Journal of Applied Botany and Food Quality 92, 143 - 150 (2019), DOI:10.5073/JABFQ.2019.092.020 1Oases Aridoculture and Culture Laboratory of the Arid Region Institute (IRA), Tunis, Tunisia 2University of Tunis El Manar (FST), Tunis, Tunisia 3Postharvest and Refrigeration Group, Department of Food Engineering, Technical University of Cartagena (UPCT), Cartagena, Spain 4National Agronomic Institute of Tunis (INAT), Tunis, Tunisia Phytochemical content, antioxidant potential, and fatty acid composition of dried Tunisian fig (Ficus carica L.) cultivars Marwa Khadhraoui1, 2*, Mohamed Bagues1, Francisco Artés3, Ali Ferchichi4 (Submitted: December 8, 2018; Accepted: April 6, 2019) * Corresponding author Summary This study reports the main phenolic compounds, as well as phenolic profiles and antioxidant activity in nine sun-dried fig cultivars with different skin color, originating from South-Eastern and Middle- Eastern Tunisia. For all evaluated parameters, a considerable variability with high significant differences was observed among the cultivars studied. Dark fruits exhibited a higher total polyphenol contents (201.77 mg GAE/100g DM in cultivar Saoudi Douiret) compared to green fruits (73.74 mg GAE/100g DM in cultivar Bayoudhi Douiret). Fatty acid methyl esters, identified by GC-MS, distinguished the presence of (C16: 0), (C18: 1), ((C18: 2) 9, 12), ((C18: 3) 9, 12, 15) and (C20: 0). Strong correlations between the amounts of total phenolics, phenolic acids, flavonoids, fatty acids and antioxidant capacity were found. A principal component analysis showed three groups of cultivars regarding their similarity level. Key Words: Bioactive compounds; fatty acids; Ficus carica L.; GC- MS; LC-ESI-MS. Introduction Ficus carica L. is considered one of the world’s oldest fruit trees, belonging to the Moraceae botanical family (Solomon et al., 2006). This species is characterized by various chemical components and biological activities, which allow it to be a typical element of the Mediterranean diet that has been favorable to health for millennia; comparing its phenolic composition with red wine and tea, its level seems to be higher (Vallejo et al., 2012). All over the world, figs are consumed fresh or dried because of their richness in minerals, carbohydrates, essential amino acids, vitamins and polyphenols (Solomon et al., 2006; Veberic et al., 2008; Viuda-martoS et al., 2015). Furthermore, they are exploited in traditional medicine and have been studied and proven their potential therapeutic value (Khairuddin et al., 2017; moniruzzaman et al., 2017). This plant is cultivated in all Mediterranean regions and countries with similar climatic conditions. About 1,184,884 tons of figs are produced worldwide. Turkey is the leading producer of figs providing approximately 23.5% of the total production in the world; about 51.6% of this crop is marketed in dry form (FaoStat, 2015). In Tunisia, total fig production is 26,000 tons/year representing 3% of world production (FaoStat, 2015), mainly produced in the South- Eastern regions (34% of the national production) (marS et al., 2008). Fig cultivars (cvs) and the wild form of the fig can show a wide va- riety of fruits with respect to color, shape, weight, acidity, sugar and mineral contents, etc, while the region where the figs are mainly cul- tivated is at the origin of their name (meziant et al., 2015). Thus, a morphological and chemical study must be performed in order to show the variation among cultivars. Despite the prominence of this crop in arid, semi-arid and sub-humid regions, research on natural substances and molecules of this species has been a major topic for several years. These molecules, which con- stitute the active ingredient of medicinal plants, belong predominant- ly to secondary metabolites such as polyphenols, essential oils and alkaloids. Several research programs on figs are being developed in order to analyze their content in polyphenols (Soloman et al., 2006; caliSKan and Polat, 2011; harzallah et al., 2016; KonaK et al., 2017). Since dried figs are a more concentrated form of fruit, and due to its economic benefits which are appreciated by both industrial users and individual consumers, the current work investigated the quantity and quality of antioxidants contained in these fruits to de- termine the richness in these elements. Few studies investigated the phytochemical contents in dried figs. The current study evaluates the contents of phytochemical com- pounds and the antioxidant activity by using ABTS and DPPH tests and characterizing the phenolic and fatty acid profiles of light and dark skin dried fig cultivars cropped in South-East and Mid-East of Tunisia. The aim is to determine which cultivars can be