Synthesis and antibacterial properties of 2,3-dideoxyglucosides of terpene alcohols and phenols

Terpenoids as potential phytoconstituent in the treatment of diabetes: From preclinical to clinical advancement

BACKGROUND

Diabetes mellitus, a hyperglycemic condition associated with multitudinous organ dysfunction, is a hallmark of the metabolic disorder. This life-threatening condition affects millions of individuals globally, harming them financially, physically and psychologically in the course of therapy.

PURPOSES

The course therapy for illnesses has undergone ground-breaking transformations due to recent technical advances and insights. Alternatively, the administration of hyperglycemia-reducing agents results in several complications, including severe cardiovascular disease, kidney failure, hepatic problems, and several dermatological conditions. Consideration of alternate diabetic therapy having minimal side effects or no adverse reactions has been driven by such problems.

STUDY DESIGN

An extensive literature study was conducted in authoritative scientific databases such as PubMed, Scopus, and Web of Science to identify the studies elucidating the bioactivities of terpenoids in diabetic conditions.

METHODS

Keywords including 'terpenoids', 'monoterpenes', 'diterpenes', 'sesquiterpenes', 'diabetes', 'diabetes mellitus', 'clinical trials', 'preclinical studies', and 'increased blood glucose' were used to identify the relevant research articles. The exclusion criteria, such as English language, duplication, open access, abstract only, and studies not involving preclinical and clinical research, were set. Based on these criteria, 937 relevant articles were selected for further evaluation.

RESULTS

Triterpenes can serve as therapeutic agents for diabetic retinopathy, peripheral neuropathy, and kidney dysfunction by inhibiting several pathways linked to hyperglycemia and its complications. Therefore, it is essential to draw special attention to these compounds' therapeutic effectiveness and provide scientific professionals with novel data.

CONCLUSION

This study addressed recent progress in research focussing on mechanisms of terpenoid, its by-products, physiological actions, and therapeutic applications, particularly in diabetic and associated disorders.

The recent discovery of a promising pharmacological scaffold derived from carvacrol: A review

Carvacrol, called CA, is a dynamic phytoconstituent characterized by a phenol ring abundantly sourced from various natural reservoirs. This versatile scaffold serves as a pivotal template for the design and synthesis of novel drug molecules, harboring promising biological activities. The active sites positioned at C-4, C-6, and the hydroxyl group (-OH) of CA offer fertile ground for creating potent drug candidates from a pharmacological standpoint. In this comprehensive review, we delve into diverse synthesis pathways and explore the biological activity of CA derivatives. We aim to illuminate the potential of these derivatives in discovering and developing efficacious treatments against a myriad of life-threatening diseases. By scrutinizing the structural modifications and pharmacophore placements that enhance the activity of CA derivatives, we aspire to inspire the innovation of novel therapeutics with heightened potency and effectiveness.

Antifungal Activities of Natural Products and Their Hybrid Molecules

The increasing cases of drug resistance and high toxicity associated with the currently used antifungal agents are a worldwide public health concern. There is an urgent need to develop new antifungal drugs with unique target mechanisms. Plant-based compounds, such as carvacrol, eugenol, coumarin, cinnamaldehyde, curcumin, thymol, etc., have been explored for the development of promising antifungal agents due to their diverse biological activities, lack of toxicity, and availability. However, researchers around the world are unable to fully utilize the potential of natural products due to limitations, such as their poor bioavailability and aqueous solubility. The development of hybrid molecules containing natural products is a promising synthetic approach to overcome these limitations and control microbes' capability to develop resistance. Based on the potential advantages of hybrid compounds containing natural products to improve antifungal activity, there have been different reported synthesized hybrid compounds. This paper reviews different literature to report the potential antifungal activities of hybrid compounds containing natural products.

