DESCRIPTION TECHNICAL FIELD

The present invention relates to a method for preparing a green colouring mixture from plant material of plants belonging to the Myrtus genus, the green colouring mixture obtainable by said method and its use in colouring procedures. The method and the products of the invention are used in the dyeing of animal fibres, plant fibres, leathers, paper and other products.

PRIOR ART

Natural colourants have been used for millennia in the textiles, cosmetics, food and artistry industries. With th e d iscovery i n 1 853 of the first synthetic colourant, mauveine, and, above all, with the discovery of the chemical synthesis of alizarin and of indigo, there was an extremely rapid substitution of natural colourants with synthetic colourants due to the lower cost, the greater reproducibility of the colour and standardization of the process. By the end of the 19 ^th century synthetic colourants had almost completely replaced many natural colourants (Marotti M, 1997. Le piante colouranti. Edagricole, Bologna).

In the textiles industry the rediscovery of natural colours was linked in part to the growing number of individuals suffering from contact dermatitis (Manzini B M et al. 1996 Sensitization to reactive textile dyes in patients with contact dermatitis. Contact Dermatitis, 36, 91 -96. Contact Dermatitis, 34, 172-175; Giusti F et al. 2003 Contact sensitization to disperse dyes in children. Pediatric Dermatology, 5, 393- 397; Giusti F et al. 2003 Textile dyes sensitization: a study on 49 patients allergic to disperse dyes alone. Contact Dermatitis, 48, 54-55.; Seidenari S et al. 2002 Sensitization to 7 disperse dyes in a patch test population over a 5-years period. Am. J. Contact Dermat 13, 101 -107). Furthermore, the greater attention to natural, hand-made products of greater quality, associated with tradition and territory and with the need to identify processes with lower ecological costs further contributed to the d evelopment of methods and processes for obtaining natural colourants (Bhuyan R et al. 2005 Isolation of colour components from native dye-bearing plants in northeast India. Bioresource Technology, 96, 363-372; Li et al . 2003 Current application status and developments of natural dyes. Ranliao Yu Ranse, 40, 1 , 36- 38.; Sood A et al. 2005 Effect of union dyeing of wool with Litchi and Apricot dye material. Man-made Textiles in India, 48,5,205-207).

However, not all the colours are available in the plant world with the same level of ease. In fact, some pigments are present in a reduced number of plants, as is the case with blue which is extracted from Indigofera tinctoria L, Polygonum tinctorium Ait., Isatis tinctoria L. by a rather laborious process which makes it possible to extract indigo blue. For other colours, as is the case with green obtained from plants containing chlorophyll, the problem is instead caused by the low light fastness of these pigments. In fact, although chlorophylls are extremely widespread in the plant world, they are characterised by high instability and, above all, low light fastness (Marotti M, 1997. Le piante colouranti. Edagricole, Bologna).

For this reason, in the ancient world and still today in fact, the colouration in different shades of green is largely carried out by dyeing the fibres first with a yellow plant and then by dipping them in the blue dye obtained from indigo plants (Indgofera tinctoria L, Polygonum tinctorium Ait., Isatis tinctoria L.,). This process requires the use of suitable reagents (caustic soda, sodium hydrosulphite) which enable a first phase of solubilisation of the indigo powder by a reduction reaction and subsequent air oxidation with consequent precipitation of the blue pigment and colouration of the fibre (Cardon D, 2003 Le monde des teintures naturelles, Belin, Paris). However, this process already has some drawbacks linked in part to the limited availability, as already indicated above, of "blue" plants represented basically by Indigofera tinctoria L, Polygonum tinctorium Ait., Isatis tinctoria L, and in part to the laboriousness and higher environmental cost of the process of extraction of the primary blue pigment, i.e. indigo blue (Angelini L et al. 2008 Vegetative production and indigo yield of woad (Isatis tinctoria L.) and dyer's knotweed (Polygonum tinctorium Ait.) under irrigation in central Italy. Ital.J.Agron., 3 Suppl . , 427-428.; Cardon D, 2003 Le monde des teintures naturelles, Belin, Paris; Marotti M, 1997 Le piante colouranti. Edagricole, Bologna).

