Bioherbicide Potential of Eucalyptus saligna Leaf Litter Essential Oil

We aimed to evaluate the bioherbicide potential of Eucalyptus saligna leaf litter essential oil, its fractions and major compounds. Six essential oil fractions were obtained by preparative thin‐layer chromatography and analyzed by gas chromatography/mass spectrometry. Effects of the oil, its fractions and major compounds (1,8‐cineole and/or α‐pinene) diluted in aqueous solution were assessed on germination and seedling growth. Recipient species were Lactuca sativa (model), Amaranthus viridis (weed), Eragrostis plana (weed), and Paspalum notatum (forage). The essential oil was more phytotoxic on A. viridis and L. sativa, followed by E. plana, and caused no effects on P. notatum. Amaranthus viridis was inhibited by all treatments, mainly the essential oil, α‐pinene and fraction 6, whereas E. plana was more affected by the oil fractions. Results revealed the species‐specific phytotoxic effects of E. saligna essential oil, indicating its potential use for controlling A. viridis and E. plana. Phytotoxic effects of essential oils or their components should not be generalized, as effects may change according to recipient species.     

Herbicidal and Cytotoxic Constituents from Aralia armata (Wall.) Seem.

Two new triterpenoids, 3β‐hydroxyoleana‐11,13(18)‐diene‐28,30‐dioic acid ( 1 ) and 3‐oxooleana‐11,13(18)‐diene‐28,30‐dioic acid ( 2 ), one novel triterpenoid glycoside, 3β‐O‐(6′‐O‐methyl‐β‐d‐ glucuronopyranosyl)oleana‐11,13(18)‐dien‐28‐oic acid ( 3 ) along with six known compounds ( 4  –  9 ) were isolated from the stem bark of Aralia armata (Wall .) Seem . Their structures were elucidated through extensive spectroscopic methods. The herbicidal activities of these compounds against Bidens pilosa L., an invasive weed in P. R. China, were evaluated. Compounds 3 , 5, and 6 exhibited more significant herbicidal activities on B. pilosa than the positive‐control pendimethalin. Their possible use as herbicidal chemicals or model compounds deserved more attention. The effects of compounds 1  –  9 on Spodoptera litura cultured cell line Sl‐1 cell proliferation and its morphology were also evaluated. The results indicated that compounds 1  –  5 affected Sl‐1 cell proliferation. Compound 3 showed more obvious proliferation inhibition activities on Sl‐1 cell than the positive‐control rotenone. With regard to the effect on morphology, compound 2 significantly changed Sl‐1 cell, resulting in cell blebbing and vacuole forming. Triterpenoids aremedicinally and agriculturally important, and cytotoxicity of the three new compounds 1  –  3 deserved further studies.     

Wine phenolic compounds influence the production of volatile phenols by wine-related lactic acid bacteria

Aims: To evaluate the effect of wine phenolic compounds on the production of volatile phenols (4‐vinylphenol [4VP] and 4‐ethylphenol [4EP]) from the metabolism of p‐coumaric acid by lactic acid bacteria (LAB). Methods and Results: Lactobacillus plantarum, Lactobacillus collinoides and Pediococcus pentosaceus were grown in MRS medium supplemented with p‐coumaric acid, in the presence of different phenolic compounds: nonflavonoids (hydroxycinnamic and benzoic acids) and flavonoids (flavonols and flavanols). The inducibility of the enzymes involved in the p‐coumaric acid metabolism was studied in resting cells. The hydroxycinnamic acids tested stimulated the capacity of LAB to synthesize volatile phenols. Growth in the presence of hydroxycinnamic acids, especially caffeic acid, induced the production of 4VP by resting cells. The hydroxybenzoic acids did not significantly affect the behaviour of the studied strains. Some of the flavonoids showed an effect on the production of volatile phenols, although strongly dependent on the bacterial species. Relatively high concentrations (1 g l^?1) of tannins inhibited the synthesis of 4VP by Lact. plantarum. Conclusions: Hydroxycinnamic acids were the main compounds stimulating the production of volatile phenols by LAB. The results suggest that caffeic and ferulic acids induce the synthesis of the cinnamate decarboxylase involved in the metabolism of p‐coumaric acid. On the other hand, tannins exert an inhibitory effect. Significance and Impact of the Study: This study highlights the capacity of LAB to produce volatile phenols and that this activity is markedly influenced by the phenolic composition of the medium.     