Creation of Chitosan-Based Nanocapsule-in-Nanofiber Structures for Hydrophobic/Hydrophilic Drug Co-Delivery and Their Dressing Applications in Diabetic Wounds

Nanofiber meshes (NFMs) loaded with therapeutic agents are very often employed to treat hard-to-heal wounds such as diabetic wounds. However, most of the NFMs have limited capability to load multiple or hydrophilicity distinctive-therapeutic agents. The therapy strategy is therefore significantly hampered. To tackle the innate drawback associated with the drug loading versatility, a chitosan-based nanocapsule-in-nanofiber (NC-in-NF) structural NFM system is developed for simultaneous loading of hydrophobic and hydrophilic drugs. Oleic acid-modified chitosan is first converted into NCs by the developed mini-emulsion interfacial cross-linking procedure, followed by loading a hydrophobic anti-inflammatory agent Curcumin (Cur) into the NCs. Sequentially, the Cur-loaded NCs are successfully introduced into reductant-responsive maleoyl functional chitosan/polyvinyl alcohol NFMs containing a hydrophilic antibiotic Tetracycline hydrochloride. Having a co-loading capability for hydrophilicity distinctive agents, biocompatibility, and a controlled release property, the resulting NFMs have demonstrated the efficacy on promoting wound healing either in normal or diabetic rats.

Effect of potassium salts on the structure of γ-cyclodextrin MOF and the encapsulation properties with thymol

BACKGROUND

Thymol is a natural essential oil with strong volatility, low solubility, poor dispersion, strong irritation, and an unpleasant smell, which often requires appropriate porous materials to encapsulate thymol during the application process. However, the encapsulation efficiency of thymol in inclusion complexes is low, and new methods of encapsulation need to be developed. In the present study, the encapsulation capacity, storage stability, and antibacterial activity of thymol were investigated using γ-cyclodextrin (γ-CD) metal-organic frameworks (MOFs) by cocrystallization and high-temperature adsorption methods. The effect of different potassium salts (i.e. KOH, KCl, and KAc) on the structure and complexation of γ-CD-MOFs was also analyzed.

RESULTS

Compared with γ-CD, the thymol encapsulation capacity of γ-CD-MOFs was increased by two- to three-fold, with the encapsulation content following the order: KAc-γ-CD-MOF (293.8 mg g^-1 ) > KOH-γ-CD-MOF (287.7 mg g^-1 ) > KCl-γ-CD-MOF (249.3 mg g^-1 ). The anions in the solution participate in the coordination and influence the symmetry relationship between atoms and ions. This explains the differences in both the three-dimensional γ-CD-MOF structure and the thymol encapsulation amount, as well as the high storage stability of thymol.

CONCLUSION

The in vitro release kinetics and antibacterial experiments showed that the inclusion complexes prepared by γ-CD-MOFs had higher stability, sustainability, and antibacterial activity, which suggests that it is an excellent complex material for industrial and agricultural applications. © 2022 Society of Chemical Industry.

The multi-faceted mechano-bactericidal mechanism of nanostructured surfaces

The mechano-bactericidal activity of nanostructured surfaces has become the focus of intensive research toward the development of a new generation of antibacterial surfaces, particularly in the current era of emerging antibiotic resistance. This work demonstrates the effects of an incremental increase of nanopillar height on nanostructure-induced bacterial cell death. We propose that the mechanical lysis of bacterial cells can be influenced by the degree of elasticity and clustering of highly ordered silicon nanopillar arrays. Herein, silicon nanopillar arrays with diameter 35 nm, periodicity 90 nm and increasing heights of 220, 360, and 420 nm were fabricated using deep UV immersion lithography. Nanoarrays of 360-nm-height pillars exhibited the highest degree of bactericidal activity toward both Gram stain-negative Pseudomonas aeruginosa and Gram stain-positive Staphylococcus aureus bacteria, inducing 95 ± 5% and 83 ± 12% cell death, respectively. At heights of 360 nm, increased nanopillar elasticity contributes to the onset of pillar deformation in response to bacterial adhesion to the surface. Theoretical analyses of pillar elasticity confirm that deflection, deformation force, and mechanical energies are more significant for the substrata possessing more flexible pillars. Increased storage and release of mechanical energy may explain the enhanced bactericidal action of these nanopillar arrays toward bacterial cells contacting the surface; however, with further increase of nanopillar height (420 nm), the forces (and tensions) can be partially compensated by irreversible interpillar adhesion that reduces their bactericidal effect. These findings can be used to inform the design of next-generation mechano-responsive surfaces with tuneable bactericidal characteristics for antimicrobial surface technologies.

