RESUMEN Los cítricos son frutos atractivos buscados por los consumidores en todo el mundo por su elevada calidad organoléptica y por los beneficios que tienen para la salud humana. Después de la cosecha, los frutos cítricos para consumo en fresco deben ser sometidos a diferentes tratamientos postcosecha antes de llegar al consumidor. El proceso de desverdizado con exposición al etileno es un tratamiento postcosecha ampliamente utilizado comercialmente para acelerar el cambio de color externo de los cítricos, dado que en las condiciones climáticas del Mediterráneo, las variedades tempranas alcanzan la madurez interna antes que la plena coloración. Sin embargo la aplicación del etileno exógeno puede inducir alteraciones fisiológicas asociadas a la senescencia de la piel y sobre todo del cáliz (ennegrecimiento y caída). Con la finalidad de minimizar estas alteraciones, uno de los objetivos de la presente Tesis fue la optimización del proceso de desverdización así como la evaluación de tratamientos previos a la aplicación del desverdizado en diferentes variedades de mandarinas y naranjas de interés comercial. La aplicación de tratamientos de desverdizado combinando periodos sin exposición al etileno exógeno con periodos con aplicación de etileno, lo que se ha denominado tratamientos combinados, redujo significativamente estas alteraciones sin afectar al cambio de color externo de los frutos. La aplicación del regulador de crecimiento HF-Calibra¿, previamente al desverdizado con etileno, disminuyó el ennegrecimiento y caída del cáliz en las variedades ensayadas, incrementándose este efecto con la dosis de aplicación. Otro objetivo de la presente Tesis fue estudiar el efecto de la aplicación de etileno exógeno, así como del tiempo de exposición al mismo, durante el proceso de desverdizado sobre los componentes bioactivos en diferentes variedades de clementina. La aplicación de etileno durante los diferentes periodos ensayados no afectó al contenido en ácido ascórbico total (TAA), ácido ascórbico (AA) y ácido dehidroascórbico (DHAA) y tampoco a la capacidad antioxidante. Además se evaluó el efecto del tratamiento de desverdizado en condiciones comerciales seguido de un tratamiento de cuarentena por frío en el contenido de vitamina C, compuestos fenólicos y capacidad antioxidante, así como en los compuestos volátiles de diferentes variedades de cítricos. El tratamiento de desverdización seguido del almacenamiento en cuarentena por frío no provocó cambios relevantes en la capacidad antioxidante determinada por DPPH y FRAP ni en el contenido del AA, TAA, DHAA, fenoles totales, flavanonas y flavonas de las variedades ensayadas. Además, estas condiciones postcosecha no afectaron los componentes aromáticos-activos. Por otra parte, la introducción de nuevas variedades de cítricos exige el estudio de su calidad fisico-química y nutricional, así como de su comportamiento durante el periodo postcosecha. Esta evaluación ha sido llevada a cabo en la presente Tesis sobre nuevas variedades triploides de mandarina de recolección tardía, obtenidas en el Departamento de Biotecnología y Protección Vegetal del Instituto Valenciano de Investigaciones Agrarias. Los resultados obtenidos mostraron que las variedades objeto de estudio presentan elevada calidad organoléptica, con altos contenidos en azúcares y ácidos orgánicos, que las hacen altamente atractivas para su consumo en fresco. Además estas variedades muestran alta calidad nutricional, por lo que pueden considerarse como una importante fuente de componentes bioactivos en la dieta humana. La condición de recolección tardía de las nuevas variedades triploides, hace necesario el estudio de su aptitud a la conservación frigorífica. Además de los cambios en la calidad interna que sufren los frutos durante la conservación a baja temperatura hay que tener en cuenta que algunas variedades de cítricos son susceptibles de presentar alteraciones denominadas daño por frío cuando son expuestas a bajas temperaturas. En la presente Tesis, frutos de las nuevas variedades triploides fueron almacenados a 1ºC, 5ºC y 9ºC durante un periodo máximo de 30 días. Todas las variedades ensayadas mantuvieron una elevada calidad interna durante el almacenamiento prolongado, por lo que ésta no resultó un factor limitante. Sin embargo algunas variedades presentaron síntomas externos de daño por frío que limitaron su conservación por lo que las condiciones de temperatura-tiempo de almacenamiento recomendadas serán diferentes en función de la variedad. / Sdiri, S. (2013). Mejora de la Tecnología de desverdización de cítricos y aptitud a la frigoconservación de nuevas variedades. Estudios sobre parámetros de calidad y composición nutricional [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/28213 / TESIS