The known prior art reports numerous attempts to identify colouring plants in order to obtain a natural green colour. For example, Chinese green (introduced to France from China towards the middle of the 19 ^th century) affords the advantage of being easily used and is extracted from Rhamnus dahurica Pall, and Rhamnus tinctoria Waldst & Kit. However, the previously high cost of the material led to the current need to find alternative, more economical sources such as Rhamnus catartica L. which, according to Cooksey et al. (Cooksey C et al. 2005. Chinese green, an enduring mystery. Dyes in history and archaeology, 20, 155-164) makes it possible to obtain a similar colour even if, still today, complete phytochemical characterisation has not been achieved. Furthermore, the known prior art reports methods for obtaining the green colourant from other plants, as described for example by Gupta et al. (Gupta AP et al. 2005 A process for the extraction of stable green dye from Eclipta alba. IN 1999 D00234) Eclipta alba or from Tulsi basil leaves, as described by Patel et al. (Patel et al . 2006. Eco-friendly dyeing with extracts of Tulsi leaves. Natural Dyes: Scope and Challenges, 185-195). With regard to Tulsi in the procedure reported, the green colour is obtained by extraction in methanol whilst in water the acquisition of a brown colour is described; the green from Eclipta is instead obtained after a double extraction first in polar solvent, and then in organic solvents. Furthermore, in the Mediterranean region the green musk colouration is reported by extract obtained in wild lavender water (Lavandula stoechas L), as reported by the M. EIda Salice Association of Natural Dyeing (Associazione M.EIda Salice 2003 Per erbe e per tinture in Sardegna). As already highlighted, the method used nowadays to obtain a natural green colourant remains, however, substantially linked to the combination of yellow and blue colours obtained from indigo plants.

The object of the present invention is to identify an effective method which makes it possible to obtain a green colouring mixture from plant material which makes it possible to overcome the drawbacks regarding the extraction and dyeing with natural green colourants present in the known prior art and described above.

SUMMARY OF THE INVENTION

The present invention is based on the surprising discovery that plants belonging to the Myrtus gen us can be used as starting plant material for the preparation of a green colouring mixture. In particular, such a green colouring mixture, in accordance with that disclosed herein, is extracted directly from the plant material harvested from species belonging to the Myrtus genus.

The preparation of a green colouring mixture, in accordance with that disclosed in the present invention, is obtained by the selection of experimental conditions and of the solvent used for extraction, these conditions making it possible, more specifically, to obtain directly by single extraction a green colouring mixture from plant material of species belonging to the Myrtus genus.

However, a first object of the present invention is a method for preparing a green colouring mixture comprising a step wherein the colouring mixture is extracted from berries belonging to plants of the Myrtus genus or from berries and plant material belonging to plants of the Myrtus genus by heating in distilled water at a temperature comprised in the range of 50-80 °C, extremes included, for a time of about 30-120 min.

In a specific embodiment, said plant belonging to the Myrtus genus is the Myrtus communis L species.

In a further embodiment of the invention the plant material is formed by the combination of berries and leaves and/or twigs. The present invention secondly relates to a green colouring mixture which is obtainable by the method disclosed above.

The invention thirdly relates to a composition comprising said colouring mixture and at least one or more thickeners, adjuvants, oxidizing or preservative agents.

The invention further relates to the use of said mixture or composition in a process of colouration of a material.

The invention also relates to a dyeing method comprising the step of adding material to be dyed in a colour bath comprising said green colouring mixture or said composition maintaining a temperature of about 50-80 °C for a time of about 30-120 minutes.

The present invention affords advantages over the known prior art: it identifies a new plant from which a green colouring mixture can be extracted. This m ixtu re makes it possi ble to dye th i n gs i n d ifferent shades of green , all characterised by greater light fastness compared with the green colour obtainable by the methods described in the known prior art. Furthermore, the method of extraction is a highly eco-compatible method since the only solvent used is water.

The method uses a plant belonging to the Myrtus genus, which is a genus which is extremely widespread over the entire territory of the Mediterranean region and is a plant material which is readily available, economical and of which the exploitation may provide a valid contribution to the safeguarding of biodiversity. Furthermore, its use makes it possible to attribute to the products obtained a strong link with the region.

The method developed is characterised by increased eco-compatibility both with regard to the choice of starting material and with regard to the characteristics of the method itself. In fact, the use of distilled water as a solvent facilitates the removal of the residues and makes it possible for them to be recovered easily.

From an agronomic point of view, the harvesting limited to the aerial portion of the plant (berries and leaves) ensures a better coverage of the ground, above all in areas which are vulnerable in terms of erosion. GLOSSARY

Plant material In the present invention the expression 'plant material' means any part of the plant, that is to say for example leaves, branches, roots, flowers.

