Phytochemical and Biological Investigation of Jatropha pelargoniifolia Root Native to the Kingdom of Saudi Arabia

Extensive phytochemical and chromatographic analysis of different root fractions of Jatropha pelargoniifolia Courb. (Euphorbiaceae) resulted in the isolation and identification of 22 distinct secondary metabolite compounds. Two new compounds, 6-hydroxy-8-methoxycoumarin-7-O-β-D-glycopyranoside and (3-(2-(methylamino) ethyl)-1H-indol-2-yl) methanol, were isolated and identified for the first time from a natural source. In addition, other known compounds, such as hovetricoside C and Nmethyltryptamine were isolated from Euphorbiaceae, and hordenine, Nmethyltyramine, their salts, cynaroside and linarin were identified in Jatropha spp. for the first time. Some isolated metabolites, such as β-sitosterol, β-sitosterol glucoside, curcusons D and C, naringenin, apigenin, cleomiscosins B and A, spruceanol, propacin, jatrophadiketone, and uracil were previously identified in various Jatropha species. The structures of the isolated compounds were determined using different spectroscopic techniques. The anti-inflammatory, antinociceptive, antipyretic, and antioxidant activities were evaluated for some adequately available isolated compounds. Compounds showed significant antinociceptive activity compared with the standard analgesic drug indomethacin. The edema size was significantly reduced (p< 0.05–0.001) in the animals treated with low doses (5 and 10 mg/kg) of the isolated compounds compared with those treated with a high dose (100 mg/kg) of standard anti-inflammatory drug (phenylbutazone). Furthermore, all tested compounds showed a significant (p< 0.05–0.001) reduction in the rectal temperature of hyper-thermic mice.


Introduction
The Euphorbiaceae family, which is considered as one of the largest families of flowering plants, includes approximately 7,800 species distributed among approximately 300 genera and five subfamilies worldwide.These species occur preferentially in tropical and subtropical regions [1,2].Among the main genera of this family, Jatropha L. belongs to the subfamily Crotonoideae (tribe Jatropheae) and is represented by approximately 200 species.This genus is widely distributed in tropical and subtropical regions of Africa and the Americas [2].
Jatropha is a Greek word derived from "jatros" meaning "physician" and "trophe" meaning "food" and is associated with its medicinal uses [3].Jatropha species are used in folk medicine to treat various diseases, such as skin inflammation, eye infection, chest pain, stomach pain, itching, and as a vermifuge or as ornamental plants and energy crops in Latin America, Africa, and Asia [3].Several known species from the genus Jatropha, such as J. gossypiifolia, J. elliptica, J. curcas, and J. mollissima, among others, have been reported for their chemical constituents, biological activities, and medicinal uses [4].
Jatropha glauca, J. curcas, J. spinose, and J. pelargoniifolia are the only four species distributed in Saudi Arabia and employed as traditional herbal medicines owing to their anti-inflammatory, antioxidant, antiseptic, and analgesic properties [5,6].Among these species, J. pelargoniifolia Courb. is discussed here.It is a shrub that can grow 20-200 cm tall and is widely known as "Obab" in Arabic.The plant is sometimes harvested from the wild for local medicinal use; especially, the sap of its petiole is applied to treat ulcers and severe skin inflammation and for wound healing [7].It is widely distributed in East Tropical Africa (Sudan, Eritrea, Ethiopia, Somalia, and Kenya) and Arabian Peninsula (Yemen, Oman, and Saudi Arabia) [7].
Reviewing the current literature for the phytochemical importance of the plants belonging to the genus Jatropha revealed a broad range of isolated secondary metabolites, such as diterpenoids, triterpenoids, non-conventional coumarino-lignoids, alkaloids, coumarins, flavonoids, cyclic peptides, and steroids [8].This is indeed a reflection of the versatility of the enzymatic system present in Euphorbiaceae plants, but nothing was reported regarding the J. pelargoniifolia species.Thus, it was of interest to explore the active constituents and biological importance of J. pelargoniifolia.

