand 80thday were substantially the same,both slightly lower than CK,yet,Chl a / b almost remained unchanged for all the time; 3) The activity of Superoxidedismutase(SOD) did not change apparently in low and medium addition of leaf litter,but increased in high addition from beginning to the end in this experiment; 4) The content of Malondialdehyde(MDA) on 50 thand 80thday did not show any conspicuous differences whether there was leaf litter in soil or not,and no matter how much leaf litter was added to the soil within the amount range of litter designed in this experiment.In summary,the impacts that different amount of P.deltoides leaf litter militated on B.chinensis illustrated that:low and medium amount treatments of P.deltoides leaf litter mixed in soil stimulated the growth of B.chinensis,on the contrary high amount inhibited the growth.Besides,the result of parallel blank test showed that there was no evident disparity in regard to the growth and physiological indexes of B.chinensis among the steamed leaf litter treatments.On the whole,low and medium addition of P.deltoides leaf litter to the soil was absolutely conducive to the growth and physiological metabolism of B.chinensis,however,the suppression of allelopathic effect was remarkable with high addition of leaf litter in its initial decomposition stage.

POLYPHENOLIC CONTENT AND IN VITRO ANTIOXIDANT EVALUATION OF THE STEM BARK EXTRACT OF PELTOPHORUM AFRICANUM SOND (FABACEAE)

Background: Peltophorum africanum has been traditionally used to relief stress induced diseases. The study was aimed to evaluate the antioxidant activities of ethyl acetate extract. 
 Material and methods: The in vitro antioxidant activities of Peltophorum africanum stem bark extract was examined in this study by means of +radical scavenging and ferric reducing power analysis using 2, 2-diphenyl-1-picrylhydrazyl (DPPH), 2, 2`-azino-bis (3-ethylbenzthiazoline-6-sulfonic acid (ABTS) kit, hydrogen peroxide (H2O2), iron (iii) chloride (Fe3+) and nitric oxide (NO). In assessing the likely effects of secondary metabolites on the activities observed; total proanthocyanidins, phenolics, flavonols, and flavonoids were determined using standard phytochemical methods. Data was analyzed by ANOVA test and the p-value < 0.05 was considered significant. 
 Results: Extract scavenging activity of 88.73± 6.69 % (25 µg mL-1), 53.93±1.09 % (25 µg mL-1), 87.293±6.64 % (25 µg mL-1), 10.55±2.16 mM (0.42 mM) and 3.8115±0.06 (25 µg mL-1) were recorded for H2O2, NO, DPPH, ABTS and Fe3+ reducing power respectively. These values were comparable to the standard compounds; DBPC*BHT, L (+) - Ascorbic acid and Trolox™ (p < 0.05). Proanthocyanidins (92.18±4.68 mg/g) occurred more (p < 0.05) in the extract when compared to all other compounds tested: phenolics (60.53±1.46 mg/g) > flavonoids (18.37± 2.11 mg/g), > flavonols (11.20±3.90 mg/g). However the difference between flavonols and flavonoids was not significant (p > 0.05) at 95% confidence interval.
 Conclusion: The results of this study validated the folkloric use of P. africanum which could be exploited as an easily available and a cheaper source of natural antioxidants.

Evidence for biological denitrification inhibition (BDI) by plant secondary metabolites.

Previous studies on the effect of secondary metabolites on the functioning of rhizosphere microbial communities have often focused on aspects of the nitrogen (N) cycle but have overlooked biological denitrification inhibition (BDI), which can affect plant N-nutrition. Here, we investigated the BDI by the compounds of Fallopia spp., an invasive weed shown to be associated with a low potential denitrification of the soil. Fallopia spp. extracts were characterized by chromatographic analysis and were used to test the BDI effects on the metabolic and respiratory activities of denitrifying bacteria, under aerobic and anaerobic (denitrification) conditions. The BDI of Fallopia spp. extracts was tested on a complex soil community by measuring denitrification enzyme activity (DEA), substrate induced respiration (SIR), as well as abundances of denitrifiers and total bacteria. In 15 strains of denitrifying bacteria, extracts led to a greater BDI (92%) than respiration inhibition (50%). Anaerobic metabolic activity reduction was correlated with catechin concentrations and the BDI was dose dependent. In soil, extracts reduced the DEA/SIR ratio without affecting the denitrifiers: total bacteria ratio. We show that secondary metabolite(s) from Fallopia spp. inhibit denitrification. This provides new insight into plant-soil interactions and improves our understanding of a plant's ability to shape microbial soil functioning.