Capparis spinosa is a wild and cultivated bush, which grows mainly in the Mediterranean Basin. Unopened flower buds, called capers are used in the Mediterranean cuisine as flavoring for meat, vegetable and other foods. Several studies evaluated bioactive component and antioxidant activity of Capparis spinosa, increasing the market demand and the economic importance of capers. The aim of this work was to evaluate the contents of bioactive compounds in floral buds fermented in salt of C. spinosa collected from different areas of Pantelleria Island (Italy), testing the effect on healthy function as total antioxidant compounds. Hydrophilic extracts of C. spinosa from Pantelleria Island were characterized by high-performance liquid chromatography-electrospray ionization/mass spectrometry. Among 24 compounds were detected and quantified by HPLC-MS technique: several Kaempherol and Quercetin derivate were characterized, based on UV spectra and MSn fragmentation pattern. The antioxidative activity of caper hydrophilic extracts was assessed in a number of chemical assays (ORAC, DPPH and ABTS). In order to determine the genetic diversity within and among populations of Capparis spinosa from Pantelleria Island, AFLPs (Amplified Fragment Length Polymorphism) markers were employed. Moreover, in the present study, a commercial model of an Electronic Nose (EN), EOS835 (Sacmi), was preliminarily used to investigate the flavor profile of capers. The EN technique was comparated with a classical techniques gas chromatography-mass spectrometry (GC-MS) analysis, using Head Space Solid-Phase Microextraction (HS-SPME) as a solvent-free sample preparation method. / Capparis spinosa es un arbusto silvestre y cultivado, que crece principalmente en la cuenca mediterránea. Cuando los botones de las flores aún no están abiertas reciben el nombre de alcaparras y se utilizan en la alimentación. Varios estudios han demostrado la presencia de un número de componentes bioactivos in C. spinosa y su actividad antioxidante, lo que ha provocado un aumento de su demanda y ha incrementado la importancia económica de las alcaparras. El propósito de este trabajo fue evaluar el contenido de compuestos bioactivos en el capullo de la flor de C. spinosa conservado en salmuera, procedente de diferentes zonas de la isla de Pantelleria (Italia). Los resultados se expresan como actividad antioxidante total. La actividad antioxidante de los extractos hidrófilos de alcaparra se evaluó mediante pruebas químicas (ORAC, DPPH, ABTS). Con el fin de determinar la diversidad genética dentro y entre poblaciones de C. Spinosa, se utilizaron marcadores moleculares del tipo AFLP (Amplified Fragment Length Polymorphism). Los extractos hidrófilos de C. spinosa se caracterizaron mediante cromatografía líquida de alta eficacia - ionización electrospray acoplada a espectrometría de masas. Se han identificado y cuantificado aproximadamente 24 compuestos con la técnica de HPLC-MS, y se han caracterizado varios derivados de kaempferol y quercetina, sobre la base de los espectros UV y con el modelo de fragmentación MSn. En el este estudio también se ha utilizado un modelo de nariz electrónica comercial (ES), EOS835 (Sacmi), para un estudio preliminar del perfil de aroma de las alcaparras. La técnica ES se ha comparado con una técnica de análisis clásicos tales como la cromatografía de gases acoplada a espectrometría de masas (GC-MS), utilizando como método de preparación de la muestra el espacio de cabeza de microextracción en fase sólida (HS-SPME) libre de disolventes. / Capparis spinosa és un arbust silvestre i conreat, que creix principalment a la conca mediterrània. Quan els botons de les flors encara no estan obertes reben el nom de tàperes i s'utilitzen en l'alimentació. Diversos estudis han demostrat la presència d'un nombre de components bioactius in C. spinosa i la seva activitat antioxidant, el que ha provocat un augment de la seva demanda i ha incrementat la importància econòmica de les tàperes. El propòsit d'aquest treball va ser avaluar el contingut de compostos bioactius en el capoll de la flor de C. spinosa conservat en salmorra, procedent de diferents zones de l'illa de Pantelleria (Itàlia). Els resultats s'expressen com a activitat antioxidant total. L'activitat antioxidant dels extractes hidròfils de tàperes es va avaluar mitjançant proves químiques (ORAC, DPPH, ABTS). Per tal de determinar la