Liposomes encapsulating catechins: a biophysical approach for skin cancer therapy

Every year, a large number of skin cancer cases caused by a prolonged ultraviolet radiation exposure, are diagnosed around the world. Epigallocatechin–3– gallate (EGCG) derived from green tea leaves, display protective effect against oxidative stress which reduce the risk of contracting skin cancer. However, frequently, the antioxidant and anti–inflammatory activities of EGCG in are compromised because this molecule is extremely unstable and rapidly degraded in physiological conditions. Considering these issues, the main goal of this thesis was developed a stable liposomal nanocarrier for topical/transdermal delivery of EGCG, firstly, to increase its bioavailability and, secondly, to offer an desirable skin protection against harmful effects of UV radiation. Primarily, the molecular mechanisms between EGCG and different phospholipids were studied using Langmuir experiments, revealling the affinity and localization of EGCG on each lipidic membrane, which according to the results depends on the molecular organization of lipidic monolayer (functional groups anchored at headgroup) and of the degree of protonation of EGCG. EGCG establishes electrostatic and hydrogenbonding interactions with zwitterionic (DMPC, DPPC) and anionic (DPPG and DPPS) phospholipids, which condense the monolayers and alter the membrane’s potential and compressibility. Regarding the irradiation experiments, the results indicated that EGCG efficiently slows down the oxidant events in monolayers and in lipid bilayers, which were produced by blue and ultraviolet radiation exposure, respectively. Lastly, the nanofibers meshes containing EGCG-loaded liposomes are biocompatible, support human fibroblasts adhesion and scavenge the oxidant species generated by UV radiation, which guarantees a higher cell survival

Fabrication of liposome-chitosan-zno nanohybrid integrated with Carissa Spinarum extract for antibacterial application

A Thesis Submitted in Fulfilment of the Requirements for the Degree of Doctor of Philosophy in Life Sciences of the Nelson Mandela African Institution of Science and TechnologyInnovative biomaterials provide a stimulating and adaptable platform for the implementation of new and more effective methods to prevent bacterial infection. Built on biomimetic- inorganic hybrid material, Dual Nanohybrid Delivery System (DN-DS) has advantageous properties for biomedical applications, such as the delivery of herbal formulations for the treatment of bacterial infections. Using microwave assisted extraction (MAE), the polyphenols of Carissa spinarum were extracted. The Dual Nanohybrid Delivery System (LipCsP-ZnONPs)-CT was formed by combining LipCsP-Chitosan and ZnO-Chitosan, which were both generated using different methods of co-precipitation and ion gelation, respectively. A Zetasizer was used to characterize the nanosystems' size, zeta potential, and polydispersity index (PDI). A UV-visible spectrophotometer was utilized for the optical study, and a scanning electron microscope was employed to investigate at the surface morphology. The interaction of coated chitosan with liposomes and ZnONPs was evaluated using Fourier Transformation Infrared (FTIR) spectroscopy. Different kinetic models were fitted to the results of the encapsulation and release profiles of polyphenols in the liposome nanosystems to determine the mechanism of release. Antibacterial activity of the nanoformulations was assessed by an agar diffusion assayand the micro plate blue assay (MABA). The Zeta potential of LipCsP changed from -45.3 ± 0.78 to +34.43 ±1.36 due to chitosan coatings. Polyphenol-encapsulation efficiency was higher in LipCsP-Chitosan (81 ± 2.5%) than in LipCsP (66.11 ± 1.11%). Conversely, the size of LipCsP (176.17 ± 1.05 nm) increasedto 365.2 ± 0.70 nm. FTIR analysis revealed the interaction of the liposome with chitosan due to the disappearance of N-H primary amine. Interaction between chitosan and zinc oxide was revealed by the formation of new absorption peaks at 670 cm-1 and 465 cm-1 as observed in the FTIR analysis. (LipCsP-ZnONPs)-CT presented high bioaccessibility of polyphenols in the simulated gastric phase (82.14 ± 0.80%) than in simulated intestinal phase (71.60 ± 0.86%), a stable system for sustained release of polyphenols, and prominent antibacterial activity. (LipCsP-ZnONPs)-CT exhibited a relative inhibition zone diameter (RIZD) of 89.60 ± 1.32, significant high viability reduction (P˂0.05) against Klebsiella pneumoniae as compared to LipCsP-Chitosan and ZnO-chitosan. The nanohybrid systems (LipCsP-Chitosan and ZnO- chitosan) exhibited synergistic effect against Klebsiella pneumoniae. This study successfully demonstrated the utility of the nanohybrid as a potential antibacterial agent against K.pneumoniae, therefore, the fabricated dual nano delivery system is an efficacy material for treatment of pneumococcal infections

