Biosynthesis of Ag and Cu NPs by secondary metabolites of usnic acid and thymol with biological macromolecules aggregation and antibacterial activities against multi drug resistant (MDR) bacteria

2019 ◽  
Vol 128 ◽  
pp. 893-901 ◽  
Author(s):  
Mehran Alavi ◽  
Naser Karimi
Keyword(s):  
Secondary Metabolites ◽  
Usnic Acid ◽  
Antibacterial Activities ◽  
Biological Macromolecules ◽  
Drug Resistant

In the search for new secondary metabolites with biopesticidal properties

2015 ◽  
Vol 62 (4) ◽  
pp. 216-228 ◽  
Author(s):  
Carlos L. Céspedes ◽  
Julio E. Alarcon ◽  
Pedro Aqueveque ◽  
David S. Seigler ◽  
Isao Kubo
Keyword(s):  
Secondary Metabolites ◽  
Chemical Defense ◽  
Insect Pests ◽  
Sesquiterpene Lactones ◽  
Antibacterial Activities ◽  
Natural Compounds ◽  
Insect Growth Regulator ◽  
Bacterial Strains ◽  
Plant Chemical Defense ◽  
Insect Growth

Secondary metabolites are involved in diverse functions in plants, including defense and protective processes. Information concerning the biosynthesis of secondary metabolites in plants points at a constitutive or induced chemical defense, generated for protection against a variety of phytopathogenic attacks. Our phytochemical studies are aimed at finding biopesticides of botanical origin. Some plant taxa of American distribution are toxic to selected insects, fungi and bacterial strains, and their effect has been associated with the presence of phenolics, phenylpropanoids and terpenes. We have isolated some diterpenes, triterpenes, sesquiterpene lactones, flavonoids, and phenylpropanoids from members of the plant families Araucariaceae, Asteraceae, Calceolariaceae, Celastraceae, and Rhamnaceae. In addition, we have identified a number of chemical derivatives of these compound classes from the plants. A major finding indicates that compounds or their derivatives that possess antioxidant, antifungal, insect growth regulator or insecticidal activity and enzymatic inhibitors are natural compounds. Insecticidal activities were assayed against strains of lepidopteran, dipteran, and coleopteran insect pests that affect many crops. Antifungal and antibacterial activities were assayed against phytopathogenic species of filamentous fungi and bacterial strains that are pests on many crops. Our results indicate that the plant-derived compounds obtained from the abovementioned plants have excellent insect growth regulatory activity and a good potency as antifungal agents. However, little is known about the effects of these natural compounds and their derivatives on insect pests. The natural compounds that we have isolated represent a valuable resource for future studies of plant chemical defense and the role of these substances in chemical ecology.

scholarly journals Phytochemical Investigation of the Australian Lichens Ramalina glaucescens and Xanthoria parietina

2009 ◽  
Vol 4 (7) ◽  
pp. 1934578X0900400 ◽  
Author(s):  
Daniel A. Dias ◽  
Sylvia Urban
Keyword(s):  
Antibacterial Properties ◽  
Usnic Acid ◽  
2D Nmr ◽  
Antibacterial Activities ◽  
2D Nmr Spectroscopy ◽  
Full Characterization ◽  
Phytochemical Investigation ◽  
Xanthoria Parietina ◽  
Shift Assignment

Phytochemical investigation of the Australian lichen, Ramalina glaucescens resulted in the isolation of a new halogenated depside, 5-chlorosekikaic acid 5, together with (+)-usnic acid 1, sekikaic acid 2, atranorin 6 and parietin 7, the latter of which was isolated from the associated (co-occurring) lichen, X. parietina. Compound 5 is suspected to be an artifact of the isolation procedure. All structures were assigned using spectroscopic methods and mass spectrometry. In addition to the full characterization of 5, this report represents the first application of 2D NMR spectroscopy to complete the unequivocal chemical shift assignment for compounds 2 and 7. Compounds 1-2 and 5-7 all displayed varying degrees of antitumor activity (ranging from an IC50 of 15 μM to >44 μM) with compounds 1, 2 and 5 also displaying antibacterial properties. Of these, (+)-usnic acid 1 displayed the most significant antitumor and antibacterial activities.

scholarly journals Two New Piperazine-Triones from a Marine-Derived Streptomycetes sp. Strain SMS636

Marine Drugs ◽  
2019 ◽  
Vol 17 (3) ◽  
pp. 186 ◽  
Author(s):  
Xiuli Xu ◽  
Jiahui Han ◽  
Rui Lin ◽  
Steven Polyak ◽  
Fuhang Song
Keyword(s):  
Staphylococcus Aureus ◽  
Minimum Inhibitory Concentration ◽  
Secondary Metabolites ◽  
Deep Sea ◽  
Spectroscopic Analysis ◽  
Inhibitory Concentration ◽  
2D Nmr ◽  
Antibacterial Activities ◽  
Bacillus Calmette Guerin ◽  
Methicillin Resistant

Two new piperazine-triones lansai E and F (1, 2), together with four known secondary metabolites lansai D (3), 1-N-methyl-(E,Z)-albonoursin (4), imidazo[4,5-e]-1,2,4-triazine (5), and streptonigrin (6) were isolated from a deep-sea-derived Streptomycetes sp. strain SMS636. The structures of the isolated compounds were confirmed by comprehensive spectroscopic analysis, including HRESIMS, 1D and 2D NMR. Compound 4 exhibited moderate antibacterial activities against Staphylococcus aureus and methicillin resistant S. aureus (MRSA) with Minimum Inhibitory Concentration (MIC) values of 12.5 and 25 μg/mL, respectively. Compound 6 displayed significant antibacterial activities against S. aureus, MRSA and Bacillus Calmette-Guérin (BCG) with MIC values of 0.78, 0.78 and 1.25 μg/mL, respectively.

Three new species of Parmelia subgen. Xanthoparmelia (Lichens) from south-eastern Australia

1976 ◽  
Vol 24 (5) ◽  
pp. 663 ◽  
Author(s):  
JA Elix
Keyword(s):  
New Species ◽  
Secondary Metabolites ◽  
New South ◽  
New South Wales ◽  
Usnic Acid ◽  
Australian Capital Territory ◽  
South Eastern ◽  
South Wales ◽  
Eastern Australia ◽  
Three New Species

Parmelia (subgen. Xanthoparmelia) barbatica, Parmelia (subgen. Xanthoparmelia) burmeisterii and Parmelia (subgen. Xanthoparmelia) pseudohypoleia are described as new from the Australian Capital Territory and New South Wales. The former two species are the first representatives of this subgenus to be described in which usnic acid, barbatic acid and 4-O-demethylbarbatic acid are the major secondary metabolites.

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