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- The synthesis, crystal structure and Hirshfeld analysis of 4-(3,4-dimethylanilino)-N-(3,4-dimethylphenyl)quinoline-3-carboxamidePublication . Gomes, Lígia Rebelo; Low, John Nicolson; Borges, Fernanda; Gaspar, Alexandra; Mesiti, FrancescoThe structure of the title quinoline carboxamide derivative, C26H25N3O, is described. The quinoline moiety is not planar as a result of a slight puckering of the pyridine ring. The secondary amine has a slightly pyramidal geometry, certainly not planar. Both intra- and intermolecular hydrogen bonds are present. Hirshfeld surface analysis and lattice energies were used to investigate the intermolecular interactions.
- Structural and electronic effects of the C2’ substituent in 1,4–benzodiazepinesPublication . Gomes, Lígia Rebelo; Santos, Luís Manuel Neves Belchior Faia; Beleza, José; Low, John Nicolson; yesBenzodiazepines are drugs used for treatment of several central nervous system disorders, such as anxiety and sleep. In spite of their wide and popular usage in clinics, the mechanism explaining why a certain pharmacological activity is superimposed onto another for a given benzodiazepine remains unclear. The knowledge of the conformation of benzodiazepines and their electronic charge distribution at molecular surfaces may give new insights into the pharmaco‐benzodiazepine receptor interactions, contributing to the improvement of the existing models. In the present study, the solid state geometric and conformational parameters of the available X‐ray benzodiazepine structures were analyzed and reviewed. The electronic features of two groups of benzodiazepines with different substituents at C7 and C2’ positions were studied by DFT quantum chemical calculations. The conformations of the molecules with optimized geometry were also analyzed. The relative charge distribution around the benzodiazepinic rings and electrostatic potential mapped on electronic density surfaces were obtained. The ring geometric parameters for the diazepine moiety in 1,4‐ benzodiazepines, do not vary significantly except for a few compounds in which steric and/or intermolecular interactions play a part. The benzodiazepine ring assumes a pseudosymmetrical boat conformation and the torsion angle around the C5‐Ph bond varies depending on the nature of the substituent on C2’. Also, the presence of the nitro or chloride substituent on the C7 position and the presence of a fluorine atom on the C2’ position significantly alter the relative charge distributions at the attached carbon atoms and the topology of the surface electrostatic potential.
- 4,4′-(1,8-Naphthalene-1,8-diyl)dibenzonitrilePublication . Lima, Carlos F.; Gomes, Ligia R.; Santos, Luís M. N. B. F.; Low, John NicolsonIn the title mol-ecule, C(24)H(14)N(2), the exterior C-C-C angle of the naphthalene ring system involving the two phenyl-substituted C atoms is 126.06 (11)° and the dihedral angles between the mean plane of the naphthalene ring system and those of the benzene rings are 66.63 (5) and 67.89 (5)°. In the crystal, mol-ecules are linked into a ladders by four weak C-H⋯π inter-actions.
