Phytochemistry and Biological Activities of Iris Species Growing in Iraqi Kurdistan and Phenolic Constituents of the Traditional Plant Iris postii

A dozen Iris species (Iridaceae) are considered traditional remedies in Kurdistan, especially for treating inflammations. Phytochemical studies are still scarce. The information reported in the literature about Iris species growing in Kurdistan has been summarized in the first part of this paper, although, except for Iris persica, investigations have been performed on vegetal samples collected in countries different from Kurdistan. In the second part of the work, we have investigated, for the first time, the contents of the methanolic extracts of Iris postii aerial parts and rhizomes that were collected in Kurdistan. Both extracts exhibited a significant dose-dependent free radical scavenging and total antioxidant activities, comparable to those of ascorbic acid. Medium-pressure liquid chromatographic separations of the two extracts afforded l-tryptophan, androsin, isovitexin, swertisin, and 2″-O-α-l-rhamnopyranosyl swertisin from the aerial parts, whereas ε-viniferin, trans-resveratrol 3,4′-O-di-β-d-glucopyranoside, and isotectorigenin were isolated from the rhizomes. This is the first finding of the last three metabolites from an Iris species. The various remarkable biological activities of isolated compounds scientifically sustain the traditional use of I. postii as a medicinal plant.


Introduction
Traditional medicines still hold an important role among health care practices of many countries, including Arab countries and Iraqi Kurdistan [1]. A Neanderthal burial discovered at Shanidar cave (number IV in the series of skeletons) in northern Iraq, dated approximately 60,000 years ago [2], is evidence that herbal medicine has probably been practiced in the mountains and plains of Kurdistan since the dawn of civilization. Indeed, a well-organized form of medicine, which made intense uses of plant-derived drugs, remedies, potions and oils, can be traced back in Iraq to the Sumerian period (3000-1970 B.C.) and then to the Babylonian and Assyrian periods (1970-539 B.C). Later, this knowledge Despite the wide use of herbal remedies, phytochemical studies on Kurdistan medicinal plants are still in their infancy and only a few papers have been published so far that describe the structures and bioactivities of isolated metabolites. As part of our ongoing project on scientific validation of Kurdistan traditional plants, we directed our attention toward the genus Iris. This large genus of the family Iridaceae (Angiosperms) contains about 260−300 species [6,7] of perennial plants growing from creeping rhizomes (rhizomatous irises) or, in drier climates, from bulbs (bulbous irises). The showy flowers are characterized by a violet-like scent. The plants grow in temperate regions across the Northern Hemisphere, from Eurasia to North America [8]. Many Iris species are ornamental plants; however, they are also used in various traditional medicines for the treatment of inflammations, cancer, bacterial and viral infections, and other diseases. Extensive phytochemical investigations of the genus have led to the isolation of different isoprenoids, flavonoids, isoflavonoids and their glycosides, xanthones, quinones, and stilbene glycosides, among others [8,9]. On the other hand, isolated bioactive compounds have shown antibacterial, anti-neoplastic, antioxidant, cytotoxic, anti-plasmodial, molluscicidal, anti-inflammatory, phytoestrogenic and antituberculosis properties [9]. Moreover, an essence called "orris butter" and an absolute essential oil with the scent of the flowers are derived from the bulbs of some Iris, e.g., I. florentina and I. germanica; they are used in the manufacture of luxury expensive perfumes, such as Chanel No. 19 (1970) and So pretty by Cartier (1995) [10].
Twelve species of Iris are reported to grow in Iraq; in the Kurdistan region, they occur especially on mountainous regions, such as Halgurd Mountain  [11]. Of these species only I. germanica L. and I. persica L. have been investigated phytochemically. I. persica has been investigated by a Kurdish research group [12,13]; instead, due to the wide geographical distribution and economic importance, I. germanica has been subjected to several investigations in countries different from Kurdistan. The results of these investigations have Despite the wide use of herbal remedies, phytochemical studies on Kurdistan medicinal plants are still in their infancy and only a few papers have been published so far that describe the structures and bioactivities of