Highest Phytotoxic Activity Research Articles

Phytotoxic Potential and Phenolic Profile of Extracts from Scrophularia striata.

A large number of plants produce secondary metabolites known as allelochemicals that are capable of inhibiting the germination of competitive species. This process is known as allelopathy and is mediated by several classes of chemicals, among which phenolic compounds are the most frequent. Thus, plant allelochemicals can be used to control weeds in agricultural systems. In the present work, we analyzed the phenolic profile and phytotoxic potential of different extracts (pure water or water: ethanol 50:50) from Scrophularia striata plants that were collected from two ecological regions in Iran (Pahleh and Lizan). The total polyphenolic content (TPC), as evaluated by the Folin-Ciocolteau method, ranged from 28.3 mg/g in the aqueous extract obtained from the Lizan ecotype to 39.6 mg/g in the hydroalcoholic extract obtained from the Pahleh ecotype. Moreover, HPLC analysis was aimed at determining the content of eight phenolic compounds, namely eugenol, rosmarinic acid, hesperetin, hesperedin, trans-ferulic acid, vanillin, and caffeic acid. According to the results, rosmarinic acid appeared to be the most abundant component. The phytotoxic activities of S. striata extracts were examined on the seed germination of a crop species, Lepidium sativum, and two weeds, Chenopodium album and Malva sylvestris. All extracts showed inhibitory effects on these species. The efficiency of these inhibitory effects depended on the type of plant species, origin, and concentration of extract. The highest phytotoxic activity was caused by approximately 1% concentration of extract. The most susceptible weed was M. sylvestris. The extracts that were obtained from the Pahleh ecotype, notably the hydroalcoholic ones, showed higher phytotoxicity against L. sativum, C. album and M. sylvestris. These results encourage further studies to support the use of S. striata as a source of bioherbicides.

Phytotoxic activity of crop residues from Burdock and an active substance

Problems related to weed management such as outbreaks of herbicide-resistant weeds have recently increased. An interesting approach to such problems is to use plant materials with phytotoxic activity. Burdock (Arctium lappa L.) is a biennial herb belonging to Asteraceae and is cultivated in several countries. The present study investigated the phytotoxic activity of burdock and its active substances. Extracts of both burdock leaves and roots inhibited the shoot and root growth of cress and barnyard grass, where the level of inhibition increased with increasing extract concentration. The leaf extracts had 2.0–2.5 times higher activity than the root extracts. Bioassay-guided separations of the leaf extracts led to isolation of a phytotoxic substance, onopordopicrin. Onopordopicrin significantly inhibited the shoot and root growth of cress and barnyard grass. The concentrations of the substance required for 50% growth inhibition were 0.27 and 0.26 mM for cress shoots and roots, respectively, and 1.86 and 0.35 mM for barnyard grass shoots and roots, respectively. The present results suggest that burdock leaves have high phytotoxic activity and onopordopicrin may play a major role in the activity. Burdock leaves may be a good resource for weed management.

Influence of six essential oils on invasive Solidago canadensis L. seed germination

Solidago canadensis L. (SC) (Canadian goldenrod) is a dangerous plant invader in Europe, which suppress the indigenous flora. Essential oils (EOs) are considered biological control agents. GC-MS analysis for identification of main components was conducted and the potential phytotoxicity of six EOs were also evaluated. Limonene and β-thujone were dominant components in Salvia officinalis L., menthone and menthol in Mentha × piperita L., carvacrol in Origanum vulgare L., estragole/anisole and anethole in Foeniculum vulgare Mill., limonene and carvone in Anethum graveolens L., and anethole in Pimpinella anisum L. Along with EOs, anethole, anisole, camphor, carvone, estragole, limonene, menthol, menthone, thujone and thymol were used independently to evaluate phytotoxic effect against Canadian goldenrod seed germination. A significant inhibitory effect was registered for origanum (1.250 µg.ml−1). The influence of single components was significant. The highest phytotoxic activity was registered with anethole and estragole. Phenolic compounds were the inhibitoriest, followed by oxygenated and hydrocarbon monoterpenes.