- Effect of extraction methodology on the phytochemical composition for camelia sinensis “powdered tea extracts” from different provenancesPublication . Barreira, Sérgio; Silva, André M. N.; Moutinho, Carla; Seo, Ean-Jeong; Hegazy, Mohamed-Elamir F.; Efferth, Thomas; Gomes, Lígia Rebelo(1) Background: beverages based on extracts from Camellia sinensis are popular worldwide. Due to an increasing number of processed teas on the market, there is a need to develop unified classification standards based on chemical analysis. Meanwhile, phytochemical characterizations are mainly performed on tea samples from China (~80%). Hence, data on teas of other provenances is recommended. (2) Methods: in the present investigation, we characterized lyophilised extracts obtained by infusion, maceration and methanolic extraction derived from tea samples from China, Japan, Sri Lanka and Portugal by phytochemistry (catechins, oxyaromatic acids, flavonols, alkaloids and theanine). The real benefits of drinking the tea were analysed based on the bioavailability of the determined phytochemicals. (3) Results: the infusions revealed the highest total phenolic contents (TPC) amounts, while methanolic extracts yielded the lowest. The correlation matrix indicated that the levels of phenolic compounds were similar in the infusions and methanolic samples, while extractions made by maceration were significantly different. The differences could be partially explained by the different amounts of (-)-epigallocatechin gallate (EGCG), (-)-epicatechin gallate (ECG) and gallic acids (GA). The catechin percentages were significantly lower in the macerations, especially the quantity of EGCG decreases by 4- to 5-fold after this process. (4) Conclusions: the results highlight the importance of the processing methodology to obtain “instant tea”; the composition of the extracts obtained with the same methodology is not significantly affected by the provenance of the tea. However, attention should be drawn to the specificities of the Japanese samples (the tea analysed in the present work was of Sencha quality). In contrast, the extraction methodology significantly affects the phytochemical composition, especially concerning the content of polyphenols. As such, our results indicate that instant tea classification based on chemical composition is sensible, but there is a need for a standard extraction methodology, namely concerning the temperature and time of contact of the tea leaves with the extraction solvent.
- Crystal structures of ethyl 6-(4-methylphenyl)-4-oxo-4H-chromene-2-carboxylate and ethyl 6-(4-fluorophenyl)-4-oxo-4H-chromene-2-carboxylatePublication . Gomes, Ligia R.; Low, John Nicolson; Fernandes, Carlos; Gaspar, Alexandra; Borges, FernandaThe crystal structures of two chromone derivatives, viz. ethyl 6-(4-methylphenyl)-4-oxo-4H-chromene-2-carboxylate, C19H16O4, (1), and ethyl 6-(4-fluorophenyl)-4-oxo-4H-chromene-2-carboxylate C18H13FO4, (2), have been determined: (1) crystallizes with two molecules in the asymmetric unit. A comparison of the dihedral angles beween the mean planes of the central chromone core with those of the substituents, an ethyl ester moiety at the 2-position and a para-substituted phenyl ring at the 6-position shows that each molecule differs significantly from the others, even the two independent molecules (a and b) of (1). In all three molecules, the carbonyl groups of the chromone and the carboxylate are trans-related. The supramolecular structure of (1) involves only weak C-H...[pi] interactions between H atoms of the substituent phenyl group and the phenyl group, which link molecules into a chain of alternating molecules a and b, and weak [pi]-[pi] stacking interactions between the chromone units. The packing in (2) involves C-H...O interactions, which form a network of two intersecting ladders involving the carbonyl atom of the carboxylate group as the acceptor for H atoms at the 7-position of the chromone ring and from an ortho-H atom of the exocyclic benzene ring. The carbonyl atom of the chromone acts as an acceptor from a meta-H atom of the exocyclic benzene ring. [pi]-[pi] interactions stack the molecules by unit translation along the a axis.
