Browsing by Author "Bernardo-Gil, Maria Gabriela"
Now showing 1 - 4 of 4
Results Per Page
Sort Options
- Chemical profiling and biological screening of Thymus lotocephalus extracts obtained by supercritical fluid extraction and hydrodistillationPublication . Costa, Patrícia; Gonçalves, Sandra; Grosso, Clara; Andrade, Paula B.; Valentão, Patrícia; Bernardo-Gil, Maria Gabriela; Romano, AnabelaEssential oil and extracts from the aerial parts of Thymus lotocephalus were obtained by hydrodistillation (HD) and supercritical fluid extraction (SFE) in two different collectors, respectively. SFE was conducted at 40 ◦C and a working pressure of 12 or 18 MPa. The chemical profiles were determined using GC-FID and GC–IT–MS. Oxygen-containing monoterpenes were the primary constituents in the essential oil and SFE extracts collected in the second separator, while the extracts obtained in the first separator were predominantly oxygen-containing sesquiterpenes. A large number of compounds were identified by hydrodistillation and, in contrast, the highest extraction yields were obtained using SFE. Linalool(10.43 ± 1.63%) was the main component in essential oil, whereas camphor (7.91 ± 0.84%) and cis-linalool oxide (7.25 ± 1.45%) were the major compounds in the extracts-2nd separator obtained at pressures of 12 and 18 MPa, respectively. Caryophyllene oxide was the primary constituent identified in the extracts-1st separator (4.34 ± 0.51 and 4.41 ± 1.25% obtained at 12 and 18 MPa, respectively). The antioxidant activity was assessed by ORAC and DPPH assays, and the anti-cholinesterase activity was evaluated in vitro using Ellman’s method. The essential oil and SFE extracts (first separator) of T. lotocephalus possessed antioxidant activity and strongly inhibited cholinesterases. We also demonstrated that the acetylcholinesterase and butyrylcholinesterase inhibitory activities of the essential oil could be attributed to 1,8-cineole and caryophyllene oxide, respectively.
- Recovery of high purity plumbagin from Drosera intermediaPublication . Grevenstuk, Tomás; Gonçalves, Sandra; Nogueira, José Manuel F.; Bernardo-Gil, Maria Gabriela; Romano, AnabelaIn this study a simple process encompassing an efficient extraction and fractionation method to obtain high purity plumbagin from micropropagated D. intermedia plants is described. Plumbagin is a naphthoquinone derived from a diverse but restricted group of plant species that includes the Drosera spp. and is in demand for pharmacological research. It was brought initially to the attention of researchers due to its broad antimicrobial and antitumor properties but has continued to find application against new pharmacological targets. The procedure described in this work involved testing four extraction methods to maximize product recovery and separating the 30–50% acetonitrile in water fraction (v/v) on a SPE column followed by lyophilisation. By applying ultrasonic treatment to the plant matrix leached in nhexane followed by a single step purification process, 2.74 mg of plumbagin per gram of plant material could be obtained with a recovery of 86.3% and over 99% purity.
- Supercritical fluid extraction and hydrodistillation for the recovery of bioactive compounds from Lavandula viridis L’HérPublication . Costa, Patrícia; Grosso, Clara; Gonçalves, Sandra; Andrade, Paula B.; Valentão, Patrícia; Bernardo-Gil, Maria Gabriela; Romano, AnabelaThe chemical profiles of bioactive essential oil and extracts obtained by hydrodistillation (HD) and supercritical fluid extraction (SFE), respectively, from Lavandula viridis were compared. The SFE was performed at 40 C and at extraction pressures of 12 or 18 MPa in two different separators. Evaluation of the essential oil and SFE extracts by GC–FID and GC–IT–MS revealed that oxygen-containing monoterpenes were the major constituents in both cases, but there were important differences between the chemical profiles produced by the different extraction techniques. More compounds were isolated by HD but higher yields were achieved by SFE. Camphor was the main component identified in the essential oil (31.59 ± 1.32%), and in extracts from the first (1.61 ± 0.34%) and second SFE separators (22.48 ± 1.49%) at 12 MPa. In contrast, the first separator SFE extract at 18 MPa (heavy compounds) was dominated by myrtenol(5.38 ± 2.04%) and camphor (4.81 ± 1.93%), whereas the second separator SFE extract (volatiles) was dominated by verbenone (13.97 ± 5.27%). The essential oil and heavy compound extracts from the first separator possessed antioxidant and anti-cholinesterase activities. Our data show that phytochemicals from the aerial parts of L. viridis could be developed as natural antioxidant and anti-cholinesterase drugs, with particular applications in the symptomatic treatment of Alzheimer’s disease.
- Supercritical fluid extracts with antioxidant and antimicrobial activities from myrtle (Myrtus communis L.) leaves. Response surface optimizationPublication . Pereira, Paula; Bernardo-Gil, Maria Gabriela; Cebola, M. João; Mauricio, Elisabete; Romano, AnabelaSupercritical Fluid Extraction (SFE) was used to obtain myrtle leaf extracts, and to study the antioxidant capacity (AOC) and in vitro antimicrobial activity of those extracts. To optimize the SFE operational conditions, the response surface methodology (RSM) was adopted. The parameters studied were: pressure (P), within the range 10 to 30 MPa; temperature (T), between 35 C and 60 C and supercritical carbon dioxide (SCCO2) flow rate (Q) within the range 0.15 to 0.45 kg h-1. The results show a good fit to the proposed model and the optimal conditions obtained (23 MPa, 45 C, and SCCO 2 flow rate of 0.3 kg h-1) were within the experimental range. The predicted values agreed with experimental ones, thus indicating the suitability of the RSM model for the optimization of the extraction conditions being investigated. With those values remaining constant, ethanol as a co-solvent was then studied. There was an observed rise in AOC as the amount of ethanol increased, within the range studied (0-30 wt% ethanol). The extract with the highest AOC was tested for its antimicrobial activity against gram-positive and gram-negative bacteria. The minimum inhibitory concentration (MIC) values obtained showed significant inhibitory effect against gram-positive bacteria.