Aktivitas Antioksidan Ekstrak Kulit Buah Manggis (Garcinia mangostana L.) Secara
Bentuk Dosis Larutan Oral
Ros Sumarny, Siti Sofiah, Liliek Nurhidayati, Fatimah Faculty of Pharmacy, Pancasila University, Jakarta
E-mail: rosaries15@yahoo.com
ABSTRAK
Garcinia mangostana L kulit mengandung xanthones yang memiliki aktivitas antioksidan yang tinggi. Xanthone tidak larut dalam air. Untuk meningkatkan kelarutannya, metode penambahan cosolvent digunakan. Xanthones diekstraksi dari kulit buah manggis menggunakan etanol 70% dan kemudian dirumuskan ke dalam larutan oral dengan melarutkan ekstrak dalam berbagai cosolvents dan penambahan sorbitol dan larut dalam air violet pewar-na. Komposisi cosolvents adalah PEG 400-gliserol (20:20, 20:40, 40:20, 40:40). Untuk menyelidiki apakah komposisi cosolvent mempengaruhi aktivitas antioksidan larutan oral, dalam penelitian ini aktivitas antioksidan dari ekstrak kulit buah manggis dalam larutan oral telah diuji dengan menggunakan metode DPPH. Larutan oral dengan cosol-vent PEG 400-gliserol (40:40) memiliki aktivitas antioksidan tertinggi dengan IC50 24,81 ppm.
Kata kunci: kulit buah manggis, sediaan oral, pelarutan, aktivitas antioksidan.
ABSTRACT
Garcinia mangostana L rind contains xanthones that has a high antioxidant activity. Xanthones are not soluble in water. To improve its solubility, cosolvent addition method was used. The xanthones were extracted from
man-gosteen rind using 70% ethanol and were then formulated into oral solution by dissolving the extract in various cosolvents and addition of sorbitol and water soluble violet dye. The composition of cosolvents were PEG 400-glycerol (20:20, 20:40, 40:20, 40:40). To investigate whether composition of cosolvent influence the antioxidant
acivity of oral solution, in this research the antioxidant activity of mangosteen rind extract in oral solution were
examined using DPPH methods. Oral solution with cosolvent of PEG 400-glycerol (40:40) has the highest antioxi
-dant activity with IC50 of 24.81 ppm.
INTRODUCTION
Garcinia mangostana L. or Mangosteen fruit rind is generally discarded by consumers as it can be termed as an agricultural waste. Mangosteen fruit rind contains xanthones which have anti-oxi-dant, anti-proliferation and anti-microbial activity that are not found in any other fruit. Mangosteen rind extract as been shown to have strong antioxi-dant activity.
Xanthones have a poor solubility in water (Maryadele, 2006). Solubility is one of the impor -tant physicochemical properties that have to be considered in the preparation of solution dosage form. To produce more soluble active substances, it needs an additional supporting materials and appropriate methods. One of the methods to en-hance the solubility of xanthones in mangosteen rind extract is cosolvency method (Martin, 1990).
Four composition of mixture of PEG 400 and glycerin were used to enhance the solubility of xan-thones in mangosteen rind extract. Based on the α- mangosteen solubilizied content, PEG 400-glycer -in (40:40) is the best composition (Nurhidayati et al., 2013). To investigate whether composition of
cosolvent influence the antioxidant activity, in this research antioxidant activity of mangosteen rind extract oral solution with various compositions of cosolvent were examined using DPPH methods.
The oral solution composition of four formulas is showed in Table 1.
Table 1. Oral solution composition
Four composition of mixture of PEG 400 and glycerin were used to enhance the solubility of xan-thones in mangosteen rind extract. Based on the α- mangosteen solubilizied content, PEG 400-glycer -in (40:40) is the best composition (Nurhidayati et al., 2013). To investigate whether composition of
cosolvent influence the antioxidant activity, in this research antioxidant activity of mangosteen rind extract oral solution with various compositions of cosolvent were examined using DPPH methods.
MATERIALS AND METHOD Materials
Ripened G. mangostana L. fruit was ob-tained from a local fruit farm in Tasikmalaya. Taxo-nomic determination was performed by Herbar-ium Bogoriense LIPI, Bogor. The fruit rinds were separated from the edible part. The rinds were chopped before drying at temperature of 40oC and
then were grinded to obtain powders.
Antioxidant activity test of oral solution
Preparation of DPPH solution (0.4 mM)
Carefully weighed approximately 8 mg of DPPH (MW 394.32) was dissolved in metha -nol pa to 50.0 mL, placed in dark bottles.
Preparation solution control
1 mL of DPPH solution (0.4 mM) was pi -petted into a 5.0 mL volumetric flask. Metha -nol p.a was added up to the mark and the final solution was homogenized.
Preparation of test solution
Exact amount (74, 147, 294, 589, 883 and 1178 micro liters) of the formula 1 - for -mula 4 was pipetted into 5.0 mL volumetric flask.
