Phytochemical, biological, and molecular docking studies on Fraxinus excelsior, Stachys arabica, Pelargonium sidoides, and Pelargonium reniforme

Plants have a long history of use in traditional medicine and several plant species are natural cures for tuberculosis (TB) or TB-related symptoms. Such natural sources can be a worthy starting point in the search for new drugs since they are rich in diverse phytochemicals which may possess antimicrobial and/or immunomodulatory activity. TB is still a growing public health concern worldwide, especially with the emerging challenge of drug resistance to current anti-TB drugs. There is an urgent need for effective and safe therapeutic interventions to tackle TB globally. One approach to achieve this goal is to combine host directed therapies (HDT) with current anti-TB therapies. Pro-inflammatory cytokines (TNF-α and IL-12) are essential for an effective immune response against bacterial infections and play a crucial role in controlling TB. Another promising approach is to identify compounds that could target key virulence enzymes of Mtb such as protein kinase G (MtPKnG). This study describes the phytochemical investigation of two medicinal plants (Fraxinus excelsior and Stachys arabica) selected based on their traditional and/or chemo-taxonomical use in the treatment for TB or TB-related symptoms. The work also focused on the evaluation of these plant extracts and selected isolated phytochemicals for their potential immunomodulatory effect in LPS-stimulated THP-1 cells. A total of 28 phytochemicals were isolated and characterised from both plants. The phytochemical investigation of the n-hexane and ethyl acetate extracts of F. excelsior leaves revealed the presence of 20 phytochemicals. The isolated phytochemicals included two pentacyclic triterpenoids (oleanolic acid and ursolic acid), squalene, one flavonoid (pinocembrin), five phenylethanoid esters (4-hydroxyphenethyl dotriacontanoate, 4-hydroxyphenethyl triacontanoate, 4-hydroxyphenethyl octacosanoate, 4-hydroxyphenethyl hexacosanoate, and 4-hydroxyphenethyl tetracosanoate), steryl fatty acid esters (β-sitosterol oleate), phytyl fatty acid esters (phytyl palmitate, phytyl oleate, and phytyl linolenate), and a mixture of acyclic alkanes (heptacosane, octacosane, nonacosane, triacontane, hentriacontane, dotriacontane and tritriacontane). Although ursolic acid, phytyl linolenate, nonacosane, and hentriacontane have already been reported in F. excelsior leaves, all other phytochemicals are reported here for the first time A total of 17 phytochemicals were isolated from the n-hexane and ethyl acetate extracts of S. arabica leaves. This included pheophytins (pheophytin a, 132 (R,S)-hydroxy pheophytin a, and pheophytin b), a mixture of phytosterols (stigmasterol, β-sitosterol and campesterol), a mixture of steryl fatty acid esters (β-sitosterol oleate & campesterol oleate), a mixture of phytyl fatty acid esters (phytyl palmitate, phytyl oleate), and a mixture of acyclic alkanes (heptacosane, octacosane, nonacosane, triacontane, hentriacontane and tritriacontane). Although all are known compounds, they are reported from S. arabica for the first time. When screened for potential Immunomodulatory effect in LPS-stimulated THP-1 cells, all the plant extracts and selected purified phytochemicals (oleanolic acid, ursolic acid, pinocembrin, and pheophytins) were able to reduce the production of the pro-inflammatory cytokines (TNF- α and IL-12). The mixture of phenylethanoid esters did not appear to influence the production of either of the cytokines studied. Our results indicate that the two plant extracts and their selected phytochemicals (oleanolic acid, ursolic acid, pinocembrin, and pheophytins) exhibited anti-inflammatory effect that could validate to a certain extent their potential use for complications associated with inflammation including TB as adjunct host therapy. Molecular docking using AutoDock Vina was conducted to predict the interactions between MtPknG and eighty-four phytochemicals from Pelargonium sidoides and Pelargonium reniforme as well as six selected phytochemicals identified through the phytochemical work. The flavonoids present in the aerial parts of Pelargonium plants displayed the best predicted binding energy towards MtPknG. The highest binding affinity towards MtPknG was recorded for isoorientin 2”-O-gallate (79), isovitexin 2”-O-gallate (77), nicotiflorin (61), orientin (74) and populnin (60) (−13.2, −12.6, −12.2, −11.8, and −11.6 kcal/mol, respectively) accompanied with SILE values (4.27, 4.11, 3.98, 4.17 and 4.10, respectively) that were superior to the control inhibitor AX20017 (−7.9 kcal/mol and SILE value of 3.32, respectively). Medicinal plants and their phytochemicals, owing to their abundance and diversity, could provide valuable alternatives for design of new generation of anti-TB drugs by