Juliana Vinholes

Valuable compounds in macroalgae extracts.

Bioactive compounds present in ethanolic extracts from 18 macroalgae of the Portuguese coast were analysed by gas chromatography-mass spectrometry (GC-MS), leading to the characterization of 14 compounds: proline, phloroglucinol, mannitol, 8 fatty acids and 3 sterols. A dose-dependent response against enzymes with biological significance (α-glucosidase, acetylcholinesterase and butyrylcholinesterase) and free radicals (DPPH, nitric oxide, superoxide and hydroxyl) was found, Phaeophyta being the most promising group. A PCA analysis was performed and allowed the establishment of a correlation between the algae chemical composition and the biological activity. Cystoseira tamariscifolia (Hudson) Papenfuss, Cystoseira nodicaulis (Withering) M. Roberts, Cystoseira usneoides (Linnaeus) M. Roberts and Fucus spiralis Linnaeus are among the most active species, which is in accordance with their higher contents in phloroglucinol, mannitol, oleic, arachidonic and eicosapentaenoic acids, and fucosterol. The results point to the potential interest of the use of Phaeophyta species as food additives, due to their potent antiradical activities, and especially highlights the importance of F. spiralis in the food chain of Mediterranean countries. Moreover, the incorporation of the extracts of these species in food products, nutraceutical and pharmaceutical preparations for human health should also be instigated, since they can suppress hyperglycemia and inhibit cholinesterases.

In vitro studies to assess the antidiabetic, anti-cholinesterase and antioxidant potential of Spergularia rubra

Spergularia rubra is distributed all over the world, being its infusion used as diuretic. In spite of its large use, the antidiabetic, anti-cholinesterase and antioxidant activities of this species have not been assessed and its chemical composition is scarcely known. In the work herein a hydromethanolic extract was studied. Thirty-six phenolic compounds were determined by HPLC-DAD, comprising non-acylated C-glycosyl flavones (38%), C-glycosyl flavones acylated with aromatic acids (36%), C-glycosyl flavones acylated with aliphatic acids (13%) and 10% corresponded to C-glycosyl flavones with a mixed acylation. Organic acids (oxalic, citric, malic, quinic and fumaric acids) and fatty acids (azelaic, myristic, palmitic, linoleic, linolenic and stearic acids) are described for the first time. Their determination by HPLC-UV and GC-IT-MS allowed finding concentrations of 192.15 and 34.87g/kg, respectively. The extract showed a dose-dependent response against DPPH, superoxide and nitric oxide radicals. The same effect was observed in the α-glucosidase inhibitory assay and against acetylcholinesterase and butyrylcholinesterases. The bioactivities observed may be due, at least partially, to the presence of the different metabolites determined in the present study. The results suggest that the dried extract of S. rubra may be interesting for incorporation in pharmaceutical preparations for human health, since it can suppress hyperglycaemia and inhibit cholinesterases, and or as food additive due to its antiradical activity.

Bauhinia forficata Link authenticity using flavonoids profile: Relation with their biological properties

HPLC-DAD-ESI/MS(n) was used to ascertain the authenticity of two certified and two commercial Bauhinia forficata Link samples. Different flavonoids profiles were obtained, involving 39 compounds. Just kaempferol-3-O-(2-rhamnosyl)rutinoside was found in all analysed samples. Five compounds were common to the certified samples of B. forficata Link and B. forficata Link subsp. pruinosa (Vogel) Fortunato & Wunderlin, being kaempferol derivatives the most representative ones. The phenolic composition of B. forficata Link subsp. pruinosa (Vogel) Fortunato & Wunderlin is described herein for the first time, accounting for eight compounds, while 10 new compounds were identified in B. forficata Link. Commercial B. forficata Link showed higher contents of quercetin derivatives, in addition to the presence of myricetin derivatives and flavonoids-(galloyl)glycosides, for which the MS fragmentation pattern is reported for the first time. B. forficata Link and the two commercial samples were able to inhibit α-glucosidase, with EC(50) values lower than that found for acarbose. Mild effects on cholinesterases were observed with the certified samples, while commercial ones were more effective. The same behaviour was observed concerning the scavenging of DPPH, nitric oxide and superoxide radicals. The presence of high contents of quercetin derivatives in commercial samples seems to directly influence their biological properties. The differences between phenolic profiles and their relation with the authenticity of commercial samples are discussed.

