Field of the invention
The present invention relates to dendrimer with improved moisturization properties andi process for preparing the same. More particularly, the present invention further relates to the; formulation comprising said dendrimers and processes for preparation thereof.
Background and prior art
Cosmetic compositions may be of several different kinds to suit several different purposes. Some cosmetic compositions may include moisturizers. Based upon the specific; requirement, different kinds of moisturizers may be added to cosmetic compositions. These are primarily humectants (such as polyols, urea, lactic acid, sorbitol, etc.), natural moisturizing factors (NMF) (such as ammonia, aminoacids, glucosamine, creatinine, citrate,1 sodium, potassium, chloride, phosphate, calcium, magnesium etc.), emollients (such as; lanolin, octyl dodecanol, hexyl decanol, oleyl alcohol, decyl oleate, isopropyl stearate, isopropyl palmitate, isopropyl myristate, hexyl laureate, dioctyl cyclohexane, etc.), occlusives (such as petrolatum, mineral oil, siloxanes (dimethicone, cyclomethicone, etc.), or a combination thereof.
The term "humectants" as applied herein refers to molecules which when applied to a skin surface, control its water level by binding to water and delivering it where required. Humectants are water-soluble compounds, typically polyols, gelatin, hyaluronic acid, honey, panthenol, propylene glycol, sodium and ammonium lactate and the like. The most common polyol is glycerol, but other examples include sorbitol, propylene glycol, butylene glycol etc. Improvement in moisturizing property of a cosmetic is frequently achieved by increasing the amount of moisturizers used. This may adversely affect the sensorials of the cosmetic. Even polyols, such as glycols, glycerols and sorbitol which constitute a part of most cosmetic formulations, if added in higher concentrations are known to exhibit undesirable effects such: as an oily and sticky feel. Thus, the final formulations may be thicker in consistency, higher; in viscosity and low on gloss and shine thus affecting their overall performance and usefulness.
Cosmetic technologists are therefore continually on the look out of newer molecules and cosmetically viable actives that can provide effective moisturization to the human skin and can be formulated without majoriy affecting the desirable physical parameters of a given formulation. Search for better moisturizing actives has therefore continually been the focal point of cosmeceutical research.

Water holding property of an active may be improved by increasing the number of water reactive hydroxyl groups in the active molecule. One such approach has been the designing of molecules with higher number of hydrogen binding groups through increase in chain! length. Such molecules include di-glycerols and tri-glycerols. A rise in water absorption ability in vitro, at a rate of about 0.25 mol water per hydroxyl group was described in thei consecutive set of glycerols (mono-, di- and tri-glycerol) in the article "The connection between in vitro water uptake and in vivo skin moisturization" published in Skin Res. Techno/. 2003, 9, 306. Surprisingly, this increase in water absorption ability does not; correlate with the in vivo moisturization efficacy. Glycerol which has the lowest humectant activity in vitro, was found to be the best for eliminating the signs of skin dryness indicating: that the connection between in vitro humectancy and in vivo moisturization is not a simple! correlation.
In vivo studies reported in the article " Changes in the physical properties of the stratum comeum following treatment with glycerol" published in J. Soc. Cosmet. Chem. 1988, 39, 367 suggest improved skin conditioning underwhich glycerol was found to penetrate and accumulate in the stratum comeum. Washing with soap and water did not remove it.
Further it is seen that the chain length of these molecules can be increased only to a certain; extent. Longer chained molecules restrict the ease of designing with multiple groups. These molecules tend to get assorted very easily and are hence difficult to formulate. It is also difficult to prepare them in a controlled manner.
Another approach has been the use of macromolecules for cosmetic application. US 6,001,342 disclose the use of primary amine terminated dendrimers in deodorants. US 6,180,119 disclose use of primary amine dendrimers for enhancing the photostability of cinnamate esters. US 6,582,685, US 6,284,233 and US 6,287,552 disclose the use of hydroxyl terminated dendrimers. It appears that none of the prior art patents discloses the use of dendrimers for improvement in moisturization.
WO2008135246(A1) describes the preparation of porous and nonporous epoxide polymers for use in chromatography, water treatment and other technologies. These polymers are prepared through the polyaddition of epoxides initiated by small amounts of nucleophiles such as water, ammonia, alcohol or amine in the presence of catalysts.
US 6093793 describes the production of polyether polyols by acid-catalyzed polyaddition of aikylene oxides to starter compounds having active hydrogen atoms such as alcohols, amines, acid amides or phenols.