isolated metabolites. As part of our ongoing project on scientific validation of Kurdistan traditional plants, we directed our attention toward the genus Iris. This large genus of the family Iridaceae (Angiosperms) contains about 260-300 species [6,7] of perennial plants growing from creeping rhizomes (rhizomatous irises) or, in drier climates, from bulbs (bulbous irises). The showy flowers are characterized by a violet-like scent. The plants grow in temperate regions across the Northern Hemisphere, from Eurasia to North America [8]. Many Iris species are ornamental plants; however, they are also used in various traditional medicines for the treatment of inflammations, cancer, bacterial and viral infections, and other diseases. Extensive phytochemical investigations of the genus have led to the isolation of different isoprenoids, flavonoids, isoflavonoids and their glycosides, xanthones, quinones, and stilbene glycosides, among others [8,9]. On the other hand, isolated bioactive compounds have shown antibacterial, anti-neoplastic, antioxidant, cytotoxic, anti-plasmodial, molluscicidal, anti-inflammatory, phytoestrogenic and antituberculosis properties [9]. Moreover, an essence called "orris butter" and an absolute essential oil with the scent of the flowers are derived from the bulbs of some Iris, e.g., I. florentina and I. germanica; they are used in the manufacture of luxury expensive perfumes, such as Chanel No. 19 (1970) and So pretty by Cartier (1995) [10].
Twelve species of Iris are reported to grow in Iraq; in the Kurdistan region, they occur especially on mountainous regions, such as Halgurd Mountain  [11]. Of these species only I. germanica L. and I. persica L. have been investigated phytochemically. I. persica has been investigated by a Kurdish research group [12,13]; instead, due to the wide geographical distribution and economic importance, I. germanica has been subjected to several investigations in countries different from Kurdistan. The results of these investigations have been summarized in the first part of this paper. The phytochemical literature reported in Scifinder and Google Scholar databases up to August 2020 has been reviewed. In the second part of this paper, we describe the results of our phytochemical investigation of non-volatile secondary metabolites isolated from the aerial parts and rhizomes of Iris postii Mouterdi. Iris germanica L. is probably the most thoroughly investigated Iris species. Rhizomes have been traditionally used for various oral and topical applications, e.g., sores, freckles [14], and to relieve teething-associated pain [15]. Root decoctions of the plant have been commonly applied as antispasmodic, emmenagogue, diuretic, anti-insomnia, and cathartic agents [16]. They decrease smooth muscle activity in vivo and show anti-serotonin effects [17]. Extracts of I. germanica showed cytotoxic [18,19], antioxidant [20][21][22], antimutagenic [22], antifungal [23], antimicrobial [24][25][26], anti-inflammatory [24,27], antibiofilm [28], antiulcer [29], hypolipidemic [30], molluscicidal [31], and amyloid β (Aβ) induced memory impairment activities [32]. The application of rhizomes in both traditional and modern medicine has been mainly based on the presence of isoflavones and essential oils in the extracts.

Isoflavonoids
Isoflavonoids are mainly accumulate in the rhizomes and form the largest group of flavonoids isolated from I. germanica. Their structures  are shown in Figure 2, whereas the reported biological activities are shown in Table 1.

Terpenoids
In addition to αand β-amyrin [37], the most widespread triterpenoids occurring in I. germanica are iridals ( Figure 5) [56]. These bitter tasting terpenoids can be isolated in appreciable amounts from the unsaponifiable fraction of lipid extracts from the rhizomes. Characteristic features of all iridals are a multi-substituted cyclohexane ring with a long side chain at C-11 (squalene numbering), an acrolein group at C-7, and a hydroxypropyl chain at C-6. The latter two substitutions are typical fragments of a seco A-ring of triterpenoids. Appropriate labeling experiments have shown that 2,3-epoxysqualene is the precursor of the iridals and that a bicyclic intermediate is possibly formed in the biosynthetic pathway, the A ring of which is subsequently opened to give the iridal skeleton [56]. Other labeling experiments have also proved the involvement of activated methionine for the introduction of the extra methyl group at C-22 of an open-chain precursor of methylated cycloiridals and irones [56]. The large group of iridals isolated from I. germanica include