diversitat genètica dins i entre poblacions de C. Spinosa, es van utilitzar marcadors moleculars del tipus AFLP (Amplified Fragment Length Polymorphism). Els extractes hidròfils de C. spinosa es van caracteritzar mitjançant cromatografia líquida d'alta eficàcia - ionització electrospray acoblada a espectrometria de masses. S'han identificat i quantificat aproximadament 24 compostos amb la tècnica d'HPLC-MS, i s'han caracteritzat diversos derivats de kaempferol i quercetina, sobre la base dels espectres UV i amb el model de fragmentació MSN. Al aquest estudi també s'ha utilitzat un model de nas electrònic comercial (ES), EOS835 (Sacmi), per a un estudi preliminar del perfil d'aroma de les tàperes. La tècnica ÉS s'ha acoblat amb una tècnica d'anàlisi clàssics com ara la cromatografia de gasos acoblada a espectrometria de masses (GC-MS), utilitzant com a mètode de preparació de la mostra l'espai de cap de microextracció en fase sòlida (HS-SPME ) lliure de dissolvents. / Lo Bosco, F. (2017). Evaluation of antioxidant properties and assessment of genetic diversity of Capparis spinosa cultivated in Pantelleria Island [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/79872 / TESIS

Three systems were compared in the first case study: (1). pre-dissolved β-carotene nanoemulsion (d< 200nm); (2). corn oil emulsion (d< 200nm) with β-carotene crystals being added before digestion; (3). phosphate buffer saline with β-carotene being added before digestion. Oil-in-water nanoemulsions were formed by high-pressure homogenization using Tween 20 as emulsifier and corn oil as carrier oil and then they were subjected to a simulated mouth, stomach and small intestine digestion. The rate and extent of free fatty acid production in small intestine decreased in the order (2)>(1)>(3); whereas the β-carotene bioaccessibility decreased in the order (1)>>(2)>(3). In system (3), even without any fat content, there is still noticeable consumption of NaOH, which is due to the ester bonds existing in the non-ionic surfactant (Tween 20). In the second case study, we developed two comparing groups by differentiating their oil concentration (20%, 4% respectively). The bioaccessibility of the high fat group is only half of the low fat group due to the insufficient digestion of fat in the former group. In the third case study, the bioaccessibility of nobiletin with different physical states (crystalized vs solubilized) and in different delivery system (conventional emulsion vs nanoemulsion) was compared. Not like β-carotene, the bioaccessibility of nobiletin as crystals in slightly lower than it is as solubilized state. Meanwhile, in conventional emulsion, the bioaccessibility is slightly lower than in nanoemulsion. This study provides important information for developing effective delivery systems for lipophilic bioactive components in food and beverage applications.

For thousands of years ginger rhizomes are used in traditional Chinese medicine. Because of his significant pungent flavour is commonly used in foods and beverages all over the world. Nowadays many of the beneficial pharmacological positive effects of ginger rhizomes are identified. Their occurrence is due to the high concentration of bioactive compounds. This thesis is focused on analysing of occurrence of bioactive compounds such as polyphenols and flavonoids and their influence on antioxidation and antimicrobial properties of samples of fresh and dried ginger. The results show that for extraction of bioactive compounds in different ginger samples is more suitable to use different types of extraction solvents. The highest antioxidation activity was measured for macerate of 100% bio ginger tea from Sonnentor company in 96% ethanol. Antimicrobial properties were showed only for 100% bio ginger tea against gram-positive bacteria Microccocus luteus.

Philosophiae Doctor - PhD / Actinobacteria, a Gram-positive phylum of bacteria found in both terrestrial and aquatic environments, are well-known producers of antibiotics and other bioactive compounds. The isolation of actinobacteria from unique environments has resulted in the discovery of new antibiotic compounds that can be used by the pharmaceutical industry. In this study, the fynbos biome was identified as one of these unique habitats due to its rich plant diversity that hosts over 8500 different plant species, including many medicinal plants. In this study two medicinal plants from the fynbos biome were identified as unique environments for the discovery of bioactive actinobacteria, Aloe ferox (Cape aloe) and Sutherlandia frutescens (cancer bush).