Changes in Cell Wall-bound Phenolic Compounds and Lignin in Roots of Date Palm Cultivars Differing in Susceptibility to Fusarium oxysporum f. sp. albedinis

The roots of date palm contain four cell wall‐bound phenolic acids identified as p‐hydroxybenzoic, p‐coumaric, ferulic and sinapic acids. The ferulic acid represents the major phenolic compound since it constitutes 48.2–55.8% of cell wall‐bound phenolic acids. All these phenolic acids were present in the resistant cultivar (BSTN) and the susceptible cultivar (JHL). However, the pre‐infection contents of p‐coumaric, ferulic and sinapic acids were greater in the resistant cultivar than in the susceptible one. For the contents of p‐hydroxybenzoic acid, there was no significant difference between the resistant cultivar and the susceptible cultivar. Similarly, the pre‐infection contents of lignin were approximately equal for both cultivars. Inoculation of the date palm roots by Fusarium oxysporum f. sp. albedinis induced important modifications to the contents of the cell wall‐bound phenolic compounds and lignin, which made it possible to distinguish between resistant and susceptible cultivars. The post‐infection contents of cell wall‐bound phenolic compounds underwent a rapid and intense increase with a maximum accumulation on the tenth day for p‐hydroxybenzoic acid (1.54 μmol/g), p‐coumaric acid (2.77 μmol/g) and ferulic acid (2.64 μmol/g) and on the fifteenth day for sinapic acid (1.85 μmol/g). The maximum contents accumulated in the resistant cultivar were greater than those in the susceptible cultivar, namely, 11 times for p‐hydroxybenzoic acid, 2.6 times for p‐coumaric acid, 1.8 times for ferulic acid and 12.3 times for sinapic acid. In the susceptible cultivar, p‐coumaric acid and ferulic acid contents also increased after inoculation although they did not reach the pre‐infection contents of the resistant cultivar. The contents of p‐hydroxybenzoic acid in the susceptible cultivar roots did not present post‐infection modification and those of sinapic acid decreased instead. The lignin contents increased in both cultivars with a maximum accumulation on the fifteenth day. However, the maximum contents accumulated in the resistant cultivar roots were 1.5 times greater than those of the susceptible cultivar. These results showed clear differences between the resistant BSTN and the susceptible JHL cultivars. The implication of cell wall‐bound phenolic compounds and lignin in the resistance of date palm to F. oxysporum f. sp. albedinis appears to be dependent on the speed and intensity of their accumulation with greater contents in the first stage of infection.     

Genome‐wide identification of tolerance mechanisms toward p‐coumaric acid in Pseudomonas putida

The soil bacterium Pseudomonas putida KT2440 has gained increasing biotechnological interest due to its ability to tolerate different types of stress. Here, the tolerance of P. putida KT2440 toward eleven toxic chemical compounds was investigated. P. putida was found to be significantly more tolerant toward three of the eleven compounds when compared to Escherichia coli. Increased tolerance was for example found toward p‐coumaric acid, an interesting precursor for polymerization with a significant industrial relevance. The tolerance mechanism was therefore investigated using the genome‐wide approach, Tn‐seq. Libraries containing a large number of miniTn5‐Km transposon insertion mutants were grown in the presence and absence of p‐coumaric acid, and the enrichment or depletion of mutants was quantified by high‐throughput sequencing. Several genes, including the ABC transporter Ttg2ABC and the cytochrome c maturation system (ccm), were identified to play an important role in the tolerance toward p‐coumaric acid of this bacterium. Most of the identified genes were involved in membrane stability, suggesting that tolerance toward p‐coumaric acid is related to transport and membrane integrity.

