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The findings from present study support the folklore
use of Bombax ceiba fruits for their diuretic
actions. The plant extracts, at the dose studied, do
not seem to have renal toxicity in rats. Although,
the phytochemistry of active components remain
unidentified, based on the pattern of excretion of
water and electrolytes, it appears that that there are
at least two types of active principals present in
these extracts, one having a frusemide-like activity
and the other a HTZ-like activity. However, further
systematic phytochemical studies are necessary to
elucidate the probable structure activity relationship
of biomolecules.
ACKNOWLEDGEMENTS
The corresponding author is especially thankful to Indian
Council of Medical Research, New Delhi, India, for
providing the financial assistance in the form of SRF.
REFERENCES
1.
Agunu A, Abdurahamn EM, Andrew GO, Muhammed Z. Diuretic
activity of stem bark extracts of Steganotaenia araliaceae Hoechst
[Apiaceae]. J Ethnopharmacol 2005;96:471-5.
2. Singh RG, Singh RP, Usha KP. Experimental evaluation of diuretic
action of herbal drug (Tribulus terrestris Linn.) on albino rats. J Res
Edu Indian Med 1991;3:19-21.
3. Gupta S, Neyses L. Diuretic usage in heart failure: A continuing
conundrum in 2005. Eur Heart J 2005;26:644-9.
4. Eshaghian S, Horwich T, Fonarow G. Relation of loop diuretic dose
to mortality in advanced heart failure. Am J Cardiol 2006;97:1759-64.
5. Kapoor LD. Handbook of ayurvedic medicinal plants. Boca Raton:
CRC Press; 1990. p. 80-1.
6. Mehra PN, Karnick CR. Pharmacognostic studies on Bombax ceiba
Linn. Indian J Pharm 1968;30:284.
7. Mukherjee J, Roy B. Chemical examination of Salmalia malabarica
Schott Endl. (syn. Bombax malabaricum DC.). J Indian Chem Soc
1971;48:769.
8. Seshadri V, Batta AK, Rangaswamy S. Phenolic components of Bombax
malabaricum (Root-Bark). Curr Sci 1971;40:630-1.
9. Harish G, Gupta RK. Chemical constituents of Salmalia malabarica
Schott et Endl. flowers. J Pharm Sci 1972;61:807.
10. Seshadri V, Batta AK, Rangaswamy S. Phenolic components of Bombax
malabaricum. Indian J Chem 1973;11:825.
11. Misra MB, Mishra SS, Misra RK. Pharmacology of Bombax
malabaricum (DC). Indian J Pharm 1968;30:165.
12. Saleem R, Ahmad M, Hussain SA, Qazi AM, Ahmad SI, Qazi MH,
et al. Hypotensive, hypoglycaemic and toxicological studies on the
flavonol C-glycoside shamimin from Bombax ceiba. Planta Med
1999;65:331-4.
13. Dar A, Faizi S, Naqvi S, Roome T, Zikr-ur-Rehman S, Ali M.
Analgesic and antioxidant activity of mangiferin and its derivatives:
The structure activity relationship. Biol Pharm Bull 2005;28:596-600.
14. Vieira TO, Said A, Aboutabl E, Azzam M, Creczynski-Pasa TB.
Antioxidant activity of methanolic extract of Bombax ceiba. Redox
Rep 2009;14:41-6.
15. Namsa ND, Tag H, Mandal M, Kalita P, Das AK. An ethnobotanical
study of traditional anti-inflammatory plants used by the Lohit
community of Arunachal Pradesh, India. J Ethnopharmacol
2009;125:234-45.
16. Anonymous. OECD series on testing and assessment, Number
24. Guidance document on acute oral toxicity testing. ENV/JM/
MONO(2001)4. Paris: Environment directorate, OECD; 2001.
17. Lipschitz WL, Haddian Z, Kerpscar A. Bioassay of diuretics. J
Pharmacol Exp Ther 1943;79:97-110.
18. Swain SR, Sinha BN, Murthy PN. Antiinflammatory, diuretic and
antimicrobial activities of Rungia pectinata Linn. and Rungia repens
Nees. Indian J Pharm Sci 2008;70:679-83.
