Terpenes: A Source of Novel Antimicrobials, Applications and Recent Advances
Mahendra Rai, Chistiane M. Feitosa in Eco-Friendly Biobased Products Used in Microbial Diseases, 2022
Antimicrobial agents are composed of naturally occurring components, including phytochemicals and essential oils (Moo et al. 2019). They can exist in nature either as synthetic or semi-synthetic compounds (Rudramurthy et al. 2016). Natural phytochemicals with a molecular weight ≤ 500 g/mol may have ability to serve as antimicrobial adjuvants and exert synergistic effects (Langeveld et al. 2014; Barbieri et al. 2017). The exploration of new antimicrobial agents through microbial modification is an important alternative (Yu et al. 2010). The combination of an antimicrobial agent with a low molecular weight natural compound such as terpene and terpene derivatives has shown promising effects due to their ability to remove bacterial and fungal biofilm production (Zacchino et al. 2017). Terpenes and terpene derivatives are secondary metabolites commonly present in essential oils and have exhibited excellent antimicrobial effects against susceptible and resistant microorganisms (Thapa et al. 2015). Combination therapy between antimicrobial drugs and natural products may recover the lost function of existing drugs and potentiating drug action (Lewis and Kontoyiannis 2001). The potentiation of antimicrobial drugs was accomplished by various mechanisms in combinatorial therapy, multi-targeted pharmacokinetic potential, allowing simultaneous destruction of existing resistance mechanisms in a specific microorganism.
Polymer–Silver Nanocomposites: Preparation, Characterisation and Antibacterial Mechanism
Huiliang Cao in Silver Nanoparticles for Antibacterial Devices, 2017
In addition, the agar dilution method for determining antimicrobial susceptibility is also a well-established technique. The antimicrobial agent is incorporated into the agar medium, with each plate containing certain concentration of the agent. The inocula can be applied rapidly and simultaneously to the agar surfaces using a sterile swab capable of transferring 32 to 36 inocula to each plate. Record the MIC as the lowest concentration of antimicrobial agent that completely inhibits growth, disregarding a single colony or a faint haze caused by the inoculum. Table 5.1 shows the toxicity of Ag NPs as a function of particle size. It is not possible to extract a clear trend because of the variation of the nanoparticles used with respect to functionalisation and charge and the variation of the biological systems used.
Vinca rosea (Madagascar Periwinkle) and Adhatoda vesica (Malabar Nut)
Azamal Husen in Herbs, Shrubs, and Trees of Potential Medicinal Benefits, 2022
The phytochemical content and antioxidant activity of A. vasica leaves, total antioxidant activity, 2, 2 diphenyl-1-picrylhydrazyl radical-scavenging activity, reducing power potential, and iron-chelating activity were used to determine the antioxidant activity of A. vasica methanol extract. The agar well diffusion technique was used to test antimicrobial activity. Total phenolic content was determined using the Folin-Ciocalteu reagent technique, and total flavonoid content was determined using the aluminum chloride method. Saponins, oils and lipids, phytosterol, phenolic compounds, tannins, glucose, alkaloids, flavonoids, and proteins were discovered in the leaves of A. vasica. Various antioxidant tests revealed that the extract has a strong antioxidant activity. The presence of significant quantities of polyphenolic substances (phenolic compounds and flavonoids) in the extract of A. vasica may be the cause of the plant's antioxidant action. Furthermore, the extract exhibited moderate antibacterial and cytotoxic action (lethality of brine shrimp) (Kotakadi et al., 2013).
Inhibition of Candida albicans and Staphylococcus aureus biofilms by centipede oil and linoleic acid
Published in Biofouling, 2020
Yong-Guy Kim, Jin-Hyung Lee, Jae Gyu Park, Jintae Lee
Antimicrobial agents either inhibit bacterial growth or kill microorganisms, ideally without harming the host or the environment. However, overuse of these agents has caused the worldwide emergence of drug-resistant pathogens that pose serious life-threatening issues. Microbial biofilms produced by sessile communities play an important role in antimicrobial resistance and in a variety of device-related infections (Donlan 2002; Hall-Stoodley et al. 2004; Simoes et al. 2010). Multispecies biofilms of Candida albicans and Staphylococcus aureus already demonstrated increased tolerance to conventional antimicrobial agents (Harriott and Noverr 2009; 2011; Peters et al. 2013). Hence, alternative strategies are required to control these pathogenic biofilms. Unlike conventional strategies based on antimicrobial agents that aim to inhibit planktonic cell growth, it is important to reduce the risk of drug resistance (Wright 2015).
Is there a niche for zinc oxide nanoparticles in future drug discovery?
Published in Expert Opinion on Drug Discovery, 2023
ZnO nanoparticles associated with several biological effects could be the basis of therapeutic outcome. Among those reported in literature, antimicrobial activity is one of the most studied. The mechanism for the antimicrobial activity is based on reactive oxygen species (ROS) generation at the particle surface, release of zinc ion, and membrane dysfunction. Both antimicrobial and antibacterial activities are based on the generation of ROS on the surface of ZnO. Gram negative and positive spores resistant to high temperatures and high pressure can be killed with ZnO nanoparticles depending on both concentration and extent (exposure time). This activity is believed to result from generation of hydrogen peroxide and binding of particles to the surface of the bacteria with static forces. Particle size variation and surface area/volume ratio affect the antibacterial activity [1].
Formulation and performance evaluation of emulgel platform for combined skin delivery of curcumin and propolis
Published in Pharmaceutical Development and Technology, 2023
Rafaela Said dos Santos, Jéssica Bassi da Silva, Camila Felix Vecchi, Katieli da Silva Souza Campanholi, Hélen Cassia Rosseto, Mariana Carla de Oliveira, Francielle Pelegrin Garcia, Rodolfo Bento Balbinot, Lidiane Vizioli de Castro Hoshino, Tânia Ueda Nakamura, Celso Vataru Nakamura, Mauro Luciano Baesso, Wilker Caetano, Marcos Luciano Bruschi
The antimicrobial analysis was performed using the agar diffusion test. Moreover, the analysis was also performed using the application of light, considering the possible photodynamic activity of CUR, PRP, and the synergism between them (Afrasiabi et al. 2020; Fonseca et al. 2020; Kazantzis et al. 2020; Xie et al. 2022). All formulations with and without PE and CURC3 did not show an inhibition area for P. aeruginosa. This is an environmental Gram-negative bacterium, and opportunistic pathogen, that can cause a wide range of serious infections mainly in patients displaying compromised host defences (e.g. patients with severe burns and neutropenia) (Raz et al. 2019). In previous studies, PRP did not show photodynamic antimicrobial activity against Gram-negative strains like Escherichia coli (Fonseca et al. 2020), and it showed to be more effective in PDT against Gram-positive bacteria, such as S. aureus and S. mutans (Afrasiabi et al. 2020; Fonseca et al. 2020).
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