US 4543430 and EP-A 212820 disclose processes for the preparation of low molecular weight addition products of epoxides and alcohols by catalytic reaction in a homogenous liquid phase. Alcohol nucleophiles are used in large excess to obtain high selectivity in favour of 1:1 adducts.
There is therefore a constant need to identify new molecules that offer precise control on architecture and synthesis, are safe, stable, cosmeceutically compatible, do not alter the physical or sensorial attributes of a cosmetic preparation and provide optimum moisturization even at low concentrations.
There is consequently an unmet need to provide a composition comprising a moisturizing: dendrimer. There is also a need for a process for preparing a composition comprising a moisturizing dendrimer.
Objects of the invention
The primary objective of the invention is to provide dendrimer with moisturising properties A further object is to provide a composition comprising a moisturizing dendrimer. Another objective of this invention is to provide a process for preparing a composition comprising a moisturizing dendrimer.
Brief Description of the Accompanying drawings
FIG. 1 illustrates a general structure of a dendrimer of the present invention
Summary of the invention
According to one aspect there is provided a moisturizing dendrimer comprising at least one of:
a) a vicinal hydrogen bonding group;
b) a geminal hydrogen bonding group;
c) a combination of a and b thereof.
According to another aspect there is provided a process for the preparation of the moisturizing dendrimer, comprising the steps of:
a. allylation of at least one dendrimer core comprising at least on hydroxyl group
b. oxidation of allyl group to an epoxide
c. ring opening of epoxide with nucleophile having at least one hydrogen bonding
group.

According to a further aspect there is provided a composition comprising at least one moisturizing dendrimer comprising at least one of:
a) a vicinal hydrogen bonding group;
b) a geminal hydrogen bonding group;
c) a combination of a and b thereof; and
d) conventional ingredients.
Detailed Description of the Invention
Within the scope of the present patent specification, the term "composition" refers to formulation of chemical components of various usage and properties. The definition generally includes topical, cosmetic, hair care, skin care and personal care compositions such as moisturisers, sunscreens, fairness creams, antiwrinkle creams, shampoos, conditioners, hair fixative gels, hair dyes, soaps, shower gels, talcs, deodrants, lip-balms and the like.
The nomenclature "dendrimer" or "dendritic" typically refers to macromolecules having repeating branched species. Dendrimers are generally understood to be unimolecular assemblages that possess three distinguishing architectural features, namely, (i) an initiator core, (ii) chain extenders composed of repeating units, radially attached to the initiator core, and (iii) an exterior surface of terminal functionality i.e., terminal functional groups, attached to the terminal end of the chain extender.
The size and shape of a dendrimer molecule and the functional groups present in the dendrimer molecule can be controlled by the choice of the initiator core, the number of chain extenders (i.e. tiers) employed in creating the dendrimer.
The terms "moisturization" and "moisturizing effect", sometimes used interchangeably, refers to effects shown by moisturizers on application to a skin surface. The effects may include, among others, the repair of skin barrier, retention or increase in water content, reduction in trans-epidermal water loss (commonly referred as TEWL'), restoration of a lipid barrier's ability to attract, hold and redistribution of water, and the maintenance of skin integrity and appearance.
The term "moisturizer" used herein refers to unique molecules and chemical compositions comprising varying combinations of emollients, occlusives, and humectants. Cosmetic composition may further comprise chemicals added to suit specific customer needs and may

