Asian J. Adv. Basic Sci.: 2017, 5(2), 29-33 ISSN (Print): 2454 – 7492 ISSN (Online): 2347 – 4114 www.ajabs.org Phytochemical Investigation of Dicoma tomentosa to Isolate Secondary Metabolites Venu Sharma School of Biotechnology, University of Jammu, Jammu & Kashmir, INDIA * Correspondance: E-mail: [email protected] (Received 29 Aug, 2017; Accepted 14 Sept, 2017; Published 21 Sept, 2017) ABSTRACT: Dicoma tomentosa Cass. (Family: Asteraceae) is an erect, annual herb of dry fields and sandy arid places. The whole plant is strongly bitter and is used for different ailments. Phytochemical investigation of the aerial part of plant was done to screen its secondary metabolites. Sesquiterpene lactones belonging to melampolide group of germacranolides were found to be characteristic of the species and were isolated along with triterpenes and ster- oids. Keywords: Dicoma tomentosa; Natural products; Sesquiterpenoids; Spectral analysis. INTRODUCTION: Several products isolated from General experimental procedures: Active neutral plants, marine flora and microorganisms possess the (Acme Synthetic Chemicals) and silica gel (BDH, 60-120 unique properties like greater number of chiral cen- mesh) were used as adsorbent for column chromatog- ters, increased steric complexity, fewer hetero atoms, raphy. Qualitative and quantitative thin layer fewer heavy atoms etc. It accounts for the huge struc- chromatographies were conducted on TLC aluminium tural diversity of natural products which further re- sheets Kieselgel 60 F254 (E. Merk). Preparative TLC per- 1 sults into its rich bioactive potentiality . The genera formed on TLC glass plates silica gel 60 F254 precoated Dicoma belonging to the family Compositae, tribe- (20×20 cm) layer thickness 0.5mm (E. Merk). Spots on Mutisieae and subtribe- Gochanatiinae2 is of great TLC plates were visualized by spraying with 2% cerric medicinal and economic importance. For intangible, ammonium sulphate in 2N H2SO4. physiological and structural reasons, the group seems Melting points were determined in soft glass capillaries in to be well adapted to many habitats such as deserts, an electrothermal melting point apparatus and are uncor- which are difficult for other plants. As a result the rected. The identities of compounds were confirmed by Compositae includes innumerable successful spe- comparison of their melting points and spectral data with cies3.A large numbers of plants are ornamental and literature values and also by mixed mp, co-TLC and co-IR cultivated in gardens and homes. Some of them have with authentic samples. medicinal importance. The genus Dicoma with ap- proximately 35 species distributed over tropical South The reported UV and IR spectra were recorded on Hitachi Africa with one species in Asia. Most of species are U-2000 double beam spectrophotometer and FT-IR herbs or small shrubs but even trees are known. D. spectrophototometer Magna IR-550 respectively. 1H and tomentosa Cass. is used medicinally in Western Afri- 13C NMR spectra were recorded on JEOL FX 90 Q, JEOL ca; D. anomala Sond., D. capensis Less., D. speciosa AL 300, Bruker DRX 300 and Bruker WM 400 instru- 4 E. May., D. zeyheri Sond are used in South Africa . ments using CDCl3, C6D6, d6 DMSO as solvents and TMS D. tomentosa is used as tooth cleaner5. Its leaves are as an internal reference. EIMS, CIMS and FABMS data used in the neighbourhood of Belgium as a febrifuge, were generated on JEOL D-300, Shimadzu QP-5000 and during febrile attacks in the mother after child birth6. JEOL-JMS-SX 102A spectrometers respectively. In Africa it is used as a local application to putrescent Plant materials were collected from Sawai Madhopur and wounds. It is reported to possess prominent anti- 7-9 Jaipur regions of Rajasthan and it was characterized by plasmodial activity . The versatile features of sec- the Herbarium In-charge, Department of Botany, Univer- ondary metabolites prompted us to study these phyto- sity of Rajasthan, Jaipur. chemicals from the plant D. tomentosa. The shed air dried aerial part of the plant was screened chemically Extraction and isolation of constituents from aerial to investigate its secondary metabolites. parts of Dicoma tomentosa: Air dried and coarsely powdered plant material (3kg) was extracted with MATERIALS AND METHODS: CH2Cl2-ether-mathanol (1:1:1) mixture in cold for 12 hrs. The extract was concentrated at reduced pressure 29 [(Asian J. Adv. Basic Sci.: 5(2), 2017, 29-33) Phytochemical Investigation of Dicoma tomentosa to Isolate Secondary….] and subjected to column chromatography over silica 2.10s (OAc), 0.76, 0.79, 0.83, gel. The eluants used and fractions obtained are cited 0.94, 0.97 and 1.03 (all singlets in table 1 to isolate different secondary metabolites representing six methyl groups) . + from the plant material (Figure 1). MS (m/z) 468 [M] (C32H52O2 ) , 453 [ M- Me ]+ , 450 [ M-H O]+ , 408 [ Table 1: Eluants and the fractions from column 2 M-AcOH ]+ , 242, 240, 231 and chromatography. 