Indian Journal of Fibre & Textile Research

Vol. 29, December 2004, pp. 470-476

Extraction and identification of colour components from the barks of Mimusops elengi and Terminalia arjuna and evaluation of their

dyeing characteristics on wool

R Bhuyan & C N Saikiaa

Regional Research Laboratory, lorhat 785 006, India

and

K K Das

Department of Chemistry, Dibrugarh University, Dibrugarh 786 004, India

Received 25 February 2003; revised received and accepted 4 December 2003

Dyes have been extracted from the barks of Mimusops elengi and Terminalia arjwla and the chemical constituents of the colour components responsible for dyeing identified. The dyeing behaviour of these colour components on wool has also been evaluated. Depending on the concentrations of dye ( 1 -6%) in the dye bath, the dye absorption on the fibre varies from 2 1 .943% to 27.462% and from 5 . 1 84% to 10.787% respectively for the dyes extracted from M. elengi and T. arjuna. The colour components isolated from the barks of the two plant varieties mainly contain flavonoid moiety. The dyed .and post-mordanted wool exhibits better fastness properties and therefore these dyes might be an alternative to synthetic dyes.

Keywords: Dyeing, Mimusops elengi, Terminalia arjuna, Wool fibre

IPC Code: Int. CI .7 D06P 1 /34

1 Introduction

The health hazards associated with the use of synthetic dyes and also the increased environmental awareness have revived the use of natural dyes during the recent years. Natural dyes/colourants derived from flora and fauna are believed to be safe because of their non-toxic, non-carcinogenic and biodegradable naturel . Further, natural dyes do not cause pollution and wastewater problems2-4. As the present trend throughout the world is shifting towards the use of ecofriendly and biodegradable commodities, the demand for natural dyes is increasing day by day.

The main sources of natural dyes are plants, animals and minerals5. They can be obtained from any part of plants, viz. leaves, fruits, seeds, flowers, barks and roots. In India, some 500 varieties of plants are available from which natural dyes can be extracted. Apart from plants, certain insects and

a To whom all the correspondence should be addressed.

Present address: Milanpur, Ward No. 3, Dergaon Town, Dergaon 785 614, India.

.

Phone: 238 198 1 ; Fax: +91 -376-237001 1 ; E-mail: c_saikia@yahoo.co.in

shellfish are also used for making biological dyes. Mimusops elengi Linn. (family: Sapotaceae) and Terminalia arjuna (Roxb.) Wight and Am. (family: Combretaceae) are two large evergreen trees available throughout the country6-8, the barks of which can be utilized for the extraction of colour components without destroying the whole plant.

The present work was, therefore, undertaken to isolate the colour components and then to determine their chemical structures. Further, the dyeing characteristics of the colouring matter on wool have also been studied with and without the use of mordants and the properties of the dyed fibres evaluated.

2 Materials and Methods

2.1 Materials

Fresh barks (5 kg/plant) of the two plant species, namely Mimusops elengi Linn. and Terminalia arjuna (Roxb.) Wight & Am. were collected during summer season from the reserve forests near 10rhat (26°4' N latitude and 94°1 2' E longitude), India. The bark samples were washed finely with running water, air dried and then stored at ambient temperature in sealed plastic bags.

BHUYAN el al. : EXTRACTION & IDENTIFICATION OF COLOUR COMPONENTS FROM M. ELENGI & T. ARJUNA 47 1

Four-ply worsted yarn of Australian Merino wool was used for dyeing experiments. Mordants such as CuS04.5H20 (LR, CDH), K2Cr207 (LR, CDH), SnCh.2H20 (LR, CDH) and Al(NH4)(S04h. 1 2H20 (LR, Qualigens) were used. Solvents like n-hexane, petroleum ether, benzene, chloroform, ethyl acetate, methanol and ethanol, all of LR grade, were used for the extraction and as eluents. Silica gel (60- 1 20 mesh) and silica gel G were used as adsorbents for TLC. Distilled water was used for the extraction of colour components and for the preparation of all chemical solutions, while de-ionized water was used for dyeing purpose. 2.2 Methods

2.2.1 Isolation of Colour Components

The air-dried barks of the plants containing about 13% moisture were made into powder in a Wiley mill and kept in sealed plastic covers for subsequent use.