Structure elucidation
A total of 22 compounds belonging to different chemical classes were isolated from the roots of J. pelargoniifolia growing in Saudi Arabia (Figure 1).
Compound 15 was obtained as white crystals.Its 1 H nuclear magnetic resonance (NMR) spectrum was measured in deuterated methanol (CD3OD) (Table 1 and Figure 2).It showed a coumarin skeleton by a pair of ortho-coupled doublets that appeared at δH 6.26 and 7.88 with a large coupling constant (d, J = 9.5 Hz) and were assigned to H-3 and H-4 of the α-pyrone ring system, respectively, and a singlet aromatic proton that appeared at δH 7.00 and was assigned to H-5 in the coumarin ring.The aromatic methoxyl group resonated at 3.91 ppm (H-8).Moreover, the glycosidic nature of compound 15 was observed by the appearance of a doublet at δH 4.99 with a coupling constant of 7.8 Hz, confirming the β-configuration nature of the sugar.Additionally, the 13 C NMR exhibited signals assigned at δC 106.2 (C-1'), 75.5 (C-2'), 77.8 (C-3'), 71.0 (C-4'), 78.5 (C-5'), and 62.2 (C-6'), indicating the presence of a β-Dglucopyranosyl unit in compound 15.Furthermore, the 13 C NMR spectrum displayed sixteen carbon signals; nine for the coumarin skeleton, six for β-glucopyranose unit, and one methoxylated carbon.In the 1 H-1 H correlated spectroscopy (COSY) spectrum of 15, the proton signal at δH 6.26 (H-3) showed a cross-peak correlation with that of δH 7.88 (H-4).The glucose sugar moiety was located at C-8 from the heteronuclear multiple bond correlation (HMBC) spectrum; showing a clear three-bond correlation between the H-1' (anomeric proton) and C-8 of the coumarin ring.Besides, OCH3 was unambiguously located at C-8 because of the presence of a three-bond correlation between oxymethyl protons and C-8 of aglycon.In addition, the hydroxyl group was attached to C-6 and neither C-5 and this is evidenced via HMBC, where H-5 exhibited clear long-range correlations with C-4 and C-8a (Figure 2).
From the above evidence, the structure of compound 15 was elucidated as a new compound isolated from a natural source and identified as 6-hydroxy-8-methoxy coumarin-7-O-β-D-glycopyranoside.It is worth mentioning that the closely related coumarin glycoside derivatives have been previously isolated from the leaves of Daphne pseudomezereum [9] and the gametophytes of Tetraphis pellucida [10].
The white needle crystals of compound 15 were isolated; they exhibited positive Dragendorff's test, indicating their alkaloid nature.The 1 H NMR spectrum displayed four aromatic signals for 2,3-disubstituted indole ring, which was proved by the presence of four coupled aromatic protons at δH 7.29, 7.07, 7.00, and 7.41 directly connected via one bond correlation to their carbon in heteronuclear single quantum coherence (HSQC) spectrum at H-4, H-5, H-7, and H-8, respectively.The singlet signal corresponding to the proton at position 2 of the indole ring (in compound 17) was absent and instead appeared as a singlet signal resonating at 3.91 ppm in compound 18.The disubstituted derivative was proved to be located at position 2 and 3 of the indole nucleus, and the substituents were identified as hydroxy methyl (δH 3.91) and N-methyl ethyl amine.The 13 C NMR spectrum was consistent with the structure and allowed the assignments of carbon resonances.Eight aromatic signals were observed: two of them downfield shifted corresponding to the quaternary carbons at positions 8 and 9 (δC 0.3-2.8) of the indole ring, the other four signals of the phenyl ring were observed at 122.4, 120.0, 118.6, and 112.60 ppm, and position 2 of the indole ring appeared at 128.0 ppm, which was more downfield compared to 17 (124.3ppm), confirming that position 2 of the indole ring was substituted by CH2OH, while the quaternary carbon at position 3 appeared at 107.2 ppm.In addition, the presence signal for the nitrogenated carbon (methyl) appeared at 44.9 ppm and for the aliphatic carbons (two methylene carbons of the side chain) appeared at 54.1 and 21.5 ppm.Finally, a signal appeared at 52.9 ppm and was assigned to the carbon of hydroxy methyl group (Table 2).
Additionally, the COSY spectrum showed proton-proton correlations between the aromatic indole ring protons H-6 and H-7 and between H-5 and H-4, and vice versa.As well, the side-chain α and β CH2 groups exhibited clear COSY correlation.The HMBC spectrum showed the exact site of attachment of CH2OH at position 2 of the indole ring based on the presence of obvious two-and three-bond correlations between the protons of CH2OH and C-2 and C-3, respectively.Moreover, the amino methyl part in the side chain showed a three-bond correlation with α CH2 neither β CH2 and this is evidence for the exact location of attachment for CH3 group (Figure 3).
On the basis of these evidences, the structure of compound 18 was assigned as 3-(2-(methylamino) ethyl)-1H-indol-2-yl) methanol, a new indole alkaloid isolated here for the first time from a natural source, and it is a 2-hydroxymethyl derivative of Nmethyltryptamine (compound 17).

