Indian Journal of Chemical Technology Vo l. I 0. M arch 2003. pp. 13 1-1 36

Articles

Extraction of natural colourants from roots of Morinda angustifolia Roxb.­Their identification and studies of dyeing characteristics on wool

R Bhuyan & C N Saikia*

Ce llulose Pulp and Paper Di vision. Reg ional Research Laboratory. Jorhat 785 OOo. India

Necei1•ed II .!ulv 2002: revised received II October 2002: accep1ed 5 December 2002

The co lour components in the roo ts of the plant Mnrinda angu.l·f(fr1lia Roxb. were iso lated and their structures were eluc ida ted based on chemica l and spectroscopic investi gati ons. Further. the dyeing behav iour or the co lour component on woo l in aqueuus medium was also eva luated. Depending on concentrations of dye ( 1-5%) in the dye bath . the dye absorp­ti on on the fi bre varied from 12.50-3 1.58%. The fastness properti es of the dyed yarn s were determined. Opti cal densiti es (OD) and colou r strength (KIS) va lues of the dye solutions as we ll as the dyed yarns and also co lour co-ordin ates for dyed ya rn s were determined.

The natural dycs/co lourants deri ved from fl ora and fauna have proved to be ceo-fri endl y, biodegradable and highl y compatible with the env ironment. The use of natural dyes has been known in India from time immemori al. But w ith the advent of synthetic dyes, the use o f natural dyes has decreased to a large extent. The worldwide increased envi ronmental awareness and health hazards assoc iated with the use of sy n­theti c dyes, have aga in led to the rev iva l o f natural d

1-7 yes .

Natural dyes are mos tl y deri ved from plants. in­sects and minerals. Any part o f pl ants viz. leaves, fruit s, seeds, fl owers, barks and roots can be em­ployed for ex trac ti on. In India, some 500 vari eti es o f plant are avail able th at can y ield natural dyes8

·9

. The pl ant, Morinda angustifolia Roxb. is a small decidu­ous shrub belonging to the Rubi aceae famil y and is found in eas tern Himalayas and many other states of India up to an altitude o f 1800 m 11

l.11 . The plant grows

in abundance in the fo res ts o f north eas tern reg ion of the country . Th e roots o f the plant were used for ex ­tracting the co louring matters. The principal colour component iso lated from the roo ts was morindone, which is chemicall y I ,2,5-trihydroxy-6-methyl an­thraquinone1 2 Besides morindone, the co louring matters also contained some other colour imparting components.

In the present work , the probable components in the co louring matter were iso lated and their structures

* For correspondence (E-mai l: drrlj t@cs ir.res .in ; Fax: (0376) 33700 II )

were determined. A lso, the dyeing characteri sti cs of the co louring matter on woo l were studi ed with and w ithout the use of mordants and the properti es o f the dyed fibres were evaluated.

Experimental Procedure

Raw materials Fresh roots of Morinda angust(f'olia (5 kg) were

co llec ted from a fo rest near Jorhat , India during w in­ter season . The roots were finely washed w ith tap water and dried. The dried roots were cut in to small pieces and then ground to fine powder.

Four-ply worsted yarn of Australian M erino Woo l was used for dyeing experiments. M ordants such as

CuS04.5H20 (LR, CDH), K2Cr20 1 (LR, CDH ), SnCI2.2H20 (LR, CDH ) and AI (NH4)(S04h. I 2H20 (LR , Qualigens) were used.

Di sti ll ed water was used for ex trac ti on of the co l ­our components and for preparation of all chemical solutions, while de-ioni sed water was used for dyeing purpose.

Isolation of colour components from the roots by solvent extraction

The air-dried powder o f the roots o f Morindo an­gustifolia ( I kg) was ex tracted with ethanol in a sox­hlet apparatus fo r I 0 h. The ethanol w as then removed under reduced pressure to get a solid mass, whi ch was then successi ve ly ex tracted with petrol eum ether, ben zene and meth anol.

