225 research outputs found
Recommended from our members
American Council for Medicinally Active Plants (ACMAP)-11th ANNUAL HYBRID CONFERENCE
Aplicação das tecnologias de fluidos supercríticos e de líquidos pressurizados para a valorização dos rejeitos de cúrcuma : obtenção de compostos bioativos, custo de manufatura, equilíbrio de fases e encapsulamento dos extratos
Orientador: Maria Angela de Almeida Meireles PetenateTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia de AlimentosResumo: Além de ser uma perspectiva atual, a obtenção de compostos bioativos a partir de
rejeitos agroindustriais é uma alternativa viável para o aproveitamento destes materiais, o que
resulta na formação de produtos com características diferenciadas e alto valor agregado. No
caso da cúrcuma (Curcuma longa L.), que possui vasta aplicação como corante natural, a
quantidade de rejeito sólido gerado a partir dos processos de extração de óleos voláteis e
curcuminóides (pigmentos amarelos) é elevada, e chega a atingir aproximadamente a
quantidade de matéria-prima bruta utilizada para se realizar os procedimentos; por exemplo,
para se obter óleo volátil por hidrodestilação, 98% de rejeito sólido é gerado para se obter da
matéria-prima bruta apenas 2% de extrato. Esses resíduos possuem composição atrativa em
termos de carboidratos que lhe conferem aplicação para a formulação de novos produtos, seja na forma de amido isolado, seja para produção de biofilmes ou açúcares simples e etanol a partir de hidrólise. Além de carboidratos, esses rejeitos possuem curcuminóides, que lhe conferem poder corante e efeitos antioxidantes. Diante disso, esta tese propõe alternativas sustentáveis para a valorização dos rejeitos de cúrcuma gerados a partir de processos que empregam fluidos supercríticos e líquidos pressurizados. Inicialmente foi investigado o cenário promissor da utilização de fontes não convencionais de amido para fins comerciais, além das tendências e perspectivas futuras para inclusão dos resíduos de cúrcuma como fonte complementar para o mercado de amidos. Posteriormente, foram investigadas duas alternativas para o aproveitamento dos rejeitos de cúrcuma, que consistem na realização de ensaios de hidrólise parcial com o uso de água pressurizada e na investigação do impacto das tecnologias de extração com dióxido de carbono supercrítico e etanol pressurizado na modificação física dos rejeitos de cúrcuma e nos subsequentes amidos isolados. A partir da reação de hidrólise foram estudados dois produtos, um extrato líquido e o rejeito sólido, ambos constituídos de curcuminóides e carboidratos. Não fugindo dessa questão do aproveitamento, o comportamento a altas pressões do rejeito parcialmente hidrolisado e dos óleos voláteis de cúrcuma foi estudado a partir do levantamento de dados de equilíbrio de fases empregando-se o método sintéticovisual sem retirada de amostra, cujo aparato experimental foi construído e validado nesta tese. Diante da baixa estabilidade e pobre absorção dos compostos bioativos da cúrcuma no organismo humano, foram realizados ensaios de encapsulação dos extratos de curcuminóides e óleos voláteis em polietilenoglicol com o intuito de oferecer um novo produto de maior estabilidade em termos de biocompostos com efeitos antioxidantesAbstract: In addition to being a current perspective, obtaining bioactive compounds from
agroindustrial wastes is a viable alternative for the use of these materials, which results in the
formation of products with differentiated characteristics and high added value. In the case of
turmeric (Curcuma longa L.), which has a wide application as a natural dye, the amount of
solid waste generated by the extraction of volatile oil and curcuminoids (yellow pigments) is
elevated and reaches approximately the amount of the raw material used to carry out the
procedures, i.e., to obtain volatile oil using hydrodistillation, 98% solid waste is generated
to obtain only 2% crude extract from raw material. These residues have attractive composition in terms of carbohydrates that give it application for the formulation of new products, either as an isolated starch or for the production of biofilms or simple sugars and ethanol from hydrolysis. In addition to carbohydrates, these materials have curcuminoids, which attribute it colorant power and antioxidant effects. In this context, this thesis proposes sustainable alternatives for the valorization of the turmeric wastes generated from processes that use supercritical fluids and pressurized liquids. We initially investigated the promising scenario of the use of unconventional sources of starch for commercial purposes, as well as future