     

Enhanced production of the pharmaceutically important polyphenolic compounds in Vitex agnus castus L. shoot cultures by precursor feeding strategy

Agitated Vitex agnus castus L. shoot cultures were established to analyse the content of selected pharmaceutically important flavonoids and phenolic acids. Two variants (selected from nine ones) of MS medium were prepared: A (BAP 1 mg/L; NAA 0.5 mg/L; GA₃ 0.25 mg/L) and B (BAP 2 mg/L; NAA 0.5 mg/L). The biomass was harvested after 1, 2, 3,4, 5 and 6 weeks. Four‐week cultures (variant A) were selected to perform the precursor feeding experiment. The L‐phenylalanine dose of 1.6 g/L appears to be the most advantageous. Compared to the control cultures, the content of the individual compounds increased in a range from 1.4 to 17.3‐fold (e.g. p‐coumaric acid – 17.3 fold; casticin – 4.8‐fold). The biomass from in vitro cultures is richer in neochlorogenic acid (16‐fold), p‐coumaric acid (5.3‐fold), rutin (2.8‐fold), caffeic acid (1.5‐fold) and cinaroside (1.5‐fold) than the leaves of its parent greenhouse‐cultivated plants. Extracts contained 30 mg/100 g DW of casticin, but after the hydrolysis its amount increased up to 200 mg/100 g DW and twice exceeded the content in the greenhouse leaves. The results indicate that V. agnus castus agitated shoot cultures might be considered as a potential biotechnological source of some pharmaceutically important compounds, especially casticin, rutin, neochlorogenic and p‐coumaric acids.     

Fragmentation pathways of acylated flavonoid diglucuronides from leaves of Medicago truncatula

Introduction – Flavonoids are important plant compounds occurring in tissues mostly in the form of glycoconjugates. Most frequently the sugar moiety is comprised of mono‐ or oligosaccharides consisting of common sugars like glucose, rhamnose or galactose. In some plant species the glycosidic moiety contains glucuronic acid and may be acylated by phenylpropenoic acids. Methodology – Flavonoid glyconjugates were extracted from leaves of Medicago truncatula ecotype R108 and submitted to analysis using high‐performance liquid chromatography combined with high‐resolution tandem (quadrupole‐time of flight, QToF) mass spectrometry. Results – The studied leaf extracts contained 26 different flavonoid glycosides among which 22 compounds were flavone (apigenin, luteolin, chrysoeriol and tricin) glucuronides and 13 were acylated with aromatic acids (p‐coumaric, ferulic or sinapic). The fragmentation pathways observed in positive and negative ion mass spectra differed substantially between each other and from these of flavonoid glycosides which did not contain acidic sugars. The application of high‐resolution MS techniques allowed unequivocal differentiation between ions with the same nominal m/z values containing different substituents (e.g. ferulic acid or glucuronic acid). Eleven of the identified flavonoids have not been reported previously in this species. Perspectives – The presented unique fragmentation pathways of flavonoid glucuronates enable detection of these compounds in tissue extracts from different plant species. Copyright © 2009 John Wiley & Sons, Ltd.     

香蕉园施用白花鬼针草的控草增效作用

[目的] 探索香蕉园施用白花鬼针草的可行性。[方法] 采用培养皿萌发试验生物测定法,以发芽率、发芽势、发芽指数、活力指数等化感效应指标评价白花鬼针草对蕉园4种优势杂草的化感作用,同时通过盆栽模拟试验探讨香蕉园施用白花鬼针草后杂草、香蕉和土壤三者的关系。[结果] 当白花鬼针草浸提液浓度为0.0125 g·mL^-1时,对马唐综合化感效应为促进作用,对短叶水蜈蚣、牛筋草、柔弱斑种草综合化感效应为抑制作用,白花鬼针草浸提液浓度为0.025~0.1 g·mL^-1,对4种受体杂草综合化感效应均为抑制作用;白花鬼针草处理具有降低种子发芽率,延缓种子发芽时间的作用,同时对杂草萌发后的鲜重有微弱促进作用,但这种促进作用较弱,综合化感效应表现为抑制作用。随着白花鬼针草茎、叶施用量的增加,控草增效作用不断提升,当施用量为400 g·株^-1时,控草增效作用最佳,对杂草综合株防效为78.99%,综合鲜重防效为70.60%,香蕉苗生物量增加19.79%,土壤有机碳、碱解氮、速效钾依次增加8.72%、10.36%、16.30%。[结论] 本研究初步探明了在香蕉园施用白花鬼针草具有防控蕉园优势杂草、提高土壤肥力和促进香蕉生长的效应。     