be selected from the group consisting of cleansers, age masking factors, sunscreens, antioxidants and the like. The definition generically includes compositions used to restore the barrier function of the epidermis, to cover tiny fissures in the skin, provide a soothing protective film and to increase the water-content of the epidermis. The scope also includes compositions that slow-down the evaporation of moisture from skin, thus maintaining the skin's hydration and improving the appearance and tactile properties of dry and aging skin.
The term "high-density" as applied to hydrogen bonding groups, refers to molecules with close proximity and multiplicity of hydrogen bonding groups within a single dendritic macromolecule. The term refers to the presence of vicinal, geminal, or a combination of vicinal and geminal hydrogen bonding groups at the terminal end of the dendrimer.
The term "hydrogen bonding group" as used herein refers to groups that can form hydrogen. bonds. These include hydroxyls, amines, carboxyls, mercaptans, amides and the like.
The term "vicinal" as used herein refers to two hydrogen bonding groups bound to adjacent carbon atoms and can sometimes have either cis- or trans- orientations.
The term "geminal" as used herein refers to two hydrogen bonding groups attached to the same carbon atom,
The term "humectants" as applied herein refers to molecules which when applied to a skin surface, control its water level by binding to water and delivering it where required. Humectants include urea, amino acids, polyols, gelatin, hyaluronic acid, honey, panthenol, propylene glycol, sodium and ammonium lactate and the like.
The term "polyol" as used herein refers to chemical compounds containing multiple hydroxyl groups. Examples of polyol compounds suitable for use in the present invention include, but are not limited to, glycerol, ethylene glycol, propylene glycol, pentaerythritol, diglycerol, and polyglycerol.
As used herein the term "glycerol", refers to a chemical compound with the formula HOCH2CH(OH)CH2OH. Glycerol is also known as glycerin or glycerine or its derivatives.
The mathematical percentages stated in the present invention, unless otherwise specified, are typically used in weight/weight.
The invention generally provides compositions comprising novel macromolecules that show high moisturization. The invention discloses design of novel molecules with high density of

hydrogen bonding groups whereby the density of hydrogen bonding groups is increased without an increase in the chain length.
Accordingly, the invention provides a composition comprising at least one moisturizing dendrimer comprising at least one of vicinal hydrogen bonding groups, geminal hydrogen bonding groups, or a combination of vicinal bonding groups and geminal bonding groups.
Sometimes, the at least one moisturizing dendrimer comprises at least one hydrogen bonding group selected from the group consisting of a hydroxyl, an amine, a mercaptan, an amide, a carboxyl, or a combination thereof. On other occasions, the at least one moisturizing dendrimer comprises at least one vicinal hydrogen bonding group at the terminal end. On still other occasions, the at least one moisturizing dendrimer comprises at least one geminal hydrogen bonding group at the terminal end. The at least one moisturizing dendrimer may also comprise at least one vicinal diol at the terminal end.
In another embodiment, the present invention provides a process for preparation of a composition comprising at least one moisturizing dendrimer wherein the process comprises mixing the moisturizing dendrimer with other conventional ingredients.
In another embodiment, the present invention provides a moisturizing dendrimer comprising at least one of vicinal hydrogen bonding groups, geminal hydrogen bonding groups, or a combination of vicinal bonding groups and geminal bonding groups.
In another embodiment, the present invention provides a process for the preparation of a moisturizing dendrimer wherein the process comprises allylating at least one dendrimer core comprising at least one hydroxyl group to provide an allyl group, oxidizing the allyl group to provide an epoxide group, and opening the epoxide ring structure with a nucleophile having at least one hydrogen bonding group to provide the moisturizing dendrimer.
In another embodiment, the present invention provides a process for the preparation of a moisturizing dendrimer wherein the process comprises alkylating at least one dendrimer core comprising at least one hydroxyl group with epichlorohydrin to provide an epoxide group, as described in US 5162547, followed by ring opening of the epoxide with a nucleophile having at least one hydrogen bonded group to provide the moisturizing dendrimer.
Sometimes, the nucleophile is water and in such case a diol group is obtained. In other instances, the nucleophile is a primary or secondary amine in which case an amino alcohol

