Dataset on functional and chemical properties of the medicinal halophyte Polygonum maritimum L. under greenhouse cultivation

This data article includes data and analyses on the effect of different agronomic techniques on the production of Polygonum maritimum L. (sea knotgrass), namely different salinity irrigation treatments (0, 100, 200, 300 and 600 mM of NaCl) and a multi-harvest regime, and their relation with the chemical profile (ultra-high-resolution mass spectrometry - UHRMS), in vitro antioxidant [radical-scavenging activity (RSA) of DPPH and ABTS, copper chelating activity and ferric reducing antioxidant power] and anti-inflammatory (nitric oxide reduction on lipopolysaccharide-stimulated macrophages) activities. For further interpretation of the data presented in this work, please see the related research article “The irrigation salinity and harvesting affect the growth, chemical profile and biological activities of Polygonum maritimum L.” (Rodrigues et al., 2019).


Data
The sea knotgrass plants were produced in a greenhouse under different irrigation conditions (freshwater, 100, 200 and 300 mM of NaCl), and submitted to three consecutive harvests. Obtained biomass (above ground organs) were extracted with acetone, and the extracts were tested for in vitro antioxidant [radical-scavenging activity (RSA) of DPPH and ABTS, copper chelating activity (CCA) and ferric reducing antioxidant power (FRAP)] and anti-inflammatory (nitric oxide reduction on lipopolysaccharide-stimulated macrophages) properties. The results of half maximal inhibitory concentration (IC 50 ) are reported in Tables 1 and 2, for antioxidant and anti-inflammatory, respectively. For the same treatment, the RSA towards DPPH and ABTS, and CCA increased with the harvest. The same tendency was observed in FRAP, except on freshwater-irrigated plants that showed decreased activity from 1st to 2nd harvest, however decreasing in the 3rd harvest. The anti-inflammatory activity decreased with the harvest, and the lowest IC 50 values were obtained on biomass from the 1st harvest, for all treatments. A detailed chemical profiling was performed by LC-UHRMS [1] and differences between treatments and harvests were analysed by PCA and PLC-DA statistics (Figs. 1e3). Striking differences on the chemical composition of statistically significant peaks tends to differ along with consecutive harvests and showed clear separation of salt concentration treatments disregarding the harvest sequence.

Extraction
The dried biomass of aerial parts (leaves, stems and shoots) was extracted with pure acetone (1:40, w/v) in an ultrasonic bath [1]. The extracts were filtered (Whatman no. 4) and acetone was removed by Specifications Table   Subject area  Agronomy, biology, chemistry  More specific subject area  Biological and chemical profiling of Polygonum maritimum cultivated under saline irrigation  Type of data  Table, [1].

Value of the data
The first dataset on the effect of agronomic techniques (irrigation salinity and harvesting) on the chemical profile and in vitro antioxidant and anti-inflammatory properties of the medicinal halophyte P. maritimum (sea knotgrass) This dataset provides relevant information to other researchers for understanding the influence of cultivation conditions, including saline irrigation and multi-harvest regime, on halophyte plants functional properties Data could be relevant for the improvement of sustainable production of halophytes using salinized soils or brackish waters, as high value-added crops for commercial purposes.
rotary evaporation. The dried extracts were weighed, resuspended in methanol at 10 mg/mL, and stored at À20 C.

Radical-scavenging activity (RSA) on DPPH and ABTS
The DPPH and ABTS RSA of the extracts at different concentrations (10e1000 mg/mL) was performed as reported earlier [2]. Differences in absorbance were measured in a microplate reader (Biotek Synergy 4). Butylated hydroxytoluene (BHT) was used as standard at concentrations equal to those of the samples. Results were expressed as an inhibition percentage, comparative to a control containing methanol instead of the sample, and as half maximal inhibitory concentration (IC 50 values, mg/mL).

Ferric reducing antioxidant power (FRAP)
The extracts' capacity to reduce Fe 3þ (at concentrations amongst 10e1000 mg/mL) was evaluated as described by Rodrigues et al. [2]. An increase in the absorbance at 700 nm in the reaction mixture indicates an increased reducing power of the samples (Biotek Synergy 4). Results were calculated as a percentage in relation to the standard (BHT, 1000 mg/mL), and as IC 50 values (mg/mL).

Metal chelating activity on copper (CCA)
The CCA of the extracts (at concentrations varying between 10 and 1000 mg/mL) was assayed as depicted before [2]. The color switch was measured on a microplate reader (Biotek Synergy 4), and ethylenediaminetetraacetic acid (EDTA) was applied as the positive control at the identical concentrations of the extracts. Results were presented as an inhibition percentage comparatively to a control using methanol as substitute of the sample, and as IC 50 values (mg/mL).