Articles

The petroleum ether ex tract on preparative TLC and subsequent column chromatography eluting with 11-hexane, n-hexane:ethy I acetate at ratios 30: I , 25: I , 25 :2, I 0: 2 y ielded three fracti ons - F-1 , F-2 and F-3. The benzene extract was then passed through a col­umn of silica gel (60-120 mesh) and eluted with n­hexane: ethy l acetate at ratios 30: I , 20: I , I 0:2 , which y ielded two more fractions - F-4 and F-5. The methanol ex tract gave another three fractions - F-5, F-6 and F-7 upon eluting with different ratios of n-hexane and ethy l acetate.

Evaluation f~[ the colour components by .\pectral analyses

Infra reel ( IR ) spectra of the above isolated com­pounds were recorded on a Perkin-Elmer spectro­photometer (Model 5808) using K8r disk technique, in the range 4000-200 cm-1

• The ultra violet/visible (UV/V is) absorption spectra of compounds were re­corded on a Shimaclzu 1601 PC UV/Vis spectropho­tometer using methanol in the range 200-800 nm. The nuclear magnetic resonance (NM R) spectra were re­corded on a EM 360 L (60 MHz) NMR spectropho­

tometer using DMSO-clr, in the range 0-108 w ith tri­methy lsi lane as an internal standard. The mass spectra were recorded on a Finnigan-MAT (INCIOS-50) spectrophotometer. The melting point of the com­pounds were cletenni ned on 8uechi 8-540 melting point apparatus and were un-corrected. The elemental analyses were clone in a Perkin-Elmer 2400 elemental analyzer.

Aqueous extraction of colour components from roots ./(u· dyeing purpose

The finely ground root materials ( 100 g) with 12% moi sture were ex tracted with 500 mL distilled water for about 2 h at temperature 90"C. The extract was then concentrated under reduced pressure over a boiling water bath. The y ield of the dried powder was found to be 15.2%.

Optical density and colour strength measurement

Dye solutions varied from 1-5% were prepared and definite amounts were taken in the dye-bath by main­taining the material to liquor (M:L) ratio at I: 10. The absorbance of the solution was recorded before and after dyeing of wool at 440 nm in each case. An aver­age of 3 absorbance measurements at each concentra­tion was recorded. The dye absorbance was calculated as given below:

132

Indi an J. Chem. Tcchnol.. March "0()]

Ah~orbance Abso d)ancc before cl ye in!!- after dyeino

% Dye absorbance = ~ "' x I()() Absorbance before dye ing

Further the colour strength (K/S) values o f the dye so lutions as well as the dyed samples were evaluated by light refl ectance technique usi ng a Shimaclzu 160 I PC UV /Vis spectrophotometer. The KIS va lues were assessed using the Kubelka-Munk equation 1

·':

where, R. is the observed reflectance, K is the absorp­ti on coefficient and S is the light scattering coelli­cient.

Dyeing of wool

The worsted yarn was first scoured as per the 81S method (IS:I349:1964) 14

. The scoured yarn was sub­j ec ted to ethanol ex traction in a sox hlet apparatus at the rate of six siphons/h for 3 h, rinsed with distill ed water and finally dried at room temperature. Thi s was clone to ensure the removal of residual soap etc from the fibre.

The dyeing was carried ou t at temperatu re 97-98"C in a dye bath containing 3% dye at m:L rati o I: 10 for 45 min . Then, a 2% sod ium chloride solution on the basis of material was added to the dye bath and the system was further kept at that tempera ture for I 5 min. The dyed yarn s were th en washed and dried at room temperature.

Method of mordanting Pre- and post-morclanting methods using 2% so lu­

ti ons of each of CuSO.J .5HcO. K2Cr20 7 , SnCI 2 .2 H20 and AI(N H4)(SO.Jh. 12H20 were employed at m: L ratio I: 10 and mordanting was carried out for 30 min at 97-98"C. The fibres were then washed and dried.

Measurement of fastness properties

Colour fastness tes ts to li ght, washing and crocking were carried out in a Faci-O-meter. Launcler-0-metcr and Crock-0-meter respectively as per th e standard methods 15

.

Hullter coordillates

The Hunter coordinates L. a and h were calculated from the tri stimulu s va lues x. v. z. using the l'ollowing

. 16 d equations an were converted to C l ELab co-ordinates.