recommen- ded as natural healthy food products basing on their biochemical and nutritional facts, thus allowing their labeling as a superior product. Materials and methods Plant material The nine local fig cultivars were harvested by hand in the summer of 2015 and 2016 in several commercial farms located in southern and central Tunisia during the ripening stage (Tab. 1, Fig. 1). Figs were then traditionally sun-dried for seven days using the direct solar dryer, consisting of a single piece that is both a drying chamber and a solar collector, which produces an uncontaminated final product of good quality on the hygienic and nutritious plan (ouaouich et al., 2005). After drying, figs were stored in closed jars in cold rooms. Tab. 1: Origin and description of studied dry fig cultivars. Accession name Label Geographical origin Description (Color) Saoudi douiret SD Douiret Tataouine Black Bayoudhi douiret BD (South-East) Green – yellow Wedleni bir amir WBA Bir Amir Tataouine Purple Hamouri bir amir HBA (South-East) Light purple Zidi bni khdech ZBK Bni Khdech Medenine Black Bayoudhi bni khdech BBK (South-East) Light green Hamouri bni khdech HBK Purple Kahli karkenah KHK Karkenah Sfax Purple Mahdoui karkenah MK (Mid-East) Light green 144 M. Khadhraoui, M. Bagues, F. Artés, A. Ferchichi Total polyphenols content determination The polyphenols were extracted with 80% methanol (1 g of each sample is ground with 6 mL of methanol), then the samples were placed in a box with ice and kept in the dark during the extraction which was performed on an orbital shaker (Stuart, Staffordshire, UK) for one hour at 200 × g. After that, fig extracts were centrifuged at 15,000 rpm (4 °C) for 10 min and the supernatant was recovered and stored for total phenolic compounds (TPC) and total antioxi- dant capacity (TAC) quantification. Total phenolic content in fig ex- tracts was evaluated, using the Folin-Ciocalteu method, in 96-well plates, with a spectrophotometer (Tecan Infinite M200 Mannedorf, Switzerland) at the absorbance of 750 nm, estimated by the method of Singleton and roSSi (1965) with some modifications proposed by martinez-hernandez et al. (2011). In each sample, the total polyphenol contents were expressed in mg of gallic acid equivalent (GAE) per 100g of dry matter (mg GAE/100g DM) through a calibra- tion curve based on gallic acid at different concentrations (mg/mL). Total flavonoids content determination Total flavonoids content in the methanolic extracts of dried figs was monitored by the colorimetric method of aluminum chloride (AlCl3) (brighente et al., 2007) with slight modifications. Then, 1 mL of each fig extract was added to 1 mL of a methanolic solution of AlCl3 (2%). After 10 min incubation at room temperature and using a spec- trophotometer at 430 nm, the absorbance of the mixture was deter- mined. The flavonoid concentrations were deduced from the calibra- tion curve established with quercetin. The results were expressed as mg quercetin equivalents per 100 g of dry matter (mg QE/100g DM). Antioxidant capacity DPPH assay The DPPH assay (2, 2-diphenyl-1-picrylhydrazil) was determined by a spectrophotometric method at 515 nm, adapted from brand- WilliamS et al. (1995) with slight modifications made by martinez- hernandez et al. (2011). The test is based on the capacity of sca- venging free radicals. The DPPH radical solution was prepared by dissolving 12 mg of DPPH in 50 mL of methanol and then stored at -5 °C in the dark. The absorbance was adjusted to 1.1 ± 0.02. An aliquot of 21 μL of extract was placed in a 96-well plate and 194 μL of DPPH solution were added. After incubation for 35 min under dark conditions, the absorbance of the aqueous solution was measured against a blank using a spectro- photometer. The results were expressed as mg TROLOX equivalent antioxidant capacity (TEAC) per 100 g DM through a TROLOX cali- bration curve at different concentrations (mg/mL). All measurements were performed in triplicate. ABTS assay The ABTS assay (2, 2’-Azino-bis (3-ethylbenzothiazoline-6-sulfonic acid)) was determined by a spectrophotometric method at 734 nm, which was adapted from arnao et al. (2001) with slight modifica- tions. The assay is based on the ability to reduce the radical cation 2, 2’-Azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) by antioxidant. The mixture solution contained 14 mM ABTS and 4.9 mM K2S2O8 solutions diluted in methanol and ad- justed to 1.1 ± 0.02 (absorbance), and then incubated for 16 h in the dark. An aliquot of 10 μL of extract was placed in a 96-well plate and added with 190 μL of ABTS solution. After 35 min of incuba- tion, the absorbance of the aqueous solution was measured against a blank using a spectrophotometer. Results were expressed in