Determination of antioxidant in phytocosmetics

การศึกษาฤทธิ์ตานออกซิเดชั่นในเครื่องสําอางสมุนไพร
Determination of antioxidant in phytocosmetic
ไชยโรจน พิณทุกานนท, สุวิภา ภัทรเมธีวงศ, ลลนา คงคาเนรมิตร และ นริศา คําแกน
Chairoj Pintukanon, Suwipa Pattarameteewong, Lalana Kongkaneramittra and Narisa
Kamkaen
Faculty of Pharmacy, Srinakharinwirot University, Ongkharak, Nakhon-Nayok,
26120, Thailand
E-mail address: [email protected]
บทคัดยอ:
การศึกษาวิจัยนี้มีวัตถุประสงค เพื่อประเมินหาประสิทธิภาพในการตานออกซิเดชั่นของ
ตํารับครีมลอกหนา ที่มีสารสกัดจากชาเขียวและวิตามินอี ซึ่งมีฤทธิ์ในการตานอนุมูลอิสระ เปน
สารสําคัญ พบวา เปอรเซ็นตการยับยั้งการเกิดอนุมูลอิสระ มีคาเทากับ 87.54 สารสกัดเมทานอล
จากครีมลอกหนามีประสิทธิภาพใกลเคียงกับสารมาตรฐานชาเขียวและวิตามินอี เปอรเซ็นตการ
สกัดสารสําคัญออกจากผลิตภัณฑ มีคาเทากับ 95.57 สวนการวิเคราะหเพื่อหาปริมาณ
สารประกอบฟโนลิคโดยรวมในรูปของกรดแกลลิคในครีมลอกหนาสูตรตานออกซิเดชั่น มีคา
เทากับ 80.78 มิลลิกรัมตอกรัมของน้ําหนักแหง ดังนั้นปริมาณสารประกอบฟโนลิคโดยรวมแสดง
ความสัมพันธเชิงเสนตรงกับประสิทธิภาพในการตานออกซิเดชั่น
Abstract:
The purpose of this study was to estimate the phenolic content and evaluate
the anti-oxidant activity of green tea and vitamin E in a peel-off face mask cream. The
percent recovery of the active ingredients from the methanolic extract was 95.57%.
The total phenolics in the green tea/ vitamin E mix, as percent yield of gallic acid
equivalent (GAE), was 80.78 mg/g dry weight. Antioxidant activity was assessed by
measuring the cream’s capacity to inhibit free radical formation. The cream
containing both green tea and vitamin E resulted in 87.54% inhibition of free radical
formation compared with the control. This study demonstrates that a face cream
containing both green tea and vitamin E has both high phenolic concentration and
high antioxidant activity.
Methodology:
A cream base consisting of polyvinyl alcohol, stearic acid, glyceryl
monostearate SE, propylene glycol, tween 80, kaolin, paraben concentration and
purified water was prepared. Freeze-dried green tea powder was triturated into the
cream base to a final concentration of 0.82 mg/mL. A portion of the mixture was
sampled for quantitative analysis of phenolic compound determined as gallic acid
equivalent (GAE mg/g dry weight). A 0.80 mg/mL vitamin E in cream base was
prepared by adding vitamin E solution into the previous mixture of cream base and
green tea. This mixture was sampled to quantify phenolic content. The peel-off face
mask cream was prepared by adding the coloring agent (brilliant blue) into the
mixture of cream base, green tea and vitamin E. A portion of this face mask cream
was also analyzed for the percent of recovery from the methanolic extract as same as
phenolic content.
Total content of phenolic compound (gallic acid equivalent (GAE) mg/g dry
weight) was determined by the following method. First each sampled mixture was
added to 10 mL of methanol and centrifuged for 30 minutes. The supernatant was
filtered and the UV absorbance of the sample. A calibration curve of gallic acid was
also prepared according the procedure described for the samples. Sample phenolic
concentration was determined against the calibration curve and the results were
expressed as mg GAE (gallic acid equivalent) per gram dry weight.