- Phytochemical characterization and biological activities of green tea (Camellia sinensis) produced in the Azores, PortugalPublication . Barreira, Sérgio; Moutinho, Carla; Silva, André M.N.; Neves, José Manuel Gomes da Silva; Seo, Ean-Jeong; Hegazy, Mohamed-Elamir F.; Efferth, Thomas; Gomes, Lígia RebeloBackground: Green tea is not only one of the most widely consumed beverages worldwide, but is also known for its health promoting and therapeutic effects. Green tea is cultivated in areas with high humidity and acidic soils in China, Indonesia and Japan. Those places have well-marked dry and rainy seasons. In opposite, Azores have a climate with constant average annual rainfall and, unlike eastern regions, relatively constant air humidity throughout the year. While a brand implemented on the Portuguese market, the quality of green tea produced in Azores must be guaranteed. Quality control measures based on phytochemical determination of the chemical composition and biological activities are needed in order to address whenever climate changes interferes significantly with composition and biological effects. Purpose: Make the phytochemical characterization of various extracts of green tea leaves coming from Azores and evaluate the anti-cancer activities of the extracts in order to compare the obtained results with those of teas coming from eastern regions. Methods: Phytochemical characterization (catechins, oxyaromatic acids, flavonols, alkaloids and theanine) and total catechins contents (TCC) was performed by using HPLC-DAD analysis, in infusions (5–7 min and 30 min), maceration and methanolic extracts of Camellia sinensis samples coming from Azores, Portugal. The antioxidant activity of extracts was measured by the DPPH assay and the total phenolics contents (TPC) were estimated using the Folin-Ciocalteu colorimetric method. The cytotoxic activity towards drug sensitive and multidrug-resistant leukemia cell lines was determined by the resazurin assay. Results: The TCC was higher in methanolic extracts and lower in maceration, as epigallocatechin gallate (EGCG) and epicatechin gallate (ECG) concentrations were significantly higher in methanolic extracts and were only residual in maceration extracts. Maceration extracts showed the highest content of gallic acid, indicating that methanol extracts contained more flavonols of higher molecular weight and/or that maceration may lead to the degalloylation of catechins. The amount of o-caffeoylquinic acid extracted was significantly higher in methanolic samples. Short-term extraction at high temperatures resulted in high amounts of neochlorogenic acid. The contents of glycosylated quercitin-3-d-galactoside and kaempferol-3-glucoside were small in maceration samples and high in methanolic samples. Caffeine was easily extracted by methanol (99%) compared with water, while extraction of the amino-acid l-theanine was impossible with methanol. TPC values correlated linearly with DPPH• IC50, with infusion samples showing the best antioxidant capacities. The aqueous and the methanol/water extracts were active in multidrug-resistant and drug sensitive cancer cells.
- Phytochemical characterization and biological activities of green tea (Camellia sinensis) produced in the Azores, PortugalPublication . Barreira, Sérgio; Moutinho, Carla; Silva, André M.N.; Neves, José Manuel Gomes da Silva; Seo, Ean-Jeong; Hegazy, Mohamed-Elamir F.; Efferth, Thomas; Gomes, Lígia RebeloBackground: Green tea is not only one of the most widely consumed beverages worldwide, but is also known for its health promoting and therapeutic effects. Green tea is cultivated in areas with high humidity and acidic soils in China, Indonesia and Japan. Those places have well-marked dry and rainy seasons. In opposite, Azores have a climate with constant average annual rainfall and, unlike eastern regions, relatively constant air humidity throughout the year. While a brand implemented on the Portuguese market, the quality of green tea produced in Azores must be guaranteed. Quality control measures based on phytochemical determination of the chemical composition and biological activities are needed in order to address whenever climate changes interferes significantly with composition and biological effects. Purpose: Make the phytochemical characterization of various extracts of green tea leaves coming from Azores and evaluate the anti-cancer activities of the extracts in order to compare the obtained results with those of teas coming from eastern regions. Methods: Phytochemical characterization (catechins, oxyaromatic acids, flavonols, alkaloids and theanine) and total catechins contents (TCC) was performed by using HPLC-DAD analysis, in infusions (5–7 min and 30 min), maceration and methanolic extracts of Camellia sinensis samples coming from Azores, Portugal. The antioxidant activity of extracts was measured by the DPPH assay and the total phenolics contents (TPC) were estimated using the Folin-Ciocalteu colorimetric method. The cytotoxic activity towards drug sensitive and multidrug-resistant leukemia cell lines was determined by the resazurin assay. Results: The TCC was higher in methanolic extracts and lower in maceration, as epigallocatechin gallate (EGCG) and epicatechin gallate (ECG) concentrations were significantly higher in methanolic extracts and were only residual in maceration extracts. Maceration extracts showed the highest content of gallic acid, indicating that methanol extracts contained more flavonols of higher molecular weight and/or that maceration may lead to the degalloylation of catechins. The amount of o-caffeoylquinic acid extracted was significantly higher in methanolic samples. Short-term extraction at high temperatures resulted in high amounts of neochlorogenic acid. The contents of glycosylated quercitin-3-d-galactoside and kaempferol-3-glucoside were small in maceration samples and high in methanolic samples. Caffeine was easily extracted by methanol (99%) compared with water, while extraction of the amino-acid l-theanine was impossible with methanol. TPC values correlated linearly with DPPH• IC50, with infusion samples showing the best antioxidant capacities. The aqueous and the methanol/water extracts were active in multidrug-resistant and drug sensitive cancer cells.