terms of mg TROLOX equivalent antioxidant capacity (TEAC) per 100 g DM through a TROLOX calibration curve at different concentrations (mg/mL). Identification and quantification of phenolic compounds After pressurized liquid extraction and solid-phase extraction, the polyphenolic patterns of figs were identified and quantified using a liquid chromatography-electrospay ionization-tandem mass spec- trometry (LC-ESI-MS). The extract was filtered through a 0.45 μm membrane filter and then injected into the High Performance Liquid Chromatography system (HPLC). Quantification was achieved by injection of standard chemical solutions of known concentrations at the purity > 98%. The mobile phase was composed of a mixture of two solutions: The first contains 0.1% formic acid in H2O and the second contains 0.1% formic acid in methanol. The column tem- perature was set at 40 °C and the flow rate of the mobile phase was 0.4 mL/min. The auxiliary gas used is the N2 which was very pure. The results were expressed as mg/100 g DM. All extracts were ana- lyzed in triplicate. Fig. 1: Nine fig cultivars with different skin colour at ripening stage. Zidi bni khdech Kahli karkenah Wedleni bir amir Saoudi douiret Bayoudhi bni khdech (ZBK) (KHK) (WBA) (SD) (BBK) Bayoudhi douiret Hamouri bni khdech Mahdoui karkenah Hamouri bir amir (BD) (HBK) (MK) (HBA) Bioactive substances and fatty acids of dry figs 145 Fatty acids composition The total lipid content was determined by the Soxhlet method which allows extracting the dry extract as much as possible. The Fatty acid methyl esters (FAMEs) were extracted using a hexane solvent and were determined by gas chromatography coupled with GC-MS mass spectrometry (Supelcowax TM10 FUSED SILICA CAPILLARY COLUMN), 30 m × 0.25 mm × 0.25 μm film thickness (Supelco, Milan, Italy), according to mondello et al. (2004) with slight modi- fications. GC-MS analysis was performed using a GCMS-QP2010 Ultra mass spectrometer (Shimadzu, Kyoto, Japan), with a split/split less injector and a Shimadzu AOC-20i auto-injector and a Shimadzu AOC-20s auto sampler. The data was obtained by the GCsolution / GCMSsolution software. The identification of Fatty acid methyl esters (FAMEs) was achieved by comparing their retention time with pure standards analyzed under the same conditions. Statistical and multivariate analysis Statistical analyzes were performed using an ANOVA with SPSS version 22.0 software. Duncan test was used to compare significant differences with the level of significance at P < 0.05 and Pearson’s correlation coefficient (r) involved to determine correlations between studied parameters. Each assay was performed three times from the same extract and the value was expressed as mean ± standard devia- tion (SD). The structure of genetic variability among the figs cultivars based on mean values of total polyphenol contents, phenolic compounds such as phenolic acids and flavonoids, fatty acids and antioxidant activity was analyzed using principal component analysis (PCA). These mul- tivariate analyzes were carried out using the Xlstat 9.0 software to evaluate the influence of phenolic compounds in the differentiation of Tunisian dried fig samples. Results and discussion Total polyphenol contents (TPC) The TPC of dried fig cultivars are shown in Fig. 2. The fig cultivars were classified into seven different homogenous subsets according to the Duncan test (P < 0.05). Cultivars belonging to different sub- sets presented significant differences in terms of phytochemical cha- racters. The TPC ranged from 73.74 mg GAE/100g DM in (BD) cv to 201.76 mg GAE/100g DM in (SD) cv. Our findings are inferior to those of Pourghayoumi et al. (2017), who mentioned that dried Iran fig contained 1120 to 2681.8 mg GAE/100g DM, but are in ac- cordance with the results reported by caPanoglu (2014) who found 169.4 mg GAE/100g DM in Turkish dried fig. These differences in TPC can be attributed to differences in crop region and cultivar type, as well as to cultivation practices, geographical origin, experimental conditions, and postharvest storage conditions (SouFi et al., 2014; hoxha et al., 2015). Furthermore, the drying processes used (air or sun drying) may be responsible for these differences (arVaniti et al., 2019). On the other hand, there was no significant difference between cultivars harvested in South-East and Mid-East of Tunisia in terms of TPC, since these two regions have almost the same cli- matic conditions (arid climate and semi-arid climate, respectively). MK cv (from Mid-East) contained 90.96 mg GAE/100g DM while BBK cv (from South-East) contained 81.21 mg GAE/100g DM). As expected, the polyphenol contents in dark-skinned figs were signifi- cantly higher than those in light ones. The