Orientador: Cassia Roberta Malacrida Mayer / Resumo: O pequi (Caryocar brasiliense Camb.), fruto típico do Cerrado brasileiro, é rico em lipídios e compostos antioxidantes. Além de ser utilizado na alimentação, de sua polpa é extraído um óleo de relevante valor comercial. A extração do óleo da polpa feita por prensagem a frio origina uma torta residual (TR) parcialmente desengordurada. As tortas resultantes desse processo, bem como as partes descartadas como o endocarpo espinhoso (EE), possibilitam a extração de compostos de interesse, como óleo residual e compostos bioativos. Considerando a crescente demanda desse óleo e consequentemente a elevada quantidade de resíduos gerados, surgiu a necessidade de compilar informações sobre seu potencial nutricional, investigando sua possível utilização como matéria-prima para reaproveitamento sustentável de forma eficiente e segura. Para tanto foi determinada a composição centesimal, os biocompostos (compostos fenólicos totais, flavonoides totais, carotenoides totais e vitamina C), a composição mineral, a composição em ácidos graxos do óleo extraído da TR e do EE do pequi, bem como a avaliação da atividade antioxidante de ambos. A TR e o EE apresentaram consideráveis teores de proteínas, fibras, carboidratos e principalmente de lipídios (30,9% na TR e 32,6% no EE). Na fração lipídica de ambos os materiais avaliados prevalecem os ácidos graxos oleico (60,29% na TR e 57,44% no EE) e palmítico (33,41% na TR e 35,08% no EE). Os mesmos apresentaram-se como fontes interessantes de compostos fe... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The Pequi (Caryocar brasiliense Camb.),a typical fruit of the Brazilian Cerrado, is rich in lipids and antioxidant compounds. In addition to being used in feeding, from its pulp is extracted an oil of relevant commercial value. The extraction of pulp oil madebycold pressinggives riseto a partially defatted residual pie (TR). The pies resulting from this process, as well as discarded parts such as the thorny endocarp (EE), allow the extraction of compounds of interest, such as residual oil and bioactive compounds. Considering the growing demand for this oil and consequently the high amount of waste generated, the need to compile information about its nutritional potential arose, investigating its possible use as a raw material for sustainable reuse in an efficient and safe way. Therefore, thecentesimal composition, biocompounds (total phenolic compounds, total flavonoids, total carotenoids and vitamin C), mineral composition, fatty acid composition extracted from TR and pequi EE were determined, as well as the evaluation of antioxidantactivity ofboth. RTand EE presented considerable levels of proteins, fibers, carbohydrates and mainly lipids (30.9% in RT and 32.6% in EE). In the lipids of both materials evaluated, oleic fatty acids prevail (60.29% in RT and 57.44% in EE) and palmitic(33.41% in RT and 35.08% in EE). They presented themselves as interesting sources of total phenolic compounds (372 and 480.5 mg EAG/100g in RT and EE, respectively) and total carotenoids (7.75 and ... (Complete abstract click electronic access below) / Mestre

Cowpeas (Vigna unguiculata L. Walp) are legumes recognised as a good source of proteins in developing countries. Cowpeas are mostly utilised as cooked whole seeds. This is often achieved only after boiling for up to 2 hours, resulting in high energy consumption and a long time for food preparation. Micronisation of pre-conditioned cowpeas (± 41 % moisture at 153 °C) reduces their cooking time. During micronisation, cowpea seeds are exposed to electromagnetic radiation with a wavelength range of 1.8 to 3.4μm. For biological materials, the penetration of infrared rays into the food material causes intermolecular vibration, this result in a rapid increase in temperature and water vapour pressure within the seed. Micronisation changes physico-chemical properties of cowpea seeds that may affect sensory properties of cooked cowpeas. Micronisation may also affect cowpea bioactive components such as phenolic compounds and hence their antioxidant properties and bioactive properties. This study aimed at (1) determining the effects of micronisation of pre-conditioned cowpeas on sensory properties of cooked cowpeas and (2) determining the effects of mironisation of pre-conditioned cowpeas on the phenolic compounds, radical scavenging properties and their protective effects against oxidative damage of biomolecules (i.e. low density lipoproteins (LDL), deoxyribonucleic acid (DNA) and red blood cells (RBC). © University of Pretoria vi Micronisation significantly reduced cowpea cooking time by 28 to 49 %, depending on cowpea type. There were significant (P<0.05) increases in roasted aroma and flavour, mushy texture and splitting in all micronised samples. Bechuana white, a light brown cowpea type, was more mushy and split than others. There were significant decreases in firmness, mealiness and coarseness after micronisation for all cowpea types. Micronised