is obtained. The nucleophile may alternately be a sulphur carrying moiety in which case a thiol (or mercaptan) is obtained. All such diols, amino alcohols, thiols, or a combination thereof would typically constitute the moisturizing dendrimer of the present invention. The terminal alcohol can further be oxidized to the carboxylic acid.
The ring opening reaction of epoxides with nucleophiles is known in prior art. However, when molecules containing multiple epoxide units are used as substrates, polymeric materials are obtained due to intermolecular polyaddition reactions. This is particularly true when water is added as a nucleophile as the alcohol groups formed during the reaction can act as nucleophiles resulting in polyaddition products.
Large polymers as described in WO 2008/135246 and US6093793 having a very high density of hydroxyl groups are not suited for the present invention.
Unlike US 4543430 and EP A212820 alcohols cannot be used as nucleophiles for the present invention as they would lead to dendrimers having the end group protected. Thus there is a need to develop conditions for controlled ring opening of polyglycidyl ethers with; _ nucleophiles leading to low molecular weight dendrimers.
In some embodiments the invention discloses macromolecules that are spherical in shape and dendritic in spatial arrangement. Turning to figure 1, the dendrimer of the present invention typically comprises a central core with hydrogen bonding groups at the terminal ends. As properties of dendrimers are generally independent of the core, any core irrespective of its structure, shape and size may be used to prepare moisturizing dendrimers of the present invention without departing from the essential features of the invention. The core must therefore be held non-restrictive to the scope of the present invention. In one preferred embodiment, the core of the dendrimer of the present invention is pentaerythritol.
The invention discloses moisturizing macromolecules that may be designed in a controlled manner for precision in shape, size, density of hydrogen bonding units, efficiency of moisturization.
In another embodiment the invention discloses dendrimers with 2 to 25 hydrogen bonding groups, preferably between 5 to 15 hydrogen bonding groups and most preferably between 6 to 8 hydrogen bonding groups.
in still another embodiment the invention discloses dendrimers with a molecular weight of less than 500.

The process steps disclosed herewith are particularly suitable for preparation of actives for cosmetic application. As may be evident to a person skilled in the art, the processes can be suitably modified. Such modifications must therefore be considered to be within the scope of the present invention.
The invention also relates to compositions comprising the dendrimer of the present invention such as body and face moisturizers, day and night time moisturizers, anti-aging, skin lightening and anti-inflamatory preparations to be used during day or night time, cosmetic preparations applicable to children, teens and adults, anti-perspirants, aftershave lotions, shaving creams, shampoos, conditioners, scalp serums, shower gels, soaps, wipes, hydroalcoholic skin disinfectants, therapeutic creams, after-shower day care preparations, preparations for localized-action as under eye marks and regions, sunscreens and the like comprising dendrimers with high-density hydrogen bonding groups or their derivatives thereof disclosed in the present invention. These and similar compositions and formulations may be applied topically to the hair or skin or to the various mucous membranes of the body, including but not limited to those of the oral, nasal, vaginal or rectal cavities.
In yet another preferred embodiment the invention relates to oil in water emulsion compositions comprising, besides the dendrimer of the present invention, silicones, vitamins, polyols, acceptable vehicles, structurants, emoilient/s, gelling agent/s, a thickening agent/s, a hydrophilic or hydrophobic polymer/s, an emulsifying agent/s, alcohol/s etc. Examples of these ingredients include but are not limited to such substances as surfactants, binders, emollients, preservatives (such as methyl paraben), colorants, perfumes, skin-lightening agents, anti-wrinkle agents, antimicrobials and the like.
Emulsifying agents which may be optionally added to the compositions of the present invention include but are not restricted to oxyalkylenated fatty acid esters of polyols, for example polyethylene glycol stearates, for instance PEG-100 stearate, PEG-50 stearate and PEG-40 stearate; and mixtures thereof, mixture of glyceryl monostearate and of polyethylene glycol stearate (100 EO) (Simulsol 165), oxyalkylenated fatty acid esters of sorbitan comprising, for example, from 20 to 100 EO such as Tween 20 or Tween 60, oxyalkylenated (oxyethylenated and/or oxypropylenated) fatty alcohol ethers; alkoxylated or non-alkoxylated sugar esters, such as sucrose stearate and PEG-20 methylglucose sesquistearate; sorbitan esters such as the sorbitan paimitate ( Span 40), esters of diacid and of fatty alcohol, such as dimyristyl tartrate; mixtures of these emulsifiers, for instance the mixture of glyceryl stearate and of PEG-100 stearate(Arlacel 165), and mixtures comprising these emulsifiers, such as the mixture of dimyristyl tartrate, cetearyl alcohol, Pareth-7 and PEG-25 laureth-25, (Cosmacol PSE), steareth - 2, steareth 21, PPG-15 stearyl ether.