Current Insights on Lipid-Based Nanosystems

Lipid-based nanosystems, including solid lipid nanoparticles (SLNs) and nanostructured lipid carriers (NLCs), cationic lipid nanoparticles, nanoemulsions, and liposomes, have been extensively studied to improve drug delivery through different administration routes. The main advantages of these systems are their ability to protect, transport, and control the release of lipophilic and hydrophilic molecules (either small-molecular-weight molecules or macromolecules); the use of generally recognized as safe (GRAS) excipients that minimize the toxicity of the formulations; and the possibility to modulate pharmacokinetics and enable the site-specific delivery of encapsulated payloads. In addition, the versatility of lipid-based nanosystems has further been demonstrated for the delivery of vaccines, the protection of active cosmetic ingredients, and the improvement of moisturizing properties of cosmetic formulations.Lipid-based nanosystems are well established and there are already different commercially approved formulations for various human disorders. This success has paved the way for the diversification of the pipeline of development, to address unmet medical needs for several indications, such as cancer, neurological disorders, and autoimmune, genetic, and infectious diseases.This Special Issue aims to update readers on the latest research on lipid-based nanosystems, both at the preclinical and clinical levels. A series of 15 articles (six reviews and nine studies) is presented, with authors from 12 different countries, showing the globality of the investigations that are being carried out in this area

Current Insights on Lipid-Based Nanosystems

Lipid-based nanosystems, including solid lipid nanoparticles (SLNs) and nanostructured lipid carriers (NLCs), cationic lipid nanoparticles, nanoemulsions, and liposomes, have been extensively studied to improve drug delivery through different administration routes. The main advantages of these systems are their ability to protect, transport, and control the release of lipophilic and hydrophilic molecules (either small-molecular-weight molecules or macromolecules); the use of generally recognized as safe (GRAS) excipients that minimize the toxicity of the formulations; and the possibility to modulate pharmacokinetics and enable the site-specific delivery of encapsulated payloads. In addition, the versatility of lipid-based nanosystems has further been demonstrated for the delivery of vaccines, the protection of active cosmetic ingredients, and the improvement of moisturizing properties of cosmetic formulations.Lipid-based nanosystems are well established and there are already different commercially approved formulations for various human disorders. This success has paved the way for the diversification of the pipeline of development, to address unmet medical needs for several indications, such as cancer, neurological disorders, and autoimmune, genetic, and infectious diseases.This Special Issue aims to update readers on the latest research on lipid-based nanosystems, both at the preclinical and clinical levels. A series of 15 articles (six reviews and nine studies) is presented, with authors from 12 different countries, showing the globality of the investigations that are being carried out in this area

Therapeutic Potential of Plant Secondary Metabolites in the Treatment of Diseases and Drug Development

The importance of natural products, and especially plant secondary metabolites, for the treatment of diseases and drug development has already been obvious in medicine for several thousand years. Thus, this Special Issue of MDPI Biomedicines collects eight top articles from the field as regular full papers in addition to five reviews. All of the published papers are a vibrant source of information on the therapeutic potential of plant secondary metabolites in the treatment of diseases and drug development

Polymers Enhancing Bioavailability in Drug Delivery

This Special Issue provides an update on the state of the art and current trends in polymeric drug-delivery systems specifically designed for improving drug bioavailability. The multiple contributions received further strengthen the role of polymers in modern drug delivery and targeting, illustrating the different approaches possible and unveiling what the future may bring