Green colouring mixture For the purposes of the present invention the expression 'green colouring mixture' means all pigments responsible for the colouring power of a natural extract within the green colour scale.

Mordanting The term 'mordanting' generally means the subjection of one or more fibres to be dyed to the action of a substance which fixes the colour.

Colour bath A 'colour bath' is the solution containing the colouring mixture or a composition thereof in which the material to be dyed is dipped.

DETAILED DESCRIPTION OF THE DRAWINGS

Fig. 1 image A is in colour; image B is in black and white; The figure shows fibres of new wool (a) dyed with dried berries of Myrtus communis L (b) and dried berries and leaves (c) after extraction in distilled water.

Fig. 2 image A is in colour; image B is in black and white; The figure shows fibres of new wool (a) dyed with dried berries of Myrtus communis L (b) and dried berries and leaves (c) after extraction in tap water.

DETAILED DESCRIPTION

The present invention provides, for the first time, a method for preparing a green colouring mixture from plants belonging to the Myrtus genus.

The method disclosed herein makes it possible to prepare directly a green colouring mixture from the species of the Myrtus genus by a single extraction in which the starting material is represented by the plant material belonging to said genus and from which, instead, until now it was known to extract only the colour yellow from the leaves and the colour blue-violet from the berries, which are colours which, if obtained individually and mixed, do not give rise to a green colour as would be expected by the average person skilled in the art.

This description therefore reports a method which makes it possible to prepare a green colouring mixture which is obtainable directly by extraction from only berries or from a combination of berries and plant material.

This present invention therefore provides a method for preparing a green colouring mixture from plants belonging to the Myrtus genus comprising a step wherei n the green colou ring m ixtu re is extracted from berries or from the combination of berries and plant material by heating in distilled water at a temperature comprised in the range of 50-80 °C, extremes included, for a time of about 30-120 minutes.

The plants which are suitable for the present invention are plants belonging to the Myrtus genus, which is a genus of the family of Myrtaceae which is known to originate from hot and subtropical regions and which is widespread, above all, in the Mediterranean region. Species belonging to said genus are Myrtus communis, which is extensively widespread in the Mediterranean region, and Myrtus nivellei which is present in southern Algeria and Chad.

In one embodiment of the present invention, the plant is the Myrtus communis L. species.

Said species has a shrubby arrangement or that of a small sapling formed of bark, leaves, flowers and berries. It has opposing, persistent, oval-pointed, tough, smooth, shiny, straight-edged leaves with many translucent points in line with the aromatic glands. The flowers are solitary and axillary, perfumed, pedunculated, wh ite an d rose-coloured flowers. It has rayed symmetry with a persistent gamosepalous calyx and a dialypetalous corolla. The androecium is formed of numerous stamen which are obvious by the long filaments. The ovary is lower, subdivided into 2-3 cells terminating with a simple stylus which is mixed up among the stamen and a small stigma. The bloom, which is abundant, appears in late spring and at the start of summer, from May to July. The fruits are spherical-ovoid berries which are black-bluish, dark red or more rarely whitish berries with numerous kidney-shaped seeds. They ripen from November to January, remaining on the plant for a long period (Pignatti A. 2002. Flora d'ltalia, Ed agricole, Bologna).

A key condition of the method described herein is that the colouring mixture is extracted from plant material by heating in distilled water. I n a particular embodiment the distilled water which can be used for the extraction described herein is characterised by resistivity equal to approximately 18 ΜΩ-cm.

The heating in distilled water is carried out at a temperature of 50-80 °C, more specifically a temperature of approximately 50 °C, or approximately 55 °C, approximately 60 °C, approximately 65 °C, approximately 70 °C, approximately 75 °C, approximately 80 °C. The heating is carried out, as is also easily deducible by the person skilled in the art, for a time which is sufficient to achieve extraction of a colouring mixture from the plant material. In particular, the heating in distilled water may be carried out for a time of about 30-120 minutes.

This time period makes it possible to obtain an extraction which is optimal in quantitative and qualitative terms. I n fact, a shorter period defines a reduced extraction of the colour and/or leads to a mixture with a very weak colouring power. Furthermore, the inventors observed that heating for longer or shorter periods alters the colouring mixture, for example in that a fibre dyed with the colouring mixture according to the present invention assumes colourations which fall within the GY - G - BG tables of the Munsell Colour Atlas whereas a green colouring mixture obtained with times and temperatures which are different from those defined before assumes a colouration which falls within the Y table of the Munsell Colour Atlas.