Thickeners which may be used in the present invention include but are not restricted to alkyloamides, carbomer 934, 940, 941, 960, 961, cetearyl alcohol, cetyl alcohol, gelatin, gums, magnesium aluminium silicates, ozocarite, paraffin, tragacanth, sodium alginate, Tinovis ADM and the like.
Structurants which may be used in compositions of the present invention include those materials which are well known in the art and include fatty acids, fatty alcohols, fatty acid esters, and fatty acid amides, having fatty chains of from 8 to 30 carbons atoms. Preferably the structurant used is stearic acid.
Various emollients as are known to a person skilled in the art and as are available in the market can be employed as an optional constituent in the present invention. These include but are not restricted to the group consisting of lanolin, octyl dodecanol, hexyl decanol, oleyl alcohol, decyl oleate, isopropyl stearate, isopropyl palmitate, isopropyl myristate, hexyl laureate, dioctyl cyclohexane, PPG-15 stearyl ether, isohexadecane, stearic acid, cetyl alcohol, mineral oil etc.
Various chelating agents may be used as optional constituents of the present invention. These may be selected from a group consisting of but not limited to Dimercaptosuccinic acid (DMSA), Dimercapto-propane sulfonate (DMPS), Alpha lipoic acid (ALA), Calcium disodium versante (CaNa2-EDTA), Disodium EDTA, Dimercaprol (BAL).
Various cosmetically and dermatologically suitable preservatives may be added to the present composition. These may be selected from the group consisting of, but not limited to, 2-phenoxyethanol, para-hydroxybenzoic acid esters (also known as parabens) for instance methyl para-hydroxybenzoate (methyl paraben), ethyl para-hydroxybenzoate (ethyl paraben) and propyl para-hydroxybenzoate (propyl paraben) and mixtures thereof; formaldehyde-releasing agents, for instance imidazolidinylurea or diazolidinylurea; haloalkyny! carbamates, for instance 3-iodo-2-propynyl butyl carbamate (IPBC); caprylyl glycol, also known as 1,2-octanediol; sodium benzoate; N-(3-chloroallyl)-hexaminium chloride (or Quaternium-15); polyhexamethylene biguanide hydrochloride (CTFA name: polyaminopropyl biguanide); alkyltrimethylammonium bromides, for instance dodecyltrimethylammonium bromide, myristyltrimethylammonium bromide and hexadecyltrimethylammonium bromide, and mixtures thereof.
Anti-ageing active agents which may optionally be added to the compositions of the present invention may be chosen from free-radical scavengers, keratolytic agents, vitamins, anti-elastase and anti-collagenase agents, proteins, fatty acid derivatives, steroids, trace

elements, bleaching agents, algal and plankton extracts, enzymes and coenzymes, flavonoids, ceramides, tensioning agents and muscle relaxants, and mixtures thereof.
Skin lightening agents which may optionally be added to the compositions of the present invention may be chosen from niacinamide, kojic acid, hydroquinones and their derivatives, arbutin, glabridin, genistein etc. Various natural extracts such as licorice, marigold extract, centella as/at/ca, terminalia arjuna, boswellia serrata and galanga extract have also been used for skin lightening.
Free-radical scavengers and antioxidants which may be optionally added to the compositions of the present invention include but are not restricted to phosphonic acid derivatives such as ethylenediaminetetra (methylenephosphonic acid), methylene phosphonic acid, methylenephosphonic acid and salts thereof, in particular the sodium salts thereof; ethylenediaminetetraacetic acid and its salts, such as the sodium salt; guanosine superoxide dismutase; tocopherol (vitamin E) and its derivatives (acetate); ethoxyquine lactoferrin; lactoperoxidase, and nitroxide derivatives; superoxide dismutases; glutathione peroxidase; plant extracts with free-radical-scavenging activity, such as the aqueous extract: of wheatgerm (Detoxiline), green tea, and mixtures thereof.
Anti-inflamatory agents which may optionally be added to the compositions of the present invention may be chosen from allantoin, phytic acid, lutein, azulene, forskolin, etc.
Commonly used penetration enhancers may also be used for enhancing the penetration of the aforementioned actives. Typical penetration enhancers may include, without limitation, ethanol, oleic acid and urea.
Various cosmetically acceptable vehicles may be used for the preparation of compositions. as per the present invention. These may be selected from the group consisting of but not restricted to water, alcohols, oils, or a combination therof.
Accordingly, when the surface contemplated is skin, the composition of this invention may contain ingredients, which are added to known creams, lotions, ointments, gels or medicaments, which are physiologically acceptable to skin and which do not contain ingredients, which will reverse or retard the action of skin-moisturizing agent(s).
Optionally, the composition may be added to pre-existing formulations provided that the ingredients in those formulations do not prevent or retard the activity of the claimed composition. In a preferred embodiment, the present composition may be added to commercially available cosmetic and therapeutic compositions.