Biocidal effect of lichen secondary metabolites against rock-dwelling microcolonial fungi, cyanobacteria and green algae

The use of commercial biocides in outdoor environments is increasingly discouraged because of their ecotoxicity, new methods being thus invoked to control patinas of biological origin on the stone cultural heritage. The effects of secondary metabolites (usnic acid, norstictic acid, parietin) produced by saxicolous lichens, natural competitors of rock dwelling microorganisms, were investigated in vitro against microcolonial fungi (MCF: Coniosporium apollinis, Coniosporium perforans, Coniosporium uncinatum, Phaeococcomyces-like sp.), coccoid cyanobacteria (Chroococcus minutus) and green algae (Scenedesmus ecornis) which commonly occur on stonework. An acetone/water 10/90 vol/vol mixture was screened as suitable to solubilise the lichen metabolites and to not affect the bioassay results. Benzalkonium chloride 1% was used as positive control.All the three metabolites (approx. 10−2 mM) inhibited the growth of the assayed MCF species, displaying the same effect of benzalkonium chloride. Chroococcus and Scenedesmus exhibited sensibility to the lichen metabolites when exposed to high incubation temperatures (35 °C), chemicals and temperature synergically yielding percentage decreases of intact cells with red chlorophyll epifluorescence. These findings suggest lichen secondary metabolites as allelopathic agents against rock dwelling microorganisms and as potential natural sources for their control on stone materials in restoration and conservation programmes. In this perspective, the detection of a negligible chromatic alteration (ΔE<0.5) caused by LSM to the white Carrara marble is reported as the first step of the necessary extensive evaluation of the LSM-stone material interactions.

URUGUAYAN NATIVE FRUITS PROVIDE ANTIOXIDANT PHYTONUTRIENTS AND POTENTIAL HEALTH BENEFITS

Consumer awareness about health beneficial effects of secondary metabolites from fruits has increased interest in fruits with high levels of these compounds. Globally, non-traditional fruits are generating growing interest for their nutraceutical potential. Uruguay is a primary center of origin of several species of fruits with unique flavor, aroma, appearance and nutritional properties. Those traits have led to their domestication and development as commercial crops. Involved species Guayabo del Pais (Acca selowiana (Berg.) Burret); Pitanga (Eugenia uniflora L.); Araza (Psidium cattleianum Wis) and Guaviyu (Myrcianthes pungens (Berg) Legr.) belong to the family Myrtaceae. The objective of this work was to evaluate total polyphenol (TP) content, total anthocyanins (TA) and the free radical scavenging activity (antioxidant capacity, AC) of native fruits in regard to nutraceutical potential. Guaviyu showed a range between 158-349 mg TP /100 g fresh weight; 19-75 of AC; 51-132 mg anthocyanins/100 g fresh weight. Values for Pitanga were 252-575 mg TP/100 g; 14-34 AC; 83-110 mg of TA. Araza gave values ranging between 132-644 mg of TP/100 g; 33-68 of AC and 12-17 mg of TA. Guayabo del Pais showed a range of 129-648 mg of TP/100 g and 24-82 for the AC. This study indicated that Uruguayan native fruits have potential as valuable sources of antioxidant components. Data illustrated interesting variability both at the intra-species level as well as among different species under study, indicating a significant input for the breeding of commercial cultivars derived from native Uruguayan germplasm.

Anatomy and morphology of Nicotiana glauca with regard to its crystals characterization.

Nicotiana glauca belongs to the Solanacese family of which Nicotiana tabacumand Nicotiana rustica are best known for their use as tobacco. N. glauca attains the greatest abundance and diversity in Central Argentina where it is considered native, and has been known as a weed in South Africa since the 19th Century. Extensive work on toxic effect of secondary metabolites extracted from this plant was conducted but their sources of origin and structure were not known. The leaves of N. glauca were characterized by the presence of solitary crystals and crystal-sand which originated from the cytosol and vacuoles. The presence of the compact tissues, isobilateral leaf with thick-cuticular epidermis and abundant crystals was assumed to be of ecological importance as this species appeared to be adapted to the xeromorphic habitats. Key words: Anatomy, morphology, crystals in Nicotiana glauca.