highest values were found on dark colored figs (SD-cv, ZBK-cv, HBA-cv and KHK-cv) which shows that the skin color was the major contributor of this diffe- rence. These results were confirmed by debib et al. (2014) who found similar findings and reported that dark-colored dried fig varieties contained a higher level of phenolics than the green and yellow ones (harzallah et al., 2016). Comparing the levels found in dried figs with those of fresh figs, several studies have shown that the TPC in dried figs was higher than that of fresh ones (KonaK et al., 2017). However, other studies have shown that drying methods have a nega- tive impact on the phytochemical contents (bachir bey et al., 2016). Nevertheless, these levels remain higher than those of certain fruits (dates for example) (al-turKi et al., 2010). It is interesting to note that a large number of biochemical properties are identified in these compounds and are conceivably useful for inhibiting the develop- ment of diseases such as cancer, cardiovascular diseases and diabetes (chang et al., 2016). Total flavonoid contents (TFC) As shown in Fig. 2, TFC of dried fig extracts ranged from 57.96 mg QE/100g DM to 112.28 mg QE/100g DM. Statistically significant differences in TFC were found between dark and light cultivars (P < 0.05) (Fig. 2); SD cv (South-East) appears to have a significantly higher TF content, while a low BD cv (South-East) content was ob- served. There is no data available on TFC in black and light dried figs; only one study reported the total number of carotenoids in Algerian figs (ouchemouKh et al., 2012; arVaniti et al., 2019). These results are consistent with those obtained by bey and louaileche (2015) who indicated that flavonoids content in dark cultivars (126.55 mg/100 g) was higher than that of light ones (87.24 mg/100 g) which confirm that dark-colored figs had more TFC compared to light-colored ones. Regarding the factors that af- fected this phytochemical composition, our study demonstrated that color and fig cv were responsible for TFC variation, but other studies have shown that other factors were accountable such as drying me- thods used and the level of maturity of this fruit (Pereira et al., 2017; Sedaghat and rahemi, 2018). As antioxidants, flavonoids exert therapeutic effects such as antihepa- totoxic, antitumor and prevent diabetes and infections (chang et al., 2016). In addition, a set of flavonoids provides protection against cardiovascular mortality and heart disease (Wang et al., 2018). Antioxidant capacity (AC) The Antioxidant capacity (AC) of dried fig cultivars was assessed by two assays: the DPPH and the ABTS tests. Results shown in Fig. 3 proved that all fig extracts were characterized by antioxidant Fig. 2: Contents of total phenolics (mg GAE/100 g DM) and flavonoids (mg QE/100 g DW) in nine cultivars of dry figs. Data are displayed as mean ± standard deviation of three replications for each cultivar. Letters above columns represent the groups given by Duncan test (α = 0.05) in arising order. Different letters indicate significant differ- ence at P < 0.05. 146 M. Khadhraoui, M. Bagues, F. Artés, A. Ferchichi activities with significant differences (P < 0.05). The antioxidant ac- tivity (AAO) against DPPH ranged from 131.55 mg TEAC/100 g DM to 418.51 mg TEAC/100 g DM, respectively for BD cv and SD cv. Similarly, SD cv exhibited the highest level of TEAC using the ABTS test up to 207.43 mg TEAC/100 g DM, while the BD cv presented the lowest level up to 124.53 mg TEAC/100 g DM. Besides, a significant positive and high correlation was assigned between these two assay methods used to evaluate the antioxidant capacity on the one hand (r = 0.953), and between the AC and the amount of phytochemical compounds on the other hand at the P < 0.05 (Tab. 2), which infers that the value of antioxidant capacity is often due to the existence of polyphenols and flavonoids. Similarly, KSouda et al. (2018) estimated a high and positive correlation between the values of antioxidant capacities obtained by these two methods for the majority of the plant methanolic extracts of 25 Tunisian plant species. Furthermore, ouchemouKh et al. (2012) and ammar et al. (2015) showed strong correlations between the amount of phytochemical compounds and the antioxidant capacity of figs. According to breWer (2011), the antioxidant capacity is gene- rally due to the presence of phenolic acids such as Caffeic, Gallic and Chlorogenic acids, as well as to flavonoids namely Rutin, Catechin, Kaempferol and Quercetin. Moreover, the ANOVA study revealed that the difference between the green-yellow BD cv and the light-green BBK cv was not signifi- cant, neither between HBK and WBA purple cultivars nor between HBA and KHK