The invention provides for methods of using the foregoing compositions to achieve a moisturizing effect, comprising applying an effective amount of the composition to the surface. A moisturizing effect significantly diminishes the risk of drying of the skin or progression of existing skin dryness. Skin moisturization may be found to increase by at least 10% to about 200% or more depending upon dendrimer structure and chemistry.
Preparation of Cream with Moisturizing Dendrimer
All ingredients are segregated as per their boiling points and their ease of degradation at elevated temperatures. Ingredients that have a low boiling point or are prone to degradation at elevated temperatures (eg. silicones and vitamins) are weighed separately and kept aside. Rest of the ingredients are weighed individually and added to water or oil phase as per their solubility or as required. The water phase and the oil phase are heated to a temperature of 75°C. The oil phase is then slowly added to the water phase with homogenization to get an emulsion. The emulsion is stirred and allowed to cool to temperature of about 40°C. Ingredients that have a low boiling point or are prone to degradation at elevated temperatures and that had been kept aside initially are then added to the cooled emulsion to obtain the final product.
The following are specific, non-limiting examples prepared as per the present invention. The synthesized dendrimers were characterized by spectroscopic methods.
Example 1:
a. Preparation of pentaerythrito! tetraallyl ether:
Sodium hydride (7,0 g, 145 mmol, 4.8 equiv., 50% in mineral oil.) was placed in a 250 ml round-bottomed flask. 25 mL of dimethyl formamide and 25 mL of THF were added and stirred. A solution of pentaerythritol (4.0 g, 29.4 mmol, 1.0 equiv.) in THF (25 ml) was added to the flask and then cooled to 0 °C. Allylbromide (17.5 g, 145 mmol, 4.8 equiv.) was added drop wise and the reaction mixture was warmed to room temperature and stirred for 10-12 hours. The reaction was quenched by adding methanol to destroy any unreacted sodium hydride. The solution was poured into cold water (100 ml) and extracted with hexane (100 mL). The organic layers were combined, dried with anhydrous Na2S04, filtered and concentrated. The crude product mixture was purified by column chromatography (silica gel 100/200 mesh, hexane/ethylacetate = 9.8/0.2). The pure compound was obtained as pale yellow oil (6.3 g, 73%).
1H NMR (CDCI3): 3.5(s, 2H, CCH2), 3.9(d, 2H, OCH2), 5.0-5.4(m, 2H, =CH2), 5.6-6.2(m, 1H).
b. Preparation of pentaerythritol tetraglycidyl ether:
m-Chloroperbenzoic acid (9 g, 40.17 mmol, 4 equiv.) was dissolved in 50 mL of chloroform in a 250 mL 3-necked round-bottomed flask. The solution was cooled to 0 °C. Pentaerythritol

