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Terpenes: A Source of Novel Antimicrobials, Applications and Recent Advances
Published in Mahendra Rai, Chistiane M. Feitosa, Eco-Friendly Biobased Products Used in Microbial Diseases, 2022
Nawal M. Al Musayeib, Amina Musarat, Farah Maqsood
Togashi et al. (2010) screened the inhibitory potential of several terpene alcohols with a different length of aliphatic carbon chains such as linalool (C6), geraniol (C8), nerolidol (C10), plaunotol (C11), farnesol (C12) and geranylgeraniol and phytol (C16) (the numbering is from the first carbon bonded to the hydroxyl group) on the growth of S. aureus. Among all the tested compounds, only farnesol and nerolidol showed strong antibacterial activity with MBC as 20 and 40 μg/mL, respectively. They also investigated the interaction of these terpene alcohols with the cell membrane of bacteria by evaluating the leakage of intracellular K+ ion. They proposed that K+ leakage from the cells reflects the antibacterial potency of the membrane disturbing compounds. The initial rate of leakage was considered as the damage to the cell membranes while the total amount of leaked K+ was evaluated as the antibacterial activity. Again, farnesol and nerolidol were the most effective compounds. Finally, they concluded that the length of the hydrocarbon chain connected to the hydroxyl group, plays an important role in antibacterial and cell membrane disrupting activity and it should be between C10 and C12 for appropriate effect against S. aureus (Togashi et al. 2010).
A Brief Background
Published in Nathan Keighley, Miraculous Medicines and the Chemistry of Drug Design, 2020
Two organic molecules can be composed of the exact same proportions of atoms in other words have the same molecular formula, but the way in which the atoms are arranged may be completely different to give two unique molecules. These are termed isomers. There are three different types of structural isomerism. The functional group may be placed at different positions on the carbon chain in positional isomers, or the atoms may be arranged in such a way to give a different functional group, known as functional group isomerism. Equally, it can be the hydrocarbon chain itself that is arranged differently to give different chain isomers.
Antifungal Drugs and Susceptibility Testing of Fungi
Published in Rossana de Aguiar Cordeiro, Pocket Guide to Mycological Diagnosis, 2019
Débora de Souza Colares Maia Castelo-Branco, Glaucia Morgana de Melo Guedes, Marcos Fábio Gadelha Rocha
Since the 1950s, the fungicidal polyenes, such as nystatin and amphotericin B, have been used as a powerful but highly toxic last line of defense against invasive fungal infections. These are amphipathic fungicidal drugs consisting of a hydrophobic polyene hydrocarbon chain and a hydrophilic polyhydroxyl chain. For decades, the prevailing theory was that these molecules directly bound to the ergosterol molecule embedded in the phospholipid bilayer of the fungal cell membrane, creating pores on the plasmatic membrane, leading to leakage of cellular components and death. However, recent biophysical studies highlighted that polyenes act like an “ergosterol-sponge,” forming large extramembranous aggregates that extract the essential membrane-lipid ergosterol from the plasma membrane (Robbins et al., 2016). Table 2.1 shows a summary of antifungal drugs and their mechanisms of action and uses. Nystatin is highly toxic and is only available for topical use in the form of cutaneous and/or mucosal creams. Considering it is not absorbed by the gastrointestinal tract, nystatin is also available as an oral suspension to be used as a topical treatment for oral candidiasis. Amphotericin B, on the other hand, is available for systemic use, despite its toxicity, and it is currently the last-line treatment for systemic fungal infections. Lipid, liposomal, and colloidal formulations of amphotericin B have been developed as an attempt to decrease its toxicity, but they are much more expensive than the regular deoxycholate formulation.
