Unveiling the bioactive potential of the essential oil of a Portuguese endemism, Santolina impressa

Exploring the Chemical Profile, In Vitro Antioxidant and Anti-Inflammatory Activities of Santolina rosmarinifolia Extracts

In this study, the phytochemical composition, in vitro antioxidant, and anti-inflammatory effects of the aqueous and 60% ethanolic (EtOH) extracts of Santolina rosmarinifolia leaf, flower, and root were examined. The antioxidant activity of S. rosmarinifolia extracts was determined by 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assays. The total phenolic content (TPC) of the extracts was measured by the Folin-Ciocalteu assay. The anti-inflammatory effect of the extracts was monitored by the Griess assay. The chemical composition of S. rosmarinifolia extracts was analysed using the LC-MS technique. According to our findings, 60% EtOH leaf extracts showed the highest Trolox equivalent antioxidant capacity (TEAC) values in both ABTS (8.39 ± 0.43 µM) and DPPH (6.71 ± 0.03 µM) antioxidant activity assays. The TPC values of the samples were in good correspondence with the antioxidant activity measurements and showed the highest gallic acid equivalent value (130.17 ± 0.01 µg/mL) in 60% EtOH leaf extracts. In addition, the 60% EtOH extracts of the leaves were revealed to possess the highest anti-inflammatory effect. The LC-MS analysis of S. rosmarinifolia extracts proved the presence of ascorbic acid, catalpol, chrysin, epigallocatechin, geraniol, isoquercitrin, and theanine, among others, for the first time. However, additional studies are needed to investigate the direct relationship between the chemical composition and physiological effects of the herb. The 60% EtOH extracts of S. rosmarinifolia leaves are potential new sources of natural antioxidants and anti-inflammatory molecules in the production of novel nutraceutical products.

Antimicrobial activity of essential oils against biofilms formed in dental acrylic resin: a systematic review of in vitro studies

This study aimed to answer the question formulated according to the PICO strategy: 'Which essential oils show antimicrobial activity against biofilms formed on dental acrylic resin?' composed by population (dental acrylic resin), intervention (application of essential oils), comparison (denture cleansers, antifungal drugs, chlorhexidine, and oral mouthwashes), and outcome (antibiofilm activity). In vitro experimental studies evaluating the activity of EOs on biofilm formed on acrylic resin were included. PRISMA guidelines were followed, and the search was performed in the PubMed, Science Direct, Embase, and Lilacs databases and in the gray literature using Google Scholar and ProQuest in December 2023. A manual search of the reference lists of the included primary studies was performed. Of the 1467 articles identified, 37 were selected for full-text reading and 12 were included. Twelve EOs were evaluated, of which 11 showed activity against Candida spp., 3 against Staphylococcus aureus, and 1 against Pseudomonas aeruginosa. The EOs of Cymbopogon citratus, Cinnamomum zeylanicum, and Cymbopogon nardus showed higher action than chlorhexidine, C. nardus higher than Listerine, C. citratus higher than nystatin, and Melaleuca alternifolia higher than fluconazole and nystatin. However, chlorhexidine was more effective than Lippia sidoides and Salvia officinalis, sodium hypochlorite was more effective than L. sidoides, nystatin was more effective than Zingiber officinale, Amphotericin B more effective than Eucalyptus globulus and M. alternifolia. In conclusion, the EOs of C. zeylanicum, C. citratus, C. nardus, and M. alternifolia showed antimicrobial activity to reduce biofilm on dental acrylic resin.

Development of gel containing Psidium glaziovianum essential oil has in vitro antimicrobial activity and improves healing of excisional wounds in mice

Wounds encompass physical, chemical, biological, induced damages to the skin or mucous membranes. In wound treatment, combating infections is a critical challenge due to their potential to impede recovery and inflict systemic harm on patients. Previously, the essential oil extracted from Psidium glaziovianum (PgEO) demonstrated antinociceptive and anti-inflammatory attributes, along with negligible oral toxicity. Hence, our study aimed to assess the effects of topically applying a gel formulation containing PgEO to excisional wounds in mice. Additionally, an in vitro antimicrobial assessment was conducted. The formulated gel underwent characterization and toxicological evaluation on erythrocytes, as well as a dermal irritation test. Its antimicrobial activity was tested against both gram-positive and gram-negative bacteria, as well as fungi. Subsequently, an assessment of its efficacy in excisional wound healing was conducted in mice. The findings of this investigation highlight the gel's efficacy against both gram-positive and gram-negative bacteria, as well as fungi. Moreover, this study underscores that the PgEO-gel treatment enhances skin wound healing, potentially due to its capacity to trigger antioxidant enzymes and suppress pro-inflammatory cytokines. Furthermore, the gel exhibited minimal toxicity to erythrocytes and skin irritation. These findings hold promise for prospective preclinical and clinical trials across diverse wound types. In conclusion, this study sheds light on the potential therapeutic applications of the gel formulation containing essential oil from P. glaziovianum in the context of wound healing.