purple cultivars. Significant differences were found only between cultivars owning different skin color (Fig. 3). Thus, figs originated from dark-colored cultivars exhibited a higher antioxidant capacity compared to those from light-colored cultivars with a range of 3 to 4 fold differences between cultivars. These findings were con- firmed by KonaK et al. (2017) and Pereira et al. (2017). Therefore, a strong correlation between skin color and TPC and AC should be expected. These results make it possible to deduce that the two dark- colored figs, SD and ZBK, harvested in South-Eastern Tunisia, are recommended for their phytochemical contents and their antioxidant potential in order to improve their health-promoting properties. Regarding the impact of drying on the antioxidant capacity, chang et al. (2016) reported that sun-drying process had a positive effect on antioxidant activity, which increases the antioxidant activity of dried figs compared to that of fresh figs, although bachir bey et al. (2016) found that it reduced the antioxidant capacity of figs. Despite the great interest in the AC of dry figs, it is difficult to know which of the phenolic compounds has the most important antioxidant activity. That’s why we use to isolate and identify the antioxidant components in order to evaluate the mechanisms of activity. LC-ESI-MS analysis Individual antioxidants found in our extracts are shown in Tab. 3 and seventeen isolated antioxidants were detected. These compounds included different classes of phenolic acids and flavonoids (flavan- 3-of, flavanones, flavonols, and flavones). Among the phytochemi- cals, in dried figs, each extracted fraction revealed high contents of Rutin (38.05 mg/100 g DM) for SD cv, followed by Protocatechuic acid (10.6 mg/100 g DM) for WBA cv, Cirsiliol (2.72 mg/100 g DM) for SD cv and 4-O-Caffeoylquinic acid (2.42 mg/100 g DM) for KHK cv. Moreover, other phenolic compounds were detected, such as Quercetin (1.49 mg/100 g DM) for SD cv and Kaempferol (1.13 mg/100 g DM) for ZBK cv. A number of phenolic acids were also de- tected in dried figs, such as Gallic acid, p-Coumaric, trans Cinnamic and trans-Ferulic, but at very low concentrations (< 1 g/100 g DM). In addition, Salviolinic acid was detected only in WBA and SD cul- tivars with respective amounts of 0.89 and 0.939 mg/100 g DM at a retention time of 20.90 min. The Apigegin was presented in low amounts except in ZBK cv with 4.85 mg/100 g DM. According to arVaniti et al. (2019), Gallic acid, and Chlorogenic acid were the most predominant phenolic acids in dried figs, while Rutin, Quercetin-3-O-rutinoside, and Epicatechin exhibited the highest concentration levels among flavonoids. Comparing these compounds to those of fresh figs, the same target compounds were found, but with high levels (arVaniti et al., 2019). Many factors were responsi- ble for these variations; The ripening phase and drying process used seem to significantly affect the content of phytochemical compounds (Pereira et al., 2017; arVaniti et al., 2019), as well as the nature of the solvent used for extraction, the fruit color, the harvest season, the weather conditions, and the fruit variety (Sedaghat and rahemi, 2018). Moreover, the dark-colored varieties (SD and ZBK cultivars) had higher phenolic compounds compared to those from light-colored ones (BD and BBK cultivars). Furthermore, it should be emphasized that dark-colored dried figs have the highest content of phytochemi- cals and exhibited the highest antioxidant capacity due to these com- pounds. According to Pourghayoumi et al. (2017) and based on our current results, dried figs own one of the highest concentrations of poly- phenols among the commonly consumed fruits. In addition, the dark- colored dried varieties, especially the SD and ZBK cultivars, harvested in South-Eastern Tunisia, represent a rich source of two phytochemical classes such as phenolic acids and flavonoids and can offer valuable value for food and pharmaceutical industries, and should be recommended as a natural and healthy food product. Fatty acids determination (FAMEs) FAMEs composition is shown in Tab. 4. The total lipid content (TLC) analyzed for the cultivars studied, expressed in gram per 100 g of dry matter (g/100 g DM), was in the order of 1.5 g/100 g. This Tab. 2: Correlations between antioxidant capacities by ABTS and DPPH as- says, TPC and TFC of fig cultivars studied. Bold Pearson correlation coefficients are significant at 5% of confidence level. Variables DPPH (TEAC) ABTS (TEAC) TPC TFC DPPH (TEAC) 1 ABTS (TEAC) 0.953*** 1 TPC 0.961*** 0.906*** 1 TFC 0.973*** 0.963*** 0.916*** 1 Fig. 3: The total antioxidant capacity of nine dry fig cultivars using DPPH and ABTS radicals. Data are displayed