Antialgal Activities of Allelochemical Extracts from 3 Terrestrial Plant Species

[Objective] The aim was to study the antialgal activities of allelochemical extracts from three terrestrial plant species.[Method] The allelochemicals were extracted from the leaves of Magnolia grandiflora,Sophora japonica f.pendula and Buxus sinica （Rehd.et Wils.） Cheng by alcohol extraction,n-hexane,ethyl acetate and n-utanol phase.Furthermore antialgal activities of all components were determined.[Result] The active substances of M.grandiflora mainly existed in n-hexane and n-butanol phases.The active substances of S.japonica mainly existed in n-hexane phase,while the active substances of B.sinica mainly existed in ethyl acetate and aqueous phase.All the active substances showed significant antialgal activity （50% inhibition） after culture for 1 d except aqueous phase of B.sinica.In addition,inhibition rates of the tested phases increased with the increasing of culture duration and testing concentrations.The inhibition rates were over 90% against the growth of M.aeruginosa after culture for 7 d.The n-hexane and n-butanol phases of M.grandiflora exhibited the best antialgal activity,over 96% inhibition rate at the concentration of 25 μg/ml,which was significantly higher than those of the other components,furthermore it could cause shrinkage and obvious surface inanition of Microcystis aeruginosa.[Conclusion] The n-hexane and n-butanol phases of M.grandiflora have the best inhibition activities on the growth of Microcystis aeruginosa,so they are worthy of further study.

Antialgal and Antilarval Activities of Bioactive Compounds Extracted from the Marine Dinoflagellate Amphidinium carterae

Abstract With the global ban on the application of organotin-based marine coatings by the International Maritime Organization, the development of environmentally friendly, low-toxic and nontoxic antifouling compounds for marine industries has become an urgent need. Marine microorganisms have been considered as a potential source of natural antifoulants. In this study, the antifouling potential of marine dinoflagellate Amphidinium carterae, the toxic and red-tide microalgae, was investigated. We performed a series of operations to extract the bioactive substances from Amphidinium carterae and tested their antialgal and antilarval activities. The crude extract of Amphidinium carterae showed significant antialgal activity and the ECs0 value against Skeletonema costatum was 55.4 ~tg mL-1. After purification, the isolated bioactive substances （the organic extract C） exhibited much higher antialgal and antilar- val activities with ECso of 12.9μgmL-1 against Skeletonema costatum and LC50 of 15.1 μmL-1 against Amphibalanus amphitrite larvae. Subsequently, IR, Q-TOFMS, and GC-MS were utilized for the structural elucidation of the bioactive compounds, and a series of unsaturated and saturated 16- to 22-carbon fatty acids were detected. The data suggested the bioactive compounds isolated from Amphidinium carterae exhibited a significant inhibiting effect against the diatom Skeletonema costatum and Amphibalanus amphi- trite larvae, and could be substitutes for persistent, toxic antifouling compounds.

Structure modification,antialgal,antiplasmodial,and toxic evaluations of a series of new marine-derived 14-membered resorcylic acid lactone derivatives

Marine natural products play critical roles in the chemical defense of many marine organisms and are essential,reputable sources of successful drug leads.Sixty-seven 14-membered resorcylic acid lactone derivatives 3–27 and 30–71 of the natural product zeaenol(1)isolated from the marine-derived fungus Cochliobolus lunatus were semisynthesized by chlorination,acylation,esterification,and acetalization in one to three steps.The structures of these new derivatives were established by HRESIMS and NMR techniques.All the compounds(1–71)were evaluated for their antialgal and antiplasmodial activities.Among them,14 compounds displayed antifouling activities against adhesion of the fouling diatoms.In particular,9 and 34 exhibited strong and selective inhibitory effects against the diatoms Navicula laevissima and Navicula exigua(EC50=6.67 and 8.55μmol/L),respectively,which were similar in efficacy to those of the positive control SeaNine 211(EC50=2.90 and 9.74μmol/L).More importantly,38,39,and 69–71 showed potent antiplasmodial activities against Plasmodium falciparum with IC50 values ranging from 3.54 to 9.72μmol/L.Very interestingly,the five antiplasmodial derivatives displayed non-toxicity in the cytotoxicity assays and the zebrafish embryos model,thus,representing potential promising antiplasmodial drug agents.The preliminary structure–activity relationships indicated that biphenyl substituent at C-2,acetonide at positions C-5′and C-6′,and tri-or tetra-substituted of acyl groups increased the antiplasmodial activity.Therefore,combining evaluation of chemical ecology with pharmacological models will be implemented as a systematic strategy,not only for environmentally friendly antifoulants but also for structurally novel drugs.

Research on Algistatic Activities of Allelochemicals in Magnolia Grandiflora Leaves and GC-MS Analysis

[Objective]In order to investigate the antialgal activities and species of the allelochemicals in Magnolia grandiflora leaves.[Method]The antialgal substances against Microcystic aeruginosa from the extracts of Magnolia grandiflora leaves were separated,purified and identified based on the activity test,using silica gel column chromatography,gel column chromatography and GC-MS method and combining the algae inhibition experiment.[Result]The maximum inhibition rate of the extracts of Magnolia grandiflora leaves on Microcystic aeruginosa growth was 97.4% with the concentration of 8 g/L.A large amount of antialgal substances were found in the n-butanol extracts of Magnolia grandiflora and had very good inhibition effects on Microcystic aeruginosa,which were mainly small molecule substances such as alcohols,ketones and esters.[Conclusion]A new idea on developing new algal inhibitors had been provided.

Utilisation of Green Synthesised Silver Nanoparticles for Water Quality Management

In the present study silver nanoparticles (AgNPs) were synthesized using leaves of bamboo plant, Bambus vulgaris and the size of the nanoparticles was confirmed using XRD, EDAX, SEM, TEM, PSA analysis. The antimicrobial activity of the synthesized NPs showed a good antibacterial activity against the waterborne isolates, E. coli, Staphyllococcus aureus, Vibrio cholera and Salmonella sp. Further the anti algal activity of the NPs was tested against the algae, Dictyosphaerium pulchellum, and Algoriphagus chordate. The SEM studies revealed that the AgNPs breaks the cell wall of algae and inhibits the growth. The safe dose of AgNPs can be used in aquaculture farms, household water tanks and other small water bodies to wipe out waterborne pathogens and algal bloom.

Inhibitory effects of the extracts with different solvents from three compositae plants on cyanobacterium Microcystis aeruginosas

The algicidal activity of the terrestrial plants is a novel and promising means for alga control of eutrophic waters. In this study, three compositae plants-Artemisia annua （A. annua）, Conyza canadensis （ C. canadensis）, and Erigeron annuus （E. annuus） were selected and antialgal activity of petroleum ether （PE）, ethyl acetate （EA） and ethanol extracts of these plants on blue algae Microcystis aeruginosa was investigated. The result shows the EA extracts of these plants present the stronger inhibitory effects. The results of the further separation of PE and EA extracts according to water-solubility and acidity or alkalinity show that fatty acids and telpenoids in A. annua, terpenoids and organic acid in C. Canadensis and E. Annuus may be the main antialgal active constituents. This study suggested that the EA extracts of these plants could become the potential algicide to prevent water blooming.