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- Melanin: production from cheese bacteria, chemical characterization, and biological activitiesPublication . Ferraz, Ana Rita; Pacheco, Rita; Vaz, Pedro D.; Pintado, C. M. B. S.; Ascensão, Lia; Serralheiro, Maria LuisaPigments are compounds of importance to several industries, for instance, the food industry, where they can be used as additives, color intensifiers, and antioxidants. As the current trend around the world is shifting to the use of eco-friendly commodities, demand for natural dyes is increasing. Melanins are pigments that are produced by several microorganisms. Pseudomonas putida ESACB 191, isolated from goat cheese rind, was described as a brown pigment producer. This strain produces a brown pigment via the synthetic Mueller-Hinton Broth. This brown compound was extracted, purified, analyzed by FTIR and mass spectrometry, and identified as eumelanin. The maximum productivity was 1.57 mg/L/h. The bioactivity of eumelanin was evaluated as the capacity for scavenging free radicals (antioxidant activity), EC50 74.0 & PLUSMN; 0.2 mu g/mL, and as an acetylcholinesterase inhibitor, with IC50 575 & PLUSMN; 4 mu g/mL. This bacterial eumelanin did not show cytotoxicity towards A375, HeLa Kyoto, HepG2, or Caco2 cell lines. The effect of melanin on cholesterol absorption and drug interaction was evaluated in order to understand the interaction of melanin present in the cheese rind when ingested by consumers. However, it had no effect either on cholesterol absorption through an intestinal simulated barrier formed by the Caco2 cell line or with the drug ezetimibe.
- Phenolic profile and biological activities of decoctions from Santolina impressa, a Portuguese endemic speciesPublication . Rodrigues, Ana M.; Fale, Pedro; Madeira, Paulo; Pacheco, Rita; Florêncio, Maria Helena; Ascensão, Lia; Serralheiro, Maria LuisaSantolina impressa Hoffmanns & Link is an aromatic Asteraceae species endemic to the southwest of Portugal. It is used in folk medicine as an herbal tea for gastrointestinal ailments and mouthwash antiseptic. The present study aimed to relate the chemical composition of decoctions from the aerial parts S. impressa with their antiacetylcholinesterase, antioxidant, antimicrobial and cytotoxic activities, in an attempt to explain the traditional use of this species. LC–MS/MS analysis identified chlorogenic acid and cynarin as the main components. Antimicrobial activity of the extracts was investigated against two cariogenic bacteria:- Streptococcus sobrinus and Streptococcus mutans, and these decoctions were not cytotoxic towards Caco-2 and HepG2 cell lines. Decoctions from capitula and stems/leaves showed high AChE inhibition, with IC50 values of 328 μg/mL and 579 μg/mL, respectively. The antioxidant activity measured using the DPPH radical scavenging assay showed an EC50 of 14.7 μg/mL and 12.9 μg/mL for capitula and stems/leaves extracts, respectively. The biological activities were kept constant after in vitro digestive process and the HPLC analysis did not indicate changes in the extract’s chemical composition. The results may explain the traditional use of S. impressa decoctions for digestive problems and as a mouthwash antiseptic.