with mean ± standard de- viation of three replications. Letters above columns represent the groups given by Duncan test (α = 0.05). Different letters indicate significant difference at P < 0.05. Bioactive substances and fatty acids of dry figs 147 Tab. 3: Phenolic acid and flavonoid profiles in the nine Tunisian dry fig cultivars. ZBK KHK WBA SD BBK Phenolic contents m/z CC (mg/100g) Rt (min) CC (mg/100g) Rt (min) CC (mg/100g) Rt (min) CC (mg/100g) Rt (min) CC (mg/100g) Rt (min) Gallic acid 169 0.47 ± 0.02d 4.14 0.12 ± 0.07b 4.14 0.54 ± 0.14e 4.14 0.09 ± 0.01ab 4.12 0.082 ± 0.00a 4.13 Protocatechuic acid 153 4.47 ± 0.23e 7.33 1.85 ± 0.05bc 7.31 10.59 ± 0.13f 7.32 1.96 ± 0.10c 7.32 1.91 ± 0.02c 7.32 4-O-Caffeoylquinic acid 353 0.92 ± 0.03c 12.70 2.42 ± 0.13d 12.71 0.55 ± 0.02b 12.70 0.88 ± 0.05c 12.71 0.27 ± 0.02a 12.75 p-Coumaric acid 163 0.36 ± 0.01b 22.20 0.39 ± 0.01bc 22.18 0.46 ± 0.01cd 22.19 0.89 ± 0.04f 22.20 0.68 ± 0.06e 22.22 trans Cinnamic 147 0.49 ± 0.08b 33.56 0.61 ± 0.03bcd 33.56 0.58 ± 0.02bc 33.60 0.85 ± 0.16e 33.61 0.41 ± 0.03ab 33.55 trans Ferulic acid 193 0.73 ± 0.05de 24.45 0.53 ± 0.05c 24.46 0.46 ± 0.00c 24.46 0.79 ± 0.03e 24.43 0.25 ± 0.01b 24.50 Salviolinic acid 515 N.D - N.D - 0.89 ± 0.00b 29.63 0.94 ± 0.00c 29.63 N.D - Rutin 609 34.68 ± 0.74g 25.23 22.34 ± 0.62f 25.35 10.28 ± 0.10cd 25.36 38.05 ± 1.75h 25.36 9.29 ± 0.24c 25.37 Luteolin-7-o-glucoside 447 0.43 ± 0.03f 26.07 0.18 ± 0.01d 26.06 0.07 ± 0.01bc 26.06 0.08 ± 0.01c 26.06 0.02 ± 0.00a 26.04 Naringin 579 0.02 ± 0.01b 27.60 0.05 ± 0.00d 27.58 0.03 ± 0.00c 27.59 0.03 ± 0.00c 17.59 0.06 ± 0.01e 27.59 Apigenin-7-o-glucoside 431 0.91 ± 0.06 d 28.53 0.07 ± 0.00ab 28.52 0.02 ± 0.00 a 28.52 N.D - N.D - Quercetin 301 0.45 ± 0.01b 33.56 1.05 ± 0.03d 33.55 0.24 ± 0.02a 33.56 1.49 ± 0.09e 33.57 0.68 ± 0.05c 33.57 Kaempferol 285 1.13 ± 0.04g 33.56 0.24 ± 0.01e 33.56 0.11 ± 0.01c 33.57 0.10 ± 0.01c 33.60 0.08 ± 0.03bc 33.58 Naringenin 271 0.43 ± 0.02d 35.62 0.24 ± 0.03c 35.61 0.17 ± 0.01b 35.62 0.06 ± 0.01a 35.62 0.20 ± 0.02bc 35.63 Apigenin 269 4.85 ± 0.21d 36.22 0.15 ± 0.01ab 36.21 0.23 ± 0.03ab 36.22 0.05 ± 0.01ab 36.29 0.04 ± 0.00ab 36.26 Luteolin 285 0.07 ± 0.01c 36.67 0.08 ± 0.02c 36.66 N.D - 0.15 ± 0.01d 36.66 N.D - Cirsiliol 329 1.79 ± 0.05bc 37.29 1.23 ± 0.06a 37.30 1.46 ± 0.17abc 37.29 2.72 ± 0.07d 37.30 1.89 ± 0.40c 37.30 BD HBK MK HBA Phenolic contents m/z CC (mg/100g) Rt (min) CC (mg/100g) Rt (min) CC (mg/100g) Rt (min) CC (mg/100g) Rt (min) Gallic acid 169 0.07 ± 0.01a 4.10 0.08 ± 0.01a 4.16 0.12 ± 0.01b 4.12 0.38 ± 0.01c 4.15 Protocatechuic acid 153 0.95 ± 0.02a 7.32 2.60 ± 0.13d 7.32 1.50 ± 0.06 b 7.31 4.28 ± 0.15e 7.34 4-O-Caffeoylquinic acid 353 0.10 ± 0.01a 12.73 2.33 ± 0.10d 12.72 0.54 ± 0.00 b 12.71 0.25 ± 0.02a 12.72 p-Coumaric acid 163 0.49 ± 0.01d 22.20 0.36 ± 0.01b 22.23 0.32 ± 0.01 b 22.23 0.23 ± 0.01a 22.22 trans Cinnamic 147 0.28 ± 0.01a 33.57 0.71 ± 0.01cde 33.51 0.42 ± 0.03 ab 33.58 0.79 ± 0.06de 33.57 trans Ferulic acid 193 0.42 ± 0.07c 24.45 N.D - 0.68 ± 0.01d 24.45 N.D - Salviolinic acid 515 N.D - N.D - N.D - N.D - Rutin 609 2.17 ± 0.16a 25.36 17.99 ± 0.14e 25.35 12.19 ± 0.23d 25.35 6.87 ± 0.33b 25.37 Luteolin-7-o-glucoside 447 0.04 ± 0.00ab 26.03 0.28 ± 0.01e 26.06 0.04 ± 0.00a 26.02 0.24 ± 0.01e 26.08 Naringin 579 N.D - N.D - 0.02 ± 0.01b 27.59 0.01 ± 0.01a 27.62 Apigenin-7-o-glucoside 431 N.D - 0.08 ± 0.01bc 28.52 N.D - 0.14 ± 0.01c 28.55 Quercetin 301 0.25 ± 0.00a 33.55 0.45 ± 0.01b 33.54 0.95 ± 0.03 d 33.58 0.28 ± 0.01a 33.57 Kaempferol 285 0.02 ± 0.00a 33.58 0.17 ± 0.00d 33.56 0.041 ± 0.00ab 33.58 0.43 ± 0.01f 33.60 Naringenin 271 0.01 ± 0.01a 35.63 0.17 ± 0.03b 35.61 0.17 ± 0.01b 35.63 0.22 ± 0.02 bc 35.65 Apigenin 269 N.D - 0.25 ± 0.04b 36.22 N.D - 0.53 ± 0.04c 36.25 Luteolin 285 N.D - 0.04 ± 0.01b 36.68 0.15 ± 0.01d 36.67 N.D - Cirsiliol 329 0.95 ± 0.04a 37.31 1.49 ± 0.18abc 37.30 1.27 ± 0.09ab 37.31 1.38 ± 0.10abc 37.33 Note: Mean values ± SE, followed by different letters in the same column indicate significant difference at P < 0.05 according to Duncan’s multiple range test. Rt: Retention time; CC: Concentration (mg/100 g); N.D: not detected P he no lic a ci ds F la vo no id s P he no lic a ci ds F la vo no id s content varied between 1 g/100 g and 2.25 g/100 g. These levels are slightly higher than those indicated by Vidaud et al. (1997) and boStan et al. (1998) who estimated that the content was 1 g/100 g. The analysis of fatty acids presented in Tab. 3 led to the following results; Palmitic acid (C16: 0) has an average content of 0.27 g/100 g DM, the maximum content of which is detected in HBA cv and the lowest in HBK cv of a value equal to 0.91 g/100 g DM and 0.15 g/ 100 g DM respectively for these two cultivars. The average con- tent of Oleic acid (C18: 1) is