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 Table of Contents  
Year : 2023  |  Volume : 14  |  Issue : 1  |  Page : 24-28  

Increasing the stability of incense gum extract (Styrax benzoin) with a mixture of surfactants

Departments of Chemistry, Faculty of Mathematics and Natural Sciences, State University of Medan, Medan, Indonesia

Date of Submission20-Aug-2022
Date of Decision30-Sep-2022
Date of Acceptance14-Nov-2022
Date of Web Publication20-Jan-2023

Correspondence Address:
Mrs. Nora Susanti
Medan State University JI. Willem Iskandar Psr V
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/japtr.japtr_539_22

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Styrax benzoin is a type of incense produced in North Tapanuli, Indonesia. The content of metabolite compounds provides wide use in pharmaceuticals. The occurrence of deposits in the extract makes this preparation unstable; this instability creates problems, especially in the concentration of the extract and is impractical so it needs to be redissolved. The method of using surfactants can be used as a suspending agent, a mixture of two types of surfactants gives variations in hydrophilic and lipophilic balance (HLB), by finding the optimum HLB value to create optimum solution stability and organoleptic, various mixture ratios were carried out with test parameters such as organoleptic, pH, viscosity, particle size, and components of chemical compounds. The results show that the optimum HLB of S. benzoin is 12.7 in surfactants Tween 80 and Span 80.

Keywords: Chemical component, hydrophilic and lipophilic balance value, stability, Styrax benzoin, surfactant

How to cite this article:
Susanti N, Purba J, Gopas Oetama M Y. Increasing the stability of incense gum extract (Styrax benzoin) with a mixture of surfactants. J Adv Pharm Technol Res 2023;14:24-8

How to cite this URL:
Susanti N, Purba J, Gopas Oetama M Y. Increasing the stability of incense gum extract (Styrax benzoin) with a mixture of surfactants. J Adv Pharm Technol Res [serial online] 2023 [cited 2023 Mar 31];14:24-8. Available from: https://www.japtr.org/text.asp?2023/14/1/24/368248

  Introduction Top

The Indonesian frankincense is mostly produced in North Tapanuli, Indonesia, with the largest species dominance, namely, the Toba frankincense type (Styrax paralleloneurum) and the durame frankincense type (Styrax benzoin). The gum obtained from S. benzoin has a dull reddish to grayish brown with a fragrant aroma due to the presence of cinnamic acid.[1] In contrast to other types of S. benzoin tends to have high cinnamic acid compounds around 20 mg/g samples with a level of purity (86%–93%), and high levels of cinnamic acid in the sap determine the good quality of the sap.[2]

Frankincense resin has 165 bioactive compounds that can be isolated so it has many benefits, especially as pharmaceutical raw materials used traditionally or modern.[3] Frankincense resin is mostly sold in lumps and crude extracts at relatively high prices. Unfortunately, we found that the extracts sold in the market were unstable which can be observed by the appearance of unsuspend able solids within 1 month storage period. The extract decreased in its solubility due to various factors, both physically and chemically. On contrary, the stable extract is mandatory either for direct use[4] or for further use to produce any pharmaceutical dosage form.[5] Previous researches on increasing the stability of some crude extracts have shown promising results. Some methods were used such as the cosolvating.[6],[7] Another method that can be applied is reducing the particle size into the nano range.[8] Previous research showed nanosized extract enhanced its bioactivity.[9]

Furthermore, the use of surfactants enables the production of optimum organoleptic properties in the pharmaceutical industry.[10] Surfactants are compounds that have hydrophilic and lipophilic groups that cause surfactants to be oil soluble and water soluble, and surface active compounds that have the ability to reduce surface tension and interfacial tension so that they are able to mix with each other while forming micelles that carry drug molecules to dissolve in the medium.[11] Each type of surfactant has a different hydrophilic and lipophilic balance (HLB) value, a mixture of the ratios of two different types of surfactants produces a mixed HLB value. Previous researches have used HLB mixtures for medicinal compounds and provided improvement, especially on the results of particle diameter size, viscosity, and pH.[12] Therefore, the aim of this study was to assess the stability of the extract in the several mixture ratios of surfactants in nanoparticle size.

