Samanea saman: A Novel Mucoadhesive Gum


Nayana S. Baste, Dr. Ganesh. D. Basarkar

Department of Pharmaceutics, S.S.D.J. College of Pharmacy, Chandwad, Nasik, 423101, Maharashtra, India.

*Corresponding Author E-mail:



Natural polymers are the most accepted pharmaceutical excipients of formulator’s choice. The reasons for this are their cost effectiveness, biocompatibility and availability. In this research article natural gum was extracted from the seeds of Samanea saman by using ethanol as a solvent. The physicochemical characterization like Loss on drying, Total ash and Acid insoluble ash, Swelling Index, Viscosity and qualitative evaluation of purified gum was done. The percent yield of gum was found to 6% w/w and the swelling index was found to be 18.5. Total ash value (7.5% w/w) and Acid insoluble ash value (1.4%w/w) shows purity of gum whereas 3.2% w/w loss on drying suggest low moisture content of gum. Chemical evaluation shows presence of carbohydrate. X ray diffraction graph of gum shows crystalline nature. The gum has average particle size 45.0±0.32 to 50±0.18μm, and the surface texture of the particles was found to be rough and irregular by scanning Electron Microscopy. Mucoadhesive property of gum was evaluated by Swelling index, Mucoadhesive force, Shear stress measurement. For this study polymeric tablet of gum with concentrations like 10%, 30%, 50%, 70% and 90 %w/w were formulated and the results shows best mucoadhesive and swelling property. From the above result the gum may be used in the formulation of mucoadhesive dosage form.


KEYWORDS: Samanea saman Gum, Natural Polymer, Mucoadhesive, Bioerodible, Rain tree.




Mucoadhesive drug delivery systems involve binding of mucoadhesive polymer to the mucosal membrane. Due to entanglement of polymer with mucosal membrane drug remain in contact therewith for a long period of time. This increases absorption of drug. Mucoadhesive drug delivery also offers a controlled release of drugs which gives patient compliance. The approach of mucoadhesion can be applied in Oral, Buccal, Sublingual, Rectal, Ocular, Pulmonary, Vaginal and Topical drug delivery system. Mucoadhesive drug delivery system involves use of Natural, Semi synthetic and synthetic polymers1.


Natural polymers are most extensively used in development of pharmaceutical dosage forms2. This extensive use of natural polymer is due to their varied applications such as a diluent, binder, disintegrant, thickening agent, protective colloids, gelling agents, and bases in semisolid dosage forms. Natural polymers are also used in cosmetics, paints, textiles, and paper manufacturing.3,4 Different advantages of Natural polymers over synthetic polymers are their stability, availability, nontoxicity, biocompatibility and cost effectiveness.4,5 A huge productions of natural products is found in India, because of its geological and ecological position. In India large numbers of plant species are available with a huge source of Polysaccharide like mucilages, gums and glucans. Gums are the pathological product obtained from the plants. Gums and mucilage form highly viscous solution or dispersion in water. They are used in different conventional and novel drug delivery system to control the drug release6,7.


Samanea saman (Albizia saman) also known as Rain tree which give dark shadow produces dark brown pods which is used as supplement to cattle feed. The seed pods of the tree contain sticky, edible flesh. The objective of present work is to isolate gum from the seed of Samanea saman. Also to evaluate the isolated gum for mucoadhesive property.8,9,10



Materials: Legumes of Samanea saman were collected early in the morning from Ashok Nagar, Satpur, Nasik. They were washed with water two to three times and then sun dried for 48 hours. Herbarium of Samanea saman was authenticated from Botanical Survey of India, Pune with registration number BSI/WRC/ IDEN.CER/2017/H3-17/334. All other chemicals used in extraction and characterization of gum were of analytical reagent grade.



Isolation and Purification of gum from pods and seeds11,12,13,14,15

Pods were dried in oven at temperature 60°C for two days. Seeds were separated from pods and powdered separately. Powder was soaked in water for 24 hours to form a mucilaginous mass. The solution was then filtered and treated with Ethanol so that the gum totally precipitated out. The precipitated gum was then dried in a hot air oven at 40°C to remove all the traces of Ethanol. The dried gum was then powdered in a mortar pestle and again dried in oven to remove any remaining traces of ethanol.