Biological activity
Our study proved that J. pelargoniifolia roots are a source of several biologicallyactive compounds such as hordenine, which exhibited various biological activities like inhibiting melanogenesis in human melanocytes, increasing the respiratory and heart rates [31], stimulation of gastrin release, inhibition of monoamine oxidase B, and antibacterial properties [32].Furthermore, Chrisitine et al. (1979) reported that Nmethyltyramine increases blood pressure in an anaesthetized rat, relaxes guinea pig ileum, and increases both the force and rate of contraction of guinea-pig right atrium by inducing the release of noradrenaline [33].Additionally, naringenin has been reported to have several pharmacological properties, including anti-dyslipidemic, antiobesity and antidiabetic, and antifibrotic [34].Moreover, cleomiscosin A showed strong anti-inflammatory activity and has analgesic and antipyretic potencies [35].Curcuson C has been reported to have antipyretic activity in vivo [36].In the current study, the compounds isolated in good yields (1-6, 8-11, 13-14, 16, and 21-22) were evaluated for their analgesic, anti-inflammatory, antipyretic, and antioxidant activities by using in vivo and in vitro models.
The anti-inflammatory activities of some isolated compounds were evaluated by using the carrageenan-induced paw edema in rats.The size of edema was significantly reduced (p< 0.05-0.001) in the animals treated the low doses of 5 and 10 mg/kg compared with the standard anti-inflammatory drug (phenylbutazone) at a high dose of 100 mg/kg.The rats treated with compounds 10, 16, 1, 5, 6, 22, 4, 13, 3, 8, 9, 14, and 21 exhibited a significant reduction in their hind paw edema.At a low dose of 5 mg/kg, the edema size reduced by 20. 44 and 8.01%, respectively in comparison with the high dose of phenylbytazone (100 mg/kg) that produced 69.06% reduction in the size of edema, which was almost similar to that produced by the low dose (10 mg/kg) of compound 10 (64.91%;Table S12).The anti-inflammatory results were almost compatible with the antinociceptive activity results for the tested compounds.
In addition, the isolated compounds from J. pelargoniifolia roots were tested for their antipyretic activity by using the mice with yeast-induced hyperthermia.All tested compounds administered at 5 and 10 mg/kg doses showed significant (p< 0.05-0.001)reduction in the rectal temperature of the hyper-thermic mice ranging between 36.73±0.13°C and 38.56±0.16°C as compared with the hypothermic effect (36.33±0.11°C) resulting from indomethacin administration (Table S13).
The percentage inhibition ± SD of nitric oxide-scavenging activity was determined for the selected compounds that were isolated at the concentrations of 20, 40, 60, 80, and 100 µg/mL from the roots of J. pelargoniifolia, and the obtained results were compared with the standard antioxidant drug (ascorbic acid).Compounds 22, 4, 2, 10, 1, 14, 21, 9, 8, 11, 6, 3, 13, 5, and 16 exhibited significant free radical-scavenging potency when compared with the free radical-scavenging activity of a strong known antioxidant drug (ascorbic acid) 87.23±0.98.The ability of the tested compounds to produce antioxidant effects was found to be concentration-dependent.At 100 µg/mL dose, the % inhibition ± SD of the tested compounds were 77.60±4.22 S14).The significant antioxidant activity associated with the administration of J. pelargoniifolia roots was perhaps due to its content of several phenolic and polyphenolic compounds, which play an important role in free radical-scavenging activity with less cytotoxicity.
It is important to mention here that in our previous study, which was carried out on the crude alcoholic extract of J. pelargoniifolia roots, we observed a significant antiinflammatory activity and analgesic potency, likely resulting from the presence of cleomiscosin A, hovetricoside C, jatrophadiketone, naringenin, β.sitosterol glucoside, N-methyltyramine HCL, curcuson C, cynaroside, curcuson D, propacin, cleomiscosin B, linarin, and hordenine HCL in good yield.Undoubtedly, a synergistic effect between these bioactive constituents produces significant antinociceptive and antiinflammatory effects.These results justify the use of this plant in folk medicine for the treatment of pain and several inflammatory conditions.Further study will be conducted on the pure isolated compounds to investigate the exact mechanisms underlying their promising biological activities.