serving as adjunct host-directed therapy and/or pathogen-directed therapy.Plants have a long history of use in traditional medicine and several plant species are natural cures for tuberculosis (TB) or TB-related symptoms. Such natural sources can be a worthy starting point in the search for new drugs since they are rich in diverse phytochemicals which may possess antimicrobial and/or immunomodulatory activity. TB is still a growing public health concern worldwide, especially with the emerging challenge of drug resistance to current anti-TB drugs. There is an urgent need for effective and safe therapeutic interventions to tackle TB globally. One approach to achieve this goal is to combine host directed therapies (HDT) with current anti-TB therapies. Pro-inflammatory cytokines (TNF-α and IL-12) are essential for an effective immune response against bacterial infections and play a crucial role in controlling TB. Another promising approach is to identify compounds that could target key virulence enzymes of Mtb such as protein kinase G (MtPKnG). This study describes the phytochemical investigation of two medicinal plants (Fraxinus excelsior and Stachys arabica) selected based on their traditional and/or chemo-taxonomical use in the treatment for TB or TB-related symptoms. The work also focused on the evaluation of these plant extracts and selected isolated phytochemicals for their potential immunomodulatory effect in LPS-stimulated THP-1 cells. A total of 28 phytochemicals were isolated and characterised from both plants. The phytochemical investigation of the n-hexane and ethyl acetate extracts of F. excelsior leaves revealed the presence of 20 phytochemicals. The isolated phytochemicals included two pentacyclic triterpenoids (oleanolic acid and ursolic acid), squalene, one flavonoid (pinocembrin), five phenylethanoid esters (4-hydroxyphenethyl dotriacontanoate, 4-hydroxyphenethyl triacontanoate, 4-hydroxyphenethyl octacosanoate, 4-hydroxyphenethyl hexacosanoate, and 4-hydroxyphenethyl tetracosanoate), steryl fatty acid esters (β-sitosterol oleate), phytyl fatty acid esters (phytyl palmitate, phytyl oleate, and phytyl linolenate), and a mixture of acyclic alkanes (heptacosane, octacosane, nonacosane, triacontane, hentriacontane, dotriacontane and tritriacontane). Although ursolic acid, phytyl linolenate, nonacosane, and hentriacontane have already been reported in F. excelsior leaves, all other phytochemicals are reported here for the first time A total of 17 phytochemicals were isolated from the n-hexane and ethyl acetate extracts of S. arabica leaves. This included pheophytins (pheophytin a, 132 (R,S)-hydroxy pheophytin a, and pheophytin b), a mixture of phytosterols (stigmasterol, β-sitosterol and campesterol), a mixture of steryl fatty acid esters (β-sitosterol oleate & campesterol oleate), a mixture of phytyl fatty acid esters (phytyl palmitate, phytyl oleate), and a mixture of acyclic alkanes (heptacosane, octacosane, nonacosane, triacontane, hentriacontane and tritriacontane). Although all are known compounds, they are reported from S. arabica for the first time. When screened for potential Immunomodulatory effect in LPS-stimulated THP-1 cells, all the plant extracts and selected purified phytochemicals (oleanolic acid, ursolic acid, pinocembrin, and pheophytins) were able to reduce the production of the pro-inflammatory cytokines (TNF- α and IL-12). The mixture of phenylethanoid esters did not appear to influence the production of either of the cytokines studied. Our results indicate that the two plant extracts and their selected phytochemicals (oleanolic acid, ursolic acid, pinocembrin, and pheophytins) exhibited anti-inflammatory effect that could validate to a certain extent their potential use for complications associated with inflammation including TB as adjunct host therapy. Molecular docking using AutoDock Vina was conducted to predict the interactions between MtPknG and eighty-four phytochemicals from Pelargonium sidoides and Pelargonium reniforme as well as six selected phytochemicals identified through the phytochemical work. The flavonoids present in the aerial parts of Pelargonium plants displayed the best predicted binding energy towards MtPknG. The highest binding affinity towards MtPknG was recorded for isoorientin 2”-O-gallate (79), isovitexin 2”-O-gallate (77), nicotiflorin (61), orientin (74) and populnin (60) (−13.2, −12.6, −12.2, −11.8, and −11.6 kcal/mol, respectively) accompanied with SILE values (4.27, 4.11, 3.98, 4.17 and 4.10, respectively) that were superior to the control inhibitor AX20017 (−7.9 kcal/mol and SILE value of 3.32, respectively). Medicinal plants and their phytochemicals, owing to their abundance and diversity, could provide valuable alternatives for design of new generation of anti-TB drugs by serving as adjunct host-directed therapy and/or pathogen-directed therapy