Physical characterization of gum16,17,18,19:

A.      Macroscopic studies:

The macroscopic studies were carried out for color, odor and taste of the Samanea saman gum.


B.      Solubility test:

The purified dried gum was evaluated for solubility in water, ethanol, ether, chloroform and acetone in accordance with the Indian Pharmacopoeia specification


C. Loss on drying:

1.0g of the sample was transferred into each of several petri dishes and then dried in an oven at 105°C until a constant weight was obtained. The moisture content was then determined as the ratio of moisture loss to weight of sample expressed as a percentage.


D. Total ash and acid insoluble ash determination:

Ash content was estimated by the measurement of the residue left after combustionin a furnace at 450°C. The ash obtained from the determination of the ash was boiled with 25ml of 2M hydrochloric acid solution for 5 minutes and the insoluble matter was filtered and washed with hot water and ignited and the subsequent weight was determined. The percent acid insoluble ash was calculated.


E. pH determination:

This was done by shaking 1% w/v dispersion of the sample in water for 5 min and the pH determined using pH meter (Lab India).


F. Swelling index19,20:

1.0g each of the sample was placed in each of 15 ml plastic centrifuge tubes and the volume occupied was noted. 10ml of distilled water was added from a 10ml measuring cylinder and stoppered. The contents were mixed properly for 2 min. The mixture was allowed to stand for 10 min and immediately centrifuged at 1000 rpm for 10 min on a bench centrifuge. The supernatant was carefully decanted and volume of sediment measured. The swelling index was computed using equation:


S = V2 / V1



S = Swelling index

V1 = Volume occupied by the gum prior to hydration

V2 = Volume occupied by the gum after to hydration


G. Viscosity17,18:

1% w/v aqueous solutions of Samanea saman gum was prepared and the viscosity was measured at 10rpm by using spindle no 6 at room temperature by using Brookfield viscometer (RV-T)


H. Qualitative Chemical Analysis of Samanea saman Gum5,11,21,22:

The purified gum was used for the analysis of different phyto-constituents like alkaloids, carbohydrates, phenolics, flavonoids, proteins, amino acids, saponins etc.


Tests for Carbohydrates:

Barfoed's Test:

The test solution with Barfoed's reagent on boiling on a water bath shows brick red precipitate.


Benedict's Test:

Carbohydrate solution with Benedict's reagent and boiling on a water reddish brown precipitate.


Molisch's Test:

The test solution with few drops of Molisch's reagent and 2ml of concentrated sulphuric acid added slowly through the sides of the test tube, shows a purple ring at the junction of two liquids.


I) Spectral Studies19,20,21

Samples were triturated in glass mortarand pestle along with 2-3mg of KBr. There pellets were formed at a high pressure of12000 PSI. Samples were scanned from 4000 to 500 cm-1.


J) Thermal Analysis5,11,19,22:

Thermal transitions of the gum like melting temperature, crystallization temperature and thermal stability were determined by Differential scanning calorimeter


K) X-ray Powder Diffraction5,11,21,24:

X-ray powder diffraction patterns of the gum were analyzed using a Siemens D 5000 X-ray diffractometer. (Siemens, Munich, Germany)


L) Surface Morphology5,11,21,24:

Scanning electron micro-scopic analysis for the gum was performed with a JSM-5600 LV scanning electron microscope of JEOL, Tokyo, Japan. The samples were analyzed under 20kv at x1, 500, x2000, x4000 and x7500 magnification.


Characterization of Samanea saman gum as Mucoadhesive Polymer21-31:

A.      Swelling study:

For the swelling study, different concentrations of Samanea saman gum like 10%, 30%, 50%, 70% and 90 % were taken. They were passed through 120μm sieve and directly compressed with lactose (diluent) and magnesium stearate as lubricant into 8 mm flat beveled tablets using rotary tablet compression machine (karnavati). Tablet Weight, hardness and thickness were kept constant.