213, etc. Residue left after re- Components from fraction 3: Fraction 3 revealed the Fraction moval of solvent Eluant presence of two compounds on TLC plate. These No. Nature Amount compounds were separated by prep. TLC in petrole- 1. Petroleum-ether Yellow Oil 150 mg um-ether: benzene (1:1) mixture. Petroleum- Yellow 2. Isolation of Stigmasterol: It was the second com- 2. ether: Benzene 160 mg semisolid ponent separated from fraction 3 and was obtained as (3:1) shining needles, 175mg. mp 166-67 0C after crystalli- Petroleum- zation from CHCl3 – methanol (1:1) mixture. It gave 3. ether: Benzene Yellow solid 500 mg positive Liebermann–Burchard and Salkowski test for (1:1) sterol and TNM test for unsaturation. Yellow 4. Benzene 150 mg green solid IR νmax. KBr 3400-3200 (OH), 1460 (- Benzene: 5. Yellow gum 200 mg CH=CH- bending), 1380, EtOAc (3:1) 1360, 1260, 1050, 960, 800 Benzene: -1 6. Yellow gum 190 mg cm . EtOAc (1:1) 1H NMR [300 MHz 5.34 tbr (H-6), 5.04 dd(J=16, 7. EtOAc Yellow solid 120 mg 10 Hz, H-22), 5.12 dd (J=16,10 Hz, H-23), 3.52 m RESULTS AND DISCUSSION: The air–dried and (H-3α), 0.81 t (J=7 Hz, C-29 coarsely powdered aerial parts were extracted with methyl), 0.91 d (J=7 Hz, C-21 dichloromethane–ether–methanol (1:1:1) mixture in methyl), 1.56 s (OH), 1.16 s cold. The resulting extract was concentrated at re- (C-27 methyl), 0.88 s (C-19 duced pressure and chromatographed over silica gel. methyl), 0.79 s (C-18 methyl). + Subsequent fractions (Table 1) on preparative TLC MS (m/z) 412 [M] (C29H48O), 397 [M- gave following compounds. Me]+, 328, 314, 302, 300, 271, 253. Fraction 1 could not be investigated further on ac- count of complex mixture of several non polar com- 3. Isolation of β-Sitosterol: Yellowish solid obtained pounds as evidenced by the appearance of trailing on from fraction-3 after removal of solvent gave a col- TLC plate. Fractions 2-7 were found to be a mixture ourless solid, 275 mg which was crystallized from of two or more compounds and each fraction was benzene as colourless flaps, mp 136-37 0C and charac- subjected to preparative TLC to get compounds in terized as β–sitosterol. pure state. Components from fraction 4: Component from fraction 2: Fraction 2 showed a 4. Isolation of Betulin: The fraction 4 afforded yel- major spot along with some very minor spots on lowish solid after removal of solvent. After crystalli- qualitative TLC plate. It was therefore purified by zation from CHCl –methanol (1:1) betulin was isolat- preparative TLC using petroleum-ether: benzene (2:1) 3 ed as colourless needles, 120 mg, mp 253-54 0C (lit as solvent system. 254-56 0C). It belongs to lupane series of triterpenes 1. Isolation of Lupeol acetate: It was isolated as and gave positive Noller test. It also developed yellow colourless crystals 110 mg, mp 218-19 0C and belongs colour with tetranitromethane indicating its unsaturat- to lupane series of triterpenes. It responded to positive ed nature. Noller test for triterpenes. Components from fraction 5: The fraction 5 showed IR νmax. [KBr] 1725 (OAc) , 1640 (C=C) , 1160 the presence of three compounds on TLC plate. cm-1 , 990 cm-1 (C-O stretch). Recolumn chromatography followed by prep. TLC of 1H NMR [300 1.69s (Me-C=C), 4.69 sbr and this fraction afforded following compounds MHz, 4.57 s (Vinylic protons), 4.38dd CDCl3, δ ppm] (J=12, 5HZ, H-3), 2.38m (H-19), 30 [(Asian J. Adv. Basic Sci.: 5(2), 2017, 29-33) Phytochemical Investigation of Dicoma tomentosa to Isolate Secondary….] 5. Isolation of Taraxasterol: It was obtained from recolumn chromatography. It was obtained as colour- first fraction of re-column chromatography and was less gum, 80 mg. It belongs to melampolide group of crystallized from methanol as white needles, 40 mg, sesquiterpene lactones. It exhibited following spectral mp 225-226 0C. It was highly soluble in benzene, data: chloroform and acetone. It responded positively to IR ν CHCl cm-1 3500 (OH), 2970-2850, 1770 TNM test (yellow colour). It also gave pink-violet max 3 (γ-lactone), 1690-1630 colour with Libermann-Burchard reagent and red col- (C=CCHO), 1600, 1380, our with chlorosulphonic acid. It also responded posi- 1285, 1175, 1100, 1070, 940, tively to Salkowski and Noller tests. It displayed fol- 900. lowing spectral details: 1H NMR [300MHz , 6.54 ddd (J=7, 9, 1.5 Hz, H-1), ’ IR νmax [KBr] 3470 (OH), 2980, 2960, 2.49 m (H-2), 2.33 m (H-2 ), 2855 (C-Hstretch), 1650 2.76 ddd (J=6, 2, 12 Hz, H-3), (c=c stretch), 1460, 1375 2.03 ddd (J=3,11,12 Hz, H-3’), (gem dimethyl groups) and 5.18 brd (J=10 Hz, H-5), 4.76 1050 cm-1 (c-o stretch).