Terpenoids
In addition to αand β-amyrin [37], the most widespread triterpenoids occurring in I. germanica are iridals ( Figure 5) [56]. These bitter tasting terpenoids can be isolated in appreciable amounts from the unsaponifiable fraction of lipid extracts from the rhizomes. Characteristic features of all iridals are a multi-substituted cyclohexane ring with a long side chain at C-11 (squalene numbering), an acrolein group at C-7, and a hydroxypropyl chain at C-6. The latter two substitutions are typical fragments of a seco A-ring of triterpenoids. Appropriate labeling experiments have shown that 2,3-epoxysqualene is the precursor of the iridals and that a bicyclic intermediate is possibly formed in the biosynthetic pathway, the A ring of which is subsequently opened to give the iridal skeleton [56].
Molecules 2021, 26, x FOR PEER REVIEW 9 of 22 degradation affording irones from iridals is still poorly understood. The traditional process is long, troublesome and low yielding; hence, the high cost of the essence (butter).
Molecules 2021, 26, x FOR PEER REVIEW 9 of 22 degradation affording irones from iridals is still poorly understood. The traditional process is long, troublesome and low yielding; hence, the high cost of the essence (butter).

Iris persica
I. persica is used to treat tumors and wound inflammation in the traditional medicine of Kurdistan [5]. Essential oils obtained by hydrodistillation of air-dried flowers, leaves, rhizomes, and fresh bulbs were investigated by GC-FID and GC-MS; moreover, the oil antifungal activities were determined [12]. The major constituents of the flower essential oil were phenylethanol (24.8%) and furfural (13.8%). This aldehyde was also the main component of the leaf and rhizome volatile fractions, with percentages of 39.0% and 22.2%, respectively. Phenylacetaldehyde (37.1%) was the main constituent of the volatile fraction from the bulbs. The oils exhibited moderate antifungal activity in vitro against strains of the human pathogenic fungi Candida albicans, Microsporum canis, and Trichophyton mentagrophytes, the plant-fungal pathogen Pyricularia oryzae, and the fungal food contaminant Aspergillus carbonarius. The highest activity was exhibited by the essential oils isolated from leaves and flowers, so that they could be considered natural antimicrobial agents.

Iris persica
I. persica is used to treat tumors and wound inflammation in the traditional medicine of Kurdistan [5]. Essential oils obtained by hydrodistillation of air-dried flowers, leaves, rhizomes, and fresh bulbs were investigated by GC-FID and GC-MS; moreover, the oil antifungal activities were determined [12]. The major constituents of the flower essential oil were phenylethanol (24.8%) and furfural (13.8%). This aldehyde was also the main component of the leaf and rhizome volatile fractions, with percentages of 39.0% and 22.2%, respectively. Phenylacetaldehyde (37.1%) was the main constituent of the volatile fraction from the bulbs. The oils exhibited moderate antifungal activity in vitro against strains of the human pathogenic fungi Candida albicans, Microsporum canis, and Trichophyton mentagrophytes, the plant-fungal pathogen Pyricularia oryzae, and the fungal food contaminant Aspergillus carbonarius. The highest activity was exhibited by the essential oils isolated from leaves and flowers, so that they could be considered natural antimicrobial agents.

Phytochemical Studies on Iris postii
A decoction of the aerial parts of Iris postii Mouterde is used in the Iraqi folkloric medicine as a general remedy against inflammations. The plant, which is native to Middle East, grows wildly on the slopes of Mount Korek (Figure 9), a mountain located in the Erbil province not far from the Iranian border, where it was collected for this investigation.