tetraallyl ether (2.8 g, 9.4 mmol, 1 equiv.) dissolved in 5 mL of chloroform was then added; drop wise and the reaction mixture was stirred overnight at room temperature. The reaction: mixture was washed with 10% sodium sulfite solution (2*50 mL) to reduce m-CPBA to m-chlorobenzoic acid, 5 % NaOH solution (2x50 mL) and water (2x50 mL). The organic extract was dried (anhydrous Na2S04), filtered and concentrated. The crude product mixture was purified by column chromatography (Si02, n-hexane/acetone (8/2)). The yield was 2.75 g (81%).
1H NMR (CDCI3): 2.49-2.55 (dd, 2H,) 2.68-2.73 (dd, 2H), 3.01-3.08 (m, 1H), 3.26-3.34 (dd, 2H), 3.38-3.48 (quart, 2H), 3.60-3.67 (dd, 2H).
c. Preparation of the dendrimer by the ring opening of pentaerythritol tetraglycidyl ether with water:
Pentaerythritol tetraglycidyl ether (1g, 2.77 mmol) was suspended in 100 mL of dioxane-water (60:40) in a 250 mL round bottomed flask. 0.2N H2S04 solution (10 mL) was added and the reaction mixture was stirred at room temperature for 12 h. The clear solution obtained was transferred to a 500 mL round bottomed flask. NaHC03 was added to adjust the pH of the reaction medium to 7.5. Water present in the system was removed by azeotropic distillation using hexane. The excess hexane was then evaporated and the sample dissolved in methanol. The solution was filtered through sintered glass crucible over Na2S04 and the filtrate was concentrated to get yellow colored syrupy liquid. The yield obtained was 0.9 g (75%).
1H NMR (CD3OD): 3.7 (quint, 4H), 3.2-3.5 (m, 24H).
Example 2:
Preparation of dendrimer by the ring opening of trimethylolpropane triglycidyl ether with water:
Trimethylolpropane triglycidyl ether (2 g, 6.62 mmol) was suspended in dioxane: water (120:80) system in a 250mL 3-necked round bottomed flask. 0.2N H2S04 solution (20 mL) was added and the reaction mixture was stirred at room temperature for 6-10 hours. To the clear solution obtained was added NaHC03 (4.5 g) to neutralize the reaction medium (pH=7.5). The solution was extracted with dichloromethane (100 mL). To the aqueous layer was added hexane (50 mL) and dioxane(100 mL) and the water was removed by azeotropic distillation. Evaporated hexane, added methanol, filtered through sintered glass crucible over anhydrous Na2S04 and the filtrate was concentrated to get yellow colored viscous liquid. The yield obtained was 1.54 g (77%).
1H NMR (CD3OD): 0.97 (t, 3H), 1.50 (q, 2H), 3.46 (s, 6H), 3.86-3.53 (m, 12H), 4.03 (m, 3H)
Example 3:
Preparation of the dendrimer by the ring opening of pentaerythritol tetraglycidyl ether with diethylamine:
To a solution of pentaerythritol tetraglycidyl (0.9 g, 2.5 mmol) in 1 mL of water was added diethyl amine (1.2 mmol) and the reaction mixture was stirred at room temperature for 24 h.

Then the reaction mixture was diluted with water (2 mL) and extracted with dichloromethane (3x 2 mL). Organic extracts were collected, dried (Na2S04) and evaporated to get pure amino alcohol dendrimer.
1H NMR (CD3OD): 1.00-1.10 (t, J = 7.2 Hz, 24H), 2.42-2.61 (m, 24H), 3.34-3.35 (d, J = 5.6 Hz, 8H), 3.42-3.49 (m, 8H), 3.78-3.82 (m, 4H)
Example 4.
Preparation of the dendrimer by the ring opening of glycerol triglycidyl ether with diethylamine:
To a solution of glycerol triglycidyl (0.9 g, 3.44 mmol) and diethyl amine (1.2 mmol) in 1 mL of water was added and the reaction mixture was stirred at room temperature for 6-24 h. Then the reaction mixture was diluted with water (2 mL) and extracted with dichloromethane (3x 2 mL). Organic extracts were collected, dried (Na2S04) and evaporated to get pure amino alcohol.
1H NMR (CD3OD): 1.05-1.08 (t, J 7.2 Hz, 18H), 2.45-2.67(m, 18H), 3.41-3.71 (m, 11H), 3.83-3.87 (m, 3H)
Example 4: Composition of Cream with 2.0 wt% of moisturizing dendrimer
A cream comprising 2.0 wt% of moisturizing dendrimer of the present invention was prepared with the following ingredients:

Cream formulations so formed were compared with conventional moisturizing formulations comprising glycerol, diglycerols and sorbitol (linear long chained polyol). Similar cream formulations replacing dendrimer of the present invention with glycerol, diglycerols and sorbitol were prepared.
it was seen that compositions comprising dendritic macromoleules demonstrated improved physical attributes in comparison to those containing linear, long chained, polymeric molecules. Formulations containing the above dendrimers were found to have lower viscosities even when the actives were used at higher concentrations when compared to known actives like glycerol, diglycerol and sorbitol as shown in Table 1. This unique property of the dendrimer offered formulation flexibility for creams, lotions, shampoos, face wash and conditioners.