Chemicals and analytical instruments
The high-resolution electron spray ionization-mass spectrometry (HRESI-MS) analyses were carried out on an Agilent Triple Quadrupole 6410 QQQ LC-MS mass spectrometer (Central Lab.College of Pharmacy, King Saud University (KSU)).The infra-red spectra were generally recorded in the potassium bromide pellets unless otherwise specified using the FTIR spectrophotometer (Shimadzu).The melting points were recorded by using a Mettler FP 80 Central Processor supplied with a Mettler FP 81 MBC Cell Apparatus.The spectral data for proton and carbon were measured by using Bruker AVANCE 700, 500, and 600 (College of Pharmacy, KSU and Department of Chemistry in TU Dortmund), resonating at either 700, 500, and 600 MHz for proton or at 125 MHz for carbon.The chemical shift values were expressed in ppm with respect to the internal standard tetramethyl silane (TMS) or residual solvent peak, the coupling constants (J) were recorded in Hertz (Hz).The two-dimensional NMR experiments (COSY, HSQC, and HMBC) were performed using the standard Bruker program.The silica gel 60/230-400 mesh (EM Science), RP C18 silica gel 40-63/230-400 mesh (Fluka) ® , and sephadex LH-20 with particle size 18-111 µm (GE Healthcare, USA) were used for column chromatography, while the silica gel and reversed phase 60 F254 (Merck) were used for thin-layer chromatography (TLC).The detection was achieved by using 10% H2SO4 in ethanol or ceric sulfate followed by heating.Alkaloids were tested with Mayer's reagent, Hager's reagent, and Dragendorff's reagent.All solvents for analytical purpose (HPLC-and analytical-grade) and drugs for biological investigation (sodium nitroprusside, sulphanilamide, λ-carrageenan, acetic acid, ascorbic acid, and phenylbutazone) were procured from Sigma Chemical Company (Sigma-Aldrich, USA), and the solvents were distilled prior to use.The preparative and semipreparative Shimadzu HPLC were performed; characterized by Rp-18 (ODS-80 TM, TSK, Japan), 10 μm PS, 30 cm L × 2.15 cm i.d.fitted with a guard column (10 μm PS, 7.5 cm L × 2.15 cm i.d.) (ODS-80 TM, TSK, Japan), and VP 250/10 NUCLEODUR C18 HTec, 6 μm PS, 25 cm L × 2 cm i.d., respectively both used PDA detector.

Plant material
The roots of J. pelargoniifolia were harvested from Wadi Mojasas, Jazan district (south of Saudi Arabia) in September 2015.The plant was authenticated by Dr. Jacob Thomas, a botanist of the Science College Herbarium, KSU, where a voucher specimen (#23064) was deposited.

Animals
Male Wistar rats and white male Swiss albino mice with approximate body weights of 200 g and 20-25 g, respectively, were divided into groups of six animals.The animals were obtained from the Experimental Animal Care Center, College of Pharmacy, KSU.After a 7-day period in animal accommodation, they were divided into groups and maintained at 12 h:12 h light-dark conditions at 55% humidity.Purina chow rat diet (UAR-Panlab, Barcelona, Spain) and drinking water were supplied to the animals ad libitum.The protocols for the present study were based on the recommendations of the Ethical Committee of the Experimental Animal Care Center of KSU (approval number CPR-7569).