trends and perspectives for inclusion of turmeric residues as a complementary source for the starch market. Afterwards, we investigated two alternatives aimed for the reuse of turmeric wastes, which consists of application of partial hydrolysis using pressurized hot water and the investigation of the impact generated by extraction technologies using supercritical carbon dioxide and pressurized liquid ethanol in the physical modification of turmeric wastes and the subsequently isolated starches. From the hydrolysis reaction, two products, i.e., a liquid extract and the solid waste, both consisting of curcuminoids and carbohydrates, were studied. High-pressure phase behavior of the turmeric partial hydrolyzed waste and volatile oils was studied through acquisition of phase equilibrium data using the synthetic-visual method without sample withdrawal, which experimental apparatus was constructed and validated in this thesis. In view of the low stability and poor absorption of turmeric bioactive compounds in the human body, encapsulation tests of curcuminoids ethanolic extract and volatile oils in polyethylene glycol were carried out in order to provide a new product with greater stability in terms of bioactives with antioxidant effectsDoutoradoEngenharia de AlimentosDoutora em Engenharia de AlimentosCAPE
Plant Essential Oil with Biological Activity
Plant essential oils (PEOs) are hydrophobic liquids that contain volatile chemical components that are derived from various plant parts. They are among the most important plant natural products because of their diverse biological features as well as their therapeutic and nutritional applications. In addition, several aromatic PEOs are used to flavor food and add aromas to incense in the culinary sector. Recently, many PEOs have demonstrated promising antimicrobial activity against different post-harvest diseases and have been considered as possible natural alternatives for chemical treatments. This Special Issue titled “Plant Essential Oil with Biological Activity” provided an overview of several elements of PEOs, including their biological applications, antimicrobial activities, bio-pharmaceutical properties, principal single constituents, and mechanisms of action. This Special Issues fills in knowledge gaps and aids in the advancement of EO applications around the world. This issue contains thirteen research articles and two review papers that address a wide range of topics and applications relevant to the bioactivity of PEOs
Advances in Green Extraction and Isolation Methods
Three plants of interest and their active ingredients were examined throughout this thesis: γ-irone of Iris germanica L., the curcuminoids of Curcuma longa L., and cinnamaldehyde of Cinnamomum cassia. They also dictate the structure of the presented study.
Chapter 3 deals with the extraction and concentration of the odiferous γ-irone from Iris Barbata-Elatior, a cultivar of Iris germanica L. The dried and ground rhizomes were extracted in four different approaches with solvents based on myristic acid. The best result with a γ-irone yield of ~ 66% was achieved through the extraction of rhizomes soaked in water with pure myristic acid. This model extraction was scaled up in order to obtain enough extract to successively perform molecular distillation for concentration purposes. The optimum distillation method was developed beforehand by taking the Clausius-Clapeyron relation as a theoretical basis and validating it with experiments using structural analogues of γ-irone. Eventually, the γ-irone content could be concentrated 18-fold after two molecular distillation cycles.
The curcuminoids of Curcuma longa L. were the molecules of interest throughout Chapters 4 and 5. A screening of different natural deep eutectic solvents in terms of curcumin solubility was performed. The most promising ones were the mixtures of choline chloride with lactic and levulinic acid. They were chosen to replace the aqueous phase in ternary mixtures with ethanol and triacetin. Successively, the phase behavior of these ternary mixtures was examined while also mapping the solubility of curcumin depending on the weight ratios of these ternary mixtures. In the domains of highest solubility, extraction experiments were performed. It was possible to achieve curcuminoid extraction yields of up to 79% (lactic acid) and 84% (levulinic acid). Consecutively, cycle extractions were investigated, showing that the solvents could be concentrated through repeated extraction of fresh rhizomes. The change of the solvent during these cycle extractions was monitored and determined to be the limiting factor of cycles.