Plant-derived bioactive compounds for inflammatory diseases

Tese de doutoramento em Engenharia de Tecidos, Medicina Regenerativa e Células EstaminaisA Organização Mundial da Saúde qualifica as doenças inflamatórias crónicas como a principal causa de morbilidade e mortalidade no mundo. A inflamação crónica é caracterizada por uma resposta inflamatória anormal e persistente que conduz à disfunção de tecidos e órgãos (p. ex. artrite). Nas últimas décadas, foram observadas melhorias significativas no tratamento destas doenças. No entanto, a contínua administração de fármacos anti-inflamatórios é limitada devido à sua associação com efeitos secundários graves. Assim, terapias mais seguras e eficazes devem ser exploradas. As plantas, sendo a base da medicina tradicional em muitas culturas por milhares de anos, são uma excelente fonte de moléculas bioativas, tornando-se algumas delas marcos na indústria farmacêutica (p. ex. morfina). Duas plantas tradicionalmente utilizadas no tratamento de doenças imunológicas são a Salvia officinalis e a Echinacea purpurea. Todavia, a sua atividade imunomoduladora ainda não foi amplamente estudada de forma a fornecer evidências científicas sólidas acerca da sua eficácia. Neste trabalho foram preparados extratos de diferentes órgãos dessas plantas (flores, folhas e raízes) para explorar o seu potencial como formulações pró- ou anti-inflamatórias. Diferentes solventes e métodos de extração foram usados para preparar extratos com diferentes características. Em particular, os extratos da E. purpurea foram separados em duas frações (fenóis/ácidos carboxílicos e alquilamidas) para permitir identificar a classe de compostos responsável pela maior bioatividade. A composição química dos extratos e das frações foi caracterizada por diferentes técnicas cromatográficas. A atividade antioxidante das diferentes formulações foi avaliada na presença de espécies reativas relevantes. Os efeitos pró- e anti-inflamatórios dos diferentes extratos e frações foram investigados, respetivamente, em macrófagos não estimulados e estimulados com lipopolissacarídeos. Relativamente às propriedades pró-inflamatórias, somente os extratos aquosos de E. purpurea demonstraram bioatividade ao induzir as principais vias de sinalização inflamatória e os mediadores pró-inflamatórios. Considerando as atividades antioxidantes e anti inflamatórias, todos os extratos e frações preparados apresentaram grande eficácia, a qual foi influenciada pelo método de extração, solvente utilizado e órgão da planta selecionado. Posteriormente, o extrato mais promissor foi encapsulado em vesículas unilamelares grandes, funcionalizadas com ácido fólico, com o objetivo de melhorar a sua biodistribuição. Por fim, demonstrou-se a segurança e a eficácia terapêutica desta formulação num modelo experimental de inflamação em ratos. Assim, concluiu-se que os extratos de plantas são formulações com grande potencial para serem posteriormente utilizadas como base no tratamento eficaz de doenças que afetam o sistema imunológico, seja quando este está comprometido ou hiper-reativo.Chronic inflammation-related diseases are ranked by the World Health Organization as the major cause of morbidity and mortality in the world. Chronic inflammation is characterized by a persistent and abnormal inflammatory response that leads to tissue damage and/or dysfunction (e.g., arthritis). There were remarkable improvements in the last decades in the management of chronic inflammatory diseases. However, the constant administration of the clinically available anti-inflammatory drugs is limited due to their association with serious side effects. Therefore, alternative, safer and more effective therapies must be investigated. Plants, being the basis of traditional medicine in many cultures for thousands of years, are a rich source of bioactive molecules. Some of them became landmarks in the pharmaceutical field (e.g., morphine). Two plants traditionally used in the treatment of immune-related diseases are Salvia officinalis and Echinacea purpurea. However, their immunomodulatory activity has not been extensively studied in a scientifically soundness. Therefore, in this work, we obtained extracts from different organs of those plants (flowers, leaves, and roots) to explore their potential as pro- or anti-inflammatory formulations. Different solvents and extraction methods were used to prepare a variety of extracts. Particularly for E. purpurea extracts were fractionated into phenolic/carboxylic acids and alkylamide fractions to identify the class of compounds responsible for the strongest bioactivity. Then, the chemical fingerprint in the extracts and fractions was evaluated by different chromatographic techniques. The antioxidant activity of the different formulations was evaluated against relevant reactive species. The proand anti-inflammatory effects of the different extracts and fractions were evaluated using non-stimulated and lipopolysaccharide-stimulated macrophages, respectively. Regarding pro-inflammatory properties, aqueous E. purpurea extracts were the most promising by the induction of main inflammatory signaling pathways and pro-inflammatory mediators. Considering antioxidant and anti-inflammatory activities, all the developed extracts displayed strong efficacy that was influenced by the extraction method, solvent used, and source organ of the plant. Afterward, the most promising extract was loaded in folic acidfunctionalized large unilamellar vesicles (FLUVs) to improve its therapeutic biodistribution. Finally, it was demonstrated in an experimental rat model of inflammation the safety and enhanced therapeutic efficacy of the most powerful extracts loaded in FLUVs. Therefore, we showed that the plant extracts are promising natural formulations that can be further used as a basis for the effective treatment for disorders in which the immune system is either overactive or impaired.Fundação para a Ciência e Tecnologia (FCT) for my Ph.D. scholarships (PD/BD/135246/2017 and COVID/BD/152012/2021) and the Ph.D. programme in Advanced Therapies for Health (PATH, PD/00169/2013)