Фітотоксична активність деяких мікроміцетів

Weeds worsening the conditions of growth and development of agricultural plants cause great damage to the Ukrainian agriculture. One of the methods of biological control of weeds is the use of biogenic products of biosynthesis of microscopic fungi or preparations based on living microorganisms. The aim of work was to test phytotoxic activity of cultural filtrates of 82 micromycete strains of genus Penicillium, Cladosporium, Botrytis, Beauveria, Chaetomium, Curvularia, Endomyces, Fusarium, Gliocladium, Aspergillus, Alternaria, Aureobasidium, Paecilomyces, Mortirella, Nigrospora, Pseudallescheria, Scopulariopsis, Trichoderma, Ulocladium and separate strains Nectria sp., Phialophora sp., Verticillium dahliae isolated from different ecological niches. The micromycetes were grown on a basic nutritive Czapek medium. After 14 days the mycelium was removed through filtration. The culture liquid filtrates were tested against green algae Chlorella vulgaris 190 and seeds of couch-grass, white goosefoot and wheat. The screening phytotoxic study of culture liquid filtrate of micromycete strains against green algae Chlorella vulgaris 190 used standard agar well diffusion method. It is shown that 19 cultures were biological activities only. The wide spectrum of phytotoxic activity was characterized for Cladosporium cladosporiodes 9, Mortirella vinacea 78 и Paecilomyces variotii 69. The strain C. cladosporiodes 9 suppressed the seed germination of couch-grass and white goosefoot and did not suppress the germination of wheat. The strain M. vinacea 78 equally suppressed the germination of seeds like the wheatgrass and the white goosefoot. At the same time, P. variotii 69 is characterized by seed inhibition of goosefoot germination and the stimulatory effect on the germination of wheat seeds. The strain C. cladosporiodes 12 shown less active and inhibited the germination of white goosefoot seeds. The highest phytotoxic activity was shown by M. vinacea 74. He suppressed the germination of white goosefoot seeds by 50%. The strains Aspergillus ustus 103 and Penicillium acculeatum 122 showed phytotoxic activity only relative to couch-grass. It was shown that the phototoxicity of the studied strains relative to C. vulgaris 190 does not coincide with the phytotoxicity of these strains relative to the weed seeds and wheat, except M. vinacea 74. As it is no findings about phytotoxic effect of strains of C. cladosporiodes and M. vinacea and from the data obtained it might be inferred that the phytotoxic potential of these genus to be the most promising for further researches. Keywords : micromycetes, phytotoxic activity, test-organisms

Medicinal plants with phytotoxic activity harbour endophytic bacteria with plant growth inhibitory properties

The cultivable endophytic bacteria associated with two medicinal plants Hypericum perforatum L. and Ziziphora capitata L. contrasting with phytotoxic activity were investigated. The phytotoxic activity of plant extracts, and bacterial metabolites on seed germination and seedling growth of tomato were evaluated. In comparison to Z. capitata, the extract of H. perforatum contains a higher content of phenolic compounds. The crude extract of H. perforatum inhibited germination of seeds and seedling growth of tomato, whereas Z. capitata extracts only slightly reduced these parameters. Interestingly, almost half of the endophytes associated with H. perforatum had an inhibitory effect on plant growth, whereas rarely any plant inhibitory effect was found among isolates from Z. capitata. All bacterial isolates from Z. capitata were able to stimulate plant growth, by 35–80%. In contrast, only five isolates from H. perforatum caused significant improvement in plant growth (22–46%). The results showed that medicinal plants with higher phytotoxic activity were colonized with endophytic bacteria which inhibit plant growth and development. These findings indicate that plant phytochemical constituents and activity determine the physiological properties of their endophytes.

Chemical Basis for the Phytotoxicity of Indoles in Relation to the Allelopathy of Cereals

Phytotoxic activity of an indole series substituted with electron-acceptor and electron-donor groups in the aromatic ring was determined. They are potential decomposition products, of natural indole alkaloids in cereals plants with allelopathic properties. Phytotoxic selectivity was evaluated from antialgal activity against the microalga Chlorella vulgaris, seed germination seeds and biomass weight of seedling of barley, rye, wheat, oat and maize species and the weed Lolium rigidum. Lipophilia character of the compounds was determined by RP-HPLC method. Both, the electronic character of the substituents, evaluated from σp parameter, and the lipophilia character of the molecules measured from logPHPLC parameter, are involved in the phytotoxic activity. The three bio indicators has shown that the compounds with the higher electron-acceptor groups showed the higher level of phytotoxicity and the molecules with electron-donor groups showed the lowest activity, although, in some cases, this behavior is modified by the lipophilic properties of the molecules. These results are rationalized in terms of polarization of N-H bond of heterocyclic ring. Compounds with the higher logPHPLC values showed the higher phytotoxic activity. Further evidence on the role of lipophilicity was obtained from linear regression between the average inhibitions percentages of biomass and logPHPLC values. The activity increased linearly by increasing the lipophilic character of the compounds. Therefore, quantitative effects in the phytotoxic activity of the electronic properties of the substituents in the aromatic ring and lipophilic character of the indoles can be inferred from σp and logPHPLC parameters, respectively. The results strongly suggest that the potential decomposition products of the natural indole alkaloids from cereals or other natural sources may be in connection with the allelopathic phenomenon of plants when are released into the soil.

