<i>In Vitro</i> Antibacterial Activity of Flavonoid Extracts of Two Selected Libyan Algae against Multi-Drug Resistant Bacteria Isolated from Food Products

Abstract

This study aimed to evaluate the antibacterial activity of flavonoids extracted from two Libyan brown algae namely Cystoseira compressa and Padina pavonica using microwave-assisted extraction method against pathogenic bacteria isolated from meat, meat products, milk and dairy products (Staphylococcus aureus subsp. aureus (5 isolates), Bacillus cereus (3 isolates), Bacillus pumilus (1 isolate), Salmonella enterica subsp. enteric (4 isolates) and Enterohaemorrhagic Escherichia coli O157 (EHEC O157) (4 isolates)). All of these isolates were muti-drug resistant with high MAR index. The results showed that C. compressa extract exhibited better and stronger antibacterial activities against the seventeen tested isolates with inhibition zones diameter ranged from 14 -22 mm compared to P. pavonica extract which showed positive effect against 9 isolates with low inhibition zone ranged from 11 -16.5 mm. Flavonoids extracted from C. compressa also displayed the best spectrum of bactericidal effect with a ratio MBC/MIC ≤ 4 obtained on all susceptible tested bacterial strains. Flavonoids and proanthocyanidins significantly contributed to the antibacterial properties. The mode of action of these active extracts is under investigation.

Rinsing effect of 60% bay leaf (Syzygium polyanthum wight) aqueous decoction in inhibiting the accumulation of dental plaque during fixed orthodontic treatment

“…30,31 Moreover, their mode of antimicrobial action may be related to their ability to inactivated microbial adhesion, enzymes and cell envelope transport proteins. 32 The antibacterial activity of BL can be also due to compounds non-flavonoid origin. The high contents of eugenol, methyl eugenol and fatty acid methyl esters together with other active components could contribute to its overall antibacterial activity.…”

Antibacterial Activity of Bawang Dayak (Eleutherine Sp.) and Tawas Ut (Ampelocissus Sp.) From Central Kalimantan Against Propionibacterium Acnes

“…Therefore, it was justified that terpenoid compound was able to destroy the permeability of the bacterial membrane [19]. Flavonoid significantly contributed to the antibacterial properties [20].…”

Anti-bacterial Activity of Crude Flavonoid Fraction from Bidens pilosa Leaves against Selected Chronic Wound Bacterial Pathogens

“…The antibacterial sensitivity study for crude flavonoid fraction of B. pilosa was done by agar well diffusion method according to Alghazeer et al [22] but with slight modification where the concentration of the extract of flavonoid fraction of this study was increased at a concentration of 500 mg/mL. The bacterial inoculum of 1.5 × 10^ 8 CFU/mL was surface spread on pre-prepared Mueller-Hinton agar (MHA) media using a sterile cotton swab.…”

“…The MIC is defined as the lowest concentration that completely inhibits the growth of test bacteria within 24 hours of incubation. The MIC for the crude flavonoid fraction extracts was determined by the macro-broth dilution method according to Alghazeer et al [22] with modification of increasing in the initial concentration of the crude flavonoid fraction extract to 800 mg/mL. In this method, a two-fold serial dilution of the flavonoid extracts was prepared in test tubes containing 1 mL of sterile freshly prepared Mueller-Hinton broth used as diluents to achieve a decreasing concentration ranging from 800 mg/mL to 0.0244 mg/mL.…”