Bacterial and fungal infections and the emerging multidrug resistance are driving interest in fighting these microorganisms with natural products, which have generally been considered complementary to pharmacological therapies. Phlorotannins are polyphenols restricted to brown seaweeds, recognized for their biological capacity. This study represents the first research on the antibacterial, antifungal, anti-inflammatory and antioxidant activity of phlorotannins purified extracts, which were obtained from ten dominant brown seaweeds of the occidental Portuguese coast.Phlorotannins content was determined by the specific dimethoxybenzaldehyde (DMBA) method and a yield between 75 and 969 mg/Kg phloroglucinol units (dry matter) was obtained. Fucus spiralis ranked first, followed by three Cystoseira species. The anti-inflammatory potential of the purified extracts was assessed via inhibitory effect on nitric oxide (NO) production by lipopolysaccharide-stimulated RAW 264.7 macrophage cells, Cystoseira tamariscifolia being the one showing promising activity for the treatment of inflammation. NO scavenging ability was also addressed in cell free systems, F. spiralis being the species with highest capacity. The antimicrobial potential of the extracts was checked against five Gram-positive and four Gram-negative bacteria and three fungi strains, that commonly colonize skin and mucosa and are responsible for food contamination. The different extracts were more effective against Gram-positive bacteria, Staphylococcus epidermidis being the most susceptible species. Concerning antifungal activity, Trichophyton rubrum was the most sensitive species.Although the molecular mechanisms underlying these properties remain poorly understood, the results obtained turn phlorotannins purified extracts a novel and potent pharmacological alternative for the treatment of a wide range of microbial infections, which usually also present an inflammatory component. In addition to the biological properties demonstrated herein, phlorotannins extracts may also be preferred, in order to avoid side effects and allergic reactions commonly associated with synthetic drugs.

The sterol profiles of dominant macroalgae occurring in the western Portuguese coast were evaluated. An analytical procedure, involving alkaline hydrolysis and extraction followed by separation by reversed-phase HPLC-diode array detection (HPLC-DAD), was optimized for the study of their sterols composition. The validated methodology is short in analysis time (as the compounds are determined in <20 min), sensitive, reproducible, and accurate. It was then successfully applied to the determination of campesterol, cholesterol, desmosterol, ergosterol, fucosterol, stigmasterol, and β-sitosterol in 18 species (three Chlorophyta, five Rhodophyta, and 10 Phaeophyta). The profiles obtained for the several macroalgal species were considerably different. C29 sterols were predominant in Phaeophyta and Chlorophyta (71%-95% of total sterol content), while in Rhodophyta cholesterol content is significantly higher (34%-87%). Among the studied species, Asparagopsis armata Harv. contained the lowest sterol amount (555 mg · kg(-1) dry weight), and Cystoseira tamariscifolia (Huds.) Papenf. the highest one (6,502 mg · kg(-1) dry weight). Data obtained may be helpful in identifying suitable marine sources of sterols, with potential applications in the food and pharmaceutical industries.

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The central nervous system (CNS) is a mythical target for drug delivery. There is an ongoing debate over the brain accessibility of flavonoids, a group of plant-derived secondary metabolites widely known by their multifarious bioactivities achieved by distinct mechanisms. Recently, their applicability in the management of neurologic and psychiatric disorders, such as Alzheimer's and Parkinson's diseases, and major depression, has received particular attention. To reach their target, flavonoids must cross over the ultimate obstacle - the blood-brain barrier - at pharmacologically effective concentrations. This review addresses the low brain-bioavailability issue, based on in vitro and in vivo evidences. Besides the lipophilic character of the flavonoids, their permeability will depend upon the role of membrane transporters, especially those from the ABC superfamily. The enzymatic elements, namely β-glucuro-nidase, can induce a transient deconjugation process and affect permeability, as well. Novel drug delivery systems are successful strategies to overcome the low bioavailability issue, and redirect the native forms to CNS-targets. This work bridges a solid opinion over this hot topic of medicinal chemistry and natural products research.

Herbal teas are consumed for their valuable content of bioactive phytochemicals. This work represents the first attempt to establish a linkage between the chemical composition of pennyroyal (Mentha pulegium L.) infusion and its potential to prevent cellular oxidative stress. The phenolic profile was established by HPLC-DAD-ESI/ MS n , twelve out of fifteen compounds being identified for the first time in this species. The infusion presented a phenolic content of 122.92 mg g À1 (lyophilized extract) and a remarkable antiradical activity. A reduced glutathione detoxification mechanism was demonstrated to be involved in human epithelial colorectal adenocarcinoma (Caco-2) cell resistance against tert-butyl hydroperoxide-induced toxicity, while the same was not observed for human epithelial gastric adenocarcinoma (AGS) cells. For the first time, the presence of these phenolic compounds inside the cells was confirmed by 2-aminoethyl diphenylborinate (DPBA) phenol fluorescence dye staining, suggesting a direct antioxidant effect. M. pulegium infusion seems to provide bioactive compounds able to maintain a proper antioxidant balance in gastrointestinal cells.

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