In accordance with a specific embodiment, the extraction is carried out by heating of the plant material in distilled water at a temperature of 70 °C for about 60 minutes.

The extraction of the mixture provides the predisposition of plant material belonging to the species in question. In the present invention the expression 'plant material' means a specific part of the plant, that is to say for example leaves, berries and branches. ln a specific embodiment the starting plant material is formed of berries or of the combination of berries and leaves and/or branches.

I n particular, the berries should preferably be provided at th ei r poi nt of ripeness. In accordance with the present invention 'berries at the point of ripeness' means berries which have darkened, that is to say those in which a change in colour from green to dark red-violet is observed as a result of the presence of anthocyans.

The plant material can be used fresh or dried. The drying process can be carried out in accordance with any one of the methods known to the person skilled in the art, who will be able to carry it out without having to provide further technical details in this invention. Among the various drying methods, such as air drying, heated airflow d rying with a fluidised bed cabinet (tunnel), vacuum drying and lyophilisation, drying methods which provide the use of low temperatures can be preferably selected since they lead to a dried plant material which is characterised by a greater colouration power compared with that obtained using high temperature methods. Furthermore, the drying makes it possible to maintain the colouration power of the plant material over time. In particular, in accordance with the present invention low-temperature drying means a process i n wh ich the temperature is approximately 30-50°C, for example a temperature of approximately 30°C, approximately 32.5°C, approximately 35 °C, approximately 37.5 °Cm approximately 40°C, a p p roxi m atel y 42.5°C, approximately 45°C, approximately 47.5°C, approximately 50°C. Purely by way of non-limiting example a possible process of low-temperature drying which can be used is hot airflow drying with a dryer cabinet at a temperature of approximately 50°C. Furthermore, the plant material can be used entire or fragmented , for example ground, pressed, disaggregated, crushed, etc. The use of material which is not entire makes it possi ble to promote the extraction of colour more easily compared with the use of entire material . The grinding, disaggregation, pressing, or crushing can be carried out in accordance with any one of the methods known to the person skilled in the art and reported in the prior art. For example, grinding processes which can be used for the purposes of the present invention can be carried out using machines with rotating blades or blade crushers.

As mentioned above, the berries can be used as the only starting plant material for the preparation method or in combination with leaves and/or branches. I n the berries an d leaves com bi nation , depend i ng on the percentage of th e combination of such plant material, a colouring mixture in different green shades is obtained. In particular the combination of berries and leaves can occur according to berries/leaves ratios comprised in the range of approximately 1/9 to 9/1 , for example of approximately 1 to 9, 2 to 8, 3 to 7, 4 to 6, approximately 5 to 5, approximately 6 to 4, approximately 7 to 3, approximately 8 to 2, 9 to 1. It has been observed that the increase in the combination of the percentage of berries is accompanied by a shade of green which is more intense compared with that observed in preparation methods in which a combination is used which has a lower percentage of berries. In particular, the combination of berries with leaves results in a shift in the obtainable shades. In fact, said shades fall within the 2.5 GY and 5 GY tables of the Munsell Atlas. The reduction in the percentage of leaves reduces the shades which are obtainable in the 7.5 GY and 10 GY tables of the Munsell Atlas.

It is therefore obvious that the person skilled in the art, based on the teaching provided in this description, will be able, without any inventive activity, to define the optimal berries/leaves ratio to obtain a colouring mixture of the desired shade of green.

The colouring mixture thus obtained is then separated from the solid residual plant material by any separation method. This mixture is then recovered. Examples of separation methods which can be used include filtration, centrifugation, etc. These methods are routinely used in laboratory practice and are described in detail in any laboratory manual and therefore do not require further study. Purely by way of example, the mixture may be filtered using a filter which has a suitable cut off. The person skilled in the art will be able to select the filter with a cut off which is most suitable for filtration based on the amount of material to be separated present in the colouring mixture. In particular, the possibility of filtration which is more effective could be considered by selecting, more specifically, to carry out double filtration in order to initially separate the coarser material and then the finer material with the use, for example, of filters having progressively narrow meshes.