The Metschnikowia pulcherrima Clade as a Model for Assessing Inhibition of Candida spp. and the Toxicity of Its Metabolite, Pulcherrimin

Candidiasis is one of the most frequent infections worldwide. In this study, the antimicrobial properties of six strains belonging to the Metschnikowia pulcherrima clade were evaluated against twenty Candida and Candida-related Filobasidiella neoformans var. bacillispora (syn. Cryptococcus neoformans) of different origins, employing the agar cross method. The toxic effect of pulcherrimin, a red metabolite that is responsible for the antimicrobial activities of Metschnikowia spp., was evaluated in various experimental models. The results of agar tests showed that the selected M. pulcherrima strains inhibited the growth of the Candida and non-Candida strains. However, inhibition was dependent on the strain and the environment. The presence of peptone, sodium silicate, and a higher incubation temperature decreased the antifungal action of the M. pulcherrima strains. Pulcherrimin showed cytotoxic and antiproliferative activity, with oxidative stress in cells leading to apoptosis. More research is needed on the mechanism of action of pulcherrimin on somatic cells.

New Reports on the Portuguese Endemic Species, Santolina impressa: Secretory Structures, Essential Oil Composition and Antiviral Activity

Santolina impressa is an aromatic Asteraceae species endemic to Portugal, traditionally used for its anti-inflammatory properties. The aim of this study was to characterize S. impressa secretory structures, analyze the essential oil (EO) from the aerial organs, and evaluate its antiviral activity against herpes simplex viruses HSV-1 and HSV-2. Secretory structures were investigated by light and scanning microscopy, and the secretion was histochemically characterized. The EO from the aerial organs in full blooming was analyzed by gas chromatography with flame ionization detection and gas chromatography-mass spectrometry. Antiviral assays were performed by direct contact with viral suspensions (virucidal effect), and in infected Vero E6 cells, at different time periods during the viral replication cycle. Two types of secretory structures were described, biseriate glandular trichomes and secretory ducts, producing an oleoresin and a resin rich in flavonoids, respectively. Fifty compounds were identified in S. impressa EO, accounting for 87% of the total constituents. Monoterpenes constituted the main EO fraction (82%), with β-pinene (13%) and β-phellandrene (10%) being their major components. The EO interacted with HSV-1 and HSV-2 in a dose-dependent manner, thereby inactivating both viral infections. The EO did not evidence a virucidal effect but inhibited the HSV-1 and HSV-2 infection in Vero cells in a dose-dependent manner. However, further studies are needed to investigate the mode of action in the replication cycle.

The Cytotoxic and Inhibitory Effects of Plant Derivatives on Candida albicans Biofilms: A Scoping Review

Candida albicans infections are related to biofilm formation. The increase in antifungal resistance and their adverse effects have led to the search for therapeutic options as plant derivatives. This scoping review aims to identify the current status of in vitro research on the cytotoxicity and inhibitory effects of plant derivatives on C. albicans biofilms. In this study, PRISMA items were followed. After recognition of the inclusion criteria, full texts were read and disagreements were resolved with a third party. A risk of bias assessment was performed, and information was summarized using Microsoft Office Excel. Thirty-nine papers fulfilling the selection criteria were included. The risk of bias analysis identified most of the studies as low risk. Studies evaluated plant derivatives such as extracts, essential oils, terpenes, alkaloids, flavonoids and polyphenols. Some studies evaluated the inhibition of C. albicans biofilm formation, inhibition on preformed biofilms or both. The derivatives at concentrations greater than or equal to those that have an inhibitory effect on C. albicans biofilms, without showing cytotoxicity, include magnoflorin, ellagic acid, myricetin and eucarobustol from Eucalyptus robusta and, as the works in which these derivatives were studied are of good quality, it is desirable to carry out study in other experimental phases, with methodologies that generate comparable information.

