INTRODUCTION:

Emulgels are defined as biphasic systems comprising an apolar internal phase (emulsion) within an aqueous gel base. The emulgel system is a novel approach for drug delivery applications especially for hydrophobic drugs. The hydrophobic drugs is mixed in the oil phase which is later incorporated within the conventionally stable gel base. Preparation of emulgels comprises of simple and short steps which increase feasibility of the production. There are no specialized instruments needed for the production of emulgels¹. Moreover, materials used are easily available and cheap. All these; decrease the production cost of emulgels. The rheological properties and the breakdown behavior of gels filled with emulsions droplets can be varied by changing the interactions between oil droplets and gel matrix, the oil content and the oil droplet size. The selection of polymer for preparing gel is normally based on the character of external phase.

The choice of the polymer as a gelling agent depends on its ability to obtain desired release profile and its muco-adhesive property. In order to achieve optimized drug release characteristics and good retention time combination of polymers with different chemistry can be used².

Generally, the introduction of an emulsifying agent will lower the interfacial tension of the two phases and decreasing the coalescence of dispersed droplets. Percentage of internal phase volume, emulsifier type and concentration affects the particle size of the internal phase, apparent viscosity, and sedimentation volume of an emulsion which determines its stability. The smaller the particle size the more stable the emulsion will be^3,4. There are many advantages of emulgels like better stability, better loading capacity, production feasibility and low preparation cost, no intensive sonication⁵, controlled release, avoidance of first pass metabolism, avoidance of gastrointestinal incompatibility, more selective to a specific site⁶, Improve patient compliance and suitability for self-medication and Hydrophobic drugs can be easily incorporated into gels using w/o/w emulsions.

Acne vulgaris (or simply acne) is an infectious disease and one of the most prevalent human diseases. It is characterized by different areas of scaly red skin (seborrhea), pinheads (papules), blackheads and whiteheads (comedones), large papules (nodules), and sometimes scarring (piples). Severe acne is usually inflammatory, however it may also be non-inflammatory. In acne, the skin changes, due to changes in pilosebaceous unit skin structures including hair follicles and their associated sebaceous glands^7,8Tea (Camellia sinensis, Theaceae) is the most popular beverage next to water, consumed by over two third of the world’s population. The main types of tea; black, oolong and green tea differ in terms of processing and chemical composition. Green tea is prepared by initial heating to inactivate the endogenous enzymes, while oolong and black tea are fermented. Tea leaves contain main energy sources; protein, carbohydrate, lipids and other health beneficial and flavoring components such as polyphenols, tannins, vitamins, minerals, volatile compounds, pigments and caffeine⁹. The aqueous extract of the leaves has a prolonged hypertensive effect. The leaf decoction is taken as a remedy for diarrhoea, sore throat and haemorrhage; it allegedly stimulates and regulates menstruation. It is also drunk as a stomachic¹⁰. In the present study, effort had been aimed at developing a stable and easily manufactured emulgel composed of green tea extract and avocado oil that is effective as the barrier function and hydration of the skin.

MATERIALS:

Green tea extract was extracted fresh from Green tea leaves. Glycerine Monosterate, Cetostearyl alcohol, Liquid paraffin, Carbopol 934, Carbopol 940, Triethanolamine were obtained from M/s Central Drug House (Pvt) Ltd, India, Propyl paraben, Methyl paraben were obtained from M/s Fisher Scientific.

Methods:

Preparation of Emulgel.- Emulgels were prepared as per the Table 1.

Table 1: Formulations of Emulgel

INGREDIENT (mg)	F1		F2		F3	F4		F5
OILY PHASE
Glycerine monostearate	2		2		1.5	2		2
Cetostearyl alcohol	4		4		5.0	4.5		5.0
Liquid paraffin	16		14		15	16		16
Propyl myristate	0.6		0.6		0.8	0.5		0.7
Avocado oil	5		3		4	5		4
Propyl paraben	0.30		0.30		0.40	0.40		0.30
WATER PHASE
Methyl paraben		0.30	o.30	0.40			0.40		0.30
Glycerine		4	4	5			5		5
Carbopol 934		-	-	2			3		3
Carbopol 940		0.6	0.6	0.8			0.9		0.6
Triethanolamine		0.6	0.6	0.8			0.9		0.6
Green tea extract (ml)		10	15	13			20		5
Purified water (q.s.) (ml)		100	100	100			100		100

EVALUATION OF EMULGEL:

Description:

The state and colour was determined by physical evaluation.

