scholarly journals Structural Polymorphism of Chitin and Chitosan in Fungal Cell Walls From Solid-State NMR and Principal Component Analysis

2021 ◽  
Vol 8 ◽  
Author(s):  
Liyanage D. Fernando ◽  
Malitha C. Dickwella Widanage ◽  
Jackson Penfield ◽  
Andrew S. Lipton ◽  
Nancy Washton ◽  
...  
Keyword(s):  
Principal Component Analysis ◽  
Cell Wall ◽  
Cell Walls ◽  
Chemical Shifts ◽  
Principal Component ◽  
Component Analysis ◽  
Antifungal Drugs ◽  
Fungal Cell ◽  
Structural Resistance ◽  
Chitin And Chitosan

Chitin is a major carbohydrate component of the fungal cell wall and a promising target for novel antifungal agents. However, it is technically challenging to characterize the structure of this polymer in native cell walls. Here, we recorded and compared 13C chemical shifts of chitin using isotopically enriched cells of six Aspergillus, Rhizopus, and Candida strains, with data interpretation assisted by principal component analysis (PCA) and linear discriminant analysis (LDA) methods. The structure of chitin is found to be intrinsically heterogeneous, with peak multiplicity detected in each sample and distinct fingerprints observed across fungal species. Fungal chitin exhibits partial similarity to the model structures of α- and γ-allomorphs; therefore, chitin structure is not significantly affected by interactions with other cell wall components. Addition of antifungal drugs and salts did not significantly perturb the chemical shifts, revealing the structural resistance of chitin to external stress. In addition, the structure of the deacetylated form, chitosan, was found to resemble a relaxed two-fold helix conformation. This study provides high-resolution information on the structure of chitin and chitosan in their cellular contexts. The method is applicable to the analysis of other complex carbohydrates and polymer composites.

scholarly journals Evaluation of Antifungal Activity and Mode of Action of New Coumarin Derivative, 7-Hydroxy-6-nitro-2H-1-benzopyran-2-one, againstAspergillusspp.

2015 ◽  
Vol 2015 ◽  
pp. 1-8 ◽  
Author(s):  
Felipe Queiroga Sarmento Guerra ◽  
Rodrigo Santos Aquino de Araújo ◽  
Janiere Pereira de Sousa ◽  
Fillipe de Oliveira Pereira ◽  
Francisco J. B. Mendonça-Junior ◽  
...  
Keyword(s):  
Cell Wall ◽  
Mode Of Action ◽  
Cell Walls ◽  
Coumarin Derivative ◽  
Antifungal Drugs ◽  
Azole Resistance ◽  
Subinhibitory Concentration ◽  
Fungal Cell ◽  
Mycelia Growth

Aspergillusspp. produce a wide variety of diseases. For the treatment of such infections, the azoles and Amphotericin B are used in various formulations. The treatment of fungal diseases is often ineffective, because of increases in azole resistance and their several associated adverse effects. To overcome these problems, natural products and their derivatives are interesting alternatives. The aim of this study was to examine the effects of coumarin derivative, 7-hydroxy-6-nitro-2H-1-benzopyran-2-one (Cou-NO2), both alone and with antifungal drugs. Its mode of action againstAspergillusspp. Cou-NO2was tested to evaluate its effects on mycelia growth and germination of fungal conidia ofAspergillusspp. We also investigated possible Cou-NO2action on cell walls (0.8 M sorbitol) and on Cou-NO2to ergosterol binding in the cell membrane. The study shows that Cou-NO2is capable of inhibiting both the mycelia growth and germination of conidia for the species tested, and that its action affects the structure of the fungal cell wall. At subinhibitory concentration, Cou-NO2enhanced thein vitroeffects of azoles. Moreover, in combination with azoles (voriconazole and itraconazole) Cou-NO2displays an additive effect. Thus, our study supports the use of coumarin derivative 7-hydroxy-6-nitro-2H-1-benzopyran-2-one as an antifungal agent againstAspergillusspecies.

Principal component analysis in studies of substituent-induced chemical shifts of 1,4-disubstituted benzenes

2001 ◽  
Vol 39 (6) ◽  
pp. 316-322 ◽  
Author(s):  
Eduardo L. Canto ◽  
Ljubica Tasic ◽  
Roy E. Bruns ◽  
Roberto Rittner
Keyword(s):  
Principal Component Analysis ◽  
Chemical Shifts ◽  
Principal Component ◽  
Component Analysis

Principal Component Analysis and Target Testing of Substituent Effect Using Carbonyl Stretching Frequency and 13C NMR Chemical Shift Data Matrices

1993 ◽  
Vol 58 (2) ◽  
pp. 385-394 ◽  
Author(s):  
Ghazwan F. Fadhil
Keyword(s):  
Principal Component Analysis ◽  
Substituent Effect ◽  
Chemical Shifts ◽  
Linear Regression Analysis ◽  
Principal Component ◽  
Component Analysis ◽  
Multiple Linear Regression Analysis ◽  
Probe Site ◽  
C Nmr ◽  
Data Matrices

Principal component analysis technique has been applied to analyse the substituent effect on carbonyl stretching frequency and 13C NMR chemical shifts. The general formula for the investigated molecules is X-G-Y, where X represents the set of substituent (OMe, Me, F, Cl, Br, CN and NO2), Y is the probe site and G is benzene ring. According to the indicator function two significant components are responsible for the substituent effect. The validity of several substituent parameters have been investigated by target testing technique. Invariabily substituent parameters derived by iterative multiple linear regression analysis viz. σR (Reynolds), σF (Reynolds) and σR (NMR) have lower SPOIL values when compared with other substituent parameters. Model designing f IR and 13C NMR data matrices separately have shown that models which incorporate σR (Reynolds) and σF (Reynolds) or σR (NMR) and a substituent field parameters have the lowest root mean square error RMSE. Substituent effect on several properties are better correlated with Reynolds' σR and σF than with other commonly used substituent parameter(s). The orthogonality of substituent parameters used in the model can be achieved by including the methyl group in the substituent set.

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