Extraction, Fractionation and Purification
The air-dried powder of J. pelargoniifolia roots (2.5 kg) was divided into two parts A and B. Two kilograms of the plant root powder (part A) was subjected to solvent extraction, while the remaining 500 g of the root powder (part B) was exposed to the acid-base treatment.Part A was extracted by maceration with 80% ethanol (3 L×5) for three successive days with occasional shaking.This process was repeated until complete exhaustion of the plant material [37].The alcoholic extract was then concentrated to dryness under reduced pressure at 40 °C using a rotary evaporator to give 270 g of the dried alcoholic extract.The dried alcoholic extract was suspended in H2O and successively partitioned with petroleum ether, dichloromethane, ethyl acetate (EtOAc) and n-butanol (n-BuOH) (600-700 ml × 3) of each to obtain 13.3, 10.3, 5.1, and 33.6 g, respectively.
A part of the petroleum ether fraction (12.8 g) was chromatographed over silica gel column (700 g, 140 cm × 5 cm i.d.) using a gradient of petroleum ether/EtOAc followed by methanol (MeOH).The 100-ml fractions of each were collected and screened by TLC, and similar fractions were combined together to give 14 fractions, six of which were promising based on the TLC screening.Fraction 53-83 eluted by 15% EtOAc in petroleum ether (609.8 mg) was further subjected to CC and eluted by petroleum ether/acetone gradient elution, fraction 31-62 (188.9 mg) was eluted by 6% acetone in petroleum ether and further purified by preparative HPLC gradient elution (4 ml/min., acetonitrile: H2O: TFA) to yield 25.0 mg of compound 1.The direct crystallization of fraction 120-139, eluted by 20% EtOAc in petroleum ether, yielded 302.7 mg of compound 2. The fractions 167-170 and 189-196 eluted with 30 and 40% EtOAc in petroleum ether, respectively, were subjected to repeated crystallization with acetone to yield compounds 3 and 4 (14.3 and 25.4 mg, respectively).Additionally, fraction 218-248 (287.3 mg) eluted by 50% EtOAc was exposed to repeated crystallization with acetone to give 20.2 mg of compound 5, while fraction 285-287 eluted with 40% MeOH in EtOAc yielded 330.4 mg of compound 6, which was purified by crystallization with acetone.
The dichloromethane (DCM) fraction (9.8 g) was subjected to column chromatography using a column (700 g silica gel; 1 m ×4.5 cm i.d.) packed by wet method with petroleum ether.The polarity of the column was gradually increased by treating it with DCM, followed by MeOH.The 75-mL fractions of each compound were collected.Among the collected fractions (142 fractions), similar fractions were pooled together depending on their TLC similarity and then dried under reduced pressure at 40 °C.Fraction 48-64, which was eluted by 10% MeOH in DCM, was concentrated (4.6 g) and then subjected to further silica column chromatography (CC; 250 g; 1 m ×4 cm i.d.).The elution carried out by using gradient DCM/MeOH at 12% MeOH in DCM afforded subfractions 38-51 (3.6 g), which were subjected to further purification by using silica gel CC (150 g; 80 cm × 3 cm i.d).Elution was carried out by using a mixture of petroleum ether/acetone, followed by MeOH.Fraction 116-143 was eluted at 50% petroleum ether/acetone and further purified through a preparative TLC using MeOH: H2O (3: 1) as a solvent system (5 times), leading to the isolation of white crystals of compound 7 (7.5 mg).Moreover, three promising subfractions obtained by using 90% acetone in petroleum ether, 100% acetone, and 10% acetone in MeOH, followed by crystallization with MeOH afforded compounds 8 (15.1 mg), 9 (15.9 mg), and 10 (16.4 mg), respectively.
The EtOAC extract (4.6 g)_was subjected to silica gel CC (250 g, 1 m ×4 cm i.d) using a gradient of DCM/MeOH.TLC was used to monitor fractions (50 mL), followed by pooling of similar fractions.Fractions 34-39 eluted with 84% DCM afforded 17 mg of compound 11 after crystallization with MeOH.Fractions 55-57 eluted with 70% DCM afforded 8.6 mg of compound 12.The fractions eluted with 35 and 40% MeOH in DCM were further purified by repeated acetone crystallization to give 14.9 and 13.2 mg of compounds 13 and 14, respectively.Fractions 75-78 eluted with 45% MeOH and further subjected to CC using DCM/MeOH, followed by a semi-preparative HPLC (Rp-18) using gradient elution at 1 ml/min with MeOH: H2O: TFA as solvent system afforded 8.6 mg white crystals of compound 15.Finally, fractions 88-102 eluted with 50% MeOH in DCM were subjected to further purification over sephadex LH-20 (100 g, 1 m × 4 cm i.d), using water and methanol as an eluent in the gradient mode.The subfraction eluted by 20% H2O/MeOH was further purified over a reversed-phase column to give a further subfraction eluted by 75% H2O/MeOH, affording 12 mg of compound 16.
Furthermore, the remaining 500 g of the root powder was subjected to an acid-base treatment according to the Stas-Otto method I described by Mandhumitha and Fowsiya [38].The crude alkaloidal fraction was subjected to silica columns using gradient elution with solvent system DCM/MeOH: NH4OH, resulting in five fractions.The first fraction was eluted by using 17% MeOH in DCM with an addition of 1% NH4OH followed by purification through reversed-phase semipreparative HPLC using MeOH: H2O: TFA to give the white crystals of compound 17 (6.3mg).The second fraction was separated by 20% MeOH in DCM to afford a subfraction, which was further purified by a semipreparative HPLC (gradient elution 2 ml/min) using MeOH: H2O: TFA as a solvent system to afford the white needle crystals of compound 18 (9.4mg).The third and fourth fractions were eluted by 23 and 26% MeOH in DCM, followed by an addition of a few drops of NH4OH, affording 6.8 and 8.8 mg of compounds 19 and 20, respectively.The fifth fraction was eluted by 60% MeOH in DCM with an addition of a few NH4OH drops to yield 86.7 mg of a compound, which was subjected to further purification using the reversed-phase semipreparative HPLC in gradient mode with MeOH:H2O:TFA as the mobile phase, resulting in the production of the white crystals of compounds 21 and 22 (20. C NMR, and HMBC data, see Table 2 and Figure 3; HRESIMS (positive) m/z 205 [M+H] + (calculated for C12H16N2O, 204).