cowpeas were darker (lower L* values) than unmicronised cooked cowpeas. Darkening was more evident in light coloured than dark coloured cowpea types. Although micronisation reduces cowpea cooking time, it also affects sensory properties of cowpeas. This might have an influence on consumer acceptance of micronised cowpeas. Twenty seven phenolic compounds were identified in the cowpea types studied: 6 phenolic acids, 14 flavonols and 7 flavan-3-ols. Protocatechuic acid, p-coumaric acid, 4- hydroxybenzoic acid and ferulic acid were the major phenolic acids in cowpeas. Catechin, catechin-3-O-glucoside, myricetin, rutin, quercetin and its mono and diglycosides were present in all cowpea types analysed. Dr Saunders (701.7−849.2 μg/g) (red in colour) and Glenda (571.9−708.1 μg/g) (dark brown in colour) contained the highest total phenolic contents, followed by Bechuana white (361.5−602.3 μg/g) (light brown in colour) and Blackeye (152.0−224.5 μg/g) (cream in colour). More of the flavonols were identified in red and dark brown compared to light brown and cream cowpea types. The red cowpea type contained all the dimers and oligomeric flavan-3-ol species identified in this study. In all cowpea types, extracts from unmicronised (uncooked) cowpeas inhibited copperinduced LDL oxidation in a dose dependent manner. Extracts from all samples analysed exhibited protective effects against AAPH (2, 2'-azobis (2-amidinopropane) hydrochloride) induced RBC haemolysis and DNA damage. Extracts from more pigmented cowpeas, i.e. Dr Saunders, Glenda and Bechuana white, had significantly (P<0.05) higher levels of total phenolics, total flavonoids and radical scavenging properties than Blackeye (less pigmented). Extracts from more pigmented cowpeas also offered higher protection against AAPH-induced DNA and copper-induced LDL oxidation damage than extracts from less pigmented cowpeas. These results indicate protection of biomolecules e.g. DNA, LDL and RBC) from oxidative damage and have a potential to reduce oxidative stress implicated in the development of chronic diseases. This is because cowpea phenolic compounds possess the ability to reduce oxidative damage associated with development of these diseases. © University of Pretoria vii Pigmented cowpea types may be recommended for health applications as they show more potential as source of antioxidants compared to the less pigmented cowpeas. Extracts from micronised (uncooked and cooked) samples of Dr Saunders and Glenda cowpeas had significantly higher concentrations of ferulic acid and p-coumaric acid compared with unmicronised samples. Para-coumaric acid concentrations were higher in all micronised samples of Blackeye cowpeas than in unmicronised samples. The micronisation process could release cell wall bound ferulic acid and p-coumaric, increasing their concentrations in micronised samples. On the contrary, extracts from all micronised samples of Bechuana white and Glenda cowpeas had lower concentrations of catechin than unmicronised samples. Results indicated that total extractable phenolics were lower in micronised samples of cowpea types than unmicronised samples. Futhermore, extracts from micronised samples of all cowpea types showed less protective effect against LDL oxidation than extracts from unmicronised samples. However, for most cowpea types there was no significant difference in total flavonoid contents (TFC) and Trolox equivalent antioxidant capacity (TEAC) values of cooked samples of both micronised and unmicronised. Micronisation did not affect the protective effects of cowpeas against AAPH-induced RBC haemolysis and oxidative DNA damage. Micronisation, followed by cooking, may have generated heat-induced antioxidants such as Maillard reaction products contributing to radical scavenging properties in micronised (cooked) cowpea samples. Though micronised samples had lower concentrations of some phenolic compounds and total extractable phenolics than unmicronised samples, micronised cowpea samples still exhibited radical scavenging properties and offered protective effects against oxidative damage of LDL, DNA and RBC and therefore may offer potential health benefits to consumers. / Thesis (PhD)--University of Pretoria, 2013. / gm2013 / Food Science / Unrestricted

>Magister Scientiae - MSc / In modern society, diversity of marine macroalgae has become an inspiration for pharmaceutical companies and researchers because of their numerous health benefits, and a great deal of interest has developed towards the isolation of bioactive compounds to identify novel marine natural products that could eventually be developed into therapeutics or pharmaceutical products. Furthermore, marine macroalgae are valuable source of structurally diverse metabolites with scientifically proven reports. The search continues as there are many natural bioactive compounds that are in the womb of the ocean which are still a mystery. Thus, the present study investigates the natural products from green seaweed Ulva capensis.

