Four lipid-rich microalgal species from the Red Sea belonging to three different genera (Nannochloris, Picochlorum and Desmochloris), previously isolated as novel biodiesel feedstocks, were bioprospected for high-value, bioactive molecules. Methanol extracts were thus prepared from freeze-dried biomass and screened for different biological activities. Nannochloris sp. SBL1 and Desmochloris sp. SBL3 had the highest radical scavenging activity against 1,1-diphenyl-2-picrylhydrazyl, and the best copper and iron chelating activities. All species had potent butyrylcholinesterase inhibitory activity (>50%) and mildly inhibited tyrosinase. Picochlorum sp. SBL2 and Nannochloris sp. SBL4 extracts significantly reduced the viability of tumoral (HepG2 and HeLa) cells with lower toxicity against the non-tumoral murine stromal (S17) cells. Nannochloris sp. SBL1 significantly reduced the viability of Leishmania infantum down to 62% (250 µg/mL). Picochlorum sp. SBL2 had the highest total phenolic content, the major phenolic compounds identified being salicylic, coumaric and gallic acids. Neoxanthin, violaxanthin, zeaxanthin, lutein and β-carotene were identified in the extracts of all strains, while canthaxanthin was only identified in Picochlorum sp. SBL2. Taken together, these results strongly suggest that the microalgae included in this work could be used as sources of added-value products that could be used to upgrade the final biomass value.

Context: Several Polygonum species (Polygonaceae) are used in traditional medicine in Asia, Europe and Africa to treat inflammation and diabetes. Objective: Evaluate the in vitro antioxidant, anti-inflammatory and antidiabetic potential of methanol and dichloromethane extracts of leaves and roots of the halophyte Polygonum maritimum L. Material and methods: Antioxidant activity was determined (up to 1 mg/mL) as radical-scavenging activity (RSA) of 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS), copper (CCA) and iron (ICA) chelating activities and iron reducing power (FRAP). NO production was measured in lipopolysaccharide (LPS)-stimulated macrophages for 24 h at concentrations up to 100 μg/mL and antidiabetic potential was assessed by α-amylase and α-glucosidase inhibition (up to 10 mg/mL) assays. The phytochemical composition of the extracts was determined by gas chromatography-mass spectrometry (GC-MS). Results: The methanol leaf extract had the highest activity against DPPH• (IC₅₀ = 26 μg/mL) and ABTS⁺• (IC₅₀ = 140 μg/mL), FRAP (IC₅₀ = 48 μg/mL) and CCA (IC₅₀ = 770 μg/mL). Only the dichloromethane leaf extract (LDCM) showed anti-inflammatory activity (IC₅₀ = 48 μg/mL). The methanol root (IC₅₀ = 19 μg/mL) and leaf (IC₅₀ = 29 μg/mL) extracts strongly inhibited baker’s yeast α-glucosidase, but LDCM had higher rat’s α-glucosidase inhibition (IC₅₀ = 2527 μg/mL) than acarbose (IC₅₀ = 4638 μg/mL). GC-MS analysis identified β-sitosterol, stigmasterol, 1-octacosanol and linolenic acid as possible molecules responsible for the observed bioactivities. Conclusions: Our findings suggest P. maritimum as a source of high-value health promoting commodities for alleviating symptoms associated with oxidative and inflammatory diseases, including diabetes.

This work reports for the first time the in vitro anti Leishmania infantum activity of acetone and dichloromethane (DCM) extracts from 25 extremophile plants from Southern Portugal. DCM extracts from Inula chritmoides and Spergularia rubra were active against axenic promastigotes and intracellular amastigotes, had anti-inflammatory properties on lipopolysaccharide (LPS)-stimulated macrophages, inhibited acetylcholinesterase and had no haemolytic activity on human erythrocytes. Eleven phenolics were identified by high-performance liquid chromatography with diode-array detection (HPLC-DAD) in I. crithmoides and one phenolic in S. rubra. Isolation and identification of the active molecules is in progress.