Álan Alex Aleixo

Antioxidant, antibacterial and cytotoxic potential of the ripe fruits of Solanum lycocarpum A. St. Hil. (Solanaceae)

Ethanol extract (EE) and fractions obtained from the ripe fruits of Solanum lycocarpum were examined in order to determine their phenolic composition, antioxidant capacity, antibacterial activities and cytotoxic potential. High-performance liquid chromatography coupled with DAD analysis indicated that caffeic and chlorogenic acids were the main phenolic compounds present in the EE, dichloromethane (DCM) and ethyl acetate (Ac) fractions. The antioxidant activity assessed by the scavenging ability on 1,1-diphenyl-2-picrylhydrazyl radical was significantly more pronounced for DCM and Ac fractions than that of the commercial antioxidant 2,6-di-tert-butyl-4-methylphenol (BHT). EE and fractions exhibited selective antibacterial activity against Gram-positive bacteria, especially the hexane (Hex) and DCM fractions. EE and fractions exhibited low toxicity towards the LLC-MK2 cell line, especially the Hex, DCM and Ac fractions. This work provides the knowledge of phenolic composition in the extract and fractions from the ripe fruits of S. lycocarpum and their antioxidant, antibacterial and cytotoxic activities.

Synthesis, in vitro Antifungal Activity and Molecular Modeling Studies of New Mannich Bases Derived from Lawsone

Hydroxynaphthoquinones such as lawsone (2-hydroxy-1,4-naphthoquinone) have proven to be effective antifungal agents. These compounds were tested for antifungal activity against yeast standard and clinical strains by the broth microdilution method. Among the synthetic lawsone derivatives, 2-hydroxy-3-((2-hydroxyphenyl)(pyrrolidin-1-yl)methyl)naphthalene-1,4-dione, 2-hydroxy-3-(((4-nitrophenyl)amino)(phenyl)methyl)naphthalene-1,4-dione and 2-hydroxy-3-((2-hydroxyphenyl)((4-nitrophenyl)amino)methyl)naphthalene-1,4-dione showed high activity against Candida albicans ATCC 10231, with minimal inhibitory concentrations (MICs) and minimal fungicidal concentrations (MFCs) ranging from 20 to 330 and from 80 to 330 µg mL-1, respectively. Moreover, they also showed a mechanism of action on exogenous ergosterol. Therapeutic concentrations (CC50) of 2-hydroxy-3-((2-hydroxyphenyl)(pyrrolidin-1-yl)methyl)naphthalene-1,4-dione, 2-hydroxy-3-(((4-nitrophenyl)amino)(phenyl)methyl)naphthalene-1,4-dione and 2-hydroxy-3-((2-hydroxyphenyl)((4-nitrophenyl)amino)methyl)naphthalene-1,4-dione were 52.81, 52.58 and 85.94 µg mL-1, respectively, which can be considered moderate or low. In addition, docking studies showed that these compounds had similar binding energy to standard ketoconazole, which are recognized as the molecular target by van der Waals interactions. Furthermore, they are under Lipinskis rule of 5 with a druglikeness score better than ketoconazole and nystatin. These findings suggest that 2-hydroxy-3-((2-hydroxyphenyl)(pyrrolidin-1-yl)methyl)naphthalene-1,4-dione, 2-hydroxy-3-(((4-nitrophenyl)amino)(phenyl)methyl)naphthalene-1,4-dione and 2-hydroxy-3-((2-hydroxyphenyl)((4-nitrophenyl)amino)methyl)naphthalene-1,4-dione have potential as leading compounds against human fungal infections.

Antioxidant, Antibacterial, Cytotoxic, and Anti-Inflammatory Potential of the Leaves of Solanum lycocarpum A. St. Hil. (Solanaceae).