The present invention may be susceptible to various modifications and alternative forms, specific embodiments have been shown by way of example in the drawings and have been described in detail herein. However, it should be understood that the invention is not intended to be limited to the particular forms disclosed.
Detailed Description of the Accompanying drawings
The foregoing and other advantages and features of the invention will become apparent upon reading the following detailed description and upon reference to the drawing in which Figure 1 illustrates a general structure of a dendrimer of the present invention comprising a core with terminal hydrogen bonding groups labeled herein as (A).

We claim:
1. A moisturizing dendrimer comprising at least one of:
a) a vicinal hydrogen bonding group;
b) a geminal hydrogen bonding group;
c) a combination of a and b thereof.

2. The moisturizing dendrimer as claimed in claim 1 wherein at least one hydrogen bonding group is selected hydroxyl, amine, mercaptan, amide, carboxyl or combinations thereof
3. The moisturizing dendrimer as claimed in claim 1 comprising at least one vicinal hydrogen bonding group at the terminal end.
4. The moisturizing dendrimer as claimed in claim 1 comprising at least one geminal hydrogen bonding group at the terminal end.
5. The moisturizing dendrimer as claimed in claim 1 having a molecular weight less than 500.
6. A process for the preparation of the moisturizing dendrimer, comprising the steps of:
a. allylation of at least one dendrimer core comprising at least on hydroxyl group
b. oxidation of allyl group to an epoxide
c. ring opening of epoxide with nucleophile having at least one hydrogen bonding
group
7. A composition comprising at least one moisturizing dendrimer comprising at least
one of:
a. a vicinal hydrogen bonding group;
b. a geminal hydrogen bonding group;
c. a combination of a and b thereof; and
d. conventional ingredients.
8. The composition as claimed in claim 7 wherein the at least one moisturizing
dendrimer
comprises at least one hydrogen bonding group is selected from hydroxyl, amine, mercaptan, amide, carboxyl or combinations thereof.
9. The composition as claimed in claim 7 wherein the at least one moisturizing
dendrimer
comprises at least one vicinal hydrogen bonding group at the terminal end.

10. The composition as claimed in claim 7wherein the at least one moisturizing dendrimer comprises at least one geminal hydrogen bonding group at the terminal end.
11. The composition as claimed in claim 7 wherein the at least one moisturizing dendrimer comprises at least one vicinal diol at the terminal end.
12. The composition as claimed in claim 7 wherein the conventional ingredients are selected from emulsifying agents, structurants, thickeners, emollients, chelating agents, preservatives, anti aging agents, skin lightening agents, antioxidants,anti inflammatoruy agents and mixtures thereof.
13. A process for the preparation of the composition as claimed in claim 7 comprising the step of mixing the at least one moisturizing dendrimer with other conventional ingredients.
14. A moisturizing dendrimer and process for its preparation thereof substantially as herein before described with reference to examples and figures.
15. A composition and process for its preparation thereof substantially as herein before described with reference to examples and figures.

ABSTRACT

A moisturizing dendrimer comprising at least one of a vicinal hydrogen bonding group; a geminal hydrogen bonding group; or a combination thereof. A process for the preparation of the moisturizing dendrimer, comprising allylation of at least one dendrimer core comprising at least on hydroxyl group; oxidation of allyl group to an epoxide; ring opening of epoxide with nucleophile having at least one hydrogen bonding group. A composition comprising at least one moisturizing dendrimer comprising at least one of a vicinal hydrogen bonding group; geminal hydrogen bonding group; or a combination thereof; and conventional ingredients.