Effect of secondary metabolites on gall fly infestation of mango leaves

AbstractThe mango gall fly (Procontarinia) is a growing concern in many countries that import mango trees. Mangoes flush (produce opening buds) twice a year: once in spring, and the main flush, which occurs in early autumn flush and corresponds to the photoperiod necessary for the gall fly to emerge. Gall flies attack only very young mango flush leaves. Three cultivars displaying varying susceptibility were used in this study: Heidi, which typically is heavily infected; Keitt, which displays antixenosis properties; and Sensation, which is resistant to gall fly attack. Headspace profiles of the three cultivars were obtained over two full growing seasons. It was found that flush leaves emit higher levels of volatile organic compounds than mature leaves. Volatile emissions peaked during the main flush, after which they declined as the tree went into the winter dormant period. The levels of α‐ and β‐pinene increased in gall fly‐susceptible cultivars as the season progressed, while very low levels of these terpenes were emitted by resistant cultivars. The changes in the profiles of these emissions suggest that α‐ and β‐pinene may be linked to gall fly susceptibility. In addition, chemometric analysis confirmed the correlation between volatile emissions and gall fly susceptibility. Copyright © 2010 John Wiley &amp; Sons, Ltd.

Use of the in vitro model for studying the effects of secondary metabolites produced by indoor fungi

Use of the in vitro model for studying the effects of secondary metabolites produced by indoor fungi

Effects of secondary metabolites produced by indoor fungi on isolated lung cells

Effects of secondary metabolites produced by indoor fungi on isolated lung cells

Genome size in Dahlia Cav. (Asteraceae–Coreopsideae)

The genus Dahlia (Asteraceae–Coreopsideae) is monophyletic according to a recent DNA phylogeny (ETS and ITS of rDNA). Traditionally, the genus has been divided into sections, but these have been shown not to be monophyletic. We have studied variation in genome size (DNA C-values) in a sample of species to investigate the possible effects of secondary metabolites on flow cytometry and Feulgen densitometry, and to see whether genome size variation has any systematic or phylogenetic significance. Using a range of cultivars, secondary compounds from corollas were shown to have only minor effects on the Feulgen method; the floral pigments were found to be relatively inert and seemed to have been extracted on fixation with acetic methanol. Freshly expanded corollas showed apparent apoptotic DNA decay in epidermal cells, so need to be used with caution. Flow cytometric measurements with propidium iodide in some cultivars resulted in a very similar average genome size (2C = 8.62 pg) as compared with Feulgen densitometry (2C = 8.84 pg). Leaf cytosol of D. variabilis has a demonstrable inhibitory effect on propidium iodide fluorescence, which may explain some of the intraspecific variation of C-values observed. DNA 2C-values ranged from 3.30 pg in D. dissecta (2n = 34) to 9.62 pg in a D. variabilis cultivar (2n = 64). The D. variabilis cultivars had broadly similar C-values showing a 1.16-fold range between cultivars. Some of this variation probably results from technical variables and the extent of genuine variation is uncertain. The highest 2Cx-value occurred in one D. coccinea accession (2.47 pg, 2n = 32; x = 8). D. coccinea with 2n = 64 showed slightly reduced Cx-values compared to D. coccinea with 2n = 32. Artificially produced interspecific hybrids had C-values that corresponded closely with expectations from the measured values obtained from their parents.

Effects of cyanobacterium Fischerella ambigua isolates and cell free culture media on zebrafish ( Danio rerio) embryo development

The toxic effects of several species of fresh water cyanobacteria, notably Microcystis species and associated toxins, the microcystins, Anabaena species (anatoxin), Nodularia sp. (nodularin), and Cylindrospermopsis raciborskii (cylindrospermopsin), are well known. Little, however, is known about the effects of secondary metabolites other than alkaloids. Early life stage tests with zebrafish ( Danio rerio) were used to detect bioactive properties of compounds released by healthy cyanobacteria ( Fischerella ambigua), particularly on the early developmental stages of fish. This approach, using F. ambigua is probably most valuable as it shows the toxicity of healthy growing cyanobacteria. The effects of cyanobacterial secondary metabolites on the embryonic stages of fish are of considerable interest as many aquatic creatures, particularly fish, are unable to avoid the potential toxins that may be released by undesirable algal blooms or as a result of allelopathic effects. In the current study, the zebrafish ( D. rerio) was used as a model experimental system to investigate the effects of ambigols A and C, tjipanazole D and C, 2,4-dichlorobenzoic acid, cell free culture media, and media extracts of a terrestrial/fresh water strain of the cyanobacterium F. ambigua on embryo development. Fish embryo tests performed with the cell free culture medium showed that after 3 h of exposure to undiluted culture medium all fish embryos died. At a tenfold dilution the process of epiboly (formation of the gastrula) was retarded in all embryos, lesions were observed, and their general development was significantly arrested, finally followed by death. The same tests performed with extracts (dichloromethane, n-butanol, and residual cell free culture medium) of the cell free culture medium, ambigol A, ambigol C, 2,4-dichlorobenzoic acid and tjipanazole D showed only ambigol A to have an influence on zebrafish development at concentrations ≥1 mg/l (2.06 μM). After 55 h all embryos showed pectoral oedema, irregularly shaped fin folds, bent tails, and unusual circular neoplasms in the dorsal tail fin fold. Due to the high concentration of ambigol A used in this assay these effects were considered to be of minor importance when compared to those of the culture medium.