Preparation of vitamin C as a positive control solution
Carefully weighed approximately 5 mg of vitamin C was dissolved in 5.0 mL metanol p.a (1.000 ppm) to prepare the stock solution which was then pipetted as much as 10, 20, 30, 40 and 50 microliters into 5.0 mL volumetric flask to obtain a serial concentrations (2, 4, 6, 8 and 10) ppm.
Antioxidant activity assay
Into each flask test solution and refer -ence solution (positive control), it was added 1 mL of DPPH solution (0.4 mM) and methanol p.a up to 5.0 mL and homogenized. The blank solution (without inhibition of DPPH),test and reference solution (positive control) were im -mediately incubated for 30 min at temperature of 37 °C.
(Blank absorbance – Sample absorbance )
% Inhibition = x 100% Blank absorbance
IC50 (Inhibition Concentration 50) is the anti -oxidant concentration (ug /ml) which is able to inhibit 50% of the activity of free radicals. IC50 values were obtained from the linear re -gression equation y = a + bx (x: concentration of the sample; y: percentage inhibition). When the value of y = 50, then the value of X is the IC50. The extracts were confirmed to be active as an antioxidant when IC50 values are less than 200 ug/ml.
RESULTS AND DISCUSSION
Antioxidant activity assay results preparations oral solution.
Table 2. Test result data antioxidant activity of vitamin C
Concentration (ppm) ( x ) Absorbance (A) % Inhibition ( y ) for 30 min at temperature of 37 °C. The result -ing absorbance was measured at a wavelength of 517 nm using a UV-VIS spectrophotometer. Vitamin C serves as a control (Mardawati, 2008).
The calculation method
Figure 1. The relationship of concentration with percentage of inhibition of vitamin C
Table 3. Test result of antioxidant activity of the oral solution
Formula Concentration (ppm) (x) Absorbance (A) % Inhibition ( y )
2.5 0.8050 6.7963 5 0.7730 10.5013 10 0.7238 16.1978 I 20 0.6644 23.0751
30 0.5717 33.8080
40 0.4146 51.9972 a = 3.6890 b = 11.1853 r = 0.9870 IC 50 = 41.403 ppm 2.5 0.8096 6.2637
5 0.7667 11.2308 10 0.6854 20.6437 II 20 0.6222 27.9611 30 0.5323 38.3698 40 0.4029 53.3519 a = 5.3098 b = 11.7174 r = 0.9924 IC 50 = 38.140 ppm 2.5 0.7964 7.7921
5 0.7170 16.9851 10 0.6930 19.7638 III 20 0.5706 33.9354 30 0.4183 51.5688 40 0.3373 60.9471 a = 6.8061 b = 13.9680 r = 0.9933 IC 50 = 30.924 ppm 2.5 0.7018 18.7449
Figure 2. The relationship of concentration with percentage of inhibition of formula I
Figure 4. The relationship of concentration with percentage of inhibition of formula III
The linear regression equation of formula I-IV has positive value of b (slope), indicating that the curve of inhibition of antioxidant is a im-provement curve. The regression curve also shows that there is a close relationship be-tween the concentrations of each extract for-mula with the percentage of inhibition. This is shown by the values of r (correlation coef -ficient) for all formulas over 0.90. R states that there is a correlation between the concentra-tions of each extract formula with the percent-age of inhibition.
The measured values of inhibition con-centration 50 (IC50) of the antioxidant activ -ity of a compound is the concentration of anti-oxidants that could inhibit 50 of free radicals. The smaller the IC50 value, the more active the compound is as an antioxidant. The IC50 values wereobtained from the curve of antioxi-dant activity assay which was formulated from the data of percentages of inhibition (Y) and of concentrations (X). The linear curve has an equation: y = ax + b, where the IC50 value is the X value resulting in Y = 50.
From the results of antioxidant assay of formula I-IV, the smallest IC50 (the highest an -tioxidant activity) was given from formula IV (24.809 ppm) with concentration of PEG 400 and glycerin in the ratio of 40:40. The IC50 val -ue of formula I-III are 41.403, 38.140 and, 30. 924 ppm, respectively. Formula I with the con -centration of PEG 400 and glycerin in the ratio of 20:20 gave the highest IC50 results (lowest antioxidant activity). This is consistent with the results of the assay of xanton of formula I-IV at a wavelength of 320 nm where the larg -est concentration was represented by the for-mula IV and the smallest one was represented by the formula I (Nurhidayati et al., 2013).
From the table t-test, probability values obtained (sig. [2-tailed]) of 0.018; 0.014; 0.014 and 0.002. This means that less than 5 signifi -cance value (0.05); thus it can be concluded that there are differences in the effect of mixed
activity of extracts of mangosteen rind after formulated into oral solution.
CONCLUSION
The oral solution with the mixture of PEG 400-glycerol (40:40) as cosolvent has the highest antioxidant activity with IC 50 of 24.81 ppm.
ACKNOWLEDGEMENT
The Authors are Grateful to Ditlitab -mas Ditjend Dikti for Hibah Bersaing research funding as DIPA Kopertis Wilayah III Number 023.04.2.189705/2013.
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