Chemical composition and insecticidal activity of edible garland (Chrysanthemum coronarium L.) essential oil against the granary pest Sitophilus granarius L. (Coleoptera)

The essential oil composition and biological activities of Chrysanthemum coronarium L. from three locations in Cyprus were investigated. A total of 35 components were identified in the oils representing 86.2 ± 0.7%–93.8 ± 0.0% (n = 3) of the oils. Camphor 25.2 ± 0.1%–9.1 ± 0.3%, santolinatriene 21.7 ± 0.1%–3.6 ± 0.1%, yomogi alcohol 12.6 ± 0.1%–3.6 ± 0.1%, cis-chrysanthenyl acetate 10.7 ± 0.1%–6.8 ± 0.1% and bornyl acetate 11.0 ± 0.5%–5.7 ± 0.0% were identified as the main components. Highest DPPH scavenging and PRAP activity was observed for the Lefkoşe sample (49.59 ± 0.19% (n = 5) and 812.77 ± 4.34 AU (n = 5)). Highest phytotoxic activity against Lemna minor L. was observed for the Salamis sample (100.0%). Lefkoşe sample showed the highest insecticidal activity (97.82 ± 1.79% mortality, S. granarius). Bornyl acetate/cis-chrysanthenyl acetate/hexadecanoic acid and camphor/santolinatriene/ yomogi alcohol chemotypes of C. coronarium are proposed from Cyprus samples according to cluster analysis of the oils together with the literature data.

The Effect of Ionic Liquids With (–)-Menthol Derivative Containing a Chloride Anion to Weed

Abstract Weeds constitute a huge group of undesirable plants, widespread throughout the world. They represent a big problem for most farmers, who implement different methods to fight against them. Thanks to their wide occurrence, weeds however, can be an excellent indicator of the quality of soil and the whole environment where they are present. In this paper, we present the impact of four alkylimidazolium chlorides with a natural terpene component introduced into the soil: (1R,2S,5R)-(–)-menthol and alkyl substituents containing 1, 4, 9 or 12 carbon atoms, on the growth and development of selected weed species. Compounds with the highest phytotoxic activity towards gallant soldier, white goosefoot and common sorrel were chlorides with methyl and butyl substituents, while compounds with nonyl and dodecyl substituents demonstrated a weak effect on these weeds. Phytotoxicity of the salts tested was largely dependent on the applied concentration of the compound and the genetic make-up of plant species used in the experiment. This was reflected in the inhibition of plants’ length and their roots, as well as changes in the content of dry matter and photosynthetic pigments.

Phytotoxic and antimicrobial activity of volatile and semi-volatile organic compounds from the endophyte Hypoxylon anthochroum strain Blaci isolated from Burseralancifolia (Burseraceae).

To evaluate the phytotoxic, antifungal and antioomycete activity; and, determine the chemical composition of the volatile organic compounds (VOCs) and semi-volatile metabolites produced by the endophyte Hypoxylon anthochroum strain Blaci isolated from Bursera lancifolia. Based on its macro- and micro-morphological features, the strain Blaci was identified as Nodulisporium sp.; partial analysis of its ITS1-5.8-ITS2 ribosomal gene sequence revealed the identity of the teleomorphic stage of the fungus as H.anthochroum. Phytotoxic and antimicrobial activities of VOCs, and culture medium and mycelium organic extracts from H.anthochroum Blaci were determined by simple and multiple antagonism bioassays, and gas phase and agar dilution bioassays respectively. The volatile and semi-volatile metabolites were identified by gas chromatography-mass spectrometry. VOCs from a 5-day H.anthochroum strain Blaci culture caused the inhibition of seed germination, root elongation and seedling respiration on Amaranthus hypochondriacus, Panicum miliaceum, Trifolium pratense and Medicago sativa. In addition, extracts, phenylethyl alcohol and eucalyptol main compounds present in the VOCs and extract displayed a high phytotoxic activity, inhibiting the three physiological processes on the four test plants in a concentration-dependent manner. The results revealed that H.anthochroum strain Blaci produces a mixture of VOCs. These VOCs showed a strong phytotoxic activity on seed germination, root elongation, and seedling respiration of four plants and slightly affected the growth of phytopathogenic fungi and oomycetes. Also, the culture medium and mycelium extracts of H.anthochroum showed a high phytotoxic activity on the four test plants and, generally, the culture medium extract was more phytotoxic than the mycelium extracts. This work firstly reports the phytotoxic activity of volatile and semi-volatile compounds produced by the endophyte H.anthochroum strain Blaci on seed germination, root elongation, and seedling respiration of four different plants; consequently, these compounds could be useful in biocontrol of weeds and plant pathogens.