PREY NUTRITIONAL QUALITY INTERACTS WITH CHEMICAL DEFENSES TO AFFECT CONSUMER FEEDING AND FITNESS

Numerous studies have assessed the individual effects of prey nutritional quality or chemical defenses on consumer feeding behavior. However, little is known about how these traits interact to affect consumer feeding and performance. We tested the separate and interactive effects of prey chemical defenses and nutritional quality on the feeding behavior and fitness of six sympatric crustacean mesograzers. Natural concentrations of diterpene alcohols (dictyols) from the brown alga Dictyota menstrualis were incorporated, or not incorporated, into lower quality and higher quality foods to create artificial diets mimicking prey of variable value and defense. Five amphipods (Ampithoe longimana, A. valida, Cymadusa compta, Gammarus mucronatus, and Elasmopus levis) and one isopod (Paracerceis caudata), representing a continuum of closely to distantly related organisms, were fed intact algae or lower and higher quality diets containing or lacking dictyols. All six mesograzers preferred the green alga Enteromorpha intestinalis to the dictyol producing alga Dictyota menstrualis. In assays allowing consumers to choose between simultaneously available foods, dictyols deterred feeding by all five amphipods, but not the isopod; this occurred for both lower and higher quality foods. In no-choice assays, where consumers were confined with only one of our four treatment diets, effects on feeding became more complex. Nutritional quality alone affected feeding by five of the six species. These grazers compensated for lower quality by increasing consumption. Dictyols suppressed feeding for four of the six species. More interestingly, there were significant dictyol × quality interactions for three species. Dictyols decreased feeding more when placed in lower quality foods than higher quality foods. Two amphipods deterred by dictyols in the choice assays readily consumed dictyol-containing foods in no-choice situations and suffered few negative effects of doing so. Although all amphipods were deterred by dictyols in choice assays, dictyols decreased fitness (survivorship, growth, or reproduction) for only four of the five species. These effects included large and immediate decreases in survivorship, dramatic effects on reproduction, and modest effects on female growth. Dictyols enhanced survivorship of the isopod. Thus, the effects of secondary metabolites on feeding in choice situations vs. fitness in long-term assays were inconsistent. For three amphipods, certain effects of food quality, dictyols, or their interaction were detected only for females. In general, negative effects of dictyols on fitness were greater in lower than in higher quality foods, suggesting that prey nutritional value may counteract the effects of defensive metabolites. For example, when G. mucronatus consumed dictyols in lower quality foods, mortality was >80% by day 5; for dictyols in higher quality foods, 80% mortality took 28 days to develop. Lower quality foods alone significantly decreased growth for the isopod, three of the amphipods, and the females of a fourth amphipod, concomitantly reducing fecundity for four of the five amphipods studied. The effects of both chemical defenses and nutritional quality were unrelated to consumer phylogeny; responses of congeners varied as much, or more, than responses of more distantly related consumers. Understanding mechanisms and consequences of food selection requires that the interactive effects of both chemical defenses and prey nutritional characteristics be considered explicitly. Corresponding Editor: J. D. Witman.