Effects of Macroautophagy and Mitophagy on the Pathogenicity of Fusarium graminearum

Fusarium graminearum is the main pathogen of Fusarium head blight (FHB), which causes huge economic losses every year. In this study, an attempt was made to control FHB from the point of view of the physiological behavior of the pathogen itself. Autophagic inhibitors and activators were used, and the pathogenicity-related indices of F. graminearum were measured. The results showed that under nitrogen-rich conditions, macroautophagy inhibition and activation greatly reduced the mycelium weight to 0.28 and 0.25 g/ml at 24 h, which were 17.82 and 24.77% lower than that of the control treatment, respectively. Mitophagy inhibition also significantly decreased the mycelium weight (P < 0.05). Conidial yield was found to be affected by factors related to autophagy occurrence. It was found that both autophagy inhibition and activation could reduce the conidiation of F. graminearum. The toxin contents in wheat medium of macroautophagy activation treatments were 0.678, 0.190, 0.402, and 0.195 μg/g when cultured for 8 and 24 h under 0% N and 100% N conditions, respectively, which were significantly higher than those of the control treatments (P < 0.05). The infection length was measured to characterize the infectivity of F. graminearum, and we found that the length was short under macroautophagy activation conditions. However, mitophagy did not seem to affect the infectivity of F. graminearum. In summary, the above results indicate that macroautophagy and mitophagy inhibition could reduce the pathogenicity of F. graminearum, which may provide a new perspective for management of plant fungal diseases.

Natural Compounds: A Hopeful Promise as an Antibiofilm Agent Against Candida Species

The biofilm communities of Candida are resistant to various antifungal treatments. The ability of Candida to form biofilms on abiotic and biotic surfaces is considered one of the most important virulence factors of these fungi. Extracellular DNA and exopolysaccharides can lower the antifungal penetration to the deeper layers of the biofilms, which is a serious concern supported by the emergence of azole-resistant isolates and Candida strains with decreased antifungal susceptibility. Since the biofilms' resistance to common antifungal drugs has become more widespread in recent years, more investigations should be performed to develop novel, inexpensive, non-toxic, and effective treatment approaches for controlling biofilm-associated infections. Scientists have used various natural compounds for inhibiting and degrading Candida biofilms. Curcumin, cinnamaldehyde, eugenol, carvacrol, thymol, terpinen-4-ol, linalool, geraniol, cineole, saponin, camphor, borneol, camphene, carnosol, citronellol, coumarin, epigallocatechin gallate, eucalyptol, limonene, menthol, piperine, saponin, α-terpineol, β-pinene, and citral are the major natural compounds that have been used widely for the inhibition and destruction of Candida biofilms. These compounds suppress not only fungal adhesion and biofilm formation but also destroy mature biofilm communities of Candida. Additionally, these natural compounds interact with various cellular processes of Candida, such as ABC-transported mediated drug transport, cell cycle progression, mitochondrial activity, and ergosterol, chitin, and glucan biosynthesis. The use of various drug delivery platforms can enhance the antibiofilm efficacy of natural compounds. Therefore, these drug delivery platforms should be considered as potential candidates for coating catheters and other medical material surfaces. A future goal will be to develop natural compounds as antibiofilm agents that can be used to treat infections by multi-drug-resistant Candida biofilms. Since exact interactions of natural compounds and biofilm structures have not been elucidated, further in vitro toxicology and animal experiments are required. In this article, we have discussed various aspects of natural compound usage for inhibition and destruction of Candida biofilms, along with the methods and procedures that have been used for improving the efficacy of these compounds.

Essential Oils in Respiratory Mycosis: A Review

Respiratory mycosis is a major health concern, due to the expanding population of immunosuppressed and immunocompromised patients and the increasing resistance to conventional antifungals and their undesired side-effects, thus justifying the development of new therapeutic strategies. Plant metabolites, namely essential oils, represent promising preventive/therapeutic strategies due to their widely reported antifungal potential. However, regarding fungal infections of the respiratory tract, information is disperse and no updated compilation on current knowledge is available. Therefore, the present review aims to gather and systematize relevant information on the antifungal effects of several essential oils and volatile compounds against the main type of respiratory mycosis that impact health care systems. Particular attention is paid to Aspergillus fumigatus, the main pathogen involved in aspergillosis, Candida auris, currently emerging as a major pathogen in certain parts of the world, and Cryptococcus neoformans, one of the main pathogens involved in pulmonary cryptococcosis. Furthermore, the main mechanisms of action underlying essential oils’ antifungal effects and current limitations in clinical translation are presented. Overall, essential oils rich in phenolic compounds seem to be very effective but clinical translation requires more comprehensive in vivo studies and human trials to assess the efficacy and tolerability of these compounds in respiratory mycosis.