19. Martin-Herrera D, Abdala S, Benjume D, Gutierrez-Luis J. Diuretic
activity of some Withania aristata Ait. fractions. J Ethnopharmacol
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20. Mukherjee PK. Evaluation of diuretic agents, in: Quality control of
herbal drugs. New Delhi: Business Horizons; 2002.
21. Jackson EK. Drugs affecting renal and cardiovascular function, In:
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Hardman JC, Gilman AG, Limbird LE, editors. 9th ed. New York:
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parsley. J Ethnopharmacol 2002;79:353-7.
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response in chronic renal failure. J Nephrol 1997;10:232-7.
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p. 2-24.
Accepted 10 May 2011
Revised 3 May 2011
Received 27 October 2010
Indian J. Pharm. Sci., 2011, 73 (3): 306-311
Microencapsulation of Eugenol by Gelatin-Sodium Alginate
Complex Coacervation
UJWALA SHINDE AND MANGAL NAGARSENKER*
Bombay College of Pharmacy, Kalina, Santacruz (East), Mumbai-400 098, India
*Address for correspondence
E-mail: [email protected]
May - June 2011
Indian Journal of Pharmaceutical Sciences
311
www.ijpsonline.com
Shinde and Nagarsenker: Microencapsulation of Eugenol by Complex Coacervation
Present study describes microencapsulation of eugenol using gelatin-sodium alginate complex coacervation. The
effects of core to coat ratio and drying method on properties of the eugenol microcapsules were investigated.
The eugenol microcapsules were evaluated for surface characteristics, micromeritic properties, oil loading and
encapsulation efficiency. Eugenol microcapsules possessed good flow properties, thus improved handling. The
scanning electron photomicrographs showed globular surface of microcapsules prepared with core: coat ratio1:1.
The treatment with dehydrating agent isopropanol lead to shrinking of microcapsule wall with cracks on it. The
percent oil loading and encapsulation efficiency increased with increase in core: coat ratio whereas treatment with
dehydrating agent resulted in reduction in loading and percent encapsulation efficiency of eugenol microcapsules.
Key words: Complex coacervation, eugenol, gelatin, microencapsulation, sodium alginate
Microencapsulation of essential oils or flavors has
been reported for offering protection and to reduce
volatilization as well as degradation. Yet another
objective of encapsulating essential oils or flavors
was to design solid particulate forms of liquid core
material[1,2], and to provide longer shelf life as a raw
material which has better handling characteristics
and is compatible with dry ingredients. Extended
shelf life of microencapsulated flavors is attributed to
limited exposure to temperature, moisture, oxidation
and light during storage and processing [3-7]. Of the
different encapsulation processes, spray drying is the
one of the most frequently used technique, despite its
limitations of use of relatively high temperature which
may lead to coalescence of size of microcapsules and
loss of core material[1,8]. Encapsulation by complex
coacervation could serve a suitable alternative for
microencapsulation [3,9-11]. Encapsulating polymer is
required to possess unique emulsifying and film
forming properties defining its ability to function
as an encapsulant, therefore correct selection of
coating material for each application is an important
task. Coating material must retain and protect the
encapsulated component from volatilization and
chemical degradation during manufacture, storage
and handling; moreover, it must release them into
final product during desirable state of manufacture.
Carbohydrate such as starches, maltodextirns, gum
acacia and other gums, sodium alginate and proteins
such as gelatin, albumin, lactoglobulin and whey
proteins are reportedly used as flavor encapsulants[1].
This study presents complex coacervation using
gelatin and sodium alginate for microencapsulation
of eugenol. It also evaluates influence of core: coat
compostion and drying methodology on properties of
microcapsules.
Eugenol, clear pale yellow liquid extracted from clove
and cinnamon, is used in perfumeries, flavorings,
312
essential oils and medicine as local antiseptic and
analgesic. Eugenol has wide application in dentistry
for analgesic and antiseptic properties. Its derivatives
are used in perfumery and flavoring, and also used
in formulating insect attractants and UV absorbers.
Microencapsulation of eugenol with gelatin-sodium
alginate complex coacervation system is expected to
offer protection against oxidization and volatilization
and also ease of handling.
Eugenol was obtained as a gift sample from S. H.