Each of the sample powders ( 1 kg) was subjected to extraction with distilled water at 90-95°C. The extract was collected and fresh distilled water was added again and the same procedure was repeated till the colour in the extract was negligible. The extract was then concentrated under reduced pressure over water bath to get a solid mass. The solid mass so obtained was then subjected to extraction with 70 : 30 (v/v) alcohol : water mixture and then filtered. The filtrate was evaporated under reduced pressure to get a concentrated mass of the colour component.

About 50 g concentrated colour residue obtained from the extracted barks of M. elengi was then partitioned and mixed separately with ether and ethyl acetate. The ether concentrate was chromatographed over silica gel using various ratios of CHCh and MeOH and two compounds C- I and C-2 were obtained. Both the compounds were then crystallized as yellow needles. The ethyl acetate concentrate upon column chromatography over silica gel afforded two pure compounds C-3 and C-4 after repeated crystallization from methanol9•

Similarly, about 50 g of the concentrate obtained from the barks of T. arjuna was chromatographed on a column of silica gel in benzene and eluted with benzene, benzene : ethyl acetate, ethyl acetate, ethyl acetate : methanol and methanol. The elution with benzene : ethyl acetate ( 1 0 : 1 ) afforded compound F- l which was further purified by re-column chromatography on silica gel. Further elution of column with benzene: ethyl acetate afforded another

compound F-2. Continued elution of the column with ethyl acetate furnished a third compound F-3 (ref 10). 2.2.2 Spectral Analyses

IR spectra of the above isolated compounds were recorded on a Perkin Elmer spectrophotometer (Model 580 B) in the range 4000-600 cm" . The ultravioletivisible (UVlVis) absorption spectra were recorded on a Shimadzu 1 60 1 PC UV / Vis spectrophotometer in the range 200-800 nm. The NMR spectra of the compounds were recorded on a EM 360 L (60 MHz) NMR spectrophotometer in the range 0- 1 0 8 using TMS as internal standard. The mass spectra were recorded on a Finnigan-MAT (INCIOS-50) spectrophotometer.

The melting points of the compounds were determined on Buechi B-540 melting point apparatus and were uncorrected. The elemental analyses were done in a Perkin Elmer 2400 elemental analyzer. 2.2.3 Measurement of Absorbance and Colour Strength

Dye solutions ( 1 - 6%) of both the extracted dyes were prepared and definite amounts were taken in the dye bath, maintaining the M : L ratio at 1 : 1 0. The absorbance of the dye solutions was recorded before and after dyeing on a Shimadzu 1 60 1 PC UV/ Vis spectrophotometer. An average of 3 measurements at each concentration was recorded. The amount of dye absorbed was calculated by using the following relationship" :

Absorbance Absorbance before dyeing after dyeing X 1 00 % Dye absorbance = Absorbance before dyeing

Further, the colour strength (KJS) values of the dye solutions as well as the dyed samples were evaluated by light reflectance technique and the values were assessed using the following Kubelka­Munk equation ' 2 :

KJS = ( I _R)2/ 2R

where R is the observed reflectance; K, the absorption coefficient; and S, the light scattering coefficient.

2.2.4 Dyeing of Wool

The worsted yarn was first scoured as per the BIS method1 3, subjected to ethanol extraction in a soxhlet apparatus at the rate of six siphons/h for 3 h, rinsed with distilled water and finally dried at room

472 INDIAN J. FIBRE TEXT. RES. , DECEMBER 2004

temperature. This was done to ensure the removal of residual soap from the fibre.