After determining the natural deep eutectics’ capability to solve and extract curcuminoids, the mechanism of solubility was investigated. Nine different eutectics based on the quaternary ammonium compounds choline chloride, betaine, and carnitine mixed with lactic, levulinic, and pyruvic acid were examined. UV/Vis spectroscopy was used to monitor the eutectics’ capability to solve curcumin. The underlying intermolecular interactions were assessed theoretically by using COSMO-RS predictions of the chemical potential and experimentally backing those with 1H and NOESY NMR measurements. Different additional functionalities of the quaternary ammonium compounds did not influence the solubility of curcumin in ethanolic solutions, while functionalities had a significant effect when regarding ethanolic solutions of the acids. The natural deep eutectics containing levulinic acid yielded the highest curcumin solubilities based on a solubility synergy between the acid and the quaternary ammonium compounds. Non-specific and directed intermolecular interactions were identified as the driving force behind the strong solubility increase.
In the last part, Chapter 6, the curcumin solubility in ethanolic solutions of natural aromas was examined. A series of natural aromas with different functionalities were screened experimentally with UV/Vis spectroscopy and theoretically with COSMO-RS, yielding cinnamaldehyde as the molecule of highest solving ability. Natural essential cinnamon oils of Cinnamomum cassia and Cinnamomum verum, high in cinnamaldehyde, were examined in view of composition and solving capability. The phase behavior of ternary mixtures of the best cinnamon essential oil (Cinnamomum cassia oil), water, and ethanol was characterized, and the curcumin solubility was mapped. Cycle extraction experiments showed that rather the loss of solvent was the limiting factor of cycles than the solvent change over time. A theoretical model for cycle extractions was developed
Sustained delivery system of curcuminoids rich plant Curcuma longa, L for topical application
Abstract : The research conducted in this study was aimed at extracting and studying the most bioactive elements found in the Southern Asian plant known as Curcuma longa, commercially is known as Turmeric. Curcumin is the most bioactive component of turmeric, it and other phytochemicals including essential oils, particularly the ones relevant for its topical application for skin care were studied. This plant was chosen because of its documented history as an effective active in skin care. This is because some of the plant’s phytochemicals have high antioxidant and anti-inflammatory activities, providing skin with nutrients that can shield or protect it from environmental harm. The plant’s antioxidant activity makes it useful as a free-radical scavenger. Free radical have oxidation properties that cause skin cancer and aging. During injury (inflammation) of skin, the anti-inflammation of the phytochemicals helps in repairing and healing the wounds. This has led to the wide use of Curcuma longa in cosmetics for wound healing, sun protection, and skin lightening. The essential oils components of turmeric were extracted by the solvent extraction technique and they were studied by 2D GCxGC-TOF/MS. This was done in order to qualitatively study the various components of the essential oils and to quantify them. Various classes of compounds were identified, where it was observed that the essential oils component of turmeric consisted of mainly terpenoids, terpenes, and alkaloids. It was also found that most of these compounds had a chain length varied between 11 and 15 carbon atoms. Most of these 11-15 carbon atoms were identified as sesquiterpenoids. These results were consistent with that turmeric is used as a beauty product because these classes of compounds have been used in cosmetics because of their anti-microbial, antioxidant and therapeutic UV-induced skin care. In another study, Curcuma longa, L was subjected to extraction with the aim of isolating curcuminoids. Curcuminoids is a term that encompasses 3 compounds, curcumin, demethoxycurcumin and bis-methoxycurcumin. The extraction was achieved by solvent extraction using various organic solvents and isolated by column chromatography. The characterization of the extracts was carried out using FTIR, UV-VIS, NMR. The fraction of interest was characterized by 3 spots observed on the TLC of the fraction. These spots were assigned to curcuminoids.M.Sc. (Applied Chemistry
Effect of curing conditions and harvesting stage of maturity on Ethiopian onion bulb drying properties
The study was conducted to investigate the impact of curing conditions and harvesting stageson the drying quality of onion bulbs. The onion bulbs (Bombay Red cultivar) were harvested at three harvesting stages (early, optimum, and late maturity) and cured at three different temperatures (30, 40 and 50 oC) and relative humidity (30, 50 and 70%). The results revealed that curing temperature, RH, and maturity stage had significant effects on all measuredattributesexcept total soluble solids
Recommended from our members
Effect of storage temperature, duration and drying technique on the major volatile organic compounds in mango ginger (Curcuma amada Roxb.)