Kelkar, Mumbai. The gelatin bacteriological grade
(Loba Chemie, Mumbai, India) was alkali processed
Type B material (180 bloom). The sodium alginate
used was of medium viscosity pharmaceutical grade
(Loba Chemie). All other regents were of analytical
reagent grade.
In all experiments, colloid encapsulating solution of
gelatin and sodium alginate in ratio 4:1 was prepared
by hydration followed by stirring till solution was
effected. Eugenol was emulsified with encapsulating
medium. Microcapsules were prepared at 40 o by
drop wise addition of dilute hydrochloric acid until
phase separation was achieved following which
mixture was chilled for 30 minutes. Formaldehyde
solution, 37% (1 ml/g of gelatin) was added and
stirred for 2 h at room temperature. A fixed volume
(20 ml/100 ml batch) of previously chilled isopropyl
alcohol (5º) as a dehydrating agent was added to
the system, which was hardened with formaldehyde.
Microcapsules were then separated by decanting the
supernatant, filtered under vacuum, washed with
water till free from formaldehyde and air-dried.
Microcapsules were sieved through 22 mesh sieve and
air-dried at room temperature. Influence of variables
i.e core:coat composition (1:1 and 2:1) and treatment
of dehydrating agent on encapsulation of eugenol
were evaluated.
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The morphology and surface topography of
microcapsules was studied using Philips XL 30
SEM scanning electron microscope. The size of
microcapsules was determined by sieve analysis
method. Hausner ratio was calculated based on
density and wall thickness [3] of microcapsules
was computed using results of particle size and
density data. The percent dry yield was estimated
by establishing a relation between the total mass
of isolated microcapsules and the total mass
used for microencapsulation. Eugenol content in
microcapsules was estimated by extracting eugenol
from microcapsules in methanol and measuring the
UV absorbance at 281nm using Shimadzu UV-160A
ultraviolet/visible spectrophotometer in 1 cm cuvettes
against methanol as blank. A percentage of oil
entrapment and oil loading was calculated from the
content of eugenol in the microcapsules.
Eugenol, chemically 2-methoxy-4-(2-propeny) phenol
was a clear pale yellow liquid. Sample had boiling
point of 254°, refractive index of 1.535 and specific
gravity 1.0597 g/ccs at 20°. Eugenol was insoluble in
water soluble in alkali solution, ethanol and acetone,
solution in 95% methanol exhibited UV maxima
at 281 nm. Gelatin-sodium alginate microcapsules
containing microdroplets of eugenol were prepared
by complex coacervation induced by shift in pH[12].
Figs. 1a-d show variation in morphology and surface
topography in scanning electron photomicrographs of
microcapsules prepared using core to coat ratios of
1:1 and 2:1. Microcapsules prepared with core:coat
ratio 2:1 showed rough surface in comparison with
smooth globular outline in case of microcapsules
prepared with core:coat ratio 1:1. The treatment of
dehydrating agent isopropanol resulted in shrinkage of
microcapsules as shown in fig. 1b, which was more
prominent in microcapsules prepared with core to coat
ratio 2:1 which could be attributed to thin wall of
microcapsules entrapping high oil content.
As indicated in Table 1 the particle size distribution
was markedly affected by the treatment with isopropyl
alcohol (IPA) as dehydrating agent. The untreated
microcapsules were yellowish in color and larger
in size than corresponding IPA treated eugenol
microcapsules. IPA treated eugenol microcapsules
were more discrete and buff colored. The change
in the pattern of particle size distribution with
isopropanol treatment could be attributed to rapid
withdrawal of moisture form microcapsule wall thus
preventing coalescence and merger of microcapsules.
Hausner ratio is the important tool for comparison
of flow behavior of the particles. It is characteristics
of fine particles and has been shown to be measure
of the frictional forces existing in moving mass.