The dyeing was carried out at 97 -98°C in a dye bath containing 3% dye at M : L ratio of 1 : 1 0 for 45 min. A 2% (owm) sodium chloride solution was added to the dye bath and the content was further kept at the same temperature for 1 5 min. The dyed yarns were then washed and dried at room temperature. 2.2.5 Method oj Mordal/til/g

Pre-/post-mordanting was done using 2% solutions, each of CuS04.5H20, K2Cr207, SnCI2.2H20 and AI(NH4)(S04h. 12H20, maintaining M : L ratio at 1 : 10 for 30 min at 97-98DC. The fibres were then washed and dried. 2.2.6 Assessment oj Fastness Properties

Fastness to light, washing and crocking were assessed in a Fad-O-meter, Launder-O-meter and Crock-O-meter respectively as per the standard methods. The fastness ratings were given in grey­scales 14. 2.2. 7 Hunter Coordinates

The Hunter coordinates (L, a and b) were calculated from the tristimulus values x, y, z using the following equations 15 and were converted to CIELab (L, a, b) coordinates:

L = lOy"2 a = 17 .5 ( 1 .02x _ y)ly"2

b = 7(y - 0.84z)lyIn

The higher values of a and b indicate brightness, which is more due to the 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.

3 Results and Discussion

3.1 Characterization of Colour Component

The principal colour components obtained from M. elengi were established spectroscopically and from colour reactions as the compounds gave a positive response to Shinoda (MgIHCI) testl 6.

Compound C- l was obtained as yellow needles with melting point 3 1 0-3 1 1 DC after crystallization from methanol . The UV absorption spectra [UV Amax (MeOH): 255 and 370 nm] and the positive Mg/HCI test suggested the compound to be a flavolle [IR Vmax (KBr): 3447 (-OH), 1 650 (C=O), 1 603 and 1494 (-C=C-) and 900-650 cm- ' (aromatic C-H). 'H NMR

(DMSO- d6) : 6.35 (d, J=2 Hz, H-6), 6.52 (d, J=2 Hz, H-8), 6.92 (d, J=8.5 Hz, H-5'), 7.62 (d, J=2 Hz, H-6') and 7.7 1 8 (d, J=2 Hz, H-2')] (C'5H I007: Found - C, 59.89% and H, 3.37%; Calcd -C, 59.9% and H, 3 .4%). The compound was thus characterized to be quercetin ' 7 .

Compound C-2 was also obtained as yellow needles with melting point >320 °c [UV Amax

(MeOH): 256, 265 and 350 nm. IR Vmax (KBr): 3530 (-OH) and 1655 cm- ' (-C=O). 'H NMR (DMSO- d6) : 6.56 (d, J=2 Hz, H-6), 6.80 (d, J=2 Hz, H-8) and 7.72 8 (s, 2H, H-2' and H-6')] (C '5H IOOs : Found - C, 56.56% and H, 3 . 1 8%; Calcd -C, 56.6% and H, 3 .2%). The compound was characterized to be myricetin from the spectroscopic data and colour reactions l s.

Compound C-3, obtained as yellow needles (melting point, 1 83- 1 85 0c) from the ethyl acetate extract, was characterized to be quercitrin from spectroscopic data and chemical reactions. On hydrolysis with 1 N HCI for 1 h, it yielded quercetin and rhamnose sugarl9.

Compound C-4, obtained as yellow needles (melting point, 1 95- 1 96 0c), was characterized to be myricitrin from spectroscopic data and chemical reactions. On hydrolysis with 1 N HCI, it yielded the aglycon, myricetin, which was identified from spectral data and the rhamnose sugar20.

The structures of the above isolated compounds are given in Fig. 1 .

The principal colouring compounds isolated from the bark of T. arjuna were identified as given below from their spectral data as well as colour reactions.

Compound F- I was obtained as yellow needles (25mg) with melting point 192- 1 93 DC [UV Ama.

