Flavonoids from Praxelis clematidea R.M. King and Robinson Modulate Bacterial Drug Resistance

Abstract

Chemical studies of Praxelis clematidea R.M. King & Robinson resulted in the isolation of six flavones: Apigenine, genkwanine, 7,4’-dimethylapigenin, trimethylapigenin, cirsimaritin and tetramethylscutellarein, which were tested for their toxicity against Staphylococcus aureus SA-1199B, a strain possessing the NorA efflux pump. Efflux pumps are integral proteins of the bacterial membrane and are recognized as one of the main causes of bacterial drug resistance, since they expel antibiotics from the cell. The inhibition of this transporter is one form of modulating bacterial resistance to antimicrobial drugs. The flavones tested did not show any significant antibacterial activity against the Staphylococcus aureus strain used, but were able to modulate bacterial drug resistance. This property might be related to the degree of lipophilicity of the flavones conferred by the methoxyl groups, since 4’,5,6,7 tetramethoxyflavone the most methoxylated compound, reduced the minimal inhibitory concentration of the drug 16-fold.

The Essential Oil from <b><i>Origanum vulgare</i></b> L. and Its Individual Constituents Carvacrol and Thymol Enhance the Effect of Tetracycline against <b><i>Staphylococcus aureus</i></b>

“…These findings indicate that the compounds tested inhibit the activity (or even the expression) of TetK efflux protein, but not of NorA and Msr efflux proteins. This activity may be related to the lipophilicity of the assayed plant compounds, which is a common feature of several putative EPIs, such as methoxylate flavonoids [12], natural amphipathic compounds [13] or even synthetic compounds [14]. …”

“…King and Robinson, Asteraceae family, modulated the NorA efflux protein in S. aureus . In these studies, the antibiotic resistance-modulating effects were also related to the degree of lipophilicity of the tested compounds - particularly the presence of methoxyl groups [17]. …”

Alternative therapies in Staphylococcus aureus diseases.

“…Flavonoids are heterocyclic compouds present in pigment plants in leaves, flowers and fruit. They are divided into 14 classes on the basis of the general structure (Cushnie & Lamb, 2011;Maia et al, 2011;Oh et al, 2011). They have a broad spectrum of biological activity such as antioxidant, anticancer, immunomodulatory, antiviral, antifungal and antimicrobial (Kilani-Jaziri et al, 2011;Fraga et al, 2010;Ozcelik et al, 2011).…”

“…Moreover, those authors proved that due to the lipophilic nature the 3-arylideneflavones influence the cel-membrane integrity causing the bacterial growth inhibition. Another mechanism of antimicrobial activity of flavonoids is modulation of antibiotic resistance (Cushnie & Lamb, 2011;Maia et al, 2011). Maia et al (2011) revealed that six flavones isolated from Praaxelis clematidea.…”

Protective effect of cirsimaritin against streptozotocin-induced apoptosis in pancreatic beta cells

“…[16] Cirsimaritin is flavonoid isolated from Cirsium spp. [17] and exhibits a variety of pharmacological activities including anti-inflammatory, [18] antibacterial, [19,20] antioxidant, [21][22][23][24] anti-anxiety, [25] antispasmodic, [26,27] antiproteinuria, [28] bacterial drug resistance, [29] cyclooxygenase-1 inhibitory, [18] renal protective [30,31] and melanogenic activities. [32] In addition, it has been suggested to have cytotoxic activity against the following human tumour cell lines: gallbladder carcinoma, GBC-SD and GBCSD18H; gastric carcinoma, BGC-823; hepatoma, SMMC-7721.…”