Curcuma amada Roxb. is an important member of the Zingiberaceae family and is commonly
known as mango ginger due to its resemblance to ginger and the green mango like aroma of the
rhizome. The biochemical profile of mango ginger is characterised by a number of volatiles that
have application in the food and pharmaceutical industries. However, due to the niche nature of
where mango ginger is cultivated, commercial production and extraction of these volatiles have
not been the subject of research. There is also insufficient literature on the effect of post-harvest
processing techniques on the sensory attributes of mango ginger. As a result, harvested mango
ginger rhizomes are often transported and stored alongside other major agricultural produce,
without a clear understanding of the optimum storage temperature and duration required for the
rhizomes. This study focuses on the changes in the content and composition of volatile organic
compounds (VOCs) in mango ginger when subjected to different storage temperatures and
durations. Additionally, the study also explores the effect of two commercially followed drying
techniques on the biochemical profile. SPME-GCMS analysis of the change in chemical profile
was also complemented by sensory analysis as part of this study.
The first phase of this study was aimed at improving the current practice prevalent among
wholesalers and retailers, of storing mango ginger rhizomes for a short period without undergoing
any commercial post-harvest treatments. The intention of the second phase was to determine
whether commercial post-harvest treatments such as drying followed by long term storage were
feasible options for mango ginger, with a view to explore new avenues on commercial use of the
dried powder. This is the first report that analyses the combined effects of drying techniques and
storage duration on the organoleptic properties of mango ginger rhizomes. To this purpose, this
study explored the effect of three storage temperatures (8 °C, 15 °C and 22 °C) across three
storage durations (1, 15 and 29 days) during its first phase. The analysis was extended to its
second phase by utilising two drying techniques (hot air drying and freeze drying) and storing
the rhizomes for three different storage durations (1, 2 and 3 months).
The study concluded that monoterpenes make up a significant proportion of the VOCs in mango
ginger, which provide the signature aroma and flavour characteristics. In terms of relative
abundance, the major terpenes were identified as myrcene, β-(E)-ocimene, β-pinene, eucalyptol,
epoxy myrcene and α-pinene. Other compounds like alcohols, aldehydes, ketones, and esters
make up the rest of the VOC composition and are responsible for imparting fresh, floral, and
spicy notes. SPME-GCMS and sensory analysis in phase 1 confirmed that storage duration had
a more significant impact on the VOC profile than storage temperature. The highest relative
abundance of terpenes was identified in samples stored at 15 °C for 15 days. Principal Component
Analysis (PCA) also aligned with these findings by displaying a strong positive correlation
between the flavour and aroma characteristics of green mango and mild turmeric for these
samples. Phase 2 concluded that the combined effect of both drying technique and storage
duration was able to significantly impact the biochemical profile. Significant variations in
relative abundance values were seen in different chemical groups, along with the formation of
new compounds like alkanes and alkenes, and the total absence of alcohols, when compared to
that of fresh rhizomes. These trends can be attributed to the formation of secondary metabolites
produced by the plant in response to stress induced by mechanical injury during peeling and
slicing, followed by Maillard and Strecker reactions that occur when the samples were exposed
to drying. Sensory analysis in phase 2 confirmed that samples that were hot air dried and then
stored for up to two months were able to retain most of the aroma and flavour attributes of fresh
rhizomes. PCA also aligned with these findings by displaying a strong correlation between green
mango and mild turmeric aroma and flavour compounds in these samples.