Phytochemical Studies on Iris postii
A decoction of the aerial parts of Iris postii Mouterde is used in the Iraqi folkloric medicine as a general remedy against inflammations. The plant, which is native to Middle East, grows wildly on the slopes of Mount Korek (Figure 9), a mountain located in the Erbil province not far from the Iranian border, where it was collected for this investigation.
I. persica is used to treat tumors and wound inflammation in the traditional medicine of Kurdistan [5]. Essential oils obtained by hydrodistillation of air-dried flowers, leaves, rhizomes, and fresh bulbs were investigated by GC-FID and GC-MS; moreover, the oil antifungal activities were determined [12]. The major constituents of the flower essential oil were phenylethanol (24.8%) and furfural (13.8%). This aldehyde was also the main component of the leaf and rhizome volatile fractions, with percentages of 39.0% and 22.2%, respectively. Phenylacetaldehyde (37.1%) was the main constituent of the volatile fraction from the bulbs. The oils exhibited moderate antifungal activity in vitro against strains of the human pathogenic fungi Candida albicans, Microsporum canis, and Trichophyton mentagrophytes, the plant-fungal pathogen Pyricularia oryzae, and the fungal food contaminant Aspergillus carbonarius. The highest activity was exhibited by the essential oils isolated from leaves and flowers, so that they could be considered natural antimicrobial agents.

