Development and clinical evaluation of green tea hair tonic for greasy scalp treatment

Abstract

Green tea has cosmetic benefits that include activities against androgen disorders. A hair tonic containing green tea for reduction of scalp sebum was developed and clinically evaluated. Stable green tea hair tonics were closed-patch tested and clinically evaluated in 20 volunteers for 28 days by using a Sebumerer (R). Hair tonic base with glycerin and butylene glycol (total 4%) gained the highest consumers' preference was incorporated with green tea extract. All of the products were stable and none caused skin irritation. Green tea hair tonic (2%) significantly (p <= 0.024) lowered scalp sebum for 21 and 28 days following the application, suggesting that this topical therapy of scalp greasiness is safe and efficient.

Full text

J. Cosmet. Sci., 67, 161–166 (May/June 2016)
161
Development and clinical evaluation of green tea hair tonic
for greasy scalp treatment
CHANCHANOK NUALSRI, NATTAYA LOURITH, and
MAYUREE KANLAYAVATTANAKUL, School of Cosmetic Science,
Mae Fah Luang University, Chiang Rai 57100, Thailand.
Accepted for publication April 17, 2016.
Synopsis
Green tea has cosmetic benefi ts that include activities against androgen disorders. A hair tonic containing
green tea for reduction of scalp sebum was developed and clinically evaluated. Stable green tea hair tonics
were closed-patch tested and clinically evaluated in 20 volunteers for 28 days by using a Sebumeter®. Hair
tonic base with glycerin and butylene glycol (total 4%) gained the highest consumers’ preference was
incorporated with green tea extract. All of the products were stable and none caused skin irritation. Green tea
hair tonic (2%) signifi cantly (p  0.024) lowered scalp sebum for 21 and 28 days following the application,
suggesting that this topical therapy of scalp greasiness is safe and effi cient.
INTRODUCTION
Green tea (Camellia sinensis) has several health benefi ts including favorable cosmetic prop-
erties. The herb is therefore widely used in skin care products for antiaging (1,2) and
hydration (3,4), either as the single active agent or in a combination with others (5) for
skin disorder treatment. Its potential as a hair growth promoter is considered to be caused
by 5α-reductase activity (6). In addition, the inhibitory effect of tea against the androgen
receptor also implies possible treatments for body and oral malodor (7,8).
The clinical setting for hair loss frequently includes oily scalp (6), which is caused by
overactive sebaceous glands (9). Excess sebum on the scalp produces the ideal environ-
ment for Malassezia spp., resulting in itching and dandruff (10). Therefore, an application
of cosmetics to reduce scalp greasiness should be used to manage this hair disorder. In
particular, products with a long contact time, such as hair tonics, tend to have enhanced
effi cacy (11). Thus, green tea hair tonic was developed and skin irritation was assessed by
means of a single closed-patch test including the tonic preference. Thereafter, the devel-
oped product was studied and monitored with a Sebumeter® (SM810; CK, Cologne,
Germany) in a randomized single-blind, placebo-controlled clinical study.
Address all correspondence to Nattaya Lourith at nattayal@mfu.ac.th.