This study opens up other avenues of research, such as the use of gas chromatography – olfactory
analysis, to determine the aroma of individual chemical groups and identify the most dominant
odour active compounds present in mango ginger. Other methods like vacuum drying need to be
explored to optimise conditions such as temperature, drying time and pressure to achieve an end
product with desirable organoleptic properties and shelf-life for commercial use of the essential
oils in the food and pharmaceutical industry. The results could then be combined with sensory
and consumer trials to determine the acceptance of the flavour and aroma attributes of mango
ginger by the end user
Nanotechnological approaches using curcumin and Withania somnifera: neuroprotection and antimicrobial activities
Tese de Doutoramento em Biologia de PlantasNeurological disorders contribute to 6.3% of the global burden of the diseases and this number is increasing every
year due to aging population. Despite enormous efforts in brain and central nervous system related research,
neurodegenerative diseases such as Alzheimer or Parkinson disease remain the world's leading cause of
disability. Moreover, neurodegenerative diseases are multifactorial pathogenesis with a complex combination of
genetic components and environmental factors. Although, several treatment methods are available to treat these
conditions, they are associated with the risk of infection, high neurosurgical cost and limited drug availability due
to the presence of blood–brain barrier (BBB).
Herbal medicine for neurological problems has gained much attention in the recent years, because of the
disadvantages of conventional therapies and increased patient compliance. Generally, the drugs obtained from
natural sources are considered to be safe alternatives. Since ancient times, plant extracts have been used in the
treatment of pathologic conditions of the central nervous system. As the methods to isolate active constituents
from plant extracts have greatly improved, the scientific understanding of psychoactive plants has also advanced
significantly. Curcuma species and Withania somnifera have been used as traditional therapeutic agents in Asian
medicine to treat various common ailments and recently reported to possess antioxidant, antidepressant and
neuroprotective effects.
Although a number of herbal-based medicines have been screened and identified, still the treatment for the
neurological disorders is not up to the required level. This is mainly because most of the herbal medicines exhibit
poor bioavailability due to low absorption, fast metabolism, and rapid systemic elimination in the body. Although
several approaches have been employed to overcome these problems, modification in the delivery method is a
promising approach. In particular, employing herbal medicine based nanocarrier system to treat neurological
disorder has gained specific interest because of its several advantages namely, the ability of nanoparticles to
deliver the drug in a pre-determined rate at a particular site of action, providing high bioavailability and low toxicity.
Compared to the conventional delivery methods, nanoparticle-mediated administration of drugs has been proven
to be the ideal way to deliver drugs for neurological disorders. Due to these advantages, pharmaceutical scientists
have started designing nanoparticle mediated drug delivery systems for herbal medicines with neurotherapeutic potential. Nanoencapsulation of bioactive compounds and extracts into the polymer matrix gives several
advantages, including protection against degradation, enhancing the solubility and bioavailability.
In this PhD thesis we have selected two important medicinal plants with proven antioxidant, antidepressant and
neuroprotective effects namely W. somnifera and Curcuma sps for nanoencapsulation and subsequent cellular
uptake with U251 glioma cells and biodistribution analysis in Zebrafish model.
First we developed HPLC methods to identify withanolides and quantify curcumin respectively from W. somnifera
extracts and Curcuma species . Extracts derived from different parts (leaves, roots and fruits) of W. somnifera were
tested. W. somnifera extract with maximum amount of withanolides and curcumin (active principle of Curcuma
sps) were selected for nanoencapsulation. We found that Purospher RP-18 e 5 µm column is ideal for efficient
separation and simultaneous quantification of withanolides whereas, Purospher C-18 column was optimum for
curcumin quantification from Curcuma sps extracts. HPLC quantification of different extracts of W. somnifera
revealed that the methanolic extract obtained from leaf tissues contain the highest amount of withanolides
compared to roots and fruits. Compared to C. aromatica, C. longa possess higher amount of curcumin.