For free flowing particles the Hausner ratio should
be nearly one. The overall lower values of Hausner
ratio for eugenol microcapsules as given in Table 2
revealed the presence of lesser dynamic friction in the
microcapsules, the lower friction being attributed to
microcapsules becoming more regular in shape. The
computed wall thickness[4] was reduced from 158.83
to 103.54 mm as the core: coat ratio was changed
from 1:1 to 2:1 for untreated microcapsules. The
b
a
c
d
Fig. 1: Scanning electron photomicrographs
Scanning electron photomicrographs of (a) formulation E-1, Scanning
electron photomicrographs of (b) formulation E-2, Scanning electron
photomicrographs of (c) formulation E-3 and Scanning electron
photomicrographs of (d) formulation E-4.
TABLE 1: MEAN PARTICLE SIZE AND GEOMETRIC MEAN DIAMETER OF EUGENOL MICROCAPSULES
Formulation
E-1
E-2
E-3
E-4
Colloid ratio
(G:SA)
4:1
4:1
4:1
4:1
Core: coat ratio
2:1
2:1
1:1
1:1
Treatment with IPA
No IPA treatment
IPA treatment
No IPA treatment
IPA treatment
Mean particle size
(m)*
715.97±2.52#
453.49±3.61#
658.53±3.6#
425.48±4.75#
Geometric mean diameter dg
(m)*
825±3.76#
530±3.5#
900±4.89#
500±2.83#
*mean of three determinations; # P<0.05-significant difference between E1/ E2 and E3/E4
May - June 2011
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313
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TABLE 2: MICROMERITIC PROPERTIES AND WALL THICKNESS OF EUGENOL MICROCAPSULES
Formulation
E-1
E-2
E-3
E-4
Aerateddensity
(g/cc)*
0.4545 (±0.003)
0.416 (±0.01)
0.5433 (±0.012)
0.3571 (±0.018)
Packed density
(g/cc)*
0.4862 (±0.011)
0.4448 (±0.022)
0.6125 (±0.01)
0.3987 (±0.014)
True density
(g/cc)*
1.3985 (±0.028)
1.3549 (±0.006)
1.3290 (±0.066)
1.3626 (±0.013)
Percent porosity*
65.23
67.17
53.91
70.74
(±3.29)
(±2.74)
(±4.24)
(±4.72)
Hausner ratio*
1.0477 (±0.014)
1.0197 (±0.003)
1.1274† (±0.0012)
1.1164† (±0.005)
Wall thickness
(m)*
103.54† (±0.58)
101.85† (±0.36)
158.83 (±1.06)
132.23 (±0.12)
*mean of three determinations; †P>0.05-no significant difference between the results. All other showed significant difference
TABLE 3: PERCENT DRY YIELD, PERCENT OIL LOADING AND PERCENT ENCAPSULATION EFFICIENCY OF
EUGENOL MICROCAPSULES
Formulation
E-1
E-2
E-3
E-4
Percent dry yield*
Percent Eugenol content*
Percent oil loading*
30.75 (±2.4)
32.28 (±1.1)
35.66 (±1.5)
38.20 (±1.48)
34.7 (±1.12)
18.24 (±1.67)
21.6 (±0.67)
8.14 (±0.64)
34.68 (±1.15)
18.24 (±0.55)
21.6 (±0.32)
8.13 (±0.92)
Percent encapsulation
efficiency*
15.99 (±0.55)#
8.83 (±0.24) #
15.41 (±0.43) #
6.21 (±0.42†)#
*mean of three determinations; #P<0.05 significant difference between E1/ E2 and E3/E4
similar trend was observed for microcapsules treated
with IPA. Percent volatile oil content in eugenol
microcapsules (Table 3) prepared with core: coat
ratio 2:1 and 1:1 was found to be 34.7 and 21.6%
w/w. The treatment with IPA as dehydrating agent
reduced the eugenol content to 18.24 and 8.13% w/w
respectively. The difference in the content of eugenol
in microcapsules was possibly due to dehydration
step preceding drying of microcapsules. Dehydrating
action of IPA resulted in shrinkage, cracks that were
confirmed by scanning electron photomicrography
and probably caused leakage of oil. The eugenol
microcapsules dried in a stream of air at lower
temperature suffered least damage to their walls.
One-way AVOVA test yielded p values, were less than
0.001 for encapsulation efficiency and mean particle
size data. This indicates that there was a significant
difference in encapsulation efficiency and mean
particle size after IPA treatment.