JOURNAL OF COSMETIC SCIENCE162
MATERIALS AND METHODS
FORMULATIONS AND STABILITY EVALUATION
Base hair tonic containing PEG 40-hydrogenated castor oil, menthol, ethyl alcohol, bu-
tylene glycol, glycerine (Namsiang, Bangkok, Thailand), and water was formulated as
shown in Table I. The pH values of the formulated hair tonics were determined using a
PC Testr 35 (Oakton Instruments, Vernon Hills, IL) multifunction analyzer. Three base
formulas were tested and found to be stable after an accelerated stability test that was
based on a centrifugation assay (3000 rpm for 30 min) in a Micromax RF centrifuge (Thermo
Fisher Scientifi c, Waltham, MA) and six cycles of heating (45°C) and cooling (4°C) for 48 h
for each cycle (11). The hair tonic base was incorporated with green tea extract with 100 mg%
of polyphenols (product code: HE-EL11-CAS) supplied by Specialty Natural Products
(Chonburi, Thailand). The obtained green tea hair tonics were stability tested as above.
PREFERENCE TESTS
Preference tests for the base hair tonics were carried out with seven female and three male
Thai volunteers aged 23–39 years by using a questionnaire with a hedonic scoring system
(scores 1–5, where 1 = dislike, 2 = strong preference). The preferred base, which also
passed the stability test, was chosen for further hair tonic development (11).
CLINICAL EVALUATION
Inclusion criteria. Healthy Thai volunteers aged between 23 and 39 years were enrolled in
the study. All recruited subjects were informed about the study both in writing and ver-
bally, and signed a written consent form that was approved by the ethical committee of
the Mae Fah Luang University before enrollment (REH-58062). All of the studies involv-
ing human volunteers were in accordance with the Declaration of Helsinki.
Table I
Formulation, Stability, and Preference of Hair Tonic Base
Ingredient
Hair tonic base (%, w/w)
ABCDE
PEG 40-hydrogenated
castor oil
Menthol
Glycerine 4 — 2 4.5 7
Butylene glycol — 4 2 4.5 7
Ethyl alcohol
Deionized water
Centrifuge Homogeneous
Freshly pH 4.10 ± 0.00 4.00 ± 0.00 4.47 ± 0.06 4.40 ± 0.10 4.37 ± 0.12
Heat cool pH 4.47 ± 0.06 4.33 ± 0.06 4.57 ± 0.15 4.47 ± 0.06 4.47 ± 0.06
Overall preference (%) 77.20 ± 6.41 79.60 ± 4.17 84.40 ± 4.79 80.00 ± 5.40 82.20 ± 4.60
91.7 86.7 81.7

GREEN TEA HAIR TONIC FOR GREASY SCALP 163
Irritation test. A closed-patch test was performed in the same group of volunteer that par-
ticipated in the preference test. Base hair tonic was tested with different green tea con-
centrations. Water was used as a negative control, whereas 3% sodium lauryl sulfate
(Namsiang) was the positive control. Observation was made immediately after removal of
the Finn chamber® (8 mm, SmartPractice, Phoenix, AZ), and at 24, 48, and 72 h after
removal. The mean irritation index (MII) was calculated (12).
Effi cacy evaluation. Twenty healthy Thai volunteers (10 female and 10 male) aged between
23 and 35 years were included. All subjects were allergy free for 1 week, and had not used
steroids or topical products for oily or greasy scalp treatment for 4 weeks prior to study
enrollment. Subjects who were pregnant, lactating, or dieting were excluded from the
study, as were those who reported smoking or drinking of liquor. The subjects were ad-
vised not to apply any product onto the scalp the night before starting the study. All
subjects were tested for scalp greasiness at baseline using a Sebumeter®. The measure-
ment was performed in triplicate at different positions on the same side of the head. The
subjects were acclimatized in a waiting room (20 ± 1°C and 40–60% relative humidity)
for 30 min before scalp measurements were carried out under the same conditions. A
randomized single-blind placebo-controlled study was designed and the volunteers were
requested to apply hair tonic once in the morning by a split-head procedure for intrain-
dividual comparative trails. The volunteers were directed to use fi ve drops of the green tea
hair tonic on one side of the head and the same quantity of base tonic on the other side.
The control cleansing shampoo (No More Tears; Johnson & Johnson, Bangkok, Thailand)
was provided and used for hair washing (10 g/wash) at 2-day intervals (11). Subjects who
showed less than 90% compliance with the assigned product were excluded from the
study. Effi cacy evaluation was conducted on days 7, 14, 21, and 28 using the Sebumeter®.
STATISTICAL ANALYSIS
The parameters were compared and analyzed using post hoc tests for stability and prefer-
ence. Independent sample t-test was for effi cacy evaluation. Signifi cance was set at a con-
fi dence level of 95%, and data were expressed as mean ± standard error.
RESULTS AND DISCUSSION
The tonic base formulation was developed by variation of humectant (glycerine and bu-
tylene glycol) content, as shown in Table I. All of the tonics were clear, colorless liquids
that remained stable following centrifugation assay. Thereafter, accelerated stability tests
were performed using repeated heating–cooling cycles, and higher pH was observed in all
of the formulations. Preferences for the hair tonics were examined for spreadability, skin
absorption, greasiness, color, and odor. Tonic C gained the highest preference for spread-
ability, skin absorption, and greasiness, but preferences for color and odor were compa-
rable. An increase of humectant contents was found to reduce the scores of all preference
criteria. Therefore, hair tonic base C was further developed into green tea hair tonic.
Various proportions of green tea extract (2–7%), delineated by the reported facial sebum
reduction (13–15), were incorporated into base C using butylene glycol (Table II). The
increased content of the extract did not affect the product pH (p > 0.05) and all of the
green tea hair tonics remained stable.