An investigation into the pharmacological properties of propolis

Propolis is a traditional value-added product from beekeeping, and has been widely used in medicine and the chemical industry because of its extensive biological activities. In this dissertation some pharmacological properties of propolis extracted by ethanol (EEP) and water (WSP) were studied by means of modem pharmacological methods. The results of the experiments show the following: 1. Both EEP and WSD led to decreased levels of fasting blood glucose (FBG), glycosylated haemoglobin (HBA1c), Fructosamine (FRU), blood urea nitrogen (BUN), uric acid (UA), malonaldehyde (MDA), nitric oxide (NO), nitric oxide synthetase (NOS), total cholesterol (TC), triglyceride (TG), low-density lipoprotein cholesterol (LDL-C) and very-low density lipoprotein cholesterol (VLDL-C) in the serum of fasting rats; and, to increased serum levels of high-density lipoprotein cholesterol (HDL-C) and superoxide dismutase (SOD) in rats with diabetes mellitus. This suggests that propolis can control blood glucose and modulate the metabolism of glucose, blood lipid and protein, leading to decreased outputs of lipid peroxidation and scavenging free radicals in rats with diabetes mellitus. 2. Both EEP and WSD showed inhibitory effects on swelling induced by Freund's complete adjuvant and decreased the degree of local inflammatory responses; significantly inhibited the increase of interleukin-6 (lL-6) in inflamed tissues, but had no significant effect on levels of interleukin-2 (IL-2) and interferon-y (IFN-y). The results are consistent with the interpretation that EEP and WSD may exert these effects by inhibiting the activation and differentiation of mononuclear macrophages. 3. Both EEP and WSD exhibited significant anti-inflammatory effects in animal models with respect to thoracic capillary vessel leakage in mice, Carrageenan-induced oedema, Carrageen-aninduced pleurisy and acute lung damage in rats. The mechanisms for the anti-inflammatory effects probably involve decreasing prostaglandin and NO levels. 4. Both EEP and WSD had an inhibitory effect on the level of TG, TC, LDL-C, glutamic-pyruvic transaminase (GPT) and glutamic-oxalacetic transaminase (GOT) in serum, and TC, TG and MDA in liver of hyperlipidemic SD rats; but were without effects on HDL-C, MDA, SOD and NO in serum. EEP also reduced body weight, liver weight and liver index, but WSD did not reduce those indexes. The results showed that the two extracts contribute to the improvement of lipid metabolism in hyperlipidemic rats and provide them with the required anti-oxidative activity. 5. The 80% ethanol extracts of propolis had the highest flavonoid content. The flavone content of water extracts of propolis were obtained with a natural surface-active agent, under ultrasonic perturbation at 80°C, for 12 h and was 6.7 times greater than that of propolis extracted with water at room temperature. Compared to EEP, WSD has the same or a greater anti-tumor or anti-inflammation effect at the same dosage, and shows considerable pharmacological potential especially because of its low side effects and ease of preparation