Bhuyan & Saik ia: Ex tracti on of natural colourants from roots of Morinda angustif'olia Roxb. Articles

L =I Oy 112

o = 17 .5( 1.02x - y )1/ 12

b =7(y- 0.84z)/y 112

The higher va lues of a and b indicate brightness, which is more clue to redness and yellowness respec­tively, and the negative values indicate greenness and blueness which are more towards the dull side. The lower the value of L, the greater is the depth .

Results and Discussion

Characterization of the colour compoueuts The characteris ti cs of the isolated compounds F 1 -

F7 were as given below:

Compound FJ: White need les (25 mg); m.p 134-135"C; UV Amax (CS2) nm: 280 nm; IR Vmax (KBr) cm·1: 3570 (-OH), 1650; 1H NMR (CDCI1) 8: 1.39 (3 H, d, 1=6.5 Hz, 29 Me), 2.75 ( I H, m, 6H), 4.9 (I H, m, 28H); Anal. for C29 H500 : Found C=83.92%, H=l 2. 12% (Calc. C=83. 98% and H=l 2.15%). MS:

m/z414 [M+], 399,396,38 1,303,273. [a] g -36° in

CHCh. These results showed that the compound is ~­Sitosterol1 7.

Co111pound F2: Orange-yellow need les ( I gm); m.p 220-221 "C; UV A111ax (M eOH) nm: 225(4.52) , 256 (4.3 1 ), 278 (4.03), 286 (4.02), 430 (4.0 I ); fR Vmax

(KBr) cm·1: 3400 (-OH), 1670 (w, C=O, unchelatecl), 1630 (s, C=O, chelatecl), I 570 (aromatic C=C); 1 H NMR (DMSO-clr,) 8: 7.20 ( I H, d, H-2), 7.42 ( I H, d, H-4), 7.81 (IH , d, H-5), 7.79 ( IH, d, H-6), 7.68 ( IH, s, H-7), 3.68 (s, -CH 2); MS: m/z 270 [M+]. Anal. for CtsHtoOs: Found C=66.5%, H=3.8% (Calc. C=66.6% and H=3 .7%).

From the above resu lts, the compound may be de­termined to be Aloe-emodin 18.

Compound FJ: Yellow-brown need les (50 mg); m.p 252"C; UV A111ax (MeOH) nm: 254, 269, 290, 438; IR Vrnax (KBr) cm"1: 3390, 1675, 163 1; 1H NMR (DMSO-clr,) 8 :7.03 ( IH, d, H-2), 7.34 ( IH, cl , H-4), 7. 15 ( I H, d, H-5), 6.8 1 (l H, d, H-7), 3. 11 (Ar­CH1, s); MS: m/z 270 [M+, 100%]. Anal. for Ct sH toOs: Found C=66.57%, H=3.79% (Calc. C=66.67% and H=3.73%). Here agai n, the compound is determined as Emodin 19.

Compound F4: White shi ny crysta ls (50 mg); m.p 283°C; IR V rnax (KBr) cm·1 3400-3500 (-OH), 1680 (-COOH), 1640 (unsaturation), 2920, 1440, 1380; 1H

NMR 8 (CDCh): 0.65 (3 H, s, t-CH1), 0.67 (3 H, s, t­CH1), 0.78 (3H, s, t-CH 1), 1.26 (6H, s, 2 t-CH,), 1.06 (6H, cl, 1=6 Hz, s- CH1), 5.27 ( I H, m, viny li c H), 4.41 ( I H, m,-CHOH); MS ; m/z 456, 248 (base peak): Anal. for C10H480 1: Found C=7R.94%, H= l 0.62% (Ca lc. C=78.89% and H=l0.59%). fa] u + 66° in

EtOH and KOH.

These res ults showed th at the compound is Ur­so lic acid20.

Compound F5: Orange-red needles (2 gm); m.p 280"C; UV Ama x (MeOH) nm: 446, 299, 29 1, 265.5 and 232; IR V 111.,, cm.1(KBr): 3400 cm·1 (- OH), 2890 and 1400 cm·1 (-CH1), 1670 (unchelated C=O). 1600 cm·1 (chelated carbonyl group). 1H NMR (DMSO­cl (,) 8: 2.29 (3H, s, benzyl Me), 7.49 (I H, d, 1=8.0 Hz, H-3), 7.73 ( IH, d, 1=8.0 Hz, H-4), 7. 17 ( II-I, cl, 1=9.0 Hz, H-7), 8.07 ( I H, d, 1=9.0 Hz, H-8); Anal. for C15H 100 5: Found C=66.59%, I-1=3.75% (Calc. C=66.67% and I-1=3.73 %). MS: m/z 270 [M+, 100%]. Thi s was found to be in perfect agreement with that of the compound Morindon21.