W. somnifera extract/curcumin loaded polycaprolactone (PCL) and methoxy polyethylene glycol- polycaprolactone
(MPEG-PCL) nanoparticles were prepared by solvent displacement method. Prepared nanoparticles were
characterized for their physico-chemical properties such as size, shape, in vitro drug release and encapsulation
efficiency. After the physico-chemical characterization, we analyzed the in vitro cytotoxicity and cellular uptake of
nanoparticles by U251 glioma cells. In addition, we evaluated the protective effect of W. somnifera extract and
curcumin loaded nanoparticles against tBHP-induced insult in U251 glioblastoma cells, as a measure of
neuroprotection. Biodistribution of W. somnifera /curcumin loaded PCL and MPEG-PCL nanoparticles in animal
system were evaluated using zebrafish larvae as model organism.
Physical characterization of the prepared nanoparticles revealed that MPEG-PCL nanoparticles were smaller in
size compared to PCL nanoparticles irrespective of W. somnifera extract or curcumin encapsulation. Transmission
scanning electron microscopy (TEM) images of nanoparticles revealed a round shape in general, although the
surface of PCL nanoparticles appeared to be rough and porous. The entrapment efficacy of W. somnifera extract
and curcumin was higher in MPEG-PCL compared to PCL. We observed an initial burst release followed by a slow extended release profile for both W. somnifera extract and curcumin irrespective of the polymer used for
encapsulation.
Treatment of U251 glioma cells with PCL and MPEG-PCL nanoparticles loaded with W. somnifera extract/
curcumin evidenced the efficient cellular uptake of nanoparticles. However, MPEG-PCL nanoparticles showed
better internalization compared to PCL nanoparticles, irrespective of their W. somnifera extract/ curcumin load.
Neuroprotection assay showed that both W. somnifera/ curcumin loaded nanoparticles protect the cells from
oxidative damage. While the neuroprotective effect of W. somnifera extract increased in a dose dependent
manner, curcumin was much effective in lower concentrations. Together, our results show that W. somnifera/
curcumin loaded MPEG-PCL nanoparticles possess significantly higher neuroprotective effect in U251 human
glioma cells compared to the free drugs and their PCL counterparts.
The in vivo localization of nanoparticles in Zebrafish model suggested that the MPEG-PCL nanoencapsulation had
efficient and quicker delivery into the larvae compared with the free drug or PCL nanoparticles. Fluorescence
imaging of nanoparticles revealed that the nanoparticles were distributed throughout the animal. However, in
terms of fluorescence, the head region of animals treated with MPEG-PCL nanoparticles was more intense than
that of PCL nanoparticles, indicating that the former might be accumulating in the brain region. Together our
results suggest that delivery of W. somnifera extract/ curcumin as MPEG-PCL nanoparticles could enhance the
neuroprotective activity.
We have also tested the possibility of green synthesis of silver nanoparticles using W. somnifera extract and
evaluated the biosynthesized silver nanoparticles for their antibacterial activity in a cream formulation. We
developed a simple, fast and cost effective green synthesis technique for silver nanoparticles with potent
antimicrobial activity using W. somnifera extract. We also found that catechin, p-couparic acid, luteolin-7-glucoside
and a non-identified withanolide are the various compounds present in W. somnifera aqueous leaf extract
responsible for green synthesis. The cream incorporated with silver nanoparticles showed antimicrobial activity
against a wide variety of clinical isolates.As doenças neurodegenerativas representam 6,3% do gasto geral na saúde e este número tem vindo a aumentar
continuamente, anualmente, devido ao envelhecimento da população. Apesar do imenso esforço feito na
investigação de doenças foro neurológico, as doenças neurodegenerativas, tais como Alzheimer ou Parkinson,
permanecem uma das maiores causas de incapacidade em humanos. Além disso, as doenças
neurodegenerativas paresentam patogénese multifactorial, com uma complexa combinação de componentes
genéticos e factores ambientais. Apesar de existirem alguns métodos usados no tratamente destas patologias,
elas estão associadas a risco de infecção, custos elevados e biodisponibilidade reduzida devido à presença da
barreira hematoencefálica (BEE).