Folin-Ciocalteu is a common method used for the determination of total
phenolic compound. The methanolic extracts were dissolved in water (1:60 v/v) prior
to 1-min reaction with Folin-Ciocalteu’s reagent (5 mL). Fifteen mL of 15% Na2CO3
solution was added to the mixture and incubated for 8 minutes. Distilled water was
then added to obtain a final volume of 100 mL in a volumetric flask, and the solution
allowed to stand for 2 hours. The absorbance at 759 nm was determined with a UV
spectrophotometer (Shimadzu, UV-1601). A standard calibration curve between gallic
acid concentration and corresponding absorbance was prepared by measuring of
absorbance of a series of standard gallic acid concentration in methanolic solution:
0.8, 0.6, 0.4, 0.2, 0.1 and 0.05 mg/mL.
The antioxidant activity of the extracts, on the basis of the scavenging activity
of the stable 1,1’-diphenyl-2-picrylhydrazyl (DPPH·) free radical, was determined by
the following method. The peel-off face mask cream was dissolved in methanol (1:1
v/v) prior to the reaction with a methanolic solution of DPPH (100 µM). Three
replicates were prepared and the absorbance at 516 nm was determined with a UV
spectrophotometer. The DPPH radical scavenging capacities were expressed as
percent inhibition, % inhibition = [(Acontrol-Asample)/Acontrol] x 100 where Acontrol is the
absorbance at time = 0 and Asample is the absorbance at 30 min.
Results, Discussion and Conclusion:
The percent of recovery of the active ingredients from the methanolic extract
was 95.57%. This could be due to the fact that methanol, known as a strong polarity
solvent, was used for the extraction of the phenolics. The total phenolic content is
shown in table 1. Consequenty, phenolic concentration in the original sample, prior to
extraction, for green tea plus vitamin E was 66.94 mg/g. This lower phenolic
concentration in the green tea+vitamin E sample relative to the other samples may be
due to the bathochromic shift (red shift) that the maximum wavelength were longer
than the observed wavelength (759 nm).
Table 1: Total amount of phenolic compound in the peel-off face mask measured as
gallic acid equivalent (GAE)
Sample
Green tea
Green tea + Vit E
Green tea + Vit E+ color
(face mask)
Measured GAE (mg/g dry
weight)
75.75
61.75
74.25
Calculated GAE (mg/g dry
weight) based on original
sample weight
82.21
66.94
80.78
Antioxidant activity was determined by the interaction of the sample with
DPPH, either transfering an electron or hydrogen atom to DPPH·, and thus
neutralizing its free radical character. The resultant colour change from purple to
yellow was assessed by measuring sample absorbance. Free radical scavenging
activity, expressed as percent inhibition, was high for green tea extract (89.62%) and
the peel-off face mask (87.54%) (Table 2). In contrast, percent inhibition by the
vitamin E extract was unexpectedly low (6.23%). This fact could be explained by the
differing solubility in water of vitamin E and DPPH.
Table 2: Free radical scavenging capacity of green tea and vitamin E in the peel-off
face mask
Sample
Concentration of active
ingredient (mg/mL)
0.82
0.80
0.80
% inhibition of
the preparation
89.62
6.23
87.54
Green tea
Vitamin E*
Green tea + Vit E + color
(face mask)
Cream base
0.00
* A mixture of cream base and vitamin E was prepared separately.
1.89
It can be concluded that total phenolic concentration, expressed as GAE shows
close correlation with the antioxidant activity. Green tea and vitamin E together have
the high capacity to scavenge free radicals. The antioxidant activity of phenolics is
mainly due to their redox properties, which allow them to act as reducing agents,
hydrogen donors and singlet oxygen quenchers. In addition, they have a metal
chelation potential. As antioxidants have capacity to reduce the effects of aging,
reduce wrinkles and soften the skin, the use of this face mask may have beneficial
actions on the skin.
Acknowledgement: The faculty of pharmacy, Srinakharinwirot University is
appreciated for research facility and financial support.
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Keyword: antioxidant, green tea, vitamin E, natural product, face mask

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