Percent loading (Table 3) increased with increase in
core: coat ratio for batches treated with IPA and also
for those without treatment with IPA. During washing
with the dehydrating agent most of surface oil was
removed from the microcapsules thus giving less oil
content which was indicated by low percent loading
in batches treated with IPA.
Encapsulation efficiency is more dependent on the
percentage oil content than percent coacervation
yield [5] . Low values of percent encapsulation
efficiency of eugenol microcapsules is in the line
with Ribeiro et al. [13], report which states that the
greatest single source of loss of the encapsulated
oil was loss of some of water-soluble components
314
of oil in aqueous phase during aqueous phase
separation coacervation process. At high oil load,
microcapsules produced were oily, indicating
leaching due to high oil content coupled with thinner
barrier in form of wall of microcapsules. There
was no significant increase in percent encapsulation
efficiency with increase in core: coat ratio irrespective
of IPA treatment. In the core coat ratio 1:1 the
amount of eugenol and coat material was same and
colloid concentration was sufficient to emulsify
and encapsulate eugenol. At higher core coat ratio,
probably emulsification of oily phase suffered
resulting in reduced encapsulation efficiency.
Eugenol was microcapsulated prepared using gelatin
sodium alginate complex coacervate system and
was converted in dry free flowing powder form.
Isopropanol treatment resulted in snap dehydration of
microcapsule wall resulting in cracks on the surface
of microcapsule. Ratio of eugenol to polymers
influenced physical properties of microcapsules as
well as encapsulation efficiency.
ACKNOWLEDGEMENTS
The authors thank S. H. Kelkar Co., Mumbai for providing
the gift sample of eugenol.
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Accepted 15 May 2011
Revised 3 May 2011
Received 16 January 2010
Indian J. Pharm. Sci., 2011, 73 (3): 311-315
Extended Hildebrand Solubility Approach: Satranidazole in
Mixtures of Dioxane and Water
P. B. RATHI* AND V. K. MOURYA1
Department of Pharmaceutics, Shri Bhagwan College of Pharmacy, N-6, CIDCO, Aurangabad-431 003, 1Department of
Pharmaceutics, Government College of Pharmacy, Vedant Hotel Road, Osmanpura, Aurangabad-431 005, India
Rathi and Mourya: Solubility Prediction of Satranidazole in Dioxane-Water Mixtures
The extended Hildebrand solubility parameter approach is used to estimate the solubility of satranidazole in binary
solvent systems. The solubility of satranidazole in various dioxane-water mixtures was analyzed in terms of solutesolvent interactions using a modified version of Hildebrand-Scatchard treatment for regular solutions. The solubility
of satranidazole in the binary solvent, dioxane-water shows a bell-shaped profile with a solubility maximum well
above the ideal solubility of the drug. This is attributed to solvation of the drug with the dioxane-water mixture,
and indicates that the solute-solvent interaction energy is larger than the geometric mean (δ1δ2) of regular solution
theory. The new approach provides an accurate prediction of solubility once the interaction energy is obtained. In
this case, the energy term is regressed against a polynomial in δ1 of the binary mixture. A quartic expression of W
in terms of solvent solubility parameter was found for predicting the solubility of satranidazole in dioxane-water
mixtures. The method has potential usefulness in preformulation and formulation studies during which solubility
prediction is important for drug design.
Key words: Dioxane, extended Hildebrand solubility approach, ideal solubility, interaction energy, regular solution
theory, satranidazole, solubility parameter
Solubility data on drugs and pharmaceutical adjuncts
in mixed solvents have wide applications in the drug
sciences. Knowledge of interaction forces between
solutes and solvents are of considerable theoretical
and practical interest throughout the physical and
biological sciences[1]. The theory of solution is one
*Address for correspondence
E-mail: [email protected]
May - June 2011
of the most challenging branch of physical chemistry.
The Hildebrand-Scatchard theory of regular solution
is the pioneer approach in this field, used to estimate
solubility only for relatively non-polar drugs in nonpolar solvents[2]. An irregular solution is one in which
self-association of solute or solvent, solvation of the
solute by the solvent molecules, or complexation
of two or more solute species are involved [3] .
Polar systems exhibit irregular solution behaviour
Indian Journal of Pharmaceutical Sciences
315