Cinnamon and Eucalyptus Oils Suppress the Inflammation Induced by Lipopolysaccharide In Vivo

Inflammation caused by bacterial lipopolysaccharide (LPS) disrupts epithelial homeostasis and threatens both human and animal health. Therefore, the discovery and development of new anti-inflammatory drugs is urgently required. Plant-derived essential oils (EOs) have good antioxidant and anti-inflammatory activities. Thus, this study aims to screen and evaluate the effects of cinnamon oil and eucalyptus oil on anti-inflammatory activities. The associated evaluation indicators include body weight gain, visceral edema coefficient, superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), malondialdehyde (MDA), nitrogen monoxide (NO), interleukin-6 (IL-6), interleukin-10 (IL-10), tumor necrosis factor alpha (TNF-α), Urea, Crea, ALT, TLR4, MyD88, NF-κB, IκB-α, iNOS, and Mn-SOD. In addition, tissue injury was determined by H&E staining. The results revealed that cinnamon oil and eucalyptus oil suppressed inflammation by decreasing SOD, TNF-α, and NF-κB levels. We also found that cinnamon oil increased the level of GSH-Px, MDA, and Mn-SOD, as well as the visceral edema coefficient of the kidney and liver. Altogether, these findings illustrated that cinnamon oil and eucalyptus oil exhibited wide antioxidant and anti-inflammatory activities against LPS-induced inflammation.

Plant Preparations and Compounds with Activities against Biofilms Formed by Candida spp

Fungi from the genus Candida are very important human and animal pathogens. Many strains can produce biofilms, which inhibit the activity of antifungal drugs and increase the tolerance or resistance to them as well. Clinically, this process leads to persistent infections and increased mortality. Today, many Candida species are resistant to drugs, including C. auris, which is a multiresistant pathogen. Natural compounds may potentially be used to combat multiresistant and biofilm-forming strains. The aim of this review was to present plant-derived preparations and compounds that inhibit Candida biofilm formation by at least 50%. A total of 29 essential oils and 16 plant extracts demonstrate activity against Candida biofilms, with the following families predominating: Lamiaceae, Myrtaceae, Asteraceae, Fabaceae, and Apiacae. Lavandula dentata (0.045–0.07 mg/L), Satureja macrosiphon (0.06–8 mg/L), and Ziziphora tenuior (2.5 mg/L) have the best antifungal activity. High efficacy has also been observed with Artemisia judaica, Lawsonia inermis, and Thymus vulgaris. Moreover, 69 plant compounds demonstrate activity against Candida biofilms. Activity in concentrations below 16 mg/L was observed with phenolic compounds (thymol, pterostilbene, and eugenol), sesquiterpene derivatives (warburganal, polygodial, and ivalin), chalconoid (lichochalcone A), steroidal saponin (dioscin), flavonoid (baicalein), alkaloids (waltheriones), macrocyclic bisbibenzyl (riccardin D), and cannabinoid (cannabidiol). The above compounds act on biofilm formation and/or mature biofilms. In summary, plant preparations and compounds exhibit anti-biofilm activity against Candida. Given this, they may be a promising alternative to antifungal drugs.

Terpenoids as Potential Geroprotectors

Terpenes and terpenoids are the largest groups of plant secondary metabolites. However, unlike polyphenols, they are rarely associated with geroprotective properties. Here we evaluated the conformity of the biological effects of terpenoids with the criteria of geroprotectors, including primary criteria (lifespan-extending effects in model organisms, improvement of aging biomarkers, low toxicity, minimal adverse effects, improvement of the quality of life) and secondary criteria (evolutionarily conserved mechanisms of action, reproducibility of the effects on different models, prevention of age-associated diseases, increasing of stress-resistance). The number of substances that demonstrate the greatest compliance with both primary and secondary criteria of geroprotectors were found among different classes of terpenoids. Thus, terpenoids are an underestimated source of potential geroprotectors that can effectively influence the mechanisms of aging and age-related diseases.

Chemical characterization and bioactivity of the essential oil from Santolina insularis, a Sardinian endemism

Santolina insularis is a Sardinian endemism that is widely used in traditional medicine. The essential oil was obtained with a yield of 2.7% and is mainly characterized by β-phellandrene (22.6%), myrcene (11.4%) and artemisia ketone (7.6%). The oil significantly reduced NO production without affecting macrophages viability. In addition, it substantially inhibited the expression of two key pro-inflammatory enzymes, iNOS and COX-2 (71% and 25% at 0.54 mg/mL). Furthermore, the oil had a promising antifungal activity being Cryptococcus neoformans (MIC = 0.13 mg/mL) and the majority of dermatophytes (MIC = 0.13 mg/mL) the most susceptible fungi. Moreover, it significantly decreased the yeast-to-hypha transition (80% inhibition at 0.13 mg/mL) on C. albicans long before showing inhibitory effects. Overall, these results show that S. insularis could be applied in the treatment of fungal infections and associated inflammatory response.