  Materials and Methods Top


The instrument used in this study was the Particle Analyzer ANALYSETTE 22 Nano Tec, Gas Chromatography–Mass Spectroscopy (GC-MS) 7890B, Ostwald viscometer, and pH meter. S. benzoin powder 80 mesh size (harvested by farmers in Parsoburan subdistrict in North Tapanuli), ethanol, polysorbate 80/Tween 80, sorbitan monooleate/Span 80, and n-hexane and filter paper. The reference extract was obtained from the market.



S. benzoin powder sample size of 80 mesh as much as 400 g was extracted by maceration method using ethanol with a ratio of 1:2. The extraction was carried out in parallel where stirring was carried out periodically for 3 × 24 h at room temperature. Then, the solution was filtered, the filtrate obtained would be thickened and washed with n-hexane, the polar fraction was collected and then evaporated again. The fraction was screened for its secondary metabolite content.

Addition of surfactants mixture

The addition of Tween 80 and Span 80 was 30% v/v with various ratios in the formula, namely, 1:2 (F1); 2:1 (F2); 1:1 (F3); 3:1 (F4); 4:1 (F5); 1:0 (F6). After obtaining the semisolid incense gum extract, its stability was tested with organoleptic parameters, pH, viscosity, particle size, and GC-MS and compared with the reference.

  Results Top

Benzoin extraction

S. benzoin used from the Parsoburan area was extracted by maceration method for 3 × 24 h. The results of the study showed that the ethanolic extract of frankincense contained 40% volatile compounds and 70% nonvolatile compounds.

Mixture of surfactants

The mixed HLB result is shown in [Table 1].
Table 1: Mixed hydrophilic and lipophilic balance results of each surfactant mixture ratio

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Organoleptic and viscosity

In formula 1–3, there is a fairly clear phase difference, whereas formula 4–6 does not experience a significant difference through observation.


The pH of the formula was demonstrated in [Figure 1].
Figure 1: Graph of sample pH

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Particle size

The particle size of the formula was demonstrated in [Figure 2]. Chromatograms for F4, F5 and F6 can be seen on [Figure 3], [Figure 4], [Figure 5], respectively.
Figure 2: The average particle size of each formula

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Figure 3: F4 particle size distribution chromatogram

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Figure 4: F5 particle size distribution chromatogram

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Figure 5: F6 particle size distribution chromatogram

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  Discussion Top

S. benzoin has a solubility of 85% w/w in pure ethanol. The extract was then washed with n-hexane. Washing with nonpolar solvents will not have much effect on polar compounds in the molecule because n-hexane solvent cannot break covalent bonds and the electrolyte is ionized because nonpolar solvents belong to the aprotic solvent group, and cannot form hydrogen bridges with nonelectrolytes, but for compounds, nonpolar molecules can dissolve under the same pressure through induced dipole interactions and solute such as oils or fats will remain soluble due to the Van der waals-london. Hence, it is expected that nonpolar compounds of oil or fat can be separated. From the results of washing with a solution of n-hexane, the color of the n-hexane becomes clear yellow which indicates the dissolution of nonpolar compounds. This step was aimed at reducing impurities and increasing the purity of the ethanol fraction.

Mixing two types of nonionic surfactants, Span 80 and Tween 80 with various ratios gives different results. These two surfactants were first mixed with the solvent to produce a clear yellow homogeneous solution and completely dissolved. The purpose of this mixing is to obtain HLB values so that optimum characteristics are obtained as can be seen in [Table 1].

In each sample formula and reference, organoleptic tests were carried out using the senses of sight and smell, where the sample was in the form of a viscous liquid with a characteristic frankincense odor as can be seen in [Table 2].
Table 2: Viscosity and organoleptic test result

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In the interaction, surfactants will interact on the surface of the drug particles with hydrophilic and the medium with lipophilic groups. On observation after 2 months, it can be seen that each formula has differences, especially in phase differences or separating, which occurs in formulas with more span of 80%. Researchers tend to see the optimum HLB of S. benzoin extract in the range of 12.7.

In the use of a mixture of surfactants, the sample has a brighter color than a single surfactant, and the ratio of the surfactant mixture affects the viscosity of the sample. The formula 5 sample provided the closest viscosity to the reference sample [Table 2]. The sedimentation rate can be reduced considerably by increasing the viscosity of the dispersion medium and within certain limits, this is practically possible, but a product having a high viscosity is generally undesirable because it is difficult to redistribute. Precipitation was observed in the reference sample after a 30-day storage period [Figure 6]. On contrary, precipitation was not observed in any of the samples even after a 6-month storage period.
Figure 6: The organoleptic of each formula and reference

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From the results of pH measurements, it can be seen that the effect of the type of surfactant is increasing high concentration of Tween 80 gave an increase in the acidity of the solution, on the other hand, an increase in Span 80 gave a decrease in the acidity value.