Tablets of each concentration were separately placed in baskets of dissolution apparatus I. Each set (the tablet and the basket) was accurately weighed and placed vertically in a beaker containing 40ml phosphate buffer pH 6.8 at 37°C. At every fixed interval (0.5, 1, 2, 3, 4, 5, and 6 hours) of time, excess fluids were discarded and the set containing the swollen tablet was weighed. The weight of the swollen tablet was calculated. The swelling index (S.I.) was determined from the following formula:]


Swelling Index (%) = (Wt-Wo/Wo) X 100



Wt is the weight of the swollen tablet at each time interval,

Wo is initial weight of the tablet.


B.      Measurement of mucoadhesive strength:

Mucoadhesive strength was determined for 10 %, 30 %, 50 %, 70 % and 90 %w/v concentrations of Samanea saman gum tablets from the above batch which were compressed for swelling study.



Bioadhesive performance was measured by the tensile strength which is force required to detach the bioadhesive tablet from the mucosal surface. The apparatus was set up in laboratory. It was mainly consist of a two-arm balance. A movable platform was kept in the bottom of left arm of the balance, to fix the model mucosal membrane. To determine bioadhesion force, goat intestine mucosa was excised and equilibrated at 37ºC ± 1ºC for 30 min in phosphate buffer pH 6.8 and then polymeric tablet was stuck to the lower side of the left hand pan. A piece of goat intestine mucosawas also fixed to the movable platform of the left arm of the balance. The exposed tablet surface was moistened with 50µL of isotonic phosphate buffer pH 6.8 and left for 30 sec for initial hydration and swelling. The platform was moved upward and the polymeric hydrated tablet was kept into contact with the mucosal surface. A preload of 20g was placed over the pan for 3 min as initial pressure and then removed from the left arm pan. Weights were added slowly to the right hand pan until the tablet separated from the mucosal surface. The total weight required for complete detachment of the polymeric tablet was recorded. The bioadhesion force was calculated per unit area of the tablet as follows:


F = (W × g)/ A



F is the bioadhesion force (dyne.cmˉ 2),

W is the minimum weight required to break the bioadhesive bond (g),

g is the acceleration due to gravity (cm.s ˉ 2),

A is the surface area of the tablet (cm2).


C.   Shear stress measurement:

Two smooth glass slabs were taken. One slab was glued with the adhesive araldite onto a glass plate that was fixed on a table top. To the upper block was a pulley is attached through which a thread is passed down. To the other end of thread a pan is attached into which the weight can be added. 2% w/v solution of Samanea saman gum was prepared using water as a solvent. One drop of this polymer solution was kept in the center of the fixed glass slab and second slab was placed over it and pressed with some pressure (100g of weight) such that the polymer solution spreads as a uniform film in between the two slabs. After keeping it for fixed time intervals of 5, 10 and 15 minutes, the weights were added to the pan. The weight just sufficient to pull the upper slab is the shear stress which shows adhesion strength of polymer.



a)    Macroscopic studies:

Isolated gum of Samanea saman was pale white powder, with mucilaginous taste and characteristic odor. The gum powder was rough and irregular in texture as well as shape. After isolation and purification of Samanea saman gum 6% w/w yield was obtained. The gum was found to be soluble in water and insoluble in alcohol, chloroform, acetone and ether. 3.2% w/w loss on drying of gum suggests the low moisture content which is very important for stability of formulations developed by using gum. The result of Total ash value and Acid insoluble ash value shows minimum contamination of gum. The swelling index was found to be 18.5 which show better water absorption capacity. pH of 1% w/v dispersion of the gum in water was 7.1 which is in neutral range. The results of all parameters are shown in Table 1.


Table No.1: Physicochemical evaluation of Samanea saman gum

Sr. No.

Properties evaluated




Pale white












Forms colloidal solution in water and insoluble in alcohol, chloroform and ethanol.


Percentage Yield



Loss on Drying

3.2% w/w


Total ash value

7.5 % w/w


Acid insoluble ash value

1.4 % w/w


Viscosity (1% w/v solution)

1.11 CP


Swelling Index



PH (By Digital pH Meter)



b)    Physicochemical Analysis of Isolated Samanea saman Gum:

For determination of purity of isolated gum different phytochemical tests were carried out including Molisch’s test, Benedict’s test and Barfoed’s test. These tests show the presence of carbohydrate. Whereas Tannins, alkaloids and proteins were found to be absent this suggests the confirmation of gum. The presence and absence of the constituents in the purified gums were mentioned in the Table 2.