Melting Point:

The melting point of the drug was determined by using Melting Point apparatus. A small amount of drug was filled in the capillary and was inserted at the inlet of the apparatus. The instrument containing silicon oil get heated up as the digital temperature of the instrument is increased and the melting point was determined¹¹.

Solubility:

The solubility of the green tea was determined in different solvents like methanol and water. Each solvent (8ml) were placed separately in a centrifuge tube and excess amount of green tea was added. These tubes were placed in a beaker (100ml) and whole as were covered with foil paper and placed in Orbital shaker machine the rpm of the machine was set at 150 and temperature was set at 32⁰±1⁰C and the whole sample was shaken for a period of 72 hours^11,12.

DSC (Differential Scanning Calorimetry):

Required quantity of the samples were weighed and placed in isolation on the aluminium pan of DSC. The instrument was sealed. On the other side, an empty aluminium pan was placed as a reference standard. The sample was heated between 40-400^oC at the rate of 10^oC/min. Nitrogen gas was introduced at a pressure of 2 bars and a flow rate of 20ml¹².

PREPARATION:

HYDROALCOHOLIC EXTRACT FROM LEAVES OF CAMELLIA SINENSIS:

The leaves of Camellia sinensis were washed with cold water to remove dust and other extraneous matter. Then these were washed with distilled water and kept in shade to dry for three days at room temperature. Sixty-four grams of leaves powder were macerated along with 150ml of 70° GL ethanol, over 3 days. After this period, the resulting suspension was placed into a percolator with 50ml of 70° GL ethanol, and left for a further 3 days. The macerated drug was percolated and a 20% hydroalcoholic extract obtained. The solvent was evaporated until dryness and the dried extract was then protected from light and humidity at room temperature¹³.

PREPARATION OF FORMULATIONS:

Emulgels were prepared in two steps, i.e., step I and step II. In step I, the gel phase was prepared; in step II, the gel phase was combined with the oily phase in order to give the final emulgel formulation.

Gel Phase:

Briefly, the gel base was prepared by dispersing Carbopol 934 or Carbopol 940 in 30mL water using a magnetic stirrer in order to obtain a homogeneous gel base. Triethanolamine solution (5%, m/m) was used to neutralize the pH and air bubbles were removed using an ultrasonic water bath for 1 h.

Water phase preparation:

It consisted of Methyl paraben, Glycerine, Triethanolamine green tea extract and Purified water (q.s.)^14,15.

RESULTS AND DISCUSSION:

ORGANOLEPTIC PROPERTIES:

Green tea extract gave a creamish brown color to the formulations.F3 showed the best spreadability and homogeneity among the five formulations and therefore this formulation was chosen as the vehicle (Base Cream) for green tea extract and avocado oil for further experiments.

Table 2: Organoleptic controls at the end of 24 h

CONTROL	F1	F2	F3	F4	F5
Oily feel^b	0	0	0	0	0
Spreadability	+++	+++	++	++	++
Ease of absorption	++	++	++	++	++
Water dilution	++	++	++	++	++
Stickiness	+++	++	++	+++	++
Homogeneity	+	+++	++	++	++
Odor	+	+	+	+	+
Color^c	W	C	C	ODC	WC

^a 0 (unavailable), + (moderate), ++ (good), +++ (best)

^b All the formulations gave an oily feel the first moment after application but after a few seconds this feeling changed to a non-oily feel. ^cC – Cream, W-white, WC– Whitish cream, ODC – Opaque and dark crea.

pH ANALYSIS:

According to the results of pH analysis presented in Table 2 when the gel was not neutralized during preparation (F3 and F4), the finished emulgel product had also a lower pH value (5.91±0.025 and 6.62±0.055, respectively) compared to that of emulgel formulations F1 and F2 based on Carbopol 934. Emulgel formulations F5 was prepared with a neutralized gel phase based on Carbopol 940. In our study, emulgel F5 showed the highest viscosity among the first five formulations. At the end of the process of storage, the decrease in viscosity of formulations was probably associated with the presence of rose oil in the formulation. Increase in viscosity followed the order F4 > F1 > F5 > F3 > F2.

Table 3: pH of the prepared formulations at different time intervals

FORMULATION	GEL PHASE (24 h)	EMULGEL (24 h)
F1	6.60 ± 0.050	7.18 ± 0.035
F2	5.95 ± 0.060	6.75 ± 0.040
F3	3.50 ± 0.031	5.91 ± 0.025
F4	3.50 ± 0.045	6.62 ± 0.055
F5	6.20 0.068	7.18 ± 0.075

CENTRIFUGATION:

It has been reported that a centrifugation process at 1500 g (3750 rpm) for 5 h can be used in order to interpret long-term stability of an emulsion¹⁶. Emulgel formulations F2, F3, F4 and F5 maintained their consistency and homogeneity after 1 and 5 h of centrifugation and no phase separation was detected.