Ethanol extract and fractions obtained from leaves of Solanum lycocarpum were examined in order to determine their phenolic composition, antioxidant, antibacterial, anti-inflammatory, and cytotoxic potential. High performance liquid chromatography coupled with DAD analysis indicated that the flavonoids apigenin and kaempferol were the main phenolic compounds present in dichloromethane and ethyl acetate fractions, respectively. The antioxidant activity was significantly more pronounced for dichloromethane, ethyl acetate, and hydroethanol fractions than that of the commercial antioxidant 2,6-di-tert-butyl-4-methylphenol. The hexane and dichloromethane fractions were more active against the tested bacteria. The hydroethanol fraction exhibited significant anti-inflammatory activity at the dose of 75 and 150 mg/kg in the later phase of inflammation. However, the antiedematogenic effect of the higher dose of the ethyl acetate fraction (150 mg/kg) was more pronounced. The ethyl acetate fraction also presented a less cytotoxic effect than the ethanol extract and other fractions. These activities found in S. lycocarpum leaves can be attributed, at least in part, to the presence of phenolic constituents such as flavonoids. This work provided the knowledge of phenolic composition in the extract and fractions and the antioxidant, antibacterial, anti-inflammatory, and cytotoxic activities of leaves of S. lycocarpum.

Antibacterial and cytotoxic antibacterial potential of ethanol extract and fractions from Aristolochia galeata Mart. ex Zucc

The aim of this investigation was to evaluate the phytochemical, antibacterial and cytotoxic activities of ethanol extract and hexane, dichlorometane, ethyl acetate and hydroethanolic fractions from Aristolochia galeata’s rhizomes. The minimum inhibitory concentration (MIC) and minimum lethal concentration (MLC) were evaluated by the broth microdilution assay to investigate the antibacterial activity of various extracts and fractions of A. galeata against Gram-positive and Gram-negative bacteria. The cytotoxicity of plant samples was evaluated in human cervix carcinoma cell line (HeLa) by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) colorimetric assay. The phytochemical study showed the presence of main secondary metabolites, steroids, flavonoids, coumarins and alkaloids. The ethanol extract and their fractions presented antimicrobial activity against Gram-positive bacteria, and Staphylococcus aureus was regarded the most sensitive strain with MIC of 250 µg/ml for the ethanol extract. The dichlorometane fraction showed bactericidal activity with the value of 1250 µg/ml and moderate cytotoxicity in front of the HeLa cell line tested (CC50 = 90 µg/ml). The results showed that A. galeata had effective antibacterial activity against Gram-positive bacteria and compounds extracted from A. galeata Mart. ex Zucc could be used as possible antimicrobials. The good antimicrobial activity and the low cytotoxicity presented by the hexane fraction can be promised for the new molecules with antibiotic activity.

High prevalence of dengue antibodies and the arginine variant of the FcγRIIa polymorphism in asymptomatic individuals in a population of Minas Gerais State, Southeast Brazil

Dengue is the most prevalent arthropod-borne viral illness in humans worldwide. Single-nucleotide polymorphisms (SNPs) in genes involved in the immune response, such as dendritic cell-specific intercellular adhesion molecule-3-grabbing non-integrin (DC-SIGN), IgG Fc receptor II-A (FcγRIIa), vitamin D receptor (VDR), and tumor necrosis factor alpha (TNF-α), were previously reported to be associated with susceptibility to dengue disease in different human populations. Therefore, due to the relevant association of host immune and genetic status with disease susceptibility/severity of dengue, this work aims to verify the frequency of anti-dengue virus antibodies and some dengue-associated risk SNPs in a population in Minas Gerais State, Southeast Brazil. A total of 1560 individuals were genotyped for polymorphisms in DC-SIGN (rs4804803), FcγRIIa (rs1801274), VDR (rs7975232), and TNF-α (rs1800629). The presence of anti-dengue antibodies (IgM and/or IgG) in these samples was also assayed. Anti-dengue antibodies were detected at an overall frequency of 16.86%, indicating a virus infection in asymptomatic individuals. The genotypic frequencies of all SNPs studied did not differ between the asymptomatic and control groups. Regarding the allelic frequencies of the four SNPs analyzed, a higher frequency was detected of the G allele of FcγRIIa/rs1801274 in the asymptomatic individuals when compared to that in the control group (p = 0.03). Therefore, the results showed a high prevalence of asymptomatic individuals in Minas Gerais State, with a potential association between the presence of the G allele of FcγRIIa/rs1801274 and protection against symptomatic disease.