Protein-liposome interactions: the impact of surface charge and fluidisation effect on protein binding
Published in Journal of Liposome Research, 2023
Efstathia Triantafyllopoulou, Natassa Pippa, Costas Demetzos
As far as the DSC profiles of DPPC, HSPC, and DSPC during heating is concerned, pure phospholipids exhibit high cooperativity due to their sharp peaks, while their main phase transition temperatures (Tm) are 41.38 °C, 53.50 °C, and 55.42 °C, respectively. According to literature the main factor, which affect phase transition temperature is hydrocarbon chain length. For pure phospholipids with the same polar head group and saturated acyl chains as the above, longer chains lead to stronger hydrophobic interactions, denser packing, and eventually higher Tm (Koynova and Caffrey 1998, Binder et al.2003, Zhao and Feng 2004, Li et al.2015). That is the reason for the gradual increase of Tm from DPPC to DSPC. All three profiles present a pretransition event due to their polar head group’s nature, which is centred at 34.96 °C, 49.08 °C, and 52.42 °C for DPPC, HSPC, and DSPC, respectively. Pretransitions started at 31.83 °C for the DPPC bilayer, 45.90 °C for HSPC, and 50.63 °C for the DSPC system with their enthalpy values being quite low 12 J/mol, 22 J/mol, and 32 J/mol, accordingly. ΔΤ½,s values are also presented thoroughly in Table 2. The cooling profiles of DPPC, HSPC, and DSPC (Table S1) indicate that there is only a slight hysteresis at the main transition temperature and as a result, the process is considered reversible. However, there is not another thermal event in the cooling thermogram equivalent to pretransition signifying that pretransition is non-reversible.
Vesicle formation mechanisms: an overview
Published in Journal of Liposome Research, 2021
The lipid structures, i.e. chain length, unsaturation, and polar head charge, are the other important parameters that influence the size of the vesicle. The hydrocarbon chain length and unsaturation in the chain affect the bending modulus. Shorter acyl chains and those with unsaturated bonds will have smaller bilayer thickness (Boal 2012). This lowers the et al. 2000) and also the et al. 2004). Some studies report that shorter chains result in larger vesicles (Phapal et al. 2017, Has et al. 2018), while some reports smaller vesicles with shorter chains (Phapal and Sunthar 2013). Therefore, from the qualitative dependence of 1992), May (1996), Vlahovska et al. (2009). The inclusion of a charged lipid into the bilayer diminishes the probability for vesicle aggregation or fusion, increasing their physical stability (Bozzuto and Molinari 2015).
Lipid-based nano-formulation platform for eplerenone oral delivery as a potential treatment of chronic central serous chorioretinopathy: in-vitro optimization and ex-vivo assessment
Published in Drug Delivery, 2021
Eman Abdelhakeem, Mohamed El-Nabarawi, Rehab Shamma
EPL-loaded NLCs were successfully prepared using the emulsification solvent evaporation method. All the prepared systems were homogenous and showed no signs of precipitation or phase separation. GMS was chosen as solid lipid to prepare EPL-loaded NLCs, owing to its inherent self-emulsifying property and low cytotoxicity. Solid lipids of long hydrocarbon chain (more than C12) are characterized by low HLB values and high solubilizing power so they are preferred as lipid excipients (Patil-Gadhe & Pokharkar, 2014). Miglyol® 812N was selected as the liquid lipid, being a medium chain triglyceride with a unique class of saturated lipids, in addition to its ability to act as emulsifier and suspender. It is well known that medium chain triglycerides excipients composed of C6–12 fatty acids, such as Miglyol® 812N are easily absorbed from the intestine (Furuse et al., 1992). Regarding the surfactants, Pluronic® F127, Solutol®HS15, and Cremophor® RH40 were evaluated as nonionic surfactants in the preparation of EPL-loaded NLCs, due to their low toxicity and high hydrophilicity and compatibility. Further, the used solvent mixture (ethanol:acetone mixture) was selected based on its ability to solubilize drug, solid lipid, and liquid lipid results in their thorough and uniform drug–lipid association (Hu et al., 2002, 2005).