Tetraclinis articulata (Vahl) Mast.: Volatile constituents, antioxidant, antidiabetic and wound healing activities of its essential oil

Type 2 diabetes mellitus (T2DM) is a metabolic syndrome known to contribute to impaired wound healing. This condition can be further worsened by excessive melanin production, elastin degradation, and chronic infections at the wound site, potentially leading to melasma and diabetic dermopathy. The purpose of this study was to investigate the phytochemical profile and inhibitory effects of Tetraclinis articulata essential oil (TAEO) on target enzymes involved in diabetes pathogenesis and chronic wound remodeling, namely α-amylase, α-glucosidase, tyrosinase, and elastase, as well as its in vitro antibacterial activity. Gas chromatography and mass spectrometry (GC-MS) analysis of TAEO led to the identification of 46 volatile compounds, representing 96.61 % of TAEO. The major metabolites were bornyl acetate (29.48 %), α-pinene (8.96 %), germacrene D (7.70 %), and d-limonene (5.90 %). TAEO exhibited limited scavenging activity against DPPH free radicals, whereas the FRAP and ABTS assays indicated a relatively higher antioxidant activity. Remarkably, TAEO disclosed a promising in vitro antidiabetic activity against α-glucosidase with an IC50 value of 178 ± 1.6 μg/mL, which is comparable to the standard inhibitor acarbose (IC50 = 143 ± 1.1 μg/mL). In silico, molecular docking analysis against α-glucosidase identified 15 compounds that interacted with the enzyme's active site, whereas skin permeability and sensitization assessments indicated that 26 out of the 44 identified volatile compounds were predicted to be free from any skin sensitivity risk. On the other hand, moderate inhibitory activity was recorded against α-amylase, tyrosinase, and elastase. Notably, TAEO at 5 % significantly suppressed biofilm formation by P. aeruginosa, S. aureus, and E. faecalis, common skin pathogens associated with wound infections, and reduced their swarming motility. Our findings suggest that TAEO may hold the potential as a natural remedy for type 2 diabetes and its associated co-morbidities, especially chronic wounds.

Assessment of the different skin sensitization potentials of irritants and allergens as single substances and in combination using the KeratinoSens assay

BACKGROUND

People are exposed to mixtures containing allergens and irritants often causing contact dermatitis. Therefore, regulatory authorities require systematic information on the effects of mixtures on the sensitization threshold. In this study a moderate (cinnamal) and a weak (ethylene glycol dimethacrylate) allergen were combined with irritants covering different mechanisms of action (sodium dodecyl sulfate, salicylic acid, and α-pinene). For a systematic approach, the single substances were initially tested using the KeratinoSens assay. Thereafter, each allergen was combined with noncytotoxic concentrations of the irritants.

METHOD

The KeratinoSens assay was applied for the single substances according to OECD (Organisation for Economic Co-operation and Development) Test Guideline 442D. Based on these results, three noncytotoxic concentrations of the irritants were selected and applied simultaneously with 12 concentrations of the allergens to the KeratinoSens cells. Sensitization threshold and cytotoxicity were measured and compared with the individual testing.

RESULTS

The combinations of allergens and irritants differed from the effects of the single substances and lowered the sensitization threshold. The quantitative approach allowed a clear description of the changes which varied by factors between 1.1 and 10.3.

CONCLUSIONS

Overall, the allergen was the prominent compound in the mixture and its nature appeared to determine the degree of the response.

Nature Exposure and Its Effects on Immune System Functioning: A Systematic Review

Given the drastic changes in our lifestyles and ecosystems worldwide, the potential health effects of natural environments have grown into a highly pervasive topic. Recent scientific findings suggest beneficial effects from nature exposure on human immune responses. This review aims at providing a comprehensive overview of literature published on immunomodulatory effects of nature exposure by inhalation of natural substances. A systematic database search was performed in SCOPUS and PubMed. The quality and potential bias of included studies (n = 33) were assessed by applying the EPHPP (Effective Public Health Practice Project) tool for human studies and the ARRIVE (Animal Research: Reporting of In Vivo Experiments) and SYRCLE (Systematic Review Centre for Laboratory Animal Experimentation) tools for animal studies. The synthesis of reviewed studies points to positive effects of nature exposure on immunological health parameters; such as anti-inflammatory, anti-allergic, anti-asthmatic effects or increased NK (natural killer) cell activity. Decreased expression of pro-inflammatory molecules, infiltration of leukocytes and release of cytotoxic mediators are outcomes that may serve as a baseline for further studies. However, partially weak study designs evoked uncertainties about outcome reproducibility and key questions remain open concerning effect sizes, duration of exposure and contributions of specific vegetation or ecosystem types.

Therapeutic Potential of Volatile Terpenes and Terpenoids from Forests for Inflammatory Diseases

Forest trees are a major source of biogenic volatile organic compounds (BVOCs). Terpenes and terpenoids are known as the main BVOCs of forest aerosols. These compounds have been shown to display a broad range of biological activities in various human disease models, thus implying that forest aerosols containing these compounds may be related to beneficial effects of forest bathing. In this review, we surveyed studies analyzing BVOCs and selected the most abundant 23 terpenes and terpenoids emitted in forested areas of the Northern Hemisphere, which were reported to display anti-inflammatory activities. We categorized anti-inflammatory processes related to the functions of these compounds into six groups and summarized their molecular mechanisms of action. Finally, among the major 23 compounds, we examined the therapeutic potentials of 12 compounds known to be effective against respiratory inflammation, atopic dermatitis, arthritis, and neuroinflammation among various inflammatory diseases. In conclusion, the updated studies support the beneficial effects of forest aerosols and propose their potential use as chemopreventive and therapeutic agents for treating various inflammatory diseases.

Cholesterol: An Inflammatory Compound

Obesity is one of the main rising causes of health problems in modern society and is correlated to type 2 diabetes mellitus, hypertension, heart disease and atherosclerosis. Bacterial products, endogenous substances such as oxidized LDL (ox-LDL) and heat shock proteins mediate activation of Toll-like receptors and reinforce the view that the innate immune system plays a key role in the genesis of atherosclerosis. In addition, natural killer T (NKT) cells respond to lipids presented via CD1d on APCs, and may also be able to affect atherosclerosis. All the main cell types involved in atherosclerosis such as endothelial cells, macrophages, T cells, smooth muscle cells and platelets express proinflammatory cytokines. In addition, CD4 ligation triggers the expression of adhesion molecules, cytokines and matrix metalloprotinease. IL-6 cytokines travels to the liver where it elicits acute phase response resolving in the release of serum amyloid-A C-reactive protein, fibrogen and plasminogen activator inhibitor-1. Therefore increasing body fat mass is associated with high levels of inflammatory cytokines such as IL-1 and TNF. In this study we revisit the interrelationship between fat and inflammation.