Abstract
Due to the rapidly growing bacterial antibiotic-resistance and the scarcity of novel agents in development, bacterial infection is still a global problem. Therefore, new types of antibacterial agents, which are effective both alone and in combination with traditional antibiotics, are urgently needed. In this paper, a series of antibacterial ocotillol-type C-24 epimers modified from natural 20(S)-protopanaxadiol were synthesized and evaluated for their antibacterial activity. According to the screening results of Gram-positive bacteria (B. subtilis 168 and MRSA USA300) and Gram-negative bacteria (P. aer PAO1 and A. baum ATCC19606) in vitro, the derivatives exhibited good antibacterial activity, particularly against Gram-positive bacteria with an minimum inhibitory concentrations (MIC) value of 2–16 µg/mL. The subsequent synergistic antibacterial assay showed that derivatives 5c and 6c enhanced the susceptibility of B. subtilis 168 and MRSA USA300 to chloramphenicol (CHL) and kanamycin (KAN) (FICI < 0.5). Our data showed that ocotillol-type derivatives with long-chain amino acid substituents at C-3 were good leads against antibiotic-resistant pathogens MRSA USA300, which could improve the ability of KAN and CHL to exhibit antibacterial activity at much lower concentrations with reduced toxicity.
Highlights
Therapeutic control of multidrug resistant bacteria has been emphasized in the area of global
As previously described [20], in the synthesis of epimers OS and OR, PPD was chosen as the starting material
The (24S)-configuration is preferred for pharmacological activity of compounds without substitution at 3-OH; substitution at 3-OH may cause changes of molecular conformation resulting in bioactive (24R)-compounds [21,25]; hydrogen donors at C-3 positions are the effective group and enhance the antibacterial activity against Gram-positive bacteria [21,23,25]; the length of
Summary
Therapeutic control of multidrug resistant bacteria has been emphasized in the area of global. The generation of drug-resistant bacteria, such as MRSA USA300, has developed blood-borne infection, MRSA USA 300 could cause lethal diseases, including severe sepsis, necrotizing much faster than the development of new antimicrobial drugs. There is an hematopoietic urgent need tosystem develop (KAN) has many side effects, ototoxicity, renal toxicity, novel antibacterial agents to cure antibiotic-resistant bacteria infections, can be used or in toxicity and neuromuscular blocking effects etc. Novel antibacterial agents to cure antibiotic-resistant bacteria infections, which can be used alone or Natural products have beenantibiotics the mostto effective of leading compounds for the in combination with traditional enhancesource their effectiveness and reduce their sidedevelopment effects. These compounds have been used in traditional medicine and been studied for their anti-inflammatory, antimicrobial, anticancer and anti-HIV effects [14,15,16,17]. Ocotillol-type derivatives, followed by antibacterial evaluations, are described in this study
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