Table 4: Results of the Zone of inhibition

S. No	Microorganism	Zone of Inhibition (Diameter in mm)
S. No	Microorganism	STD 10µg/ml	Emulgel 10µg/ml	Emulgel 20µg/ml	Emulgel 30µg/ml
1	Staphylococcus aureus	35	22	22	28
2	Escherichia coli	40	27	28	20

The result indicates that the prepared emulgel shows potent antibacterial property¹⁷. The zone of inhibition of the prepared emulgel is significant when compared to the standard solution of potent antibiotic. In most of the cases the zone of inhibition of the prepared emulgel increases with increase in the concentration of the solution. It confirms the antimicrobial property of the prepared emulgels.

Fig 1: solubility studies

UV Spectroscopy:

Maximum wavelength for absorbance was found 250 nm.

Figure 2: Calibration curve

Scanning Electron Microscopy:

Fig 3: Scanning Electron Microscopy

Specimens can be observed in high vacuum, in low vacuum, in wet conditions (in environmental SEM), and at a wide range of cryogenic or elevated temperatures.

Dynamic Light Scattering

The DLS pattern reveals that silver nanoparticles synthesized by this method have a Zeta average diameter of 701.0nm with polydispersity index (PDI) of 0.274 The DLS measured size is slightly bigger as compared to the particle size measured from SEM Micrograph because dynamic light scattering (DLS) method measures the hydrodynamic radius^15,16..

Fig 4: Dynamic Light Scattering

Table 5:-In Vitro Drug Release

TIME (h)	F1	F2	F3	F4	F5
0	0.00±0.00	0.00±0.00	0.00±0.00	0.00±0.00	0.00±0.00
0.5	12.12±9.13	13.15±9.15	12.15±9.12	12.16±9.06	12.13±9.11
1.0	11.06±8.11	12.14±8.12	12.34±8.35	11.33±7.82	12.12±9.13
1.5	12.09±7.66	11.35±6.77	13.33±7.66	13.32±8.77	13.54±7.21
2.0	10.55±7.23	12.53±7.44	13.21±7.34	11.21±7.30	13.33±7.21
2.5	11.44±8.12	11.55±7.61	13.33±8.44	12.54±8.45	12.23±8.44
3.0	13.35±8.12	12.56±8.11	12.11±8.14	11.58±7.23	11.59±8.13

VISCOCITY:

The viscosity changes in formulations, produced by ultrasonication, were as follows using magnetic stirring. Greater impact could be dependent on the tendency of the two formulations prepared by the ultrasonication method towards changes in interface stability^18,19,20.

Table 6: Viscosity of the formulations

Formulation	Viscosity (cps)
F1	13
F2	10
F3	11
F4	15
F5	12

In vivo studies:

Based on the results of our study, it can be concluded that the emulgel formulation F3, including green tea extract and avocado oil, was ideal in terms of applicability and stability. The 12 volunteers who voluntarily participated in the test the result could be concluded that single application of emulgel was not that successful. Multiple application method was more effective comparatively to the single application method. It was more favourable for dry skin. It was easy to apply and did not cause any kind of irritation. The formulation was not completely effective but it was not even a complete fail as the acne did not grow. It showed a significantly higher hydration effect on human skin by enhancing the skin barrier function. Further investigations should be considered for enhancing the stability of green tea extract and avocado oil in the formulation. In vivo studies should be performed under simulated dry or sub erythema UV exposure treatments in order to evaluate the moisturizing and skin barrier protecting effects of this emulgel formulation more accurately.

CONCLUSION:

Based on the results of our study, it can be concluded that the emulgel formulation, composed of green tea extract and avocado oil, was ideal in terms of applicability and stability. It showed anti acne effect on human skin. In vivo studies which were performed showed a positive result which helped in the treatment of acne on the affected skin area. Further investigations should be considered for enhancing the stability of green tea extract and avocado oil in the formulation. From all the parameters, it could be concluded that F2 formulation was the best in terms of being affective amongst the other formulations. There was no such adverse effect which was reported after all the studies and evaluation parameters.

ACKNOWLEDGMENT:

The authors wish to thank Amity Institute of Pharmacy, Amity University, Noida for providing all the facilities for carrying out the research.

REFERENCES:

1. Balambal R, Thiruvengadam KV, Kameswarant L, Janaki VR, Thambiah AS. Ocimum basilicum in acne vulgaris--a controlled comparison with a standard regime. The Journal of the Association of Physicians of India. 1985;33:507-8.