Assessment of chemical resistance of wild and cultivated Vigna species to the brown pod‐bug Clavigralla tomentosicollis Stal (Hem., Coreidae)

Abstract:The effects of secondary metabolites in different Vigna species on the development of Clavigralla tomentosicollis were investigated in an artificial seed system using different fractions of crude pod extracts, while the orientation response of this pod‐bug to volatile extracts was studied using a dual‐choice olfactometer. Feeding on the neutral fraction extracts, in contrast to the basic and acidic fractions, resulted in significantly higher mortalities, longer total developmental time, and lower growth index of the insects in comparison with controls. All volatile extracts elicited an avoidance reaction by C. tomentosicollis, except the volatile from the susceptible genotype IT84S‐2246 which generally attracted as many insects as controls. Extracts from wild Vigna species showed higher activity than those from their cultivated relatives. The present study which has established that most secondary metabolites in cowpea pods were localized in the neutral fraction of the crude extract, could facilitate experiments on the separation and characterization of the toxic factors involved.

Effects of secondary metabolites from the tropical Brazilian brown alga Dictyota menstrualis on the amphipod Parhyale hawaiensis

Diterpene metabolites produced by Dictyota species are known to inhibit feeding by several herbivorous species. We present the first evidence of feeding-deterrence of dictyotacean metabolites of an unusual compound belonging to a dichotomane diterpene skeleton type. Through experimental assay, we provide evidence of feeding-deterrent properties of lipid-soluble extracts of the Brazilian brown alga D. menstrualis (Hoyt) Schnetter, Hornig & Weber-Peukert against the amphipod Parhyale hawaiensis Dana. Bioassay fractionation of this extract revealed the deterrent activity to be due to the diterpenoid (6R)-6-hydroxydichotoma-3,14-diene-1,17-dial, which was found to be the second most abundant metabolite (~0.2% dry mass) in D. menstrualis. In contrast to other studies, the major diterpenoid pachydictyol A, present as 0.4% (dry mass) in D. menstrualis, showed no anti-feeding properties. Our results suggest that chemical defense of Dictyota species may vary according to geographic region, thus explaining the presence of a metabolite other than pachydictyol A which functions as the anti-feedant metabolite in D. menstrualis from the Brazilian littoral zone.

Acquired salivary dysfunction. Drugs and radiation.

When considering the effects of drugs on salivary glands, a distinction should be drawn between the complaint of oral dryness (xerostomia), a symptom, and measurable secretory hypofunction, a sign. In general, the symptom of xerostomia is often not accompanied by objective reductions in salivary output, and xerostomia is not a reliable indicator of secretory hypofunction. Whereas therapeutic pharmaceutical side effects represent the most prominent cause of xerostomia, with over 500 drugs associated with this symptom, only a small number of drugs have been demonstrated to reduce salivary output substantially. There are examples in which drugs with a high prevalence of xerostomia complaints do not affect secretory function. The mechanisms responsible for this discrepancy between subjective and objective findings have not been fully identified. It is hypothesized that alterations in systemic or mucosal hydration may play a role. Of the drugs with true salivary hypofunctional actions, most have direct anticholinergic properties. In almost all cases, the salivary effects of pharmaceuticals are not permanent, and function returns to pretreatment levels when the medication is stopped. By contrast, the effects of irradiation on the salivary glands are permanent when exposures exceed 50 Gy. About 40,000 individuals per year receive irradiation that involves the salivary glands (by external beam or internal sources--radon implants and 1311) for treatment of cancers of the head and neck region. Although these radiation effects have been recognized as a significant clinical problem for more than 80 years, the specific mechanisms responsible for radiation-induced salivary gland dysfunction are still not understood. With the exception of studies documenting the secretory functional deficits following head and neck irradiation, limited studies have been done in humans. The majority of experimental work has been done in rodents. A variety of mechanisms, including mitotic and interphase cell death, direct DNA damage or effects of secondary metabolites, damage to progenitor cells, or altered gene expression, have all been proposed to explain the salivary epithelial cell death observed. Recent experimental studies with models of radiation-induced salivary damage in rats and a human salivary cell line suggest that the small percentage of surviving epithelial cells are capable of performing functions such as signal transduction and ion transport normally. Apoptotic cell death following irradiation has not been a prominent feature in these model systems. The effects of head and neck radiation on the salivary glands and oral cavity continue to present multiple significant clinical problems both during and after radiotherapy. In recent years, there has been some progress in minimizing these effects through more careful shielding and pretreatment planning. Additionally, there are preliminary results from a clinical trial suggesting that the use of a secretagogue, pilocarpine HCl, given during the course of radiotherapy, may reduce the secretory hypofunctional effects. A multicenter trial is now underway to test this hypothesis. There is still a real need to develop more effective treatments for this condition.