Antibacterial Activity of Pinus pinaster Bark Extract and its Components Against Multidrug-resistant Clinical Isolates of Acinetobacter baumannii

Abstract

Abstract. The aim of this research was to test the antibacterial activity of Pinus pinaster aqueous bark extract (PABE) and its basic components against multidrug-resistant isolates of Acinetobacter baumannii belonging to European clone I and II, isolated previously from the clinical outbreaks. The minimum bactericidal concentration of PABE against both clones of A. baumannii was 200 mg ml -1 , while lower concentrations showed high antibacterial activity. After 24 h of treatment with 100, 50 or 10 mg ml -1 of extract, the reduction in the number of A. baumannii isolates belonging to European clone I and II was 85.8 ± 2.5 %, 78.5 ± 1.1 %, 66.3 ± 2.5 % and 90.2 ± 1.7 %, 78.6 ± 1.2 %, 69.8 ± 0.7 %, respectively. Several basic components: caffeic acid, catechin, epicatechin, gallic acid and vanillin, detected in the extract by high performance liquid chromatography, contributed to the antibacterial activity of the extract against both clones of A. baumannii. However, the antibacterial activity of extract was higher than that of each tested basic component suggesting that proanthocyanidins, which were present in quite a large amount in the extract, might have also contributed to the activity of the extract. Antibacterial activity of PABE against A. baumannii reveals that complex and inexpensive natural product might be useful in combat against naturally competent bacteria that easily acquire resistance against antibiotics.

Phytochemical and Bioactive Potential ofin vivoandin vitroGrown Plants ofCentaurea ragusinaL. - Detection of DNA/RNA Active Compounds in Plant Extracts via Thermal Denaturation and Circular Dichroism

“…Nevertheless, in comparison to extracts prepared in similar solvents as ours (methanol or ethanol) here obtained values of antibacterial activity against S. aureus were similar or higher than those reported in the literature (Arif et al , ; Tekeli et al , ). All studied extracts exhibited weak antibacterial activity against A. baumannii DURN probably due to a pronounced resistance of that bacterial strain (Ćurković‐Perica et al , ). Similar reduction in the number of A. baumannii isolates after 24 h of treatment with Pinus pinaster aqueous bark extract was observed in the studies of Ćurković‐Perica et al () and Tan et al ().…”

“…The use of plant derived natural products and medicines is a valuable resource in the fight against serious diseases in developing countries as well as in developed countries. Over the past decade, many bacterial strains have become resistant to existing antibiotics due to their uncontrolled use and these bacteria are one of the leading causes of hospital infections worldwide (Ćurković‐Perica et al , ). Plants also represent a valuable source of antioxidants.…”

Biological Activity of Flavonoids and Rare Sesquiterpene Lactones Isolated From Centaurea ragusina L.

“…Antibacterial activities of C. ragusina L. CRE extract, fractions and isolated compounds against Gram-negative A. baumannii Durn ( Ćurković-Perica et al, 2015 ) and Gram-positive S. aureus ATCC 25923 were tested using modified Clinical and Laboratory Standards Institute (CLSI), broth microdilution (BD) using 2,3,5-triphenyltetrazolium chloride (TTC) ( Lee et al, 2007 ). The TTC-BD were performed according to the guidelines of the CLSI using 96-well microplates (Clinical Laboratory Standards Institute [CLSI], 2007).…”

“…In continuation of this previous study, the aim was to investigate the biological activity of all isolated compounds, namely the interaction with DNA, the antibacterial activity against Gram-positive ( Staphylococcus aureus ) and Gram-negative bacteria ( Acinetobacter baumannii ) ( Lee et al, 2007 ; Ćurković-Perica et al, 2015 ) and anticancer activity against a panel of murine and human cancer cells.…”

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“…The yield, total phenolic content and antioxidant activity of the extracts is highly dependent on these factors. Water, ethanol, methanol, aqueous alkaline solutions, acetone, dichloromethane, are some of the solvents commonly used to extract phenolic compounds from pine bark (Aspé & Fernandez, 2011;Durkovid-Perica, Hrenovid, Kugler, Goid-Barišid, & Tkalec, 2015;Fradinho et al, 2002).…”