JOURNAL OF COSMETIC SCIENCE164
Skin irritation was examined using a single closed-patch test (12), and all of the green tea
(C1–C3) and base (C) hair tonics were negative (similar to water; MII = 0), in contrast to
the positive control (sodium lauryl sulfate; MII = 0.5). Hair tonic containing 2% green
tea extract was clinically trialed for its antioily scalp effi cacy. A similar 2% green tea ex-
tract has been reported as an effi cient treatment for acne (13).
The greasiness of skin can be assessed by several methods, including the use of absorbent
paper pads, photometric assessment, bentonite clay, or lipid-sensitive tapes. Of these
methods, Sebumeter® (photometric method) is the most commonly used (16). Sebum
content of the scalp was shown to reduce from the baseline (day 0) following the applica-
tion of hair tonic (Figure 1). Greasiness of the scalp continued to reduce signifi cantly
below the baseline after 21 and 28 days of application (p = 0.024 and 0.008). Although
the base hair tonic was able to reduce the scalp sebum, no signifi cant improvement was
observed (p > 0.05). Consequently, the antioily scalp effi cacy was calculated from the
baseline, as shown in Figure 2. The green tea hair tonic effi cacy was obviously better than
placebo, particularly after 28 days of treatment (p = 0.031).
Oily scalp was successfully treated with the developed hair tonics. The green tea tonic
and hair tonic base were able to reduce the sebum content, and the antioily scalp effi cacy
of the green tea hair tonic was 20% better than the tonic base (Figure 2). However, the
observed effi cacy was higher than the consumer satisfaction level (10%; 17). Further-
more, the sebum reducing ability of this green tea hair tonic was better than 3% and 5%
Table II
Green Tea Hair Tonic Stability
Parameter
Green tea hair tonic
C1 C2 C3
Green tea extract (%) 2 4.5 7
Centrifuge Homogeneous
pH Freshly 4.90 ± 0.10 4.83 ± 0.06 4.97 ± 0.06
Heat cool 5.03 ± 0.06 5.03 ± 0.06 5.00 ± 0.10
Figure 1. Sebum content of scalp at different time interval.

GREEN TEA HAIR TONIC FOR GREASY SCALP 165
green tea emulsions that were tested on the face (approximately 35% for 28 days and
29% for 30 days of treatment; 14,15).
Topical therapy of oily scalp by application of a green tea hair tonic has been proposed.
Overgrowth of sebaceous glands generates suitable conditions for proliferation of Malas-
sezia spp. and such conditions should be suppressed accordingly. Scalp and hair disorders
such as itching, dandruff, and hair loss can, therefore, be treated with the proposed green
tea hair tonic. The clinical effi cacy of the green tea hair tonic might be enhanced at higher
concentrations (4.5% and 7%) along with the increased antioil effi cacy and a lack of skin
irritation, although the 2% green tea may be more feasible from an economic perspective.
Further assessment of the suppression of oil on the scalp or face by these preparations is
necessary.
ACKNOWLEDGMENT
We acknowledge Mae Fah Luang University for facility support during the manuscript
preparation.
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