equal to 0.31 g/100 g DM, the highest of which is detected in HBA cv (0.51 g/100 g DM), Linoleic acid (C18: 2) has an average of 0.35 g/100 g DM. The high content of Linolenic acid (C18: 3) is observed in WBA cv (0.79 g/100 g), Ara- chidic acid is present in all cultivars studied but in trace form. Its average content is low and equal to 0.08 g/100 g DM. Linolenic and Linoleic acid were the dominant saturated fatty acids in all samples. These levels are higher than those estimated in the table of nutri- tional composition of ciqual FoodS (2013) (Palmitic acid 0.118 g/ 100 g DM, Linoleic acid 0.39 g/100 g DM, Oleic acid 0.18 g/100 g DM, Arachidic acid absent). Fatty acids play a key role in metabolism as a metabolic fuel, a necessary component of all membranes and as a regulator of genes. In addition, fatty acids are used for many industrial purposes. The level of vitamin E generally depends on the part of the plant. Indeed, this content is higher in vegetable leaves and especially those that are green when ripe (chun et al., 2006). 148 M. Khadhraoui, M. Bagues, F. Artés, A. Ferchichi Chemometric analysis: Multivariate classification of dried fig cultivars studied The weight and the impact of the different tested parameters in the dry fig cultivars classification were established using the PCA tech- nique. The PCA relies on the extraction of the most important quan- titative variables in a data table representing the observations called ‘components’, in order to construct the pattern of similarity between the variables and the observations as points on a map (SaPorta and niang, 2009). In the PCA, a multivariate technique was used to distinguish between different cultivars in terms of phytochemi- cal contents (TPC, TFC), and their antioxidant capacity (DPPH and ABTS assays) on the one hand, and the phenolic composition, such as phenolic acids and flavonoids, and fatty acids, on the other hand, to establish the possible grouping of the dried fig cultivars studied. The cluster analysis was performed on the basis of the first two main PCs (PC1 and PC2) (Fig. 4). A total of 55.42% of the whole varia- bility was explained by the relationship between PC1 vs PC2. PC1 was responsible for 32.61%, and represented the most important component which was positively related to the following variables: Phenolic acids, flavonoids, TPC, TFC, TLC, antioxidant capacity us- ing both ABTS and DPPH assays, C18:2, C18:3, and C18:1, that were positively correlated with SD and ZBK cultivars and were there- fore primarily responsible for the discrimination of dark dried figs. However, light dried figs were negatively associated with PC1 and positively with PC2 which was responsible for 22.81% of the differ- ence. In addition, both PC1 and PC2 were negatively related with C16:0 and C20:0. The cumulative variance of 55.42% shows that the fig cultivars were well discriminated by their biologically active compounds levels, fatty acids and their TAC. In fact, PC1 allowed differentiation be- tween dark and green skinned cultivars (Fig. 4). The dispersion of the cultivars on the biplot defined by the first two components revealed 6 Fig.2: Contents of total phenolics (mg GAE/100g DM) and flavonoids (mg QE/100g DW) in nine cultivars of dry figs. Data are displayed as mean ± standard deviation of three replications for each cultivar. Letters above columns represent the groups given by Duncan test (α = 0.05) in arising order. Different letters indicate significant difference at P < 0.05. Fig. 3: The total antioxidant capacity of nine dry fig cultivars using DPPH and ABTS radicals. Data are displayed with mean ± standard deviation of three replications. Letters above columns represent the groups given by Duncan test (α = 0.05). Different letters indicate significant difference at P < 0.05. ZBK KHK WBA SD BBK BD HBK MK HBA DPPH ABTS TPC TFC AP1 AP2 AP3 AP4 AP5 AP6 AP7 F1 F2 F3 F4 F5 F6 F7 F8 F9 F10 C16 :0 C18 :1 C18:2 C18:3 C20:0 TLC -6 -4 -2 0 2 4 6 8 -10 -8 -6 -4 -2 0 2 4 6 8 10 P C 2 (2 2, 81 % ) PC1 (32,61 %) Biplot (PC1 vs PC2: 55,42 %) Light cultivars Dark cultivars Purple and dark cultivars Fig. 4: Principal component analyses of nine dry fig Tunisian cultivars. Flavonoids: Rutin (F1), Luteolin-7-o-glucoside (F2), Naringin (F3), Apigenin-7-o- glucoside (F4), Quercetin (F5), Kaempferol (F6), Naringenin (F7), Apigenin (F8), Luteolin (F9), Cirsiliol (F10), and phenolic acids: Gallic acid (AP1), Protocatechuic acid (AP2), 4-O-Caffeoylquinic acid (AP3), p-Coumaric acid (AP4), trans Cinnamic acid (AP5), trans Ferulic acid (AP6), Salviolinic acid (AP7). Tab. 4: Fatty acid contents and composition (g/100g DM) of studied dry fig cultivars. SFA MUFA PUFA Cultivar Lipids C16:0 C20:0 C18:1 ((C18:2) 9, 12) ((C18:3) 9, 