Pharmaceutical Biology of Seaweeds from the Karachi Coast of Pakistan

ABSTRACTA variety of marine benthic algae belonging to the Chlorophyta, Phaeophyta, and Rhodophyta were collected from different coastal areas of Karachi (Pakistan), and several biological tests were conducted on their methanol extracts in order to investigate antibacterial, antifungal, phytotoxic, and insecticidal activities. Brown seaweeds showed greater antibacterial activity than the green and red ones. Botryocladia leptopoda. (J.Ag.) Kylin exhibited the greatest antifungal activity and the least was exhibited by Codium shameelii. Nizam. The highest phytotoxic activity was displayed by Ulva intestinalis. L., and Osmundea pinnatifida. (Huds.) Stack. showed the greatest insecticidal activity as compared to the other investigated species. Furthermore, a number of species were analyzed for their elemental composition with the help of a Perkin-Elmer 3100 atomic absorption spectrometer. Elements such as Ca, Cd, Co, Cr, Cu, Fe, K, Mg, Na, Pb, and Zn were determined quantitatively. Among them, Ca, Cr, and Pb were found to occur in the highest proportion in green seaweeds, Co, Cu, Fe, and Zn in highest proportion in brown seaweeds, and Cd, K, Mg, and Na were in highest proportion in the investigated red seaweeds.

Studies on the bioactivity and elementology of marine algae from the coast of Karachi, Pakistan

Some species of marine benthic algae belonging to the Chlorophyta, Phaeophyta and Rhodophyta collected from different coastal areas of Karachi (Pakistan) were investigated for their antibacterial, antifungal, phytotoxic and insecticidal activities. Brown seaweeds showed greater antibacterial activity than the green and red ones. Botryocladia leptopoda (J. Ag.) Kylin exhibited the greatest antifungal activity and Codium shameelii Nizam. the least. The highest phytotoxic activity (95%) was displayed by Enteromorpha intestinalis (L.) Nees at 100 microg/mL concentration, while Osmundea pinnatifida (Huds.) Stack. showed the low insecticidal activity as compared to the other investigated species. Many elements e.g. Ca, Cd, Co, Cr, Cu, Fe, K, Mg, Na, Pb, Zn were determined quantitatively. Among them Ca, Cr and Pb were found to occur in largest amount in green seaweeds, Co, Cu, Fe and Zn in greatest quantity in brown seaweeds, while Cd, K, Mg and Na in highest proportion in the investigated red seaweeds.

Phytotoxic Metabolites Isolated fromScolecotrichum graminisFuckel

Two new cercosporins, (+)-isocercosporin (1) and (+)-14-acetylisocercosporin (2), were isolated from culture filtrates of Scolecotrichum graminis Fuckel, which is the causal fungus of a leaf streak disease in orchardgrass. The structure of each was elucidated by spectroscopic analysis, and (+)-isocercosporin (1) is the first isolated enantiomer of known (−)isocercorporin (8b). Compounds 1 and 8b had higher phytotoxic activity than that of (+)-cercosporin (a), an atropisomer of 8b. The results of the bioassay suggest that the phytotoxic activity of cercosporins depends on the relative configuration, and not on the absolute configuration. In addition, three phenol compounds, 1-(2,4-dihydroxy-6-methylphenyl)ethanone (3), isosclerone (4), and fraws-3,4-dihydro-3,4,8-trihydroxy-1(2H)-naphthalenone (5), were isolated as minor components and identified. Compound 3 was isolated for the first time as a natural products.

Phytotoxic studies on azine compounds. Part I. Phytotoxic properties of .ALPHA.-substituted benzylamino-s-triazines.

α-Substituted benzylamino-s-triazines were synthesized, and their phytotoxic activity and phytotoxic symptom against paddy weeds and transplanted rice seedlings were evaluated. Some of these compounds exhibited potent phytotoxicity against the weeds, high selectivity between the rice and the weeds, and had different phytotoxic properties to atrazine and simetryn. Among these compounds, 2-chloro-4-ethylamino-6-α-methylbenzylamino-s-triazine (2), 2-chloro-4-ethylamino- 6-α-ethylbenzylamino-s-triazine (3), 2-chloro-4-diethylamino-6-α-methylbenzylamino-s-triazine (17), and 2-chloro-4-diisopropylamino-6-α-methylbenzylamino-s-triazine (19) were found to have high phytotoxic activity and selectivity. The phytotoxic symptom of these compounds was mainly growth inhibition to the weeds. Two of these, the diethylamino (17) and diisopropylamino (19) compounds, showed growth inhibition activity without burning the leaf of rice plants at high doses.

Phytotoxic activity of N-phenylsulfonylbenzamides.

Many N-phenylsulfonylbenzamides were synthesized, and their biological activities were tested. Some of these compounds showed a high phytotoxic activity against barnyardgrass with no significant effect on rice plants at their germination stage. In particular, both N-allyl-2-chloro-N- phenylsulfonylbenzamide and N-allyl-2,4-dichloro-N-phenylsulfonylbenzamide were the most active and a herbicidal test of these two compounds was done in paddy field conditions.