Compound F6: Yellow need les (30 mg); m.p > 300"C: UV Amax (MeOH) nm: 227, 265, 437 ; IR v,,.,, (KBr) cm·1: 3300 (-OH), 2990, 2980, 1698 (unchc­lated C==O), 1630 (chelated C=O) 1454, 1268; 11-1 NMR8(DMSO-dr,): 8.02 ( IH, d, 1=1.5 Hz, H-8), 7.82 (II-I , d, 1=1.5 Hz, H-7), 7.71 (11-1, d, 1=1 .5 Hz, 1=7 .5 Hz, H-6), 7.39 (I H, d, 1=7 .5 Hz, H-3), 7.57 ( II-I , d, 1=7.5 Hz, H-1 ); MS: m/z 284 (M+, 100%); Anal. for C15H80 r,: Found C=63.40%, I-1 =2 .85 % (Calc. C=63 .39% and I-1=2 .84%).

Here again, the compound is determined as Rhein22

.

Compound F7: Orange-yellow needles (50 mg) ; m.p 244"C ; UV Amax (M eOH) nm: 232, 262, 287, 298 and 440; IR V 111ax (KBr) cm·1: 3480 ( -01-1), 1675 (un­chelated C==O), 1625 (chelated C=O); 1 H NMR 8 (DMSO-dr,): 7.39 (l H, d, 1=8 Hz, H-3), 7.72 (11-1, d, 1=8 Hz, H-4), 7.16 ( II-I , d, 1=9 Hz, 1-1 -7), 7.96 ( I H, d, 1=9 Hz, H-8), 2.32 (3h, s, Ar-CI-11), 3.5- 4.9 ( 12 H, sugar protons); MS: m/z 564 (M+, 100%); Anal. for C2c,H2s0 14: Found C=55.40%, I-1=4.97% (Ca lc. C=55.32% and H=4.99%).

la lg -82.6° in dioxane. These resu lts showed that

the compound is Morindonin21.

The structures of the above isolated compounds are given in Fig. I.

133

Articles

P-Sitostcrol

Emod in

llrso lic atid

110~~ II<~()

Oil ',:;~ I , (II ll<r~o, 0 IICJ~"/

OH 0 Oil

" Cl1 20H

II 0

Murindo ne

Rhein

Fi g. ! - Structures of the compounds isolated from root s of Morindo tlll.f.: IISiifiJ!io Roxh

Indian J. Chern. Tcc l111ol. . March 2003

As evident from above, except i)-sitostero l wh ich is a steroid and urso l ic acid, a triterpenoid, the major portion of the chemical compounds presen t in the ex­tracted colouring matter are anthraquinone based compounds .

Effect of concentration of dye on optical density, absorption and colour strength

As is evident from Table I , the absorpti on of dye (%)on fibre increased with an increase in concentra­tion of dye in the dye-bath and reached max imum at 3%. Though the KIS values went on increasing with an increase in dye concentration, the maximum ab­sorpt ion (3 1.58%) was observed at 3%. At !hi s opti­mum concentration of dye, desired fastnes. properties on fibre were also obtained (Tab le 2).

Tab le I - Absorbance of dye components on woo l and KIS va lues

Dye cone Optica l dcnsit z (%) Before i\ ft er

dyeing dyei ng

016 0. 14

2 0.1 7 0.1 3

3 0.19 01:\

4 0.20 0.15

5 0.22 () 17

Absorp-ti nn

(':n

12.50

2353

3 1.5X

25.00

22.73

KIS

9.53

10.2X

11 . 12

12.64

14.XR

Table 2- Dye ing pro perti es of co lour components ex tracted from roots of Morindo ongusli/iJ/io Rox b

M ordant s Mordanting Light Crocking fastness Wash Sh<tde on fabri c

technique fastness Wet Dry fastness

N il 4 4 5 5 C)olclen brown

CuSO.,. 51-1 20 4 4 5 5 Clrcy

II 5 5 () 6 Dark brown

K2Cr20 7 4 4 5 5 Golden brown

II 5 4 5 5 Cl nlden brown

SnCI 2.2 H"O 3 3 4 4 Yellow ish brown

II 4 4 5 5 Y cllowislt brown

A I(N II.1)(S04 )" 3 3 4 4 Golden hrnwn

. 121-1 20 II 4 4 5 5 Golden brown

I - prc-rnordan ting. II - post-mordanting. I - very poor. 2 - poor. 3 - fair. 4 - very fair. 5 -good. 6 - very good.

