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- 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.
- Serum albumin modulates the bioactivity of rosmarinic acidPublication . Brito, Elsa; Silva, André; Fale, Pedro; Pacheco, Rita; Serralheiro, António; Haris, Parvez I.; Ascensão, Lia; Serralheiro, Maria LuisaRosmarinic acid (RA) is a phenolic compound with biological activity. The objective of the present study was to investigate whether this compound kept its biological activity in the presence of proteins. For this purpose, bovine serum albumin (BSA) was used as a model protein, and the capacity of the RA to inhibit acetylcholinesterase (AChE) and affect antioxidant activity was evaluated in the absence and presence of BSA. A mixture of phenolic compounds containing RA, obtained from a medicinal plant was added to this study. The AChE inhibitory activity of RA was reduced by *57% in the presence of BSA, while the antioxidant activity increased. These results lead to the investigation of the effect of RA on the BSA structure using Fourier transform infrared spectroscopy (FTIR). At 37 C and higher temperatures, RA caused a decrease in the temperature modifications onthe proteinstructure. Furthermore, FTIR and native-gel analysis revealed that protein aggregation/ precipitation, induced bytemperature, wasreduced in thepresence of RA. The novelty of the present work resides in thestudy of the enzyme inhibitory activity and antioxidant capacity of polyphenols, such as RA, in the presence of a protein. The findings highlight the need to consider the presence of proteins when assessing biological activities of polyphenols in vitro and that enzyme inhibitory activity may be decreased, while the antioxidant capacity remains or even increases.
- Bioactivities of decoctions from Plectranthus species related to their traditional use on the treatment of digestive problems and alcohol intoxicationPublication . Brito, Elsa; Gomes, Emma; Fale, Pedro; Borges, Carlos; Pacheco, Rita; Teixeira, Vítor; Machuqueiro, Miguel; Ascensão, Lia; Serralheiro, Maria LuisaEthnopharmacological relevance Decoctions of Plectranthus species are traditionally ingested after large meals for treatment of food digestion and alcohol abuse. Aim of the study This study aims at associating the digestion-related ethno-uses of Plectranthus species decoctions to molecular mechanism that might explain them: easing digestion (AChE inhibition) and treating hangover (ADH inhibition) Material and methods Decoctions from Plectranthus species were analysed for their alcohol dehydrogenase (ADH) inhibition and acetylcholinesterase (AChE) inhibition, related with alcohol metabolism and intestinal motility, respectively. Identification of the active components was carried out by LC-MS/MS and the docking studies were performed with AChE and the bioactive molecules detected. Results All decoctions inhibited ADH activity. This inhibition was correlated with their rosmarinic acid (RA) content, which showed an IC50 value of 19 μg/mL, similar to the reference inhibitor CuCl2. The presence of RA also leads to most decoctions showing AChE inhibiting capacity. P. zuluensis decoction with an IC50 of 80 μg/mL presented also medioresinol, an even better inhibitor of AChE, as indicated by molecular docking studies. Furthermore, all decoctions tested showed no toxicity towards two human cell lines, and a high capacity to quench free radicals (DPPH), which also play a helpful in the digestive process, related with their RA content. Conclusions All activities presented by the RA-rich Plectranthus decoctions support their use in treating digestion disorders and P. barbatus could explain its use also for alleviating hangover symptoms. Medioresinol, which is present in P. zuluensis, exhibited a significant AChE inhibition and may provide, in the future, a new lead for bioactive compounds.