An investigation into the pharmacological properties of propolis

Propolis is a traditional value-added product from beekeeping, and has been widely used in medicine and the chemical industry because of its extensive biological activities. In this dissertation some pharmacological properties of propolis extracted by ethanol (EEP) and water (WSP) were studied by means of modem pharmacological methods. The results of the experiments show the following: 1. Both EEP and WSD led to decreased levels of fasting blood glucose (FBG), glycosylated haemoglobin (HBA1c), Fructosamine (FRU), blood urea nitrogen (BUN), uric acid (UA), malonaldehyde (MDA), nitric oxide (NO), nitric oxide synthetase (NOS), total cholesterol (TC), triglyceride (TG), low-density lipoprotein cholesterol (LDL-C) and very-low density lipoprotein cholesterol (VLDL-C) in the serum of fasting rats; and, to increased serum levels of high-density lipoprotein cholesterol (HDL-C) and superoxide dismutase (SOD) in rats with diabetes mellitus. This suggests that propolis can control blood glucose and modulate the metabolism of glucose, blood lipid and protein, leading to decreased outputs of lipid peroxidation and scavenging free radicals in rats with diabetes mellitus. 2. Both EEP and WSD showed inhibitory effects on swelling induced by Freund's complete adjuvant and decreased the degree of local inflammatory responses; significantly inhibited the increase of interleukin-6 (lL-6) in inflamed tissues, but had no significant effect on levels of interleukin-2 (IL-2) and interferon-y (IFN-y). The results are consistent with the interpretation that EEP and WSD may exert these effects by inhibiting the activation and differentiation of mononuclear macrophages. 3. Both EEP and WSD exhibited significant anti-inflammatory effects in animal models with respect to thoracic capillary vessel leakage in mice, Carrageenan-induced oedema, Carrageen-aninduced pleurisy and acute lung damage in rats. The mechanisms for the anti-inflammatory effects probably involve decreasing prostaglandin and NO levels. 4. Both EEP and WSD had an inhibitory effect on the level of TG, TC, LDL-C, glutamic-pyruvic transaminase (GPT) and glutamic-oxalacetic transaminase (GOT) in serum, and TC, TG and MDA in liver of hyperlipidemic SD rats; but were without effects on HDL-C, MDA, SOD and NO in serum. EEP also reduced body weight, liver weight and liver index, but WSD did not reduce those indexes. The results showed that the two extracts contribute to the improvement of lipid metabolism in hyperlipidemic rats and provide them with the required anti-oxidative activity. 5. The 80% ethanol extracts of propolis had the highest flavonoid content. The flavone content of water extracts of propolis were obtained with a natural surface-active agent, under ultrasonic perturbation at 80°C, for 12 h and was 6.7 times greater than that of propolis extracted with water at room temperature. Compared to EEP, WSD has the same or a greater anti-tumor or anti-inflammation effect at the same dosage, and shows considerable pharmacological potential especially because of its low side effects and ease of preparation

Kangaroo Island Propolis: Improved Characterisation and Assessment of Chemistry and Botanical Origins through Metabolomics

Introduction: Propolis, a sticky substance produced by bees from plant resins, has a long history of safe use medicinally. Kangaroo Island, SA (KI) lacks many introduced European plants bees preferentially collect resin from; consequentially, propolis from KI is produced from resinous native plants. Several identifiably reproducible pure-source KI propolis types exist. Research into medical use of compounds from KI native plants is limited. Metabolomics is a growing field of interest in natural products chemistry, including beehive products. Metabolomic and similarity-scoring assessment of KI propolis, through statistical evaluation of 1D 1H-NMR fingerprints, provides an entry point for research into medical use of KI native plant compounds. Many avenues to product discovery in pharmaceutical chemistry are suffering diminishing returns: metabolomics-guided natural products assessment has the potential for further identification of novel therapeutic compounds from resinous plants. Aim: To assess and identify, via metabolomic investigation of NMR fingerprints, major propolis types on KI, and to produce, from this, similarity-scoring tools for assessment of propolis samples. Method: KI propolis samples, identified as pure-source by TLC, and resinous KI plants were analysed by 1H-NMR and HPLC. Data points of interest were normalised and binned to form individual sample ‘fingerprints’. Data from these fingerprints were analysed by hierarchical clustering and principal component analysis (PCA) to confirm provisionally-identified pure-source propolis types and identify subtypes within propolis and resinous plant species. From this, calculator tools were created to score similarity (out of 1000) of 1H-NMR fingerprints to the average spectrum of pure-source propolis types, as well as to calculated mixtures of these average spectra. Assessment of the chemistry of two major KI propolis types identified (CP- and F-type) was made by fractionation and NMR, with one compound, 6,8-diprenyleriodictyol, isolated from CP-type propolis in quantity, submitted for epigenetic and other biological assays. Results: Source resinous plants were demonstrated, through hierarchical clustering and PCA, to cluster with propolis types arising from these sources, with closely related plants and sub-chemotypes clustering separately, confirming specificity. A number of previously-identified pure-source propolis types and known botanical sources were shown to have very high similarity (> 800/1000) to the expected propolis type. Calculator tools were observed to accurately predict the content of mixed propolis samples to within ± 10%. A number of methylflavanones, and two novel terminally-hydroxylated prenyldihydrochalcones were isolated from F-type propolis. 6,8-diprenyleriodictyol demonstrated a range of promising activity in biological assays. Conclusion: Metabolomic evaluation of 1H-NMR fingerprints can reliably identify and assess pure-source KI propolis and identify botanical origin of source resins. Similarity scoring calculators can accurately identify mixed-source propolis samples. KI propolis types are a rich source of pharmaceutically-interesting flavanones and related compounds, many of which are prenylated. 6,8-diprenyleriodictyol displays strong anti-inflammatory and anticancer activity, especially against Burkitt’s lymphoma. A number of possible epigenetic pathways for this activity were observed