134

13huyan & Saiki a: Ex trac tion of natural co lourants fro m roots of Mo rill(/a ang u.,·tifi, /ia Roxb. Adiclcs

11.6 ,

I I

11.4 i I I

11.2 ~ I

I I

II ! ~ I ~ I

10.8 i I

I I

10.6 i I

10.4 J I

,-----., I I 1-¢- a 1

1-•-b I ~ --- c

1-o- d 1 ~.

10.2 +1 ----,----~---,..--------,-----.,

2

Cone(% ) 2.5 3

Fig. 2- K/S <ts a function of dye at di fferent concentrati ons of mordant at post ~ morcl::mting : a. CuS0~.5 H 20 . b. K,Cr,0 7• c. SnCI ,.2H,O. d. A I(N H4)(SO~h 12H,O

Eflect of mordanting conditions

It was seen that the KIS values increased with the increase in concentration o f mordants (Fig. 2). How~

ever, beyond 2% concentration of each o f the mor­dants, the increase in KIS value was not significant enough, M oreover, des ired fastness properti es on fi ­bre were also obtained at thi s concentrati on of th e mordants. It was also ev ident that a wide vari ety o f shades ranging from yellowi sh brown to go lden brown, grey to dark brown could be obtained from th e dye when mordanted w ith eli fferent mordants. The mordant acti v ity of metal ions was found to foll ow the

sequence- Cu(II)~Cr(VI)~Sn(II )~AI(III ). The bri ghter shades were obtained when mordanted with Cr(V I) and Cu(ll ). This might be due to the maximum absorpti on and easy formati on of metal-complexes with th e fiber 2

-1.25 Fair to good wash and crockin g

fastness properties were obtained when mordanted w ith CuS04.5H20 and K2Cr20 7

26, while li ghter shades

with fair to good wash and crocking fastness proper­ties were obtained with SnCI2 .2H20 and A I(NH 4)(S0 4b 12H20 27

. Further, it was also ev iden t from Table 2 th at better fas tness properti es were ob­tained while using pos t-mordantin g technique.

Evaluation of colour coordinates of dyed yams

The results on colour coordinates of dyed samples showed that the values obtained fo r L when pre­mordanted with all the four mordants were vari ed from 39.8 1 ~ 65 . 27, while the values obtained for post-

mordanted fibre vari ed from 3R .I R-63 .66. So also, the values obtained for a in both pre- and post-mord antecl fibres vari ed from 10. 19-3 1.98 and 11 .43-25. 13 and that forb from 9. 13-75. 14 and 28.78-76 .1 3 respec­ti ve ly . For unmordanted dyed fi bres, the values fo r L, a and b were 56. 16. 24. 18 and 65.84 respecti ve ly. It was observed th at all th e colour coordin ates were pos itive with respect to bri ghtness L, reel-green o, yellow-blue b and therefore, all of them I ie in the yellow-red quadrant of the co lour space di agram. The maximum bri ghtness was observed in th e samples dyed and pre-mord anted with SnCI2.2H20 (L 65.27). The lowest bri ghtness was observed in the samples dyed and post-mordanted w ith CuS0 4 .5H 20 (L 38.18).

Conclusion From the above study, it might be concluded that

the co lour components iso lated from the roots of Mo rinda ong usti/"o lia Roxb. contained anthraquinone moiety in their molecul es. Woo l yarn s could be dyed to a wide range of shades with thi s co lour component alone or by using different mordants. Thu s, the dye so ex trac ted may be an alternati ve to sy ntheti c dye for dyeing of wool.

Acknowledgement One of the authors, R B acknowledges the award of

Senior Research Fellowship of CS IR, India.

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