- Recent approaches on signal transduction and transmission in acupuncture: a biophysical overview for medical sciencesPublication . Gomes, Lígia Rebelo; Leão, PedroAcupuncture is one of the areas among the alternative therapies that arouses high curiosity in the biomedical scientific community. It is particular popular for treatment of chronic diseases and addictions. However, contrasting with its evidence based effectiveness, the lack of a reasonable explanations for its mode of action divides that scientific community. Difficulties also arise to those responsible for providing information for clinicians and professionals who wish to acquire competencies leading to the acupuncture practice and have a background based on biochemistry and physiology. The classic theories of nerve conduction do not fully explain how information is read and transmitted during the acupuncture treatment. Other theories have been proposed but they are based on concepts like biophotonic waves and quantum biochemistry that are difficult to read and understand by those that do not have knowledge in physics. It is the main objective of this review to provide a survey of the main theories and explanatory approaches to the signal transduction and conduction in acupuncture and to describe them in in terms of their explanatory hypotheses, limitations and weaknesses. The most of the literature found supports theories for neural conduction, including gate control. They explain the effects of acupuncture in pain relieve; lesser amount of studies have been made concerning the conduction based on biophotons. The primo vascular system has been referred as a possible anatomic support for conduction of information during an acupuncture treatment, which could be connected to biophoton transmission.
- Crystal structures of three 6-substituted coumarin-3-carboxamide derivativesPublication . Gomes, Lígia R.; Low, John Nicolson; Fonseca, André; Matos, Maria João; Borges, FernandaThree coumarin derivatives, viz. 6-methyl-N-(3-methyl-phen-yl)-2-oxo-2H-chromene-3-carboxamide, C18H15NO3 (1), N-(3-meth-oxy-phen-yl)-6-methyl-2-oxo-2H-chromene-3-carboxamide, C18H15NO4 (2), and 6-meth-oxy-N-(3-meth-oxy-phen-yl)-2-oxo-2H-chromene-3-carboxamide, C18H15NO5 (3), were synthesized and structurally characterized. The mol-ecules display intra-molecular N-H⋯O and weak C-H⋯O hydrogen bonds, which probably contribute to the approximate planarity of the mol-ecules. The supra-molecular structures feature C-H⋯O hydrogen bonds and π-π inter-actions, as confirmed by Hirshfeld surface analyses.
- Crystal structures of two 6-(2-hydroxybenzoyl)-5H-thiazolo[3,2-a]pyrimidin-5-onesPublication . Gomes, Ligia R.; Low, John Nicolson; Cagide, Fernando; Borges, Fernandahe title compounds, 6-(2-hydroxybenzyl)-5H-thiazolo[3,2-a]pyrimidin-5-one, C13H8N2O3S, (1), and 6-(2-hydroxybenzyl)-3-methyl-5H-thiazolo[3,2-a]pyrimidin-5-one, C14H10N2O3S, (2), were synthesized when a chromone-3-carboxylic acid, activated with (benzotriazol-1-yloxy)tripyrrolidinylphosphonium hexafluoridophosphate (PyBOP), was reacted with a primary heteromamine. Instead of the expected amidation, the unusual title thiazolopyrimidine-5-one derivatives were obtained serendipitously and a mechanism of formation is proposed. Both compounds present an intramolecular O-H...O hydrogen bond, which generates an S(6) ring. The dihedral angles between the heterocyclic moiety and the 2-hydroxybenzoyl ring are 55.22 (5) and 46.83 (6)° for (1) and (2), respectively. In the crystals, the molecules are linked by weak C-H...O hydrogen bonds and [pi]-[pi] stacking interactions.
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