Table No.2: Qualitative Analysis of Isolated Samanea saman Gums

Chemical Property

Chemical Test



a)      Dragendorff 's test


b)     Mayer's test



a)      Keller - Killaine test


b)     Balget test



a)      Barfoed's test


b)     Benedict's test


c)      Molisch's test



a)      Ruthenium Red



a)      Shinoda test


b)     Ferric chloride test



a)      Liebermann – Burchard test



a)      Liebermann – Burchard test



a)      Foam test



a)      Ninhydrin test


b)     Biuret test



a)      Gelatin test


b)     Ferric chloride test


+ Present - Absent


Spectral Studies:

FTIR spectra of Samanea saman shown in the Figure 1. Samples were triturated in glass mortar and pestle along with 2-3mg of KBr. The pellets were formed at a high pressure of 12000 PSI. Samples were scanned from 4000 to 500 cm-1. The peak shown at different wave length is mentioned in Table 3. The melting point of dried gum was 204.42ºC obtained as a small endothermic peak in the DSC spectra (Figure 2) which suggest stability of gum up to this temperature. X-ray diffraction data (Figure 3) shows characteristic peaks obtained for the gum which reveal crystalline nature of gum. The dried gum has an average particle size range of 45.0±0.32 to 50 ± 0.18μm, and the surface texture of the particles was found to be rough and irregular as shown in SEM photograph (Figure 4)


Figure 1: FTIR Spectra of Samanea saman Gum



Table No 3. FTIR peaks of Samanea saman gum.

Sr. No


Functional group



OH Stretching



C-H Stretching



C-O Stretching



C-C Deformation



Secondary OH


Figure 2 DSC Spectra of Samanea saman gum


Figure 3 X ray Diffraction Spectra of Samanea saman gum



Figure 4 Scanning Electron micrograph of Samanea saman gum


Characterization of Samanea saman gum as Mucoadhesive Polymer32,33,34,35,36:

Mucoadhesion strength and Swelling Index (%) of plain polymeric tablets of Samanea saman gum are shown in Table No. 4. Good mucoadhesive strength was given by Samanea saman gum. Mucoadhesion of Samanea saman gum associated with its swelling behavior. Highest mucoadhesion is given by concentration of gum with initial higher rate of hydration.


Table no 5 suggest that Greater shear stress is observed with increasing contact time. Water absorption of gum results in its adhesion strength. It can be concluded that may be polar groups present in gum like Hydroxyl (- OH) or carboxyl (-COOH) are responsible for its bioadhesive strength.


Table No 4. Swelling index plain polymeric Samanea saman gum tablets

Sr. No

% of polymer

Swelling Index (%) after time (hrs)

Mucoadhesive force

( x 103) dynes/cm2



























































Table No 5. Shear stress measurement of polymers Samanea saman gum


Shear stress measurement (gms)

5 minutes

88.24 ± 1.67

10 minutes

91.41 ± 0.38

15 minutes

103.52 ± 0.09



In present work by considering different advantages of natural polymers like non toxicity, availability, compatibility, cost effectiveness and diverse application in pharmaceutical field, attempt was made to isolate gum from the seed of Samanea saman plant. Isolated gum was evaluated for different physicochemical characterization and mucoadhesive property. The mucoadhesion was studied by shear stress measurement and ex-vivo method. From the above study it was found that gum isolated from Samanea saman seed had shown best mucoadhesive property. Since the method of isolation of gum simple and this material is edible and bioerodible it can be used as a best alternative for synthetic or semi synthetic mucoadhesive polymer. The gum may be explored in the formulation of mucoadhesive dosage form and as a release retardant polymer in different pharmaceutical dosage forms.



The authors are grateful to the SNJB’s S.S.D.J. College of Pharmacy, Neminagar, Chandwad, Maharashtra for providing facilities of conducting research work.



The authors declare no conflict of interest.



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Received on 27.01.2021         Modified on 26.02.2021

Accepted on 17.03.2021  ©AandV Publications All right reserved

Res. J. Pharmacognosy and Phytochem. 2021; 13(2):57-62.

DOI: 10.52711/0975-4385.2021.00010