(a) (b)

(e) (d) Fig. 1 - Structures of the" compounds isolated from barks of Mimusops elengi Linn. [(a) Querceti n, (b) Myricetin , (c) Quercitrin and (d) Myricitrinj

BHUYAN et a!' : EXTRACTION & IDENTIFICATION OF COLOUR COMPONENTS FROM M. ELENGI & T. ARJUNA 473

(MeOH): 250, 27 1 and 3 1 5 nm. IR Vmax (KBr) : 3200 (-OH), 1 648 (-C=O) and 1 6 1 5 cm' l (aromatic -C=C-). IH NMR (DMSO- d6) : 3 .64(s, 3H, -OMe), 6.30 (s, 1 H, H-3), 6.65 (s, 2H, H-5 and H-8), 7 .40 (m, 2H, H-3' and H-5') and 7.80 8 (m, 2H, H-2' and H-6') . Mass: 284 (M+, 1 00%)] (C I6H I20s: Found -C, 67.57% and H, 4.28%; Calcd -C, 67.60% and H, 4.25%).

The results were found to be in perfect agreement with that of 6, 4'- dihydroxy, 7- methoxy flavone2 1 .

Compound F-2 was obtained as yellow needles with melting point 26 1 -262°C. The UV absorption spectra [UV A.max (MeOH): 230, 273 and 322 nm] and the positive MglHCI test suggested the compound to be a flavone [IR Vmax (KBr): 3550(variable, sharp), 1 725 (-C=O), 1 620 and 1 580 cm,l (aromatic -C=C-). IH NMR (DMSO-d6): 6.6 ( lH, d, J= 2 Hz, H-3), 6.9 ( l H, d, J=2 Hz, H-8) and 7.6-8. 1 8 (5H, m). Mass : mlz 270 (M+, 100%), 168, 1 35] (CISHIOOS : Found -C, 66.65% and H, 3.7 1%; Calcd -C, 66.67% and H , 3.73%). The results showed that the compound i s baicalein22.23.

Compound F-3 was crystallized as yellow needles from dioxin with melting point >300°C. The compound gave green colour reaction with FeCh in ethanol [UV A.max (MeOH) : 25 1 and 362 nm. IR Vmax (KBr): 3545, 1 740, 1 620, 1 550 and 1450 cm'l . IH NMR (DMSO- d6) : 7.50 8 ( 1 H, s, H-5 and H-5')] . (CI4H60g : Found - C, 55.65% and H, 1 .98%; Calcd -C, 55 .64% and H, 2.00%). The results were found to be in perfect agreement with that of eUagic acid, the structure of which was further confirmed by the preparation of its tetra-o-methylellagic acid (m. p. 339 0c) as well as spectroscopically24.

The structures of the above isolated compounds are given in Fig 2. 3.2 Effect of Dye Concentration on Absorption and Colour

Strength

Table 1 shows that the absorption of dye on fibre increased with the increase in concentration of dye in the dye bath and reached maximum at 4% dye concentration for both Mimusops (3 1 .9 1 7%) and Terminalia ( 1 2.246%) dyes. Also, the K/S values increased with the increase in dye concentration up to 4%. On further increasing the dye concentration beyond 4%, the increase in colour strength is not significant. Further, at this optimum concentration of dye, the desired fastness properties on fibre were also obtained (Table 2). The increase in K/S values may be attributed to the increase in surface colour reflectance

H� ,-, OH lbCO�O)--O-

(3)

HO�

HO�O)--o (b)

o

H�OH �O�

(c) Fig. 2 - Structures of the compounds isolated from barks of Terminalia arjuna Roxb. [(a) 6,4' , dihydroxy, 7,methoxy flavone, (b) Baicalein and (c) Ellagic acid]

with the increase in dye concentration. Further, all the K/S values were quite high which seems to be caused by the strong interaction force between natural dyes and protein fibre (wool). 3.3 Effect of Dyeing Conditions

The colour variation due to the use of different mordants is a well-known phenomenon. Other variations arise from the differential uptake of the various mixtures of coloured components present in the dye plant extracts. Table 2 shows the dyeing properties of the dye extracted from the barks of M. elengi and T. arjuna. The tests were carried out on the mordanted and unmordanted wool fibres. A wide variety of colours in brown could be obtained from the dyes. This may be due to the presence of flavonoids in both the plant species, which are yellow colouring matters. These yellow colouring matters fade to brownish' shades presumably as a result of quinone formation25.