12, 15) HBK 1.41 ± 0.04b 0.152 ± 0.01a 0.02 ± 0.00ab 0.32 ± 0.01de 0.41 ± 0.01d 0.43 ± 0.01d ZBK 1.60 ± 0.02c 0.163 ± 0.00ab 0.04 ± 0.02ab 0.27 ± 0.01cd 0.47 ± 0.03f 0.60 ± 0.02e BBK 1.73 ± 0.09c 0.190 ± 0.01abc 0.04 ± 0.01ab 0.38 ± 0.01e 0.46 ± 0.01ef 0.56 ± 0.01e WBA 2.06 ± 0.07d 0.180 ± 0.01abc 0.04 ± 0.00a 0.38 ± 0.02e 0.57 ± 0.01g 0.79 ± 0.03f SD 1.39 ± 0.02b 0.153 ± 0.00a 0.01 ± 0.00a 0.33 ± 0.00de 0.42 ± 0.00de 0.40 ± 0.01d MK 1.01 ± 0.03a 0.203 ± 0.00bc 0.01 ± 0.02d 0.24 ± 0.03bc 0.19 ± 0.00ab 0.07 ± 0.03a HBA 2.25 ± 0.05e 0.913 ± 0.02e 0.28 ± 0.09e 0.51 ± 0.01f 0.23 ± 0.01c 0.23 ± 0.01b BD 1.00 ± 0.03a 0.256 ± 0.00d 0.21 ± 0.01c 0.17 ± 0.01a 0.21 ± 0.00bc 0.30 ± 0.01c KHK 1.12 ± 0.04a 0.223 ± 0.01cd 0.13 ± 0.02d 0.19 ± 0.02ab 0.15 ± 0.00a 0.12 ± 0.01a Total 1,5 ± 0.05 0.27 ± 0.04 0.08 ± 0.13 0.31 ± 0,02 0.35 ± 0.02 0.39 ± 0.04 ANOVA 68.92** 262.15*** 404.21*** 27.26** 104.59*** 124.31*** SFA: Saturated fatty acids; MUFA: Monounsaturated fatty acids; PUFA: Polyunsaturated fatty acids One-way ANOVA (α = 0.05) is expressed in F-values followed by the significance level (***) at P < 0.05. Mean values ± SE, followed by different letters in the same column indicate significant difference at P < 0.05 according to Duncan’s multiple range test. Bioactive substances and fatty acids of dry figs 149 a strong heterogeneity among cultivars. Indeed, the cultivars are sig- nificantly individualized. The graphical distribution of the dried fig cultivars presented in Fig. 4, depending on their factor scores, in- dicates that the dark cultivars were distinguished from light ones; the first group on the right side of the graph includes SD and ZBK cultivars, while the second on the left includes BD, BBK and MK cultivars, and the third one contains HBA, ZBK and WBA cultivars in the center of the graph. The highest values of TP, TF and AC were achieved on dark co- lored figs (SD and ZBK cultivars) that showed different flavonoids and phenolic acids in the polyphenol profile which are antioxi- dant compounds. Our results are consistent with those of bey and louaileche (2015) who reported that PCA plot shows a clear sepa- ration between the dark and light dried fig cultivars. The highest values of TLC and fatty acids were detected in the HBA, ZBK and WBA cultivars, which contained also fairly high levels of TP, TF and TAC. The third group which included BD, BBK and MK cultivars was poor in all compounds. In our research, using 24 parameters relative to bioactive compounds, fatty acids and antioxidant activity, PCA applied to the considered fig cultivars proved that three phenotype groups of Tunisian dried figs (black, green, and purple) can be distinguished with significant differences. Obtained results showed that dark fig (ZBK) cv, harves- ted from the South-East, is a relevant food, which provides interest- ing antioxidant compounds in sufficient amounts to the human diet; especially samples rich in Rutin (F1), Cirsiliol (F10), Apigenin (F8) and Kaempferol (F6) (the black cultivars), characterized by a large amount of polyphenols, mainly flavonoids, and fatty acids, particu- larly polyunsaturated ones. Conclusions The nine fig cultivars studied herein have a huge potential and constitute an important heritage that deserves to be valued. They are characterized by an attractive range of fruit skin colors, rang- ing from dark black to green-yellow. Dark cultivars contained the highest levels of flavonoids and phenolics and exhibited high anti- oxidant capacity, while light skinned cultivars contained the lowest levels. The determined total phenolic content indicates the richness of Southern Tunisian figs, in particular SD and ZBK cultivars. 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This is an Open Access article distributed under the terms of the Creative Commons Attribution 4.0 International License (https://creative- commons.org/licenses/by/4.0/deed.en). https://doi.org/10.1016/j.indcrop.2018.07.008 https://doi.org/10.17660/ActaHortic.2008.798.2 https://doi.org/10.1016/j.postharvbio.2011.06.015 http://dx.doi.org/10.1016/j.chroma.2004.02.058 http://dx.doi.org/10.17660/actahortic.2017.1173.40 http://dx.doi.org/10.1016/j.lwt.2012.07.022 http://dx.doi.org/10.1016/j.jfca.2017.09.006 http://dx.doi.org/10.1016/j.scienta.2018.04.003 http://dx.doi.org/10.1021/jf060497h https://doi.org/10.1016/j.foodchem.2014.02.075 http://dx.doi.org/10.1016/j.foodchem.2011.07.032 https://doi.org/10.1016/j.foodchem.2007.05.061 https://doi.org/10.1016/j.indcrop.2015.03.005 https://doi.org/10.1016/j.ajps.2017.08.004 https://doi.org/10.1016/j.ajps.2017.08.004 https://orcid.org/0000-0002-2530-3214 https://orcid.org/0000-0002-5703-4442 https://orcid.org/0000-0002-0689-7301 mailto:Khadhraoui.marwa88@gmail.com