A gas chromatography–mass spectrometry multi-target method for the simultaneous analysis of three classes of metabolites in marine organisms

In this work a fast and simple multi-target gas chromatography-mass spectrometry (GC-MS) method for the simultaneous detection and absolute quantification of amino acids, fatty acids, sterols and lupanes in marine organisms is proposed. The methodology was applied to the characterization of the echinoderm Marthasterias glacialis Linnaeus spiny sea star extracts. The main factors influencing the extraction of target compounds were evaluated by using different extraction procedures, solvent systems and temperature conditions and a comparison with a reference technique was performed. The most suitable procedure, capable of successfully extract the three classes of target compounds, was ethanol as solvent at 40°C under magnetic stirring. Good analytical parameters were obtained since calibrations curves for the 40 compounds under analysis (15 amino acids, 16 fatty acids, 6 sterols and 3 lupanes) showed regression coefficients (r(2)) ranging from 0.9844 to 0.9978, with low RSD (from 0.00 to 9.45%), and detection limits varying from 0.03 to 15.40 μg/L. The RSD values for intra- and interday variations studies were also good (RSD<13.5%, for both) and recoveries were higher than 92%. Variation in samples from different harvests and origins and their chemical composition during the year is reported. The fact that no previous treatment of samples is required can make this a useful technique for metabolite profiling in marine organisms, among others, both in biomedical and nutritional studies. Moreover, due to the fast and robust character of the proposed method it seems to be suitable for the implementation as routine analysis.

Chemical composition and biological screening of Capsella bursa-pastoris

Capsella bursa-pastoris (L.) Medik. (Brassicaceae) is a wild herb with high nutritional value that can be eaten raw or cooked. A metabolomic study was performed with different extracts of its aerial parts that were tested concerning their antiradical, acetylcholinesterase inhibitory and antibacterial activities. Phenolic compounds were identified and quantified by HPLC-DAD, organic acids and amino acids were determined by HPLC-UV, while free fatty acids and sterols were analysed by GC-ITMS. The vegetal material was rich in kaempferol-3-O-rutinoside (mean value 2247.09 mg/kg of dry plant), quinic acid (95628.00 mg/kg of dry plant), arginine (mean value of 1.18 mg/kg of dry plant), palmitic acid (284.48 mg/kg) and β-sitosterol (28%). The extracts presented a concentration-dependent antiradical activity (against DPPH•, O2•- and LOO•), being most effective against •NO (EC25 0.20 µg/mL). In addition, the extracts were also acetylcholinesterase inhibitors and antibacterial active, revealing that, besides the plants good nutritional value, it presents important biological properties as well.

In vitro studies of α-glucosidase inhibitors and antiradical constituents of Glandora diffusa (Lag.) D.C. Thomas infusion.

Glandora diffusa (Lag.) D.C. Thomas (Boraginaceae) is a species traditionally consumed as an infusion. The phenolic profile of its aqueous extract was assessed by HPLC-DAD-ESI/MS(n). Twenty-seven compounds were identified, comprising caffeic and p-coumaric acids, seventeen polymers of caffeic acid and eight 3-O-glycosylated flavonols. Caffeic, rosmarinic, and salvianolic acids were the most representative compounds, accounting for more than 75% of the phenolic fraction. The potential of G. diffusa aqueous extract to act as radical scavenger was assessed against DPPH(), superoxide and nitric oxide. A dose-dependent response was observed against all reactive species. Moreover, the extract showed promising results as inhibitor of α-glucosidase, being almost 9 times more effective than acarbose. Both activities are related with the presence of polyphenolic compounds. Therefore, the combination of α-glucosidase inhibition with its antiradical capacity opens a new perspective for the use of G. diffusa by patients with diabetes mellitus. As far as we know, this is the first study assessing the chemical composition and biological potential of G. diffusa. Our results can boost the consumption of G. diffusa species as an infusion or in food and pharmaceutical preparations.

Bioactive compounds of citrus as health promoters

Different chestnut species can be cultivated for fruit production, the most valorised part for nutritional purposes. However Castanea sativa Mill., the “European chestnut”, is one of the most valorised worldwide. Its fruits are consumed either raw or after processing, being boiling and roasting the most usual ones. The nutritional composition of fresh chestnut is variable, with interesting amounts of carbohydrates and fibre, together with low fat content, with differences between cultivars and producing regions. In respect to the presence of bioactive compounds, such as phenolic compounds, vitamins, fatty acids, among others, some studies had focused on the fruit benefits to human health but few reported the effect of processing in those compounds. In this context, this chapter intended to review the current knowledge on chestnut composition, together with the influence of diverse post-harvest technologies, such as refrigeration, flame peeling, freezing with CO2, irradiation, boiling and roasting on the bioactive compounds of chestnut.