Phytochemical Studies on Iris postii
A decoction of the aerial parts of Iris postii Mouterde is used in the Iraqi folkloric medicine as a general remedy against inflammations. The plant, which is native to Middle East, grows wildly on the slopes of Mount Korek (Figure 9), a mountain located in the Erbil province not far from the Iranian border, where it was collected for this investigation.  Neither phytochemical investigations nor evaluations of biological activities have been carried out on extracts of I. postii so far. Therefore, on the assumption that the bioactivity mostly resided in polar metabolites, we decided to examine the phytochemical contents and the antioxidant properties of polar extracts of the aerial parts and rhizomes.
At first, powdered aerial parts and rhizomes were separately defatted by soaking in hexane at room temperature; most chlorophyll was also removed in this manner. Successively, each biomass was extracted with MeOH. The yields of the residues, IPA from the aerial parts and IPR from the rhizomes, were 1.3 and 2.75% (w/w), respectively. Successively, IPA and IPR were separately partitioned between H 2 O and dichloromethane and H 2 O and n-butanol, respectively, to give fractions IPAD and IPRB, respectively. Multiple medium-pressure liquid chromatographic separations of a sample of IPAD on reversedphase (RP-18) columns afforded L-tryptophan, androsin (66), apigenin 6-C-glucoside (isovitexin) (109), swertisin (111), and 2"-O-rhamnosyl swertisin (112). Analogous chromatographic separations of a sample of IPRB gave trans-ε-viniferin (113), trans-resveratrol 3,4 -O-diglucoside (114), and isotectorigenin (115). The structures of isolated compounds ( Figure 10) were established mainly by extensive 1D-and 2D-NMR experiments and MS spectrometry. Comparing our spectroscopic data with the pertinent literature, we found some differences between our data and those reported from different laboratories, especially for the NMR signals of swertisin (111) [68][69][70][71][72][73] and 2"-O-rhamnosylswertisin (112) [71,74]; moreover, literature data are often not consistent between each other and some spectra have been recorded in solvents different from those used in this work. Therefore, although the isolated compounds are known, the physical and spectroscopic data determined by us are reported in the Experimental section, whereas the graphics are included in the Supplementary Materials. tivity mostly resided in polar metabolites, we decided to examine the phytochemical contents and the antioxidant properties of polar extracts of the aerial parts and rhizomes.
At first, powdered aerial parts and rhizomes were separately defatted by soaking in hexane at room temperature; most chlorophyll was also removed in this manner. Successively, each biomass was extracted with MeOH. The yields of the residues, IPA from the aerial parts and IPR from the rhizomes, were 1.3 and 2.75% (w/w), respectively. Successively, IPA and IPR were separately partitioned between H2O and dichloromethane and H2O and n-butanol, respectively, to give fractions IPAD and IPRB, respectively. Multiple medium-pressure liquid chromatographic separations of a sample of IPAD on reversedphase (RP-18) columns afforded L-tryptophan, androsin (66), apigenin 6-C-glucoside (isovitexin) (109), swertisin (111), and 2′′-O-rhamnosyl swertisin (112). Analogous chromatographic separations of a sample of IPRB gave trans-ε-viniferin (113), trans-resveratrol 3,4′-O-diglucoside (114), and isotectorigenin (115). The structures of isolated compounds (Figure 10) were established mainly by extensive 1D-and 2D-NMR experiments and MS spectrometry. Comparing our spectroscopic data with the pertinent literature, we found some differences between our data and those reported from different laboratories, especially for the NMR signals of swertisin (111) [68][69][70][71][72][73] and 2′′-O-rhamnosylswertisin (112) [71,74]; moreover, literature data are often not consistent between each other and some spectra have been recorded in solvents different from those used in this work. Therefore, although the isolated compounds are known, the physical and spectroscopic data determined by us are reported in the Experimental section, whereas the graphics are included in the Supplementary Materials. It is now generally accepted by scientists that excess oxidants and radicals, especially oxygen radicals, through damage and mutation of DNA and other biomolecules, play a major role in degenerative processes that may cause the insurgence and progression of inflammatory processes, cancer, cardiovascular and atherosclerotic diseases, neurodegeneration, and aging [75,76]. Antioxidants isolated from natural sources could thus become important chemotherapeutic agents in defense mechanisms against these toxic agents. Therefore, with the aim to give some scientific evidence to the traditional use of I. postii in the treatment of inflammations and in search of a new source of natural antioxidants, two simple tests were performed in vitro to determine the total antioxidant capacity (TAOC) of the crude extracts (see text) and the antiradical activity of the extracts and the isolated compounds. The TAOC values of the extracts were determined by the phosphomolybdate It is now generally accepted by scientists that excess oxidants and radicals, especially oxygen radicals, through damage and mutation of DNA and other biomolecules, play a major role in degenerative processes that may cause the insurgence and progression of inflammatory processes, cancer, cardiovascular and atherosclerotic diseases, neurodegeneration, and aging [75,76]. Antioxidants isolated from natural sources could thus become important chemotherapeutic agents in defense mechanisms against these toxic agents. Therefore, with the aim to give some scientific evidence to the traditional use of I. postii in the treatment of inflammations and in search of a new source of natural antioxidants, two simple tests were performed in vitro to determine the total antioxidant capacity (TAOC) of the crude extracts (see text) and the antiradical activity of the extracts and the isolated compounds. The TAOC values of the extracts were determined by the phosphomolybdate method (adjusted from references [77][78][79]), using ascorbic acid as the standard. The assay was based on the reduction of hexavalent molybdenum Mo (VI) to the pentavalent form [Mo (V)] by an antioxidant, and the formation of a green phosphate/Mo (V) complex at acidic pH and at high temperature. The TAOC values were expressed as µg ascorbic acid equivalent/mg extract ( Table 2). The greater this value, the higher was the antioxidant capacity. Thus, the total methanol extract of the aerial parts (IPA) and the n-butanol sub-extract of the methanolic extract of the rhizomes (IPRB) exhibited the highest total antioxidant activity. Moreover, comparing the TAOC of the IPA extract with that of the dichloromethane sub-extract (IPAD), it appears that highly antioxidant compounds, likely very polar, were not adequately extracted by CH 2 Cl 2 . Therefore, they need further study. Subsequently, the free radical scavenging (FRS) activity of the isolated compounds 66, 109, 111-115, the crude extracts and the standard ascorbic acid were determined using the 2,2-diphenyl-1-picrylhydrazyl radical (DPPH) method (adjusted from references [78,79]). DPPH is a stable, nitrogen-centered free radical which produces violet/purple color in methanol solution and fades to shades of yellow color in the presence of a hydrogen radical/electron-donor compound. The antiradical activity was expressed as EC 50 value, i.e., the concentration (µg/mL) of the sample required to scavenge 50% of the initial DPPH concentration and as µg ascorbic acid equivalents/µg sample. In the case of isolated compounds, the activity was also measured as EC 50 (µM/L), which, in our opinion, is a more accurate measurement of the intrinsic antiradical activity of a compound. The results of the DPPH assay (Table 2) essentially confirmed those obtained by the molybdate test as far as the antioxidant activity of the extracts is concerned. On the other hand, concerning the DPPH scavenging activity of single compounds, 2"-O-α-L-rhamnosyl-swertisin (112), ε-viniferin (113), and resveratrol 3,4 -O-di-β-D-glucopyranoside (114) were as effective as the standard ascorbic acid or even more efficacious. The remaining isolated compounds, androsin (66), isovitexin (109), swertisin (111), and isotectorigenin (115), were moderately active, although the EC50 values of compounds 109, 111 and 115, expressed as µM/L, were lower than that of ascorbic acid.