I t was observed that the K/S (A.max 3 10 nm for M.

elengi and A.max 305 nm for T. arjuna) values increased with the increase in concentration of mordants for both the dyes (Figs 3 and 4). However, beyond 2% concentration of each of the mordants, the increase in K/S value was not significant enough. Moreover, the desired fastness properties on fibre were also obtained at this concentration of the mordants.

It was observed that the mordant activity of metal ions followed the sequence Cu(II) --. Cr(VI) --. Sn(lI) --. AI(I1I) for both pre- and post­mordantation in case of M. elengi and the sequence Cu(II) --. Cr(VI) --. AI(III) --. Sn(II) for the mordanting techniques in case of T. arjuna. The colour intensity was found to be maximum when

474 INDIAN 1. FIBRE TEXT. RES., DECEMBER 2004

Table I - Absorption and KlS values of different concentrations of natural dyes

Plant species Am.x Dye conc. Absorbance Absorption, % KlS nm %

Before dyeing After dyeing value

Mimusops elengi 3 1 0 0.638 0.498 2 1 .943 1 0.507

2 0.654 0.486 25.688 10.781

3 0.794 0.565 28.841 1 1 . 146

4 0.824 0.56 1 3 1 .9 17 1 1 .475

5 0.898 0.631 29.733 1 1 .694

6 0.9 14 0.663 27.462 1 2.044

Terminalia arjuna 305 0.598 0.567 5. 1 84 6.732

2 1 .599 1 .456 8.943 7.429

3 2.0 1 2 1 .780 1 1 .53 1 7.977

4 2.2 1 3 1 .942 1 2.246 8.576

5 2.378 2. 1 1 2 1 1 . 1 86 9.474

6 2.401 2 . 142 1 0.787 9.673

Table 2 -Dyeing properties of fibres dyed with natural dyes extracted from the barks of Mimusops elengi Linn. and Terminalia arjulla Roxb.

Plant species Mordants Mordanting Light fastness Crock fastness Wash Shade technique Wet Dry fastness

Mimusops elellgi Nil 4 4 5 4 Brown ".

CuS04.5H2O 5 5 5 5 Brown

II 5 4 5 5 Dark brown

K2Cr207 I 4 4 5 5 Pale grey

II 5 5 5 5 Dark brown

SnCI2·2H2O I 4 4 5 4 Golden brown

II 5 5 5 5 Brown

AI(NH4)(S04h- 1 2H2O I 4 4 5 4 Pale brown II 5 5 5 5 Brown

Terminalia arjulla Nil 3 4 5 4 Pale brown

CuS04.5H2O 4 4 5 4 Grey II 5 5 5 5 Dark brown

K2Cr207 5 5 5 5 Dark brown II 5 5 5 5 Golden brown

SnCI2.2H2O 5 5 5 5 Brown II 4 5 5 5 Brown

AI(NH4)(S04h· 12H2O 4 4 5 4 Slaty II 4 5 5 5 Yellowish brown

1 - Pre-mordanting; 11 - Post- mordanting.