O uso de plantas medicinais em patologias do foro neurológico tem sido bastante estudado nos anos recentes,
em virtude das desvantagens da terapia convencional e indo ao encontro da vontade dos pacientes. De um modo
geral, os produtos farmacológicos derivados de plantas são considerados alternativas seguras. Desde tempos
remotos que o uso de extractos de plantas tem sido utilizado no tratamento de patologias do foro neurológico.
Assim como os dos métodos de extracção dos compostos de plantas têm evoluído significativamente, também o
conhecimento científico da acção destes compostos a nível neurológico tem aumentado de forma substancial. A
curcuma e Withania somnifera são utilizadas na medicina tradicional asiática no tratamento de várias patologias e
recentemente foram evidenciadas as suas actividades antioxidante, antidepressiva e neuroprotectora.
Apesar de algumas formulações, compostos e fitofármacos baseados em plantas terem sido identificados como
potenciais no tratamento de várias neuropatologias o seu desenvolvimento ainda não está no nível requerido para
a sua utilização. Uma das razões principais deve-se ao facto deste exibirem baixa biodisponibilidade devido à sua
baixa absorção, metabolismo e eliminação rápida pelo corpo humano. Comparado com os métodos
convencionais, a administração de fármacos via nanoparticulas tem provado ser uma alternativa eficaz para o uso
em neuropatologias. Devido a estas vantagens, os pesquisadores têm vindo a desenvolver sistemas baseados em
nanopartículas como veículos de extractos e compostos de plantas com actividade neurológica reconhecida, para
o uso em neuropatologias. A nanoencapsulação de compostos e extractos bioactivos numa matriz polimérica
apresenta várias vantagens, nomeadamente protecção contra a degradação, aumento da solubilidade e
biodisponibilidade. Neste trabalho foram seleccionadas duas plantas medicinais importantes, com actividade antioxidante,
antidepressivo e efeitos neuroprotetores comprovados, designadamente W. somnifera e Curcuma sp., para
nanoencapsulação e posteriores estudos em células U251 (de glioma) e análise de biodistribuição no modelo do
peixe zebra.
Metodologias de HPLC foram desenvolvidas para identificar a curcumina (princípio activo de Curcuma sp.) e
whitanólidos presentes em extractos de Curcuma sp e W. somnifera, respectivamente. Extractos obtidos de
diferentes partes (folhas, raízes e frutos) de W. somnifera foram testados. Os extractos contendo a máxima
quantidade de withanólidos e curcumina foram seleccionados para nanoencapsulação. Identificou-se que a
coluna Purospher RP18 (5Xm) é a ideal para uma separação eficiente e a quantificação simultânea dos
withanólidos e para uma eficiente quantificação de curcumina em extractos de Curcuma sp.. A quantificação por
HPLC de diferentes extratos de W. somnifera revelou que o extrato metanólico obtido a partir de tecidos foliares
contêm a maior quantidade de withanólidos, por comparação com raízes e frutos. Em comparação com C.
aromatica, a C. longa possui maior quantidade de curcumina.
Extractos de W. somnifera / curcumina foram incorporados em nanopartículas de policaprolactona (PCL) e
polietilenoglicol metoxi-policaprolactona (MPEG-PCL) usando o método de deslocamento de solvente. As
nanopartículas preparadas foram caracterizado pelas suas propriedades físico-químicas, tais como tamanho,
forma, libertação do fármaco e a eficiência de encapsulação. Após a caracterização físico-química, analisou-se a
citotoxicidade in vitro e a absorção celular das nanopartículas usando células de glioma U251. Além disso,
avaliou-se o efeito protector das nanopartículas contendo extracto de W. somnifera ou curcumina contra o insulto
oxidativo induzida por t-BHP, como uma medida de neuroproteção. A biodisponibilidade destas nanopartículas
contendo o extracto de de W. somnifera ou curcumina foi avaliada ainda num modelo animal, usando alevins de
peixe zebra.