PHYSIOLOGICAL EFFECTS OF RESVERATROL AND COUMARIC ACID ON TWO MAJOR GROUNDNUT PESTS AND THEIR EGG PARASITOID BEHAVIOR

Groundnut, Arachis hypogea L., is one of the plant species that synthesizes phenolic compounds, resveratrol and coumaric acid. They are induced as a defense strategy in plant in response to feeding lepidopterans. The present study investigated the role of resveratrol and coumaric acid in producing antiherbivore effects as a direct defense against two major groundnut pests, Spodoptera litura F. and Amsacta albistriga W., and in indirect defense by attracting the egg parasitoid Trichogramma chilonis Ishii under laboratory conditions. The phenolic compounds deterred the feeding of both pests and caused reduction in the larval weights in a dose‐dependent manner in leaf disk bioassays. Antioxidant mechanisms of larvae fed with these phenols were measured by estimating the activities of superoxide dismutase (SOD), ascorbate peroxidase (APOX), and catalase (CAT). Enzyme activities increased significantly in experimental larvae, more so in resveratrol‐treated than in coumaric acid treated larvae. Feeding larvae with resveratrol and coumaric acid resulted in enhanced activities of detoxifying enzymes, carboxyl esterase (EST), and glutathione‐S‐transferase (GST) in the midgut tissues of both species, indicating the toxic nature of these compounds. Trichogramma chilonis was more attracted toward coumaric acid treatments in Y‐olfactometer tests than to resveratrol. This study contributes to the understanding of the roles of resveratrol and coumaric acid in direct as well as indirect defense, we infer a possible utilization of these compounds in alternate measures of groundnut pest control in future.     

Flavonoids from Potentilla parvifolia Fisch. and Their Neuroprotective Effects in Human Neuroblastoma SH‐SY5Y Cells in vitro

Potentilla parvifolia Fisch . (Rosaceae) is a traditional medicinal plant in P. R. China. In this study, seven flavonoids, ayanin ( 1 ), tricin ( 2 ), quercetin ( 3 ), tiliroside ( 4 ), miquelianin ( 5 ), isoquercitrin ( 6 ), and astragalin ( 7 ), were separated and purified from ethyl acetate extractive fractions from ethanol extracts of P. parvifolia using a combination of sevaral chromatographic methods. The human neuroblastoma SH‐SY5Y cells were differentiated with all trans‐retinoic acid and treated with okadaic acid to induce tau protein phosphorylation and synaptic atrophy, which could establish an Alzheimer's disease cell model. The neuroprotective effects of these flavonoids in cellular were evaluated in vitro by this cell model. Results from the Western blot and morphology analysis suggested that compounds 3 and 4 had the better neuroprotective effects.     

Preponderance of Oxygenated Sesquiterpenes and Diterpenes in the Volatile Oil Constituents of Lactuca serriola L. Revealed Antioxidant and Allelopathic Activity

Using synthetic chemicals in industry and agriculture has led to several environmental problems. Thus, plant products derived from volatile oils (VOs) could be a potential green source for bioherbicides. Little is known about the VOs of Lactuca serriola. Hence, the present study aimed to characterize the VOs chemical composition from the aerial parts of L. serriola, assessment of antioxidant activity, and evaluate allelopathic potential against the noxious weed Bidens pilosa. The VOs were extracted by hydrodistillation and analyzed by GC/MS. The VOs from the Egyptian ecospecies of L. serriola were found to comprise 34 compounds mainly oxygenated sesquiterpenes and diterpenes. The major compounds were isoshyobunone (64.22 %), isocembrol (17.35 %), and alloaromadendrene oxide‐1 (7.32 %). So, L. serriola can be considered as a good source for isoshyobunone, considering that it has a much higher concentration than any other plants. Also, this plant has a high content of the oxygenated diterpene compound, isocembrol, which is rarely found in the VOs of most plants. The VOs expressed strong antioxidant activity. Also, for the first time, our results showed a strong allelopathic activity of VOs from L. serriola on germination and seedling growth of the noxious weed, B. pilosa. We suppose that the activity of the VOs from L. serriola could be attributed to these previously mentioned major compounds, as they represent about 89 % of the total identified oil constituents. Nevertheless, to evaluate these compounds as new allelochemicals, further study is needed to test the allelopathic activity of authenticated standard of these compounds either singular or in combination on several weeds as well as evaluate the safety, and improve the efficacy and stability at the field scale.     