Hot-plate method
The hot-plate method described by Turner (1965) was used to determine the antinociceptive activity of the compounds isolated form J. pelargoniifolia root [39].

Acetic acid-induced writhing in mice test
The method of Koster et al. (1959) was used to evaluate the analgesic effect of pure compounds isolated from J. pelargoniifolia root [40].

Tail-flick method
Acute nociception was induced using the tail-flick apparatus (Tail flick Apparatus Harvard), following the method recommended by D'amour and Smith [41].

Carrageenan-induced edema in rat paw method
The method described by Winter et al., 1962 was used to evaluate the antiinflammatory potency of the isolated compounds [42].

Yeast-Induced Hyperthermia in Rats
Hyperthermia was induced in mice followed by the administration of the isolated compounds, and their hypothermic activity was determined by applying the method described by Loux (1972) [43].

Nitric oxide radical-scavenging assay
This assay was carried out according to the procedure described by Green et al. (1982) [44].

Statistical analysis
The values in the tables are given as mean ± SE.The data were analyzed by using one-way analysis of variance (ANOVA) followed by the Student's t-test.Values with P< 0.05 were considered significant.

Conclusion
This is the first report on the phytochemical and biological investigation of J. pelargoniifolia roots resulting in the isolation of 22 secondary metabolite compounds (two steroids, five flavonoids, three coumarinolignans, seven alkaloids, four diterpenes, and one coumarin glucoside).This work has enhanced our understanding about the constituents of the selected plant.Hovetricoside C and N-methyltryptamine were isolated from the Euphorbiaceae family for the first time, while hordenine, Nmethyltyramine, their salts, cynaroside, and linarin were characterized in the genus Jatropha for the first time.Compounds 15 and 18 were isolated for the first time from a biological source.Compound 18 can be used as a starting material for the semisynthesis of related analogues aiming to produce new drug leads used for the treatment of contemporary diseases such as depression, anxiety, pain, obesity and many more.Furthermore, the roots of J. pelargoniifolia showed significant antinociceptive, anti-inflammatory, antipyretic, and free radical-scavenging activities probably because of its content of many bioactive compounds belonging to various chemical classes that have analgesic and anti-inflammatory activities as well antipyretic and antioxidant activities that work together to produce synergistic effects.These results support the efficient use of this plant in Saudi Traditional Medicine as a remedy for pain and several inflammatory conditions.Tables Table 1.The 1 H (600 MHz, δ in ppm, J in Hz) and 13 C NMR (125 MHz, δ in ppm) spectral data for compound 15 in deuterated methanol (CD3OD).