A caracterização física das nanopartículas revelou que as nanopartículas de MPEG - PCL foram menores em
dimensão em comparação com as nanopartículas de PCL, independentemente do encapsulamento ter utilizado
extracto de W. somnifera ou curcumina. A microscopia de varrimento electrónico de transmissão (TEM) das
nanopartículas revelou uma forma redonda, em geral , embora a superfície das nanopartículas de PCL parece ser
áspero e poroso. A eficácia de aprisionamento do extracto de W. somnifera e curcumina foi maior em MPEG-PCL, quando
comparado com o PCL. Observou-se uma libertação rápida. inicial, seguida de um perfil de libertação lenta e
prolongada para ambos extractos, W. somnifera e curcumina, independentemente do polímero utilizado para a
encapsulação.
O tratamento de células U251 (giloma) com nanopartículas de PCL e MPEG-PCL carregadas com extracto de W.
somnifera ou curcumina evidenciou uma absorção celular eficiente de nanopartículas. No entanto, as
nanopartículas de MPE-PCL mostraram uma melhor internalização em comparação com as nanopartículas de
PCL, independentemente da sua carga com extracto de W. somnifera ou curcumina. Ensaios de neuroproteção
mostraram que nanopartículas contendo extracto de W. somnifera ou curcumina protegem as células dos danos
oxidativos. Enquanto o efeito neuroprotector do extracto W. somnifera aumentou de uma forma dependente da
dose, a curcumina foi muito eficaz em concentrações mais baixas. Em conjunto, os nossos resultados mostraram
que em células de glioma humano U251 as nanopartículas de MPEG-PCL carregadas com extracto de W.
somnifera ou curcumina possuem, significativamente. um maior efeito neuroprotector em comparação com os
fármacos livres ou seus homólogos encapsulados em PCL .
A localização in vivo das nanopartículas no modelo de peixe zebra sugeriu que a nanoencapsulação em MPEGPCL
teve uma biodisponibilidade mais eficiente e rápida quando comparado com o fármaco livre ou em
nanopartículas de PCL. Imagiologia de fluorescência das nanopartículas revelou que as mesmas encontram-se
distribuídas por todo o animal. No entanto, a região da cabeça dos animais tratados com nanopartículas de
MPEG-PCL era mais intensa do que com nanoparticulas de PCL. Os resultados sugerem que a entrega de
extracto de W. somnifera / curcumina por nanopartículas de MPEG-PCL poderá aumentar a atividade
neuroprotetora.
Também foi testada a possibilidade de biossíntese de nanopartículas de prata usando o extrato de W. somnifera e
avaliou-se a sua atividade antibacteriana numa formulação de creme. Foi desenvolvido um método rápido, de
baixo custo e eficaz para a síntese verde de nanopartículas de prata com potente atividade antimicrobiana
utilizando o extrato de W. somnifera. Também foi evidenciado que entre os vários compostos presentes no
extracto de W. somnifera, a catequina, ácido p-couparico, luteolina -7- glicosídeo e um withanolido (não identificada) são os responsáveis pela biossíntese das nanopartículas. O creme incorporando nanopartículas de
prata mostrou actividade antimicrobiana contra uma ampla variedade de isolados clínicos (bactérias e leveduras).A tese de doutoramento aqui apresentada foi desenvolvida no âmbito de financiamento pela Fundação para a Ciência e Tecnologia (FCT) através de uma bolsa individual de doutoramento, com a referência SFRH/BD/72809/2010 (no âmbito do QREN - POPH - Tipologia 4.1 - Formação Avançada, comparticipado pelo Fundo Social Europeu e por fundos
nacionais do MCTES)
- …