Fastness rating: 1 - Much changed, 2 - Considerably changed, 3 - Noticeably changed, 4 - Slightly changed and 5 - Negligible or No change

BHUYAN e/ al. : EXTRACTION & IDENTIFICATION OF COLOUR COMPONENTS FROM M. ELENG! & T. ARJUNA 475

mordanted with Cu(lI) and Cr(VI) as compared to that when mordanted with Al (III) and Sn(lI). Further, the bright shades were obtained by using 2% of CuS04.5H20 and K2Cr207, which implied that the absorption of colour by fibre was better while using Cu(lI) and Cr(VI) as mordants. The fastness tests were applied to both mordanted and unmordanted wool fibres. Fair to good wash and crock fastness

9

8

7

6 +-�--�----�--�----�, 1.5 2 2.5 3 Mordant cone. (%)

-- AI

... .-. BI

-o- CI

-- DI

----- All

-.- BII

-- CII

-o- DII

Fig. 3 - KlS as a function of Mimusops dye at different concentrations of mordant at Ama. = 3 1 0 nm [For pre­mordanting: AI = CuS04.5HzO, BI=KzCrz07, CI=SnCI2.2H20 and DI=AI(NH4) (S04)z. 1 2HzO. For post-mordanting : All = CuS04.5HzO, BII= KZCrZ07, CIl=SnCI2.2H20 and DII=AI(NH4)(S04)z. 1 2H201

(Table 2) was observed with Cu and Cr mordants, while light shades were obtained with SnCI2.2H20 and alum. 3.4 Evaluation of Colour Coordinates of Dyed Fibres

The colour coordinates of dyed samples are given in Table 3. All the colour coordinates were positive with respect to brightness (L), red-green (a) and yellow-blue (b), and therefore all of them lie in the

9

8

7 Vl :;;: 6

5

4 +-....... -----J'------'-�---''____--'-_ 1.5 2 2.5 3

Mordant cone. (%)

-<>- AI

-.- BI

.-... CI

-o- DI

-- All

-6-- BII

-o- CII

-- DII

Fig. 4 - KlS as a function of Termillalia dye at different concentrations of mordant at Ama. = 305 nm [For pre­mordanting : AI = CuS04.5HzO, BI = KZCr207, CI = SnCI2.2HzO and DI = AI(NH4)(S04)z. 1 2HzO. For post­mordanting : All = CuS04.5HzO, BIl = KZCrZ07, cn = SnClz.2HzO and DII = AI(NH4)(�04)z. 1 2HzOl

Table 3 - Colour coordinates for wool dyed with natural dyes with and without the use of mordants

Natural dye Mordant Mordanting technique Colour coordinates

L a b

M. eiellgi dye Nil 45.820 6 1 .745 17.898 CuS04.5HzO 37.820 63.8 19 20. 172

II 22.799 65.899 15 . 1 88 KZCrZ07 68. 1 29 8. 179 3 . 1 59

n 20.872 66.9 1 5 13. 1 29 SnClz·2H2O I 48. 1 79 67. 1 89 35.2 1 8

n 42.872 65.230 19.87 1 AI(NH4)(S04)z · 1 2HzO I 52.897 59.898 39.872

II 45.981 62.985 1 6.8 13 T. arjullG dye Nil 46.54 1 2 1 .8 1 7 5 1 .82 1

CuS04.5H2O 38.732 38.290 29. 1 79

II 30.061 1 9.972 1 5 .488 K2Cr207 I 32.334 5 1 .890 30. 1 49

I I 30.872 17.8 1 1 52.589 SnClz.2H2O 42. 129 1 5 .898 69.892

I I 40.487 2 1 .872 69.87 1 AI(NH4)(S04)z. 1 2HzO I 45.484 28. 173 1 8 . 1 90

II 38.840 23.572 52.872

1 - Pre·mordanting; II - Post-mordanting

476 INDIAN J. FIBRE TEXT. RES., DECEMBER 2004

yellow-red quadrant of the colour space diagram. Further, the L values decreased corresponding to deeper shades on mordanting.

For wool fibres dyed with both Mimusops and Terminalia dyes and post mordanted with CuS04.5H20 and K2Cr207, the lowest L values indicated deeper shades on mordanting with these metal salts compared to that mordanting with SnCh.2H20 and alum with higher L values indicating lighter shades.