Winter low temperature disturbance in the southern subtropics of China promotes the competitiveness of an invasive plant

Winter low temperature disturbance in the southern subtropics has important effects on the weed community structure, but the role of uniquely low temperatures in biological invasions is unclear. Here, we examined the competitive effects of an invasive plant, Bidens pilosa L., and its native congener, Bidens biternata (Lour.) Merr. et Sherff, during high and low temperature seasons to determine whether low temperatures promote the competitiveness of B. pilosa in the southern subtropics of China. The growth and physiological responses of the two Bidens species to low (10/5 °C) and optimum (30/25 °C) temperatures were examined to determine how the invasive B. pilosa responds to low temperature stress. Our results showed that the competitive balance index values of B. pilosa in low temperature seasons were significantly higher than those in high temperature seasons, which implied that low temperatures may be more beneficial to the competitiveness of B. pilosa than high temperatures in the southern subtropics. The smaller decline in the relative growth rate and the photosynthetic ability of B. pilosa compared with B. biternata under low temperature stress indicated that the former was less negatively affected by low temperature than the latter. A higher DPPH^· (1.1-diphenyl-2-picrylhy-drazyl) scavenging rate and greater heat-stable protein content in B. pilosa under low temperatures might help the invasive plant to maintain more effective physiological functions and thus a higher growth rate. Overall, the uniquely low temperature in the southern subtropics of China is expected to promote the invasiveness of the exotic B. pilosa.

     

Response of Lactobacillus casei BL23 to phenolic compounds

Aims: To determine the inhibitory effect of phenolic compounds on Lactobacillus casei BL23, the role of two component signal transduction systems (TCS) and the response of Lact. casei BL23 to p‐coumaric acid. Methods and Results: Growth of Lact. casei BL23 and 17 derivative strains defective in each TCS harboured by this strain in the presence of p‐coumaric acid, ferulic acid, caffeic acid or methyl gallate was monitored. Furthermore, changes in the protein content of Lact. casei BL23 when exposed to p‐coumaric acid were evaluated by 2D‐SDS‐PAGE. Eleven proteins differentially expressed in the presence of p‐coumaric acid were detected. Six of them could be identified: ClpP and HtrA, involved in protein turnover and folding, acetyl‐CoA carboxylase, involved in lipid metabolism, and an arginyl‐tRNA synthetase were more abundant, whereas PurL and PurN, involved in purine biosynthesis, were less abundant. Conclusions: No significant differences were observed between the parental strain and the TCS‐defective mutants. p‐Coumaric acid elicited a response against membrane and cytoplasmic damages. Significance and Impact of the Study: The inhibitory effect of phenolic compounds on Lact. casei BL23 has been determined. For the first time, cytoplasmic proteins presumably involved in the response of Lact. casei BL23 against p‐coumaric acid have been identified.     

Antimicrobial Compounds from Drypetes staudtii

Antimicrobial‐directed phytochemical investigation of the MeOH extract of Drypetes staudtii afforded two new compounds, 4,5‐(methylenedioxy)‐o‐coumaroylputrescine ( 1 ), 4,5‐(methylenedioxy)‐o‐coumaroyl‐4′‐N‐methylputrescine ( 2 ), along with seven known natural products 4α‐hydroxyeremophila‐1,9‐diene‐3,8‐dione ( 3 ), drypemolundein B ( 4 ), friedelan‐3β‐ol ( 5 ), erythrodiol ( 6 ), ursolic acid ( 7 ), p‐coumaric acid ( 8 ), and β‐sitosterol ( 9 ). Structures of compounds 1 – 9 were elucidated with the aid of extensive NMR and mass spectral studies. All of the isolates exhibited antibacterial activity against Gram‐positive and Gram‐negative bacteria with minimum inhibitory concentration (MIC) in the range of 8 – 128 μg/ml. Compounds 1 – 2 were also moderately active against Candida albicans with an MIC value of 32 μg/ml.     