The colouring mixture obtained is characterised by an increased power of colouration and by greater light stability compared with that which can be observed for the mixtures obtained by the methods reported in the known prior art.

In one embodiment the mixture obtained as disclosed herein may be provided subsequently in the form of powder, solution, suspension, granules, paste, tablet, or freeze-dried.

These specific embodiments are developed by methods known to the person skilled in the art and described in detail in technical manuals.

The present invention also relates to a composition comprising the mixture obtained as disclosed herein, and one or more thickeners, adjuvants, anti-oxidizing, preserving or colouring agents, etc.

Said compositions may be in the form of powder, solution, suspension, granulate, paste, tablet or spray.

The above-described features of the mixture and also of the compositions that contain it make it usable for the colouration, in various shades of green, of various materials by colouring processes. Such materials can, for example, be materials comprised in the group of natural fibres, animal fibres, synthetic fibres, leather, paper, cardboard, ceramic, wood, plastic, glass.

In particular therefore, said mixture and also the compositions containing it may be used in a colouring process carried out on an industrial scale in companies that operate in different industries such as textiles, for example clothing and furnishings, cosmetics, construction, leather decoration, etc.

In one embodiment said mixture or said compositions can be used in a colouring process, in various shades of green, for natural fibres such as wool, silk and, more generally, natural fibres of animal origin.

In this instance it will be necessary, in particular, to prepare the mixture in accordance with the method described above, taking into account the weight of the fibre to be coloured. In particular, for effective colouration the ratio between the weight of the fibre and the weight of the fresh plant material should be between 1 :0.75 and approximately 1 :4. If, instead, the starting plant material is dried, the ratio of the weight of the fibre to the weight of the dried material should be comprised in the range between approximately 1 :1 and 1 :4.

As is known to the person skilled in the art, fibres are coloured efficiently once the fibres to be coloured have been mordanted . The term 'mordanting' generally means to subject one or more fibres to be coloured to the action of a substance which fixes the colour. Although this step is not part of the invention, the person skilled in the art will be aware of the fact that an effective process of colouration requires an initial phase of mordanting of the material to be coloured. For this reason , in the embodiment regarding the colouring of natural fibres of animal origin, the optional phase of mordanting can be carried out in accordance with any method known to the person skilled in the art. Purely by way of example, the mordanting of the fibres of animal origin can be carried out in accordance with the protocol reported below:

• wash i ng th e fi bres i n d isti l led water with M arsei l le soap at temperatures comprised between 30°C and 50°C

• preparation of the mordant with potassium alum (20%) and cream of tartar (5 %) in distilled water in an amount sufficient to completely cover the material to be mordanted

• mordanting by heating for a period of time comprised between 30 and 90 minutes in a temperature range comprised between 50°C and 80°C.

The material to be coloured comprises, for example, natural fibres, natural fibres of animal origin, synthetic fibres, leather, paper, cardboard, ceramic, wood, plastic, glass.

In a specific embodiment of the invention in which the colouring method is a dyeing process, said method comprises a step of adding the material to be dyed, which possibly could already be coloured per se, for example yellow, in a colour bath comprising said mixture or said composition, holding a temperature of 50-80°C for a time of about 30-120 minutes. Said temperature may be approximately 50°C, approximately 55°C, approximately 60°C, approximately 65°C, approximately 70°C, approximately 75°C, or approximately 80°C.

The dyeing method may comprise a step of eliminating the excess of colour by one or more washes in water at a temperature of about 30-50°C, for example 30°C, 32.5°C, 35°C, 37.5°C, 40°C, 42.5°C, 45°C, 47.5°C or 50°C.

A step of adding distilled water or tap water to the colour bath or to the mixture as defined above may optionally be provided. The distilled water is added in order to ensure the complete dipping of the material to be dyed in the colour bath and is also dependent on the type of shade which it is sought to achieve. It will be obvious to the person skilled in the art that the greater the volume of the material to be dyed, the more water will have to be added to the colour bath or to the mixture.

The present invention also relates to a variant of the method for colouring in green fibres of animal origin comprising the following steps

a) dipping directly said fibres and plant material belonging to a plant form the Myrtus genus into water

b) heating that provided under point a) at a temperature of 50-80°C, extremes included, for a time of about 30-120 minutes

c) recovering the fibres so coloured.

The plant material , the amounts, ratios and operating conditions have already been indicated above.