Thus, for both the dyes, Cu(II) and Cr(VI) may effectively be used as mordant salts.

4 Conclusion

The colour components isolated from the barks of M. elengi and T. arjuna contained mainly flavonoid moiety. The dyed and post-mordanted samples showed better fastness properties. Therefore, the dyes obtained from these plant sources might be an alternative to synthetic dye for dyeing of wool.

Acknowledgement

One of the authors (RB) is thankful to the Council of Scientific and Industrial Research, India for awarding a senior research fel lowship.

References

Sewekow U. Melliand Textilber, 69(4) ( 1 988) 1 45 .

2 Eom S, Shin D & Yoon K, Indian J Fibre Text Res, 26 (2001 ) 425.

3 Padhy R N & Rathi D, Text Dyer Printer, 23(25) ( 1 990) 27.

4 Garg A, Shenda S & Gupta K C, Colourage, 38(2) ( 199 1 ) 50.

5 Gupta D R, Text Dyer Printer, 23(1 0) ( 1 990) 2 1 .

6 Chadha Y R, Wealth of India : Raw Material. Vol. X (CSIR, Delhi, India), 1 976, 1 6 1 .

7 Dutta A C, Dictionary of Economic and Medicinal Plants (Assam Printing Works, Jorhat, India), 1 985.

8 Shastri B N, Wealth of India: Raw Material. Vol. VI (CSIR, Delhi, India), 1 962, 383.

9 Subramanian S S & Ramachandran Nair A G, Curr Sci� 42(2 1 ) ( 1 973) 746.

1 0 Sharma P N , Shoeb A , Kapil R S & Popli S P, Indian J Chem, 2 1 B ( 1 982) 263.

1 1 Mathur J P & Bhandari C S, Indian J Fibre Text Res. 26(4) (200 1 ) 432.

1 2 Sal igram AN, Singh S , Shrivastava R S & Shukla S R, Am Dyest Rep, 82(5) ( 1993) 30.

1 3 Indian Standard Specifications. IS: 1349 (Bureau of Indian Standards, New Delhi 1 10 002), 1964.

14 Technical Manual of MTCC, Vol 25 (American Association of Textile Chemists and Colorists, USA), 1968, 6 19.

1 5 Wyszechi G & Stiles W S , Colour Science: Concepts and Methods. Quantitative Data and Formulas (John Wiley and Sons Inc), 1 967, 460.

1 6 Chauhan S M S , Mishra M K, Prakash S & Kaushik R, J Indian Chem Soc, 75 ( 1 998) 328.

1 7 Awasthi Y C & Mitra C R, J Org Chem, 27 ( 1 962) 2636.

1 8 Rao M M , Gupta P S, Krishna E M & Singh P P, Indian J Chem, 1 7B ( 1979) 178.

19 Pollock J R A & Stevens R, Dictionary of Organic Compounds, Vol V (Eyre and Spottiswoode Publishers Ltd, London), 1 965, 2834.

20 Lamer E, Malcher E & Grimshaw J, Tet Lett, 1 2 ( 1968) 1 4 1 9.

2 1 Buckingham J & Macdonald F, Dictionary of Organic Compound, Vol 6 (Chapman and Hall Electronic Publishing Division, London), 1 996, 6247.

22 Ahmad S A, Siddiqui S A & Zaman A, Indian J Chem, 1 2B ( 1 974) 1 327.

23 Kutney J P & Hanssen H W, Phytochemistry, 1 0( 1 2) ( 1 97 1 ) 3298.

24 Nawwar M A M, Buddrus J & Bauer H, Phytochemistry, 2 1 (7) ( 1 982) 1 755.

25 Grierson S, Duff D G & Sinclair R S, J Soc Dyers Colour, 2 1 ( 1 985) 220.