Taraxerol 4‐Methoxybenzoate,an in vitro Inhibitor of Photosynthesis Isolated from Pavonia multiflora A. St‐Hil. (Malvaceae)

A phytochemical study of Pavonia multiflora A. St ‐Hil . (Malvaceae) led to the isolation through chromatographic techniques of 10 secondary metabolites: vanillic acid ( 1 ), ferulic acid ( 2 ), p‐hydroxybenzoic acid ( 3 ), p‐coumaric acid ( 4 ), loliolide ( 5 ), vomifoliol ( 6 ), 4,5‐dihydroblumenol A ( 7 ), 3‐oxo‐α‐ionol ( 9 ), blumenol C ( 10 ), and taraxerol 4‐methoxybenzoate ( 8 ), the latter being a novel metabolite. Their structures were identified by ¹H‐ and ¹³C‐NMR, using one‐ and two‐dimensional techniques, and X‐ray crystallography. In this work, we report the effect of compounds 5 and 8 on several photosynthetic activities in an attempt to search for new compounds as potential herbicide agents that affect photosynthesis. Both compounds inhibited the electron flow from H₂O to methyl viologen; therefore, they act as Hill reaction inhibitors. Using polarographic techniques and studies of the fluorescence of chlorophyll a, the interaction sites of these compounds were located at photosystem II.     

Responses of the weed Bidens pilosa L. to exogenous application of the steroidal saponin protodioscin and plant growth regulators 24‐epibrassinolide,indol‐3‐acetic acid and abscisic acid

• The exogenous application of plant hormones and their analogues has been exploited to improve crop performance in the field. Protodioscin is a saponin whose steroidal moiety has some similarities to plant steroidal hormones, brassinosteroids. To test the possibility that protodioscin acts as an agonist or antagonist of brassinosteroids or other plant growth regulators, we compared responses of the weed species Bidens pilosa L. to treatment with protodioscin, brassinosteroids, auxins (IAA) and abscisic acid (ABA).
• Seeds were germinated and grown in agar containing protodioscin, dioscin, brassinolides, IAA and ABA. Root apex respiratory activity was measured with an oxygen electrode. Malondialdehyde (MDA) and antioxidant enzymes activities were assessed.
• Protodioscin at 48–240 μm inhibited growth of B. pilosa seedlings. The steroidal hormone 24‐epibrassinolide (0.1–5 μm ) also inhibited growth of primary roots, but brassicasterol was inactive. IAA at higher concentrations (0.5–10.0 μm ) strongly inhibited primary root length and fresh weight of stems. ABA inhibited all parameters of seedling growth and also seed germination. Respiratory activity of primary roots (KCN‐sensitive and KCN‐insensitive) was activated by protodioscin. IAA and ABA reduced KCN‐insensitive respiration. The content of MDA in primary roots increased only after protodioscin treatment. All assayed compounds increased APx and POD activity, with 24‐epibrassinolide being most active. The activity of CAT was stimulated by protodioscin and 24‐epibrassinolide.
• The results revealed that protodioscin was toxic to B. pilosa through a mechanism not related to plant growth regulator signalling. Protodioscin caused a disturbance in mitochondrial respiratory activity, which could be related to overproduction of ROS and consequent cell membrane damage.

     

Screen of Chinese Weed Species for Cadmium Tolerance and Accumulation Characteristics

The cadmium (Cd) tolerance and metal-accumulation characteristics of 29 species (18 families) of weed were studied by using outdoor pot-culture experiments. The results of this screening showed that Bidens pilosa and Kalimeris integrifolia (both Asteraceae) expressed some properties that are characteristic of Cd hyperaccumulators. In 10 mg/kg Cd-spiked soil, they accumulated a good deal of Cd in shoots (28 and 25 mg/kg DW, respectively) with high Cd enrichment factors (EFs; concentration in plant/soil). Cd accumulations in shoots were greater than those in roots (translocation factor (TF) >1, concentration in shoot/root) and the shoot biomasses did not decreased significantly compared to the unspiked control. The other weed species showed little accumulation of Cd, Pb, Cu, or Zn. In a concentration-gradient experiment, the Cd accumulation potentials of B. pilosa and K. integrifolia were examined further. Cd concentrations in leaves of B. pilosa growing in soils spiked with 25, 50, and 100 mg/kg Cd were up to 145, 160, and 192 mg/kg, respectively, and the Cd content in stems in the 100 mg/kg Cd-spiked soil was 115 mg/kg, all greater than the 100 mg/kg notional criterion for Cd hyperaccumulation. The Cd EFs and TFs were all greater than 1. The shoot biomasses did not decrease significantly compared to the controls. B. pilosa was thus shown to have some characteristics of a true Cd hyperaccumulator plant.     