An Overview of Nrf2 Signaling Pathway and Its Role in Inflammation

Inflammation is a key driver in many pathological conditions such as allergy, cancer, Alzheimer's disease, and many others, and the current state of available drugs prompted researchers to explore new therapeutic targets. In this context, accumulating evidence indicates that the transcription factor Nrf2 plays a pivotal role controlling the expression of antioxidant genes that ultimately exert anti-inflammatory functions. Nrf2 and its principal negative regulator, the E3 ligase adaptor Kelch-like ECH- associated protein 1 (Keap1), play a central role in the maintenance of intracellular redox homeostasis and regulation of inflammation. Interestingly, Nrf2 is proved to contribute to the regulation of the heme oxygenase-1 (HO-1) axis, which is a potent anti-inflammatory target. Recent studies showed a connection between the Nrf2/antioxidant response element (ARE) system and the expression of inflammatory mediators, NF-κB pathway and macrophage metabolism. This suggests a new strategy for designing chemical agents as modulators of Nrf2 dependent pathways to target the immune response. Therefore, the present review will examine the relationship between Nrf2 signaling and the inflammation as well as possible approaches for the therapeutic modulation of this pathway

The Benefits of Plant Extracts for Human Health

Nature has always been, and still is, a source of food and ingredients that are beneficial to human health. Nowadays, plant extracts are increasingly becoming important additives in the food industry due to their antimicrobial and antioxidant activities that delay the development of off-flavors and improve the shelf life and color stability of food products. Due to their natural origin, they are excellent candidates to replace synthetic compounds, which are generally considered to have toxicological and carcinogenic effects. The efficient extraction of these compounds from their natural sources and the determination of their activity in commercialized products have been great challenges for researchers and food chain contributors to develop products with positive effects on human health. The objective of this Special Issue is to highlight the existing evidence regarding the various potential benefits of the consumption of plant extracts and plant-extract-based products, with emphasis on in vivo works and epidemiological studies, the application of plant extracts to improving shelf life, the nutritional and health-related properties of foods, and the extraction techniques that can be used to obtain bioactive compounds from plant extracts

SYNTHESIS OF NEW SULFURATED DERIVATIVES OF NATURAL AND SYNTHETIC SYSTEMS AS MULTITARGET ANTICANCER AGENTS AND DEVELOPMENT OF NEW DRUG DISCOVERY METHODOLOGIES

This PhD thesis is divided in two parts. The former, entitled "Design and synthesis of new derivatives of natural and synthetic systems endowed with anticancer activity, through a multitarget mechanism", has been carried out at the Universit\ue1 degli Studi di Milano under the supervision of Professor Anna Sparatore. This project treats the synthesis of new sulfurated compounds with the aim of obtaining anticancer agents acting through a multitarget mechanism. On one hand, we explored the potentialities of new sulfurated chemical scaffolds, such as dithiolethiones, methanethiosulfonates and allyldisulfides to evaluate their antiproliferative activity, as well as their ability to inhibit STAT3 and NfkB, and to design new anticancer agents. On the other hand, we evaluated the possibility of creating hybrid molecules, combining moieties with different mechanism of action, which could carry out a synergistic antitumor effect. In particular, the sulfurated compounds synthetized have been combined with different STAT3 and/or NfkB inhibiting structures such as natural products (curcumin, phenolic acids and celastrol), semi-synthetic and synthetic systems (rosmaricine and heterocyclic compounds). Some of them exhibited very interesting inhibitory activity on both transcription factors in the micromolar range and antiproliferative activity. The second part, entitled "Optimized reaction conditions for amide bond formation in DNA-encoded combinatorial libraries", has been developed at Swiss Federal Institute of Technology in Zurich (ETH Zurich) in the research group of Professor Dario Neri. This project is focused on the advantages of using DNA-encoded chemical libraries (DECLs) in drug discovery process. In particular, since in the majority of cases DECLs require at least one-step of amide bond formation between amino modified DNA and a carboxylic acid, we optimized a new methodology of synthesis in order to facilitate the construction of single-pharmacophore libraries (DECLs)

Investigation of the antioxidative and radical scavenging impact of natural compounds in-vitro and on cell metabolism

