Sea knotgrass (Polygonum maritimum L.) as a potential source of innovative industrial products for skincare applications

Several Polygonum species and related genera display diverse skincare properties and were considered as active cosmetic ingredients. Thus, this work explored the halophyte sea knotgrass (Polygonum maritimum L.) as source of phenolics and flavonoids-enriched extracts with skincare properties, for the cosmetic industry. To improve the content in these compounds, different extraction solvents and methodologies were used, and the resulting extracts were tested for total contents of phenolics (TPC) and flavonoids (TFC). The acetone extract made on an ultrasound bath for 30 min had the highest TPC (275 mg of gallic acid equivalents [GAE]/g of dry weight [DW]), TFC (48.0 mg of rutin equivalents [RE]/g DW), and yield (20.3%). This extract was selected and evaluated for its in vitro antioxidant (total antioxidant, superoxide radical-scavenging and lipid peroxidation), anti-inflammatory (nitric oxide [NO] reduction on lipopolysaccharide [LPS]-stimulated RAW 264.7 macrophages), anti-wrinkles (elastase), anti-acne (lipase), antimicrobial (Escherichia colt Staphylococcus aureus, Pseudomonas aeruginosa, Candida cdbicctris), anti-melanogenic (anti-tyrosinase and reduction of melanin production on B16 4A5 melanoma cells). The extract was also appraised for toxicity, and its chemical profile was determined by ultra-high-resolution mass spectrometry (UHRMS). The acetone extract showed a high O-2(-center dot) scavenging (half maximal inhibitory concentration [IC50] = 40.4 mu g/mL), total antioxidant capacity (TAC

IC50 = 647 mu g/mL), and late anti-lipid peroxidation (thiobarbituric acid [TBA]

IC50 = 784 mu g/mL) properties. It also had a high capacity to reduce NO production on LPS-stimulated RAW 264.7 macrophages (IC50 = 22.0 mu g/mL), and in vitro anti-melanogenic activity through tyrosinase inhibition (IC50 = 64.1 mu g/mL), reduction of melanin production in B16 melanoma cells (IC50 = 77.7 mu g/mL). It had low toxicity against mammalian cell lines. Thirty-one compounds were identified in the extract, including 24 flavonoids, 5 phenolic acids, and 1 acetophenone. Myricitrin, catechin and monogalloyl-hexose were the main compounds detected. Altogether, our results suggest sea knotgrass as a promising source of natural products with skincare properties for industrial cosmetic applications.

Foundation for Science and Technology (FCT)Portuguese Foundation for Science and Technology

Portuguese National Budget [CCMAR/Multi/04326]

FCTPortuguese Foundation for Science and Technology [IF/00049/2012, SFRH/BD/94407/2013, SFRH/BD/116604/2016]