Among the six formulas, the particle test was only carried out on F4, F5, and F6. The previous three formulas did not meet the criteria due to the presence of immiscible two layers of solution in the sample.

In the histogram above, it can be concluded that there is an effect of the ratio of the surfactant mixture to the particle diameter of a solution. The Span 80-Tween 80 tends to have a smaller diameter with a diameter of 1 μm. The use of Span 80-Tween 80 in this study has a value at F4 = 49.90 nm, F5 = 48.74 nm, and F6 = 47.71 nm experienced a decrease in the average diameter as the number of Span 80 decreased. The use of a single surfactant Tween 80 tended to produce a smaller average diameter but not too significant. Through Stokes' law approach if all factors are held constant by reducing the particle size of the dispersed phase, the researcher assumes that the settling rate will be slower so that stability increases.

An analysis of content using GC-MS was performed on the sample and the reference obtained a chromatogram containing the peaks for each compound.

Incense gum powder in the GC-MS test found many compounds with varying retention time and percent area (% area). The components that have the largest % area in the compound were selected, namely, benzoic acid, vanillin, and cinnamic acid.

[Table 3] indicates all benzoic acid, vanillin, and cinnamic acid are the most abundant metabolites found in the extract. The difference was found in the stereoisomer of cinnamic acid as can be seen in [Table 4].
Table 3: Gas chromatography–mass spectroscopy analysis of chemical components in the sample

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Table 4: Gas chromatography–mass spectroscopy analysis of chemical components in reference

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The (Z)-3-Phenyl-2-propenoic acid found in sample [Figure 7] and [Figure 8] is a stereoisomer of trans-Cinnamic acid found in reference [Figure 9] and [Figure 10]. In general, compounds that are often found in plants in the transform, this is due to the transform having lower energy so it is more stable. The researcher assumes that the rotation of the functional groups due to the conditions when making the sample which is in direct contact with ultraviolet light causes the energy given by the light. This theory is supported by[13] trans-Cinnamic isomerization to cis in the presence of light where the C–C pi electrons are excited into antibonding orbitals that allow rotation of the pi bonds.
Figure 7: Chromatogram of reference GC-MS test sample

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Figure 8: The GC-MS spectra of (Z)-3-Phenyl-2-propenoic acid

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Figure 9: Chromatogram of reference GC-MS test analysis results

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Figure 10: GC-MS spectra of trans-Cinnamic acid

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  Conclusion Top

The use of two types of surfactants has an effect on the sample, especially on organoleptic, pH, and particle size, and the most optimal results are assessed at F5 with HLB value = 12.7 which has the closest organoleptic reference with particle size = 48.74 nm, pH = 5, 1, and a viscosity of 37.2721 cP. The resulting extract exhibited better stability while maintaining the major content of the original extract.

Financial support and sponsorship

State University of Medan Research and Community Service Institute 2022.

Conflicts of interest

There are no conflicts of interest.

  References Top

Harif A, Nawaz H, Rafia R, Ayesha M, Rashid U. A review on bioactive potential of Benzoin resin. Int J Chem Biochem Sci 2016;10:106-10.  Back to cited text no. 1
Nurwahyuni I, Nababan B, Pangoloi S, Situmorang M. Cinnamic acid in frankincense sap as a criterion for determining the best mother plant for vegetative propagation of styrax benzoin (Sumatra Benzoin) in Sumatra, Indonesia. Int J Res 2022;2022. [doi: https://doi.org/10.1155/2022/4160241].  Back to cited text no. 2
Son NT, Linh NTT, Tra NT, Ha NTT, Anh LTT, Cham BT, et al. “Genus Styrax: Are source of bioactive compound1s. In: Bioactive Natural Product, Elsevier, USA; 2021. p. 299-347.  Back to cited text no. 3
Techaoei S, Jarmkom K, Dumrongphuttidecha T, Khobjai W. Evaluation of the stability and antibacterial activity of crude extracts of hydro-endophytic fungi. J Adv Pharm Technol Res 2021;12:61-6.  Back to cited text no. 4
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  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7], [Figure 8], [Figure 9], [Figure 10]

  [Table 1], [Table 2], [Table 3], [Table 4]


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