Therapeutic and Medicinal Uses of Terpenes

Terpenes, also known as terpenoids are the largest and most diverse group of naturally occurring compounds. Based on the number of isoprene units they have, they are classified as mono, di, tri, tetra, and sesquiterpenes. They are mostly found in plants and form the major constituent of essential oils from plants. Among the natural products that provide medical benefits for an organism, terpenes play a major and variety of roles. The common plant sources of terpenes are tea, thyme, cannabis, Spanish sage, and citrus fruits (e.g., lemon, orange, mandarin). Terpenes have a wide range of medicinal uses among which antiplasmodial activity is notable as its mechanism of action is similar to the popular antimalarial drug in use—chloroquine. Monoterpenes specifically are widely studied for their antiviral property. With growing incidents of cancer and diabetes in modern world, terpenes also have the potential to serve as anticancer and antidiabetic reagents. Along with these properties, terpenes also allow for flexibility in route of administration and suppression of side effects. Certain terpenes were widely used in natural folk medicine. One such terpene is curcumin which holds anti-inflammatory, antioxidant, anticancer, antiseptic, antiplasmodial, astringent, digestive, diuretic, and many other properties. Curcumin has also become a recent trend in healthy foods and open doors for several medical researches. This chapter summarizes the various terpenes, their sources, medicinal properties, mechanism of action, and the recent studies that are underway for designing terpenes as a lead molecule in the modern medicine.

Aporphinoid alkaloids as antimicrobial agents against Yersinia enterocolitica

Foodborne diseases have become a health issue worldwide, mainly due to the consumption of contaminated foods that are either raw, improperly heat treated or cross-contaminated after adequate heat treatment foods. A group of alkaloids extracted from plants were tested to evaluate their antimicrobial effect against different strains of Yersinia enterocolitica and other foodborne bacteria. The results obtained reveal that oliveridine and pachypodanthine inhibited Y. enterocolitica growth, with MIC values of 25 μmol l^-1 and 100 μmol l^-1 respectively. The results indicated that both alkaloids are good growth inhibitors, but oliveridine showed greater inhibitory effect with lower MIC values. Inhibitory alkaloids can be developed as potential antimicrobials in food system to prevent or treat foodborne diseases, thus contributing to solve the global issue of contaminated food consumption. SIGNIFICANCE AND IMPACT OF THE STUDY: Alkaloids are abundant secondary metabolites in plants and represent one of the most widespread class of compounds endowed with multiple and varied pharmacological properties. In this work, we propose two aporphinoid alkaloids extracted from plants as new antimicrobial agents. Oliveridine and pachypodanthine inhibited Yersinia enterocolitica growth for up to 96 h of culture. This is the first reported study of the activity of these alkaloids as antimicrobial compounds.

Semisynthetic Phenol Derivatives Obtained from Natural Phenols: Antimicrobial Activity and Molecular Properties

Semisynthetic phenol derivatives were obtained from the natural phenols: thymol, carvacrol, eugenol, and guaiacol through catalytic oxychlorination, Williamson synthesis, and aromatic Claisen rearrangement. The compounds characterization was carried out by ¹H NMR, ¹³C NMR, and mass spectrometry. The natural phenols and their semisynthetic derivatives were tested for their antimicrobial activity against the bacteria: Staphylococcus aureus, Escherichia coli, Listeria innocua, Pseudomonas aeruginosa, Salmonella enterica Typhimurium, Salmonella enterica ssp. enterica, and Bacillus cereus. Minimum inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) values were determined using concentrations from 220 to 3.44 μg mL^-1. Most of the tested compounds presented MIC values ≤220 μg mL^-1 for all the bacteria used in the assays. The molecular properties of the compounds were computed with the PM6 method. Through principle components analysis, the natural phenols and their semisynthetic derivatives with higher antimicrobial potential were grouped.

Nanofabrication of mechano-bactericidal surfaces

The search for alternatives to the standard methods of preventing bacterial adhesion and biofilm formation on biotic and abiotic surfaces alike has led to the use of biomimetics to reinvent through nanofabrication methods, surfaces, whereby the nanostructured topography is directly responsible for bacterial inactivation through physico-mechanical means. Plant leaves, insect wings, and animal skin have been used to inspire the fabrication of synthetic high-aspect-ratio nanopillared surfaces, which can resist bacterial colonisation. The adaptation of bacteria to survive in the presence of antibiotics and their ability to form biofilms on conventional antibacterial surfaces has led to an increase in persistent infections caused by resistant strains of bacteria. This presents a worldwide health epidemic that can only be mitigated through the search for a new generation of biomaterials.