This method is carried out by dipping, in a suitable volume of water, the natural fibres of animal origin and the plant material. 'Suitable volume of water' means a volume sufficient for the complete immersion both of the plant material and of the fibre to be dyed in said solvent. The plant material may optionally be placed in a suitable filter and then dipped in the solvent useful for extraction.

In a specific embodiment, said natural fibres of natural origin are wool fibres.

In order to carry out this variant of the colouring method, either distilled water or tap water can be used. The heating is carried out at a temperature of 50-80°C for a time of about 30- 120 minutes. The conditions regarding heating and, more specifically, temperature and time are the same as those defined for the method of extraction described above.

The fibres thus coloured are then separated by separating the filter contain ing the plant material or by the optional step of filtration , as already described. Any excess of colour from the coloured fibre can be removed by washing in tap water or distilled water at a temperature of 30°C and 50°C.

The invention also relates to the material coloured in accordance with the dyeing methods disclosed herein.

An agreed embod iment of the invention is described in the following examples which are purely illustrative of the methodology described in the present patent application. These examples are in no way to be considered as a limitation of the scope of protection afforded.

EXAMPLES

Example 1. Preparation of the colouring mixture

• Preparation of the plant material weighing 50 g of fresh berries

• Dipping of the berries in 1 .5 litres of distilled water (ratio 1 :1 between fibre and plant material)

• Heating in distilled water to a temperature of 70°C for 90 minutes

• Crushing of the berries in order to promote the release of the colour

• Double filtration of the colouring mixture with a 1 .25 mm sieve in order to separate the coarser plant material and then with a 1 .18 mm sieve in order to separate the finer material.

Example 2. Mordanting

• washing of 50 g of new wool with Marseille soap at a temperature of 40 °C and rinsing, both using distilled water

• preparation of the mordant with potassium alum (10 g) and cream of tartar (0.25 g) in 3 litres of distilled water

• Mordanting by heating at 70°C for 60 minutes

Example 3 Colouring of new wool yarn using fresh myrtle berries

• Bringing the colouring mixture to a vol u m e of 3 litres by adding distilled water

• Dipping of the mordanted fibres in the mixture

• Heating of the mixture, holding the temperature at 70°C for 60 minutes

• Removal of the excess colour by washing in distilled water at a temperature of 30 °C.

BIBLIOGRAPHY

Angelini L et al. 2008 Vegetative production and indigo yield of woad (Isatis tinctoria L.) and dyer's knotweed (Polygonum tinctorium Ait.) under irrigation in central Italy. Ital.J.Agron., 3 Suppl., 427-428

Bhuyan R et al. 2005 Isolation of colour components from native dye-bearing plants in northeast India. Bioresource Technology, 96, 363-372

Cardon D, 2003 Le monde des teintures naturelles, Belin, Paris

Cooksey C et al. 2005. Chinese green, an enduring mystery. Dyes in history and archaeology, 20, 155-164De Falco E et al., 2008 Individuazione di piante tintorie tra la flora del Parco del Cilento e Vallo di Diano. Primi risultati. VIII Convegno Biodiversita, Lecce, 21 -23 aprile, 87. Italus Hortus

Giusti F et al. 2003 Textile dyes sensitization: a study on 49 patients allergic to disperse dyes alone. Contact Dermatitis, 48, 54-55.

Giusti F et al. 2003 Contact sensitization to disperse dyes in children. Pediatric Dermatology, 5, 393-397

Gupta AP et al. 2005 A process for the extraction of stable green dye from Eclipta alba. IN 1999 D00234

Li et al. 2003 Current application status and developments of natural dyes. Ranliao Yu Ranse, 40, 1 , 36-38.

Manzini B M et al. 1996 Sensitization to reactive textile dyes in patients with contact dermatitis. Contact Dermatitis, 36, 91 -96. Contact Dermatitis, 34, 172-175

Marotti M, 1997. Le piante colouranti. Edagricole, Bologna

Patel et al. 2006. Eco-friendly dyeing with extracts of Tulsi leaves. Natural Dyes: Scope and Challenges, 185-195

Pignatti A. 2002. Flora d'ltalia, Ed agricole, Bologna

Seidenari S et al. 2002 Sensitization to 7 disperse dyes in a patch test population over a 5-years period. Am. J. Contact Dermat 13, 101 -107

Sood A et al. 2005 Effect of union dyeing of wool with Litchi and Apricot dye material. Man-made Textiles in India, 48,5,205-207