- Biological properties of phenolic compound extracts in selected Algerian honeys-The inhibition of acetylcholinesterase and alpha-glucosidase activitiesPublication . Zaidi, Hicham; Ouchemoukh, Salim; Amessis-Ouchemoukh, Nadia; DEBBACHE-BENAIDA, NADJET; Pacheco, Rita; Serralheiro, Maria Luisa; Araujo, Maria EduardaIntroduction: Honey is used in various cultures as a traditional medicine and folkloric treatment. The aim of this study was to determine the antioxidant and the anti-inflammatory activities of 31 Algerian honeys and acetylcholinesterase (AChE) and alpha-glucosidase inhibitory activities of phenolic compounds extracts of these honeys. Methods: The anti-inflammatory activity of honey was evaluated by the method of inhibition of BSA (Bovin Serum Albumin) heat-induced denaturation. The inhibition of AChE and alpha-glucosidase by the honey extracts was evaluated by in-vitro methods. Results: The highest percentage of inhibition (85.33%) of BSA denaturation was obtained with polyfloral honey (H27). Radical scavenging activity of honey samples against 1,1-diphenyl-2-picrilhydrazyl (DPPH), and 2,2'-azinobis(-3) -ethylbenzothiazoline-6-sulfonic acid (ABTS) varied from 4.41 to 83.93% and from 2.52 to 63.24%, respectively. AChE inhibitory activity is one target to prevent neurodegenerative damage in Alzheimer's disease. AChE inhibition recorded values from 20.69 to 76.04%. alpha-glucosidase inhibitors such as acarbose is preconized for the control of hyperglycemia and prevent diabetes damages. Honey extracts demonstrated a significant inhibitory effect on alpha-glucosidase activity. Moreover, the effect of Fabacece honey (H19) (IC50 = 52.20 mu g/mL) was found to be more potent than acarbose (IC50 = 204.27 mu g/mL). Correlations were observed between antioxidants and anti-inflammatory activities, AChE and alpha-glucosidase inhibitions with total phenolic compounds and flavonoids content in honey samples. Conclusion: This study showed that honey could be exploited as a potential antioxidant and anti-inflammatory agent within therapeutic medicine.
- Antiacetylcholinesterase activity and docking studies with chlorogenic acid, cynarin and arzanol from Helichrysum stoechas (Lamiaceae)Publication . Silva, Leticia; Rodrigues, Ana M.; Ciriani, Marina; Fale, Pedro Luís Vieira; Teixeira, Vítor; Madeira, Paulo; Machuqueiro, Miguel; Pacheco, Rita; Florêncio, Maria Helena; Ascensão, Lia; Serralheiro, Maria LuisaThis work was aimed at the study of the chemical composition in phenolic compounds responsible for the high antiacetylcholinesterase activity of aqueous extracts (decoctions) from Helichrysum stoechas aerial parts. Chlorogenic acid, cynarin, and arzanol were the main components of decoctions, detected by high-performance liquid chromatography with diode-array detection and liquid chromatography-mass spectrometry/mass spectrometry. Flowers and stems/leaves extracts inhibited antiacetylcholinesterase with IC50 values of 260.7 and 654.8 mu g/mL, respectively. The biological activity of these extracts was maintained after in vitro gastrointestinal digestion, indicating that the active compounds present in the extracts were not enzymatically modified by the gastrointestinal system used to simulate the digestion. Molecular docking studies with the main components were carried out in order to obtain information, at the molecular level, as to how these compounds access the enzyme's active site. The docking study showed for the first time that chlorogenic acid, cynarin, and arzanol fit nicely in the antiacetylcholinesterase active site channel, blocking all access to the catalytic triad. This explained the high inhibitory activity determined during in vitro experiments.
- Antiacetylcholinesterase activity and docking studies with chlorogenic acid, cynarin and arzanol from Helichrysum stoechas (Asteraceae)Publication . Silva, Letícia; Rodrigues, Ana M.; Ciriani, Marina; Falé, Pedro Luís Vieira; Teixeira, Vitor; Madeira, Paulo; Machuqueiro, Miguel; Pacheco, Rita; Florêncio, Maria Helena; Ascensão, Lia; Serralheiro, Maria LuisaThis work was aimed at the study of the chemical composition in phenolic compounds responsible for the high antiacetylcholinesterase activity of aqueous extracts (decoctions) from Helichrysum stoechas aerial parts. Chlorogenic acid, cynarin, and arzanol were the main components of decoctions, detected by high-performance liquid chromatography with diode-array detection and liquid chromatography-mass spectrometry/mass spectrometry. Flowers and stems/leaves extracts inhibited antiacetylcholinesterase with IC50 values of 260.7 and 654.8 μg/mL, respectively. The biological activity of these extracts was maintained after in vitro gastrointestinal digestion, indicating that the active compounds present in the extracts were not enzymatically modified by the gastrointestinal system used to simulate the digestion. Molecular docking studies with the main components were carried out in order to obtain information, at the molecular level, as to how these compounds access the enzyme’s active site. The docking study showed for the first time that chlorogenic acid, cynarin, and arzanol fit nicely in the antiacetylcholinesterase active site channel, blocking all access to the catalytic triad. This explained the high inhibitory activity determined during in vitro experiments.