Cell culture and cell viability
RAW 264.7 cells were grown in RPMI 1640 culture medium complemented with 10% heatinactivated fetal bovine serum (FBS), 1% L-glutamine (2 mM), and 1% penicillin (50 U/mL)/streptomycin (50 mg/mL) and were kept at 37 C in moistened environment with 5% CO 2 . Cells were seeded at a concentration of 1 Â 10 4 cells/well, in 96-well microplates. After 24h of incubation, the extracts were added at concentrations from 3 to 100 mg/mL, and incubated for 24h. Cells treated with the vehicle (0.5% DMSO, v/v) were used as negative control, and cell viability was assessed through the 3-(4,5dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) colorimetric test [3]. Results were calculated as a percentage of cell viability, in comparison with the control cells.

In vitro anti-inflammatory assay
The samples were tested for their capacity to decrease nitric oxide (NO) production in RAW 264.7 macrophages [3]. Cells were plated at 2.5 Â 10 5 cells/well in 96-well plates and left to adhere overnight. Then, non-toxic concentrations of the extracts (>80% of cell viability) were incubated in serum-and phenol-free culture medium, with 100 ng/mL of LPS, for 24h. The cellular NO production was evaluated by the Griess method [3]. Results were expressed as a percentage (%) of NO production comparing to a control cells containing DMSO (0.5%, v/v), and as IC 50 values (mg/mL).

Liquid chromatography/ultra-high-resolution mass spectrometry (LC-UHRMS)
Samples were pre-treated using solid phase extraction as follows: 100 mg of the extracts were suspended in 1 mL of 0.2% formic acid in purified water (HLP10Uv, Hydrolab, Gda nsk). Next, the suspension was loaded to the C18 Sep-Pak cartridges (1 cm 3 , 360 mg, Waters Corp., Milford, MA) and washed with 0.5% methanol to remove carbohydrates and then with 80% methanol to elute phenolics. The phenolic fraction was re-evaporated, dissolved in 1 mL of 0.2% formic acid in 80% aqueous methanol, centrifuged for 5 min at 23 000Âg, and filtered through 0.22 mm syringe filters (mix cellulose esters, Carl Roth, Karlsruhe, Germany) before LC-MS analysis (stored at À20 C before analysis for no longer than 3 days). All analyses were performed in triplicate for three independent samples.
Liquid chromatography (LC) À electrospray ionization (ESI)-QTOF-MS was carried out using Thermo Dionex Ultimate 3000 RS system consisting of a binary pump system, sample manager, column manager and a DAD detector (Thermo Fischer Scientific, Waltham, MA), coupled to a Bruker Compact quadrupole time-of-flight (QTOF) mass spectrometer (Bruker Daltonics, Billerica, MA).
Separations were performed on a Kinetex C18 column (2.1 Â 100 mm, 2.6 mm, Phenomenex, USA), with mobile phase A consisting of 0.1% (v/v) formic acid in water and mobile phase B containing 0.1% (v/v) formic acid in acetonitrile. A linear gradient from 1% to 60% phase B in phase A over 20 minutes was used to separate phenolic compounds. The flow rate was 0.4 mL/min, and the column was held at 30 C. Mass spectra were acquired in negative-ion mode with 5 Hz frequency over a mass range from m/z 100 to 1500. Operating settings of the ESI ion source were as follows: capillary voltage 3 kV, dry gas flow 6 L/min, dry gas temperature 200 C, nebulizer pressure 0.7 bar, collision radio frequency 700.0 V, transfer time 100.0 ms, and pre-pulse storage 7.0 ms. Ultrapure nitrogen was used as drying and nebulizer gas, and argon was used as the collision gas. The collision energy was set automatically from 15 to 75 eV depending on the m/z of the fragmented ion. For calibration of the accurate mass measurements, we used sodium formate introduced to the ion source at the beginning and end of each separation via a 20 mL loop. After data acquisition, raw UPLCÀQTOF-MS spectra (negative mode) were pre-processed using a ProfileAnalysis software (version 2.1, Bruker Daltonik GmbH, Germany). Parameters of ProfileAnalysis were used as follows: advanced bucket generation with retention time range of 0e20 min, mass range of 100e800 m/z, each bucket (spectral bins) was formed with 1 min and 1 m/z delta, 0.2 kernelizing value, without normalization, background subtraction, and time alignment. LC-MS analyses were processed with the Find Molecular Futures (FMF) function to create compounds (molecular features) with S/N-3 for peak detection. Generated bucket table consisting of tR:m/z pairs and respective compound intensity was exported and uploaded to MetaboAnalyst program. Each obtained dataset was filtered and normalized to the sum of peak areas and meancentered scaling.

Statistical analysis
Results were expressed as the mean ± standard error of the mean (SEM) of at least three repetitions. Significant differences were evaluated by analysis of variance (ANOVA) and by the Tukey HSD test (P < 0.05). Statistical analyses were made using the XLSTAT statistical package for Microsoft Excel (version 2013, Microsoft Corporation). The IC 50 values were calculated by a sigmoidal fitting of the data (GraphPad Prism v. 5.0 program).