Curcumin potentiates the fungicidal effect of dodecanol by inhibiting drug efflux in wild-type budding yeast

Tackling multi-drug resistant fungi by efflux pump inhibitors

The emergence of multidrug-resistant fungi is of grave concern, and its infections are responsible for significant deaths among immunocompromised patients. The treatment of fungal infections primarily relies on a clinical class of antibiotics, including azoles, polyenes, echinocandins, polyketides, and a nucleotide analogue. However, the incidence of fungal infections is increasing as the treatment for human and plant fungal infections overlaps with antifungal drugs. The need for new antifungal agents acting on different targets than known targets is undeniable. Also, the pace at which loss of fungal susceptibility to antibiotics cannot be undermined. There are several modes by which fungi can develop resistance to antibiotics, including reduced drug uptake, drug target alteration, and a reduction in the cellular concentration of the drug due to active extrusions and biofilm formation. The efflux pump's overexpression in the fungi primarily reduced the antibiotic's concentration to a sub-lethal concentration, thus responsible for developing resistant fungus strains. Several strategies are used to check antibiotic resistance in multi-drug resistant fungi, including synthesizing antibiotic analogs and giving antibiotics in combination therapies. Among them, the efflux pump protein inhibitors are considered potential adjuvants to antibiotics and can block the efflux of antibiotics by inhibiting efflux pump protein transporters. Moreover, it can sensitize the antifungal drugs to multi-drug resistant fungi with overexpressed efflux pump proteins. This review discusses the natural lead molecules, repurposable drugs, and formulation strategies to overcome the efflux pump activity in the fungi.

Terpenoids are involved in the expression of systemic-induced resistance in Austrian pine

Terpenoids are defense metabolites that are induced upon infection or wounding. However, their role in systemic-induced resistance (SIR) is not known. Here, we explored the role of terpenoids in this phenomenon at a very early stage in the interaction between Austrian pine and the tip blight and canker pathogen Diplodia pinea. We induced Austrian pine saplings by either wounding or inoculating the lower stems with D. pinea. The seedlings were then challenged after 12 h, 72 h, or 10 days with D. pinea on the stem 15 cm above the induction. Lesion lengths and terpenoids were quantified at both induction and challenge locations. Key terpenoids were assayed for antifungal activity in in vitro bioassays. SIR increased with time and was correlated with the inducibility of several compounds. α-Pinene and a cluster of β-pinene, limonene, benzaldehyde, dodecanol, and n-dodecyl acrylate were positively correlated with SIR and were fungistatic in vitro, while other compounds were negatively correlated with SIR and appeared to serve as a carbon source for D. pinea. This study shows that, overall, terpenoids are involved in SIR in this system, but their role is nuanced, depending on the type of induction and time of incubation. We hypothesize that some, such as α-pinene, could serve in SIR signaling.

Uncoupler SYP-14288 inducing multidrug resistance of Phytophthora capsici through overexpression of cytochrome P450 monooxygenases and P-glycoprotein

BACKGROUND

Fungicide resistance has become a serious problem for different mode of action groups except for uncouplers, which makes their resistance mechanism a hot topic, which until now, has not been well clarified. SYP-14288, a newly developed diarylamine fungicide modeled on fluazinam, has shown good toxicity to both oomycete and fungus by the action of uncoupling. In this research, the resistance of Phytophthora capsici to SYP-14288 was studied to clarify the resistance mechanism of uncouplers.

RESULTS

The toxicity tests of resistant strains against SYP-14288 showed multidrug resistance. The high-performance liquid chromatography (HPLC) results showed that resistant strains could efflux the fungicide, and this ability could be inhibited by the efflux pump inhibitor amitriptyline. The target protein of amitriptyline is P-glycoprotein (P-gp), which was overexpressed in resistant strains. Three products of nitrate reduction of SYP-14288 were detected and determined by HPLC-Q-TOF. Eight cytochrome P450 monooxygenase (P450) proteins were differentially involved in the reduction reaction.

CONCLUSION

Both fungicide efflux and detoxification metabolism were involved in the resistance mechanisms of P. capsici to SYP-14288. © 2022 Society of Chemical Industry.

Structure-activity relationships of antifungal phenylpropanoid derivatives and their synergy with n-dodecanol and fluconazole

trans-Anethole (anethole) is a phenylpropanoid; with other drugs, it exhibits synergistic activity against several fungi and is expected to be used in new therapies that cause fewer patient side effects. However, the detailed substructure(s) of the molecule responsible for this synergy has not been fully elucidated. We investigated the structure-activity relationships of phenylpropanoids and related derivatives, with particular attention on the methoxy group and the double bond of the propenyl group in anethole, as well as the length of the p-alkyl chain in p-alkylanisoles. Antifungal potency was largely related to p-alkyl chain length and the methoxy group of anethole, but not to the double bond of its propenyl group. Production of reactive oxygen species also played a role in these fungicidal activities. Inhibition of drug efflux was associated with the length of the p-alkyl chain and the double bond of the propenyl group in anethole, but not with the methoxy group. Although a desirable synergy was observed between n-dodecanol and anethole or p-alkylanisoles with a length of C2-C6 in alkyl chains, it cannot be explained away as being solely due to the inhibition of drug efflux. Similar results were obtained when phenylpropanoid derivatives were combined with fluconazole against Candida albicans.

Anti-Candida Activity of Curcumin: A Systematic Review

Curcumin is one of the important natural compounds that is extracted from turmeric. This compound and its derivatives have numerous biological properties, including antioxidant, anticancer, anti-inflammatory, antimicrobial, and healing effects. Extensive research in various fields has been conducted on turmeric as it is widely used as a food additive. The significant antifungal activity is one of the major effects of curcumin. In this paper, recent studies on the effects of different forms of curcumin drug on the candidiasis were systematically examined and discussed. The data in this study were extracted from the articles and reports published in the Web of Science, Google Scholar, PubMed, and Scopus databases. After the preliminary investigation, relevant reports were selected and classified based on the incorporated formulation and purpose of the study. After a systematic discussion of the data, it was found that the use of medicinal forms based on nanoparticles can increase the absorption and target the controlled release of curcumin with a more effective role compared to other formulations. Consequently, it can be concluded that new methods of modern medicine can be employed to increase the efficacy of natural pharmaceutical compounds used in the past. In this regard, the present study analyzed the effect of curcumin against various Candida infections, using the recent data. It was found that applying a combination of drug formulation or the formulation of curcumin and its derivatives can be an effective strategy to overcome the medicine resistance in fungal infections, especially candidiasis.

Plant Phytochemicals in Food Preservation: Antifungal Bioactivity: A Review

Synthetic food additives generate a negative perception in consumers. This fact generates an important pressure on food manufacturers, searching for safer natural alternatives. Phytochemicals (such as polyphenols and thiols) and plant essential oils (terpenoids) possess antimicrobial activities that are able to prevent food spoilage due to fungi (e.g., Aspergillus, Penicillium) and intoxications (due to mycotoxins), both of which are important economic and health problems worldwide. This review summarizes industrially interesting antifungal bioactivities from the three main types of plant nutraceuticals: terpenoids (as thymol), polyphenols (as resveratrol) and thiols (as allicin) as well as some of the mechanisms of action. These phytochemicals are widely distributed in fruits and vegetables and are very useful in food preservation as they inhibit growth of important spoilage and pathogenic fungi, affecting especially mycelial growth and germination. Terpenoids and essential oils are the most abundant group of secondary metabolites found in plant extracts, especially in common aromatic plants, but polyphenols are a more remarkable group of bioactive compounds as they show a broad array of bioactivities.