Orientador: Filipe Pereira Giardini Bonfim / Resumo: A espécie Vernonia polyanthes (Spreng.) Less., Asteraceae, popularmente conhecida como assa-peixe, assa-peixe-branco, mata-pasto,é nativa do Brasil com ampla distribuição (regiões sul e sudeste e centro-oeste) comum em área de Cerrado em São Paulo, Mato Grosso, Minas Gerais e Goiás, e na orla Atlântica. Há poucas informações na literatura, sobre técnicas de cultivo para essa espécie. Com isso, o presente trabalho teve como objetivo avaliar adubação orgânica, níveis de calagem, época de colheita e densidade de plantio na produtividade e produção de compostos bioativos de assa-peixe. Os experimentos foram realizados na Fazenda Experimental Lageado, da Faculdade de Ciências Agronômicas da UNESP, Câmpus de Botucatu - SP. O trabalho foi dividido em dois capítulos, onde no capítulo 1 foi abordada a adubação com esterco de curral curtido e níveis de calagem na produtividade e a influência na produção de óleo essencial. As variáveis analisadas foram massa seca de raízes, massa seca das folhas, altura das plantas comprimento da maior raiz, volume da raiz, diâmetro do caule e número de folhas. Houve efeito significativo da adubação no volume da raiz e na massa seca da raiz. Plantas que não receberam adubo apresentaram maior valor para essas características. O maior teor de óleo essencial foi para a dose de 9 kg m-2 de adubo. Na avaliação dos compostos químicos, foram identificadas 13 substâncias no óleo essencial e o germacreno D foi o composto majoritário, que se destacou tanto para a... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The species Vernonia polyanthes (Spreng.) Less., Asteraceae, popularly known as assa-peixe, assa-peixe-branco, cambará-branco, mata-pasto, are native to Brazil with wide distribution (south and southeast regions and central-west) common in Cerrado area in São Paulo, Mato Grosso, Minas Gerais and Goiás, and in the Atlantic coast. There is little information in the literature about cultivation techniques for this species. Thus, the present work aimed to evaluate organic fertilization, liming levels, harvest time and planting density in the productivity and production of bioactive compounds of assa-peixe. The experiments were carried out at Fazenda Experimental Lageado, Faculdade de Ciências Agronômicas, UNESP, Campus Botucatu - SP. The work was divided into two chapters, where Chapter 1 was approached fertilization with cattle manure tanned and liming levels in productivity and influence in essential oil production. The variables analyzed were dry root weight, dry leaf weight, plant height, length of the largest root, root volume, stem diameter and number of leaves. There was a significant effect of fertilization on root volume and root dry matter. Plants that did not receive fertilizer showed higher value for these characteristics. The highest content of essential oil was for the dose of 9 kg m-2 of fertilizer. In the evaluation of chemical compounds, 13 substances were identified in the essential oil and germacrene D was the major compound, which stood out both for fertilizat... (Complete abstract click electronic access below) / Doutor

Bioactive glass is a type of third generation bioactive material that can bond to both soft and hard tissue with applications ranging from bone defect repair, coatings for metallic implants, to scaffolds for tissue engineering. Design of bioactive glasses for these applications rely on a detailed understanding of the structures of these glasses which are complicated and multicomponent. In this thesis, I have applied molecular dynamics (MD) simulations with interatomic potentials developed in our group to understand the effect of modifier cation substitution on the structures and properties of two series of bioactive glasses. Particularly, MD simulations are used to understand K2O to Na2O and MgO to CaO substitution on the short and medium range structures (such as cation coordination number, pair distribution function, Qn distribution, and ring size distribution) and properties (such as bulk and Young's moduli and CTE) of 55S4.1 bioactive glasses. As Na2O is incrementally substituted with K2O in 55S4.1, a decrease of the glass transition temperature (Tg) and an increase of CTE was observed, as well as a decreasing trend in the moduli. For the MgO to CaO substitution series, Mg2+ is mainly four-fold coordinated that suggests that it can play a role as a network former in this series. Results of both series showed characteristics of the phenomena of the mixed alkali effect (MAE) that has been known to show non-linear variations in trends like Tg in glasses with alkali and alkali earth ion substitution.