2. Baradaran A, Nasri H, Rafieian-Kopaei M. Comment on: Anti-oxidative stress activity of Stachys lavandulifolia aqueous extract in humans. Cell journal. 2013;15(3):272-3.

3. Baradaran A, Nasri H, Nematbakhsh M, Rafieian-Kopaei M. Antioxidant activity and preventive effect of aqueous leaf extract of Aloe Vera on gentamicin-induced nephrotoxicity in male Wistar rats. La Clinica Terapeutica. 2014;165(1):7-11.

4. Baradaran A, Rabiei Z, Rafieian M. A review study on medicinal plants affecting amnesia through cholinergic system. Journal of Herb Med Pharmacology. 2012;1.

5. Bedi MK, Shenefelt PD. Herbal therapy in dermatology. Archives of dermatology. 2002 Feb 1;138(2):232-42.

6. Bek-Thomsen M, Lomholt HB, Kilian M. Acne is not associated with yet-uncultured bacteria. Journal of Clinical Microbiology. 2008 Oct 1;46(10):3355-60.

7. Bettoli V, Zauli S, Virgili A. Is hormonal treatment still an option in acne today?. British Journal of Dermatology. 2015 Jul;172:37-46.

8. Bhanu PV, Shanmugam V, Lakshmi PK. Development and optimization of novel diclofenac emulgel for topical drug delivery. Int J Comp Pharm. 2011;2:1-4.

9. Bhouri W, Derbel S, Skandrani I, Boubaker J, Bouhlel I, Sghaier MB, Kilani S, Mariotte AM, Dijoux-Franca MG, Ghedira K, Chekir-Ghedira L. Study of genotoxic, antigenotoxic and antioxidant activities of the digallic acid isolated from Pistacia lentiscus fruits. Toxicology in Vitro. 2010 Mar 1;24(2):509-15.

10. Bhowmik D, Gopinath H, Kumar BP, Duraivel S, Kumar KS. Recent advances in novel topical drug delivery system. The Pharma Innovation. 2012 ;1(9, Part A):12.

11. Bhuchar S, Katta R, Wolf J. Complementary and Alternative Medicine in Dermatology. American Journal of Clinical Dermatology. 2012;13:311-7.

12. Deveda P, Jain A, Vyas N, Khambete H, Jain S. Gellified emulsion for sustain delivery of itraconazole for topical fungal diseases. International Journal of Pharmacy and Pharmaceutical Sciences. 2010;2(1):104-12.

13. Bower JP, Cutting JG. Avocado fruit development and ripening physiology. Horticultural Reviews. 1988 ;10:229-71.

14. El-Hadidi T, El-Garf A. Double-blind study comparing the use of Voltaren Emulgel® versus regular gel during ultrasonic sessions in the treatment of localized traumatic and rheumatic painful conditions. Journal of International Medical Research. 1991; 19: 219-27.

15. Enshaieh S, Jooya A, Siadat AH, Iraji F. The efficacy of 5% topical tea tree oil gel in mild to moderate acne vulgaris: a randomized, double-blind placebo-controlled study. Indian Journal of Dermatology, Venereology, and Leprology. 2007 ;73:22.

16. Garg A, Aggarwal D, Garg S, Singla AK. Spreading of semisolid formulations: an update. Pharmaceutical Technology North America. 2002;26(9):84

17. Gharipour M, Ramezani MA, Sadeghi M, Khosravi A, Masjedi M, Khosravi-Boroujeni H, Rafieian-Kopaei M, Sarrafzadegan N. Sex based levels of C-reactive protein and white blood cell count in subjects with metabolic syndrome: Isfahan Healthy Heart Program. Journal of research in medical sciences: the official journal of Isfahan University of Medical Sciences. 2013 Jun;18(6):467.

18. Gross CP, Anderson GF, Powe NR. The relation between funding by the National Institutes of Health and the burden of disease. New England Journal of Medicine. 1999 Jun 17;340(24):1881-7.

19. Vikas G, Parveen B, Junaid N, Sanjiv K. Phytochemistry and pharmacology of Camilla sinensis-A review. Annals of Biological Research. 2010;1(2):91-102.

20. Chauhan, S. B., Naved, T., and Parvez, N. Formulation development and evaluation of proniosomal gel of ethinylestradiol and levonorgestrel for antifertility treatment. Asian Journal of Pharmaceutical and Clinical Research, 2019; 12, 364-8.

Received on 18.08.2019 Modified on 03.11.2019

Research J. Pharm. and Tech. 2020; 13(8):3598-3602.

DOI: 10.5958/0974-360X.2020.00636.8