Total phenolic and flavonoid contents, antioxidant and antimicrobial activities ofAlnus glutinosa(L.) Gaertn., Alnus incana(L.) Moench andAlnus viridis(Chaix) DC. extracts

Abstract

The objective of this study was to determine total phenolic and flavonoid contents, antioxidant and antimicrobial activities of methanolic extracts from the leaves and barks of three Alnus species. The phenolic and flavonoid contents of extracts were determined spectrophotometrically using Folin-Ciocalteau and aluminium chloride methods, respectively. In addition, antioxidant activity of the extracts was determined using 1,1-diphenyl-2-picrylhydrazyl radical scavenging method. The antimicrobial activity was performed by disc diffusion assay against six reference bacterial strains including Gram-negative and Gram-positive bacteria and two fungal strains. Extract of Alnus viridis bark contained the highest amounts of total phenolics (780 mg CAT/g), while extract of A. viridis leaves had the highest amount of flavonoids (30.01 mg RUT/g). All extracts showed antioxidant activity higher than thymol, which was used as a positive probe. The largest diameters of inhibition zone (25 mm) were recorded with Bacillus subtilis 168 M and Staphylococcus aureus ATCC 6538.

Antimicrobial and cytotoxic activity of Alnus glutinosa (L.) Gaertn., A. incana (L.) Moench, and A. viridis (Chaix) DC. extracts

“…Middleton et al (19) also reported antimicrobial activity of A. glutinosa against eight bacterial species and confirmed the usage of this species in traditional medicine. These results are consistent with previous reports on related plants regarding antibacterial activity (12). Earlier, it was noted that differences in the antibacterial activity are associated with secondary metabolites (tannin and phenol) (12,20).…”

“…Our previous results suggest that A. glutinosa, A. incana, and A. viridis have strong antimicrobial and antioxidant potential due to the presence of large quantities of phenols and flavonoids (12). In this study, the antimicrobial activity test showed that the leaf and bark extracts of A. viridis inhibited the growth of almost all the microorganisms, except S. abony, C. albicans, and A. brasiliensis.…”

“…secodammarane-type triterpenoids), flavonoids, diarylheptanoids, phenols, steroids, and tannins (8,5). Traditionally, extracts of Alnus species are used for gastrointestinal, skin diseases, and bacterial infections of the mouth and throat (9)(10)(11)(12). Extracts of some Alnus species have immunostimulatory properties and are used in anticancer therapy (13)(14)(15).…”

Pharmacological Assessment, Green synthesis and Characterization of Silver Nanoparticles of Sonneratia apetala Buch.-Ham. Leaves

“…Moreover, these phytochemicals are responsible for the stabilization of AgNPs. Several earlier reports correlated the plant phytochemicals with their bioactive attributes and reported the antibacterial and free radical scavenging activities of the phytochemical constituents (Ali et al, 2002;Dahija et al, 2014;Medini et al, 2014;Mohammed et al, 2014;Lunga et al, 2014). The quantity of phytochemical components may vary with the plant part, leaf and stem (Patra et al, 2011).…”

“…AgNPs forms free radicals which can be considered as another reason for the death of cells. Some Electron Spin Resonance Spectroscopy studies demonstrated that free radicals may be formed by the AgNPs when they are in contact with the bacteria, and these free radicals are able to disrupt the cell membrane and make it permeable which can finally lead to cell death (Danilcauk et al, 2006;Kim et al, 2007). These nanoparticles have been shown to accumulate inside the membrane and can subsequently penetrate into the cells causing damage to cell wall or cell membranes.…”