General Experimental Techniques and Procedures
For most general experimental techniques and procedures, see reference [80]; 1 H-NMR and 13 C-NMR chemical shifts (δ, ppm) are relative to signals of residual CHD 2 OD in CD 3  Preparative medium-pressure liquid chromatographic (MPLC) separations were carried out on a Biotage Isolera instrument (Biotage, Uppsala, Sweden).

Plant Material
Aerial parts and rhizomes of I. postii Mouterde were separately collected on Korek Mountain (GPS position: 36 • 35 20" N, 44 • 27 32" E). The plant was identified by botanist A. H. Al-khayyat of Salahaddin University-Erbil/Iraq. A voucher specimen (accession number 7230) has been deposited at the Education Salahaddin University Herbarium (ESUH). The vegetal materials were cleaned and air-dried under shade at room temperature (20-25 • C) in a ventilated room until they reached constant weight. After drying, each plant part was finely powdered using a laboratory grinding mill, and powdered materials were stored in bottles at room temperature until analyses.

Extraction of I. postii and Chromatographic Fractionation of Extracts
Powdered aerial parts and rhizomes (200 g each) were separately soaked in hexane (800 mL) with occasional shaking in an ultrasonic bath for 20 min, then left in the same solvent for 5 h under continuous stirring at room temperature. Subsequently, the mixture was decanted and filtered. This procedure was repeated three times for each part. Defatted rhizomes and aerial parts were subsequently separately suspended in MeOH (800 mL) n an ultrasonic bath for 20 min and then left in the same solvent for 5 h under continuous stirring, at room temperature. The procedure was repeated three times for each vegetable part. The mixtures were then filtered, and the solvent removed under vacuum in a rotary evaporator to afford two crude residues: IPA (2.6 g) from aerial parts and IPR (5.5 g) from rhizomes.

Free Radical Scavenging Activity
Briefly, a 0.3 mM solution of DPPH in MeOH was prepared. To 1 mL of this solution, 3 mL of sample or extract solution in 10% aqueous MeOH at different concentrations (10,25,50,100,150,200,250, 350 µg/mL) was added. Subsequently, the mixture was shaken vigorously and incubated for 30 min at 22 • C in the dark until a stable absorbance value (A) at 517 nm was obtained, that was measured using a UV-Visible spectrophotometer (Lambda 25 UV/Vis spectrometer N.3903, Perkin Elmer instruments, Waltham, MA, USA). A lower absorbance of the reaction mixture indicated higher free radical scavenging (FRS) activity. The DPPH solution (1 mL), plus 10% MeOH (3 mL), was used as the control. The FRS% was calculated using the formula: [1 − (A sample /A control )] × 100. The curve of the % scavenging activity against the concentration was plotted for each sample using the MS Excel-based program to calculate the EC 50 value, i.e., the concentration (µg/mL or µM/L) of the sample required to scavenge 50% of the initial DPPH concentration. Each analysis was carried out in triplicate and the mean ± SD (n = 3) was calculated. Ascorbic acid (Sigma-Aldrich) was used as a standard antiradical agent. The lower the EC 50 value, the higher the sample antiradical activity. The antiradical activity was also expressed as ascorbic acid equivalents (AAEs) ( Table 2), i.e., µg ascorbic acid equivalents/µg sample. These values were calculated using the formula: EC 50 ascorbic acid (µg/mL)/EC 50 sample (µg/mL) [77].