Daphnane‐Type Diterpenoid Glucosides and Further Constituents of Euphorbia pilosa

Phytochemical investigation of whole plants of Euphorbia pilosa led to the isolation and identification of two new daphnane‐diterpenoid glucosides, euphopilosides A and B ( 1 and 2 , resp.), and a new ent‐abietane, euphopilolide ( 3 ), together with eight known compounds. Compounds 1 and 2 are the first daphnane‐type diterpenoid glycosides. Their structures were elucidated by a combination of 1D‐ and 2D‐NMR, and MS analyses, and acid hydrolysis. Compounds 1 – 9 were evaluated for their in vitro cytotoxicities against five human tumor cell lines, HL‐60, SMMC‐7721, A‐549, MCF‐7, and SW‐480. Compound 7 showed moderate inhibitory activity against all five cell lines.     

Isolation,identification and characterization of soil microbes which degrade phenolic allelochemicals

Aims: To isolate and characterize microbes in the soils containing high contents of phenolics and to dissolve the allelopathic inhibition of plants through microbial degradation. Methods and Results: Four microbes were isolated from plant soils using a screening medium containing p‐coumaric acid as sole carbon source. The isolates were identified by biochemical analysis and sequences of their 16S or 18S rDNA, and designated as Pseudomonas putida 4CD1 from rice (Oryza sativa) soil, Ps. putida 4CD3 from pine (Pinus massoniana) soil, Pseudomonas nitroreducens 4CD2 and Rhodotorula glutinis 4CD4 from bamboo (Bambusa chungii) soil. All isolates degraded 1 g l^?1 of p‐coumaric acid by 70–93% in inorganic and by 99% in Luria‐Bertani solutions within 48 h. They also effectively degraded ferulic acid, p‐hydroxybenzoic acid and p‐hydroxybenzaldehyde. The microbes can degrade p‐coumaric acid and reverse its inhibition on seed germination and seedling growth in culture solutions and soils. Low pHs inhibited the growth and phenolic degradation of the three bacteria. High temperature inhibited the R. glutinis. Co²⁺ completely inhibited the three bacteria, but not the R. glutinis. Cu²⁺, Al³⁺, Zn²⁺, Fe³⁺, Mn²⁺, Mg²⁺ and Ca²⁺ had varying degrees of inhibition for each of the bacteria. Conclusions: Phenolics in plant culture solutions and soils can be decomposed through application of soil microbes in laboratory or controlled conditions. However, modification of growth conditions is more important for acidic and ions‐contaminated media. Significance and Impact of the Study: The four microbes were first isolated and characterized from the soils of bamboo, rice or pine. This study provides some evidence and methods for microbial control of phenolic allelochemicals.     

Gut microbiome helps honeybee (Apis mellifera) resist the stress of toxic nectar plant (Bidens pilosa) exposure: Evidence for survival and immunity

Honeybee (Apis mellifera) ingestion of toxic nectar plants can threaten their health and survival. However, little is known about how to help honeybees mitigate the effects of toxic nectar plant poisoning. We exposed honeybees to different concentrations of Bidens pilosa flower extracts and found that B. pilosa exposure significantly reduced honeybee survival in a dose-dependent manner. By measuring changes in detoxification and antioxidant enzymes and the gut microbiome, we found that superoxide dismutase, glutathione-S-transferase and carboxylesterase activities were significantly activated with increasing concentrations of B. pilosa and that different concentrations of B. pilosa exposure changed the structure of the honeybee gut microbiome, causing a significant reduction in the abundance of Bartonella (p < 0.001) and an increase in Lactobacillus. Importantly, by using Germ-Free bees, we found that colonization by the gut microbes Bartonella apis and Apilactobacillus kunkeei (original classification as Lactobacillus kunkeei) significantly increased the resistance of honeybees to B. pilosa and significantly upregulated bee-associated immune genes. These results suggest that honeybee detoxification systems possess a level of resistance to the toxic nectar plant B. pilosa and that the gut microbes B. apis and A. kunkeei may augment resistance to B. pilosa stress by improving host immunity.