In an aerobic environment the occurrence of reactive oxygen species (ROS) is a common phenomenon. The diverse roles of ROS in cellular function and in diseases make them a target of interest in many research areas. Substances capable of directly or indirectly reducing the (harmful) effects of ROS are referred to as “antioxidants”. However, the term is applied miscellaneously in the chemical and the biological context to describe different attributes of a substance. In this work the potential of an electrochemical assay to detect different ROS in-vitro was explored. The method was optimized to investigate the radical scavenging activities (antioxidant potential) of trolox and different plant compounds (ascorbic acid, caffeic acid, epigallocatechin gallate, ferulic acid, kaempferol, quercetin, rutin, and Gynostemma pentaphyllum extract) in-vitro. The obtained data was compared to established antioxidant in-vitro assays. Further, the impact of the plant substances on cellular parameters was evaluated with the electrochemical assay and established cell assays. The optimization of the electrochemical assay allowed the reproducible detection of ROS. The sensor electrode proved differently sensitive towards individual ROS species. The highest sensitivity was recorded for hydroxyl radicals while superoxide and hydrogen peroxide had little impact on the sensor. Extracellular ROS concentrations could be detected from cell lines releasing elevated ROS into the extracellular space. The antioxidant activity of the investigated plant substances could be demonstrated with all in-vitro assays applied. However, the absolute as well as the relative activity of the individual substances varied depending on the experimental parameters of the assays (pH, radical species, phase, detection method). The plant compounds modified redox related intracellular parameters in different cell lines. However, a direct correlation between intracellular and extracellular effects of the plant compounds could not be established. The work demonstrates the feasibility to use the electrochemical assay to sense ROS as well as to evaluate the radical scavenging activity of molecules. The in-vitro antioxidant activities demonstrated for the individual plant substances are not reliable to predict the cellular effects of the molecules.In der vorliegenden Arbeit wurde der Einsatz eines elektrochemischen Sensors zur Detektion von reaktiven Sauerstoffspezies (ROS) untersucht und dahingehend optimiert die antioxidative Aktivität verschiedener Pflanzeninhaltsstoffe zu bestimmen. Die Ergebnisse wurden mit etablierten Messmethoden und den Auswirkungen auf intrazelluläre Redox-Parameter in unterschiedlichen Zelllinien verglichen. Die Arbeit verdeutlicht die Abhängigkeit antioxidativer Aktivitäten von den experimentellen Bedingungen

Bioproducts for health II

In order to build a promising future, health and sustainability must be interelated. Marine, forestry, agriculture, and food systems are important sources of bioproducts used in health applications. To explore the potential of such sources for the development of natural products capable of biological activities, it is necessary to develop new technologically sustainable strategies. Despite the range of natural compounds already available, there is a need to identify bioactive molecules (e.g., polysaccharides, proteins and peptides, polyunsaturated fatty acids, and polyphenols) from different natural sources with positive health properties, including antihypertensive, antidiabetic, anti-obesity, antimicrobial, anti-atherosclerotic, antioxidant, antithrombotic, immune-modulatory, relaxing, and satiety-inducing effects. The Second Edition of this Special Issue aimed to identify and gather works on the latest varied sources of bioproducts, the biological and functional activities of these bioactive compounds, their mechanisms of action, and the methods used for extraction and purification, without losing our focus on alignment with the concept of green technology.info:eu-repo/semantics/publishedVersio

The effect of topical therapies on ulcer healing and the wound micro-environment in diabetes mellitus

Wounds in people with diabetes typically show abnormal healing. The diabetic wound is generally characterised by its chronicity, persistent inflammation, copious exudate, hypergranulation, increased bacterial load and reduced ability to heal. This delayed healing is thought to be attributable to a variety of factors including micro- and macrovascular disease, neuropathy, bacterial infection, local pressure due to foot deformity and the adverse local metabolic environment caused by diabetes. The series of studies presented in this thesis demonstrate for the first time that the topical growth factor CTGF is able to improve diabetic wound healing in a preclinical model. Furthermore, the potential of the anti-inflammatory agent propolis to enhance wound healing in human subjects has been established in the preliminary studies in this research. The safety of propolis has been substantiated and laboratory studies of wound fluid have provided data to enable exploratory hypotheses such as propolis’ mechanism of action to be subsequently developed in further research. This novel work contributes to our understanding of the complex and dysregulated diabetic wound micro-environment. It is anticipated that further work studying the topical therapies examined in this thesis may ultimately lead to improvement in healing rates in burdensome chronic diabetic wound