Total Antioxidant Capacity (TAOC-Ammonium Phosphomolybdate Assay)
Briefly, samples of dry extracts or standard ascorbic acid, dissolved in MeOH/distilled H 2 O (50:50), were combined with 3.0 mL of reagent solution (0.6 M sulfuric acid, 28 mM sodium phosphate and 4 mM ammonium molybdate) to achieve a series of eight final concentrations in the range of 12-450 µg/mL. The tubes were capped and incubated in a boiling water bath at 95 • C for 90 min. The samples were cooled to 22 • C and absorbance was measured at 695 nm against the blank using the cited UV-Visible spectrophotometer. From each series of measures, a sigmoidal curve was obtained by data interpolation and the EC 50 value of each sample was calculated as the concentration corresponding to 50% activity. The blank contained 3.0 mL of the reagent solution and 0.3 mL of MeOH/distilled H 2 O (50:50), and it was incubated under the same conditions as the samples. Each analysis was carried out in triplicate and the mean ± SD (n = 3) was calculated. The TAOC values were expressed as µg ascorbic acid equivalents/µg extract (Table 2). They were calculated using the formula: EC 50 (µg/mL) ascorbic acid)/EC 50 (µg/mL) extract. The EC 50 of ascorbic acid used in TAOC calculation was 26.12 ± 0.56 µg/mL.

Acid Hydrolysis of Compounds 112 and 114
Compounds 112 and 114 (2.0 mg each) were separately dissolved in 3% aqueous H 2 SO 4 in a sealed vial and heated at 90 • C for 45 min. After cooling to room temperature and extraction with CHCl 3 , the aqueous layer was repeatedly evaporated to dryness with the aid of MeCN. The residues were identified as L-(+)-rhamnose and D-(+)-glucose, respectively, by TLC and optical rotation upon comparison with authentic samples.

Conclusions
A dozen Iris species are used in the traditional medicine of Kurdistan. In the first part of this paper, we have reported the structures of the main constituents, traditional uses and biological activities found in the literature for the few species growing in Kurdistan that have been investigated so far. The most characteristic secondary metabolites are various terpenoids, among which iridal derivatives are the most typical ones, and phenolic derivatives, among which isoflavones predominate. Most of these Iris metabolites exhibited various bioactivities. Based on these data, we then investigated, for the first time, the contents of the methanolic extracts of I. postii aerial parts and rhizomes. L-tryptophan, androsin (66), apigenin 6-C-glucoside (isovitexin) (109), swertisin (111), and 2"-O-rhamnosyl swertisin (112) were isolated from the aerial parts, whereas chromatographic separation of the extract from rhizomes afforded trans-ε-viniferin (113), trans-resveratrol 3,4 -O-diglucoside (114), and isotectorigenin (115). To the best of our knowledge, this is the first finding of compounds 112-115 in the genus Iris. Isolated compounds showed a wide range of bioactivities, in addition to the excellent radical-scavenging properties exhibited in this investigation by 2"-O-α-L-rhamnosyl-swertisin (112), ε-viniferin (113), and resveratrol 3,4 -O-di-β-Dglucopyranoside (114). Thus, isovitexin (109) has been reported to be an anti-inflammatory, antihyperglycemic, sedative agent with insulin secretagogue properties and to display antioxidant, anti-inflammatory, neuroprotective, anti-diabetic, antitumor effects [88,89]; swertisin (111) exhibited antioxidant, anti-inflammatory, antihyperglycemic activities with insulin secretagogue and adenosine A1 receptor antagonist properties [90]; swertisin (111) and 2"-O-rhamnosylswertisin (112) exhibited strong α-glucosidase inhibitory activity in vitro [91] and effective mechanical antinociceptive properties [81]; ε-viniferin exhibited relatively strong inhibition of α-glucosidase in vitro [92] and inhibited both human LDL and HDL oxidation in vitro [85]; resveratrol diglucoside 114 decreased ethanol-induced oxidative DNA damage in mouse brain cells, possibly via inhibition of oxidative stress [93], and displayed highly selective antiproliferative activity against tumor cells [94].
In conclusion, the few Iris species growing in Kurdistan that have been investigated so far demonstrated to be novel viable sources of various bioactive compounds. Moreover, the remarkable antioxidant and radical scavenging activities of the methanol extracts of aerial parts and rhizomes of I. postii, as well as the anti-inflammatory properties reported for different isolated compounds, validate the traditional medicinal use of this plant in Kurdistan. Further studies aimed to evaluate the in vivo potential of Iris extracts in various models and to isolate and identify the antioxidant principles occurring in the most polar fractions of the methanolic extract of I. postii aerial parts shall be carried out in due time.