 Research
 Open Access
 Published:
Kinetic study in the extraction of xanthones from Securidaca longepedunculata roots by microwaveassistedextraction
BeniSuef University Journal of Basic and Applied Sciences volume 11, Article number: 116 (2022)
Abstract
Background
Extraction of active compounds from plants using microwave can be utilized as an alternative solution for conventional extraction. To well understand this technology, the study of the modelization and kinetics mechanism of the extraction method is necessary. This study aimed to evaluate the suitable kinetics models for MAE of the Xanthones from Securidaca longepedunculata Fresen roots.
Results
The experimental data (xanthones versus time, power and ratio, respectively) were fitted to threeparameter empirical kinetics models. The secondorder models appear to be the best fit to explain kinetics study of MAE than the first model. The secondorder model was acceptable, with elevated value of the correlation coefficient (R^{2} = 0.9861), showing that it perfectly relates the process.
Conclusion
Based on the results obtained, the extraction of xanthones from roots of S. longepedunculata is done successively in two steps, washing and diffusion of compounds from matrices as described by secondorder kinetics model. The latter could report the kinetics model of extraction process from S. longepedunculata Fresen using microwave technology.
Background
Securidaca longepedunculata (Fresen.) is a tree from Polygalaceae family and has been generally used as a medicinal plant in tropical Africa specially in Cameroon [1]. Commonly known as “Aalali” in the Fulfulde language, the roots of S. longepedunculata are used in traditional medicine to treat various ailments across to coughs, colds, fever, backache, toothache, sleeping sickness, malaria, inflammation, rheumatism [2]. The therapeutic efficacy of treatment for plant is based on the content of its bioactive components. Xanthones are the major constituents of S. longepedunculata [3] and have remarkable biological and medicinal activities, including antibacterial, antiviral, antihypertensive, antithrombotic, anticancer, cytotoxic, antioxidative and antiinflammatory activities [4]. Xanthones play an importance role because they have functional groups which have the potential to serve as acquired of new drugs. The beneficial effects of xanthonesrich natural products have been established, and supplementing processed foods with xanthones is being practiced warranting sufficient daily intake to enhance the immune system [5]. To isolate compounds from a substance, people do extraction, and this action depends on type of plant and compound of interest. Currently, the production of xanthones extracts in Cameroon is still using conventional methods such as maceration. Extraction with conventional methods has several disadvantages such as large energy and solvent requirements, long extraction times, loss of several important volatile compounds and low extraction efficiency. The research has developed new methods for extracting like supercritical fluid technology and microwaveassisted extraction (MAE). Several studies show that the extraction method using microwave permits to obtain good number of compounds extracts [6]. The study of kinetics models is necessary to calculate parameters and decide mechanism that occurs from the extraction process. Experimental data are generally analyzed using kinetic models, similarly the extraction processes [7]. On the other hand, modeling is needed to predict extraction yield of the xanthones from S. longepedunculata obtained from separation before processing it. To the best of our knowledge, there is no information available explaining the kinetic modeling of xanthones from S. longepedunculata. Therefore, in this research, the effects of microwave power, extraction time, ratio of liquid to solid and extraction yield of the xanthones will be studied. The obtained data could be used for obtaining several parameters: coefficient of determination, the rate constant, the equilibrium extraction capacity and the initial extraction rate of xanthone extract explaining the kinetic model considering microwaveassisted extraction process.
Materials and methods
Materials
The roots of S. longepedunculata (Polygalaceae) were collected in Mayo Tchabal during raining season and identified by Professor Mapongmetsem, a botanist in the Department of Biological Sciences of Faculty of Science, University of Ngaoundere, Cameroon. The plant material was dried at room temperature under shed for two weeks and kept in moisturefree atmosphere. The dried roots were ground before conducting the experiments. All other chemicals and solvents used were of analytical grade purchased from SigmaAldrich.
Methods
Microwaveassisted extraction
Extraction experiments were carried out using a modified domestic microwave oven apparatus (DAE WOO, KOG360, Combi Grill) adapted to a condenser. 100 g of dried Securidaca longepedunculata powder was extracted with 1000 mL solvent (acetone 95%) under different MAE conditions. After extraction, the vessels were allowed to cool at room temperature before opening. Microwave power (200, 400, 600, 800, 100 W), extraction time (20 to140 s, with an interval of 20 s) and solid–liquid ratio (0.25 to 2 g/20 mL with an interval of 0.25 g/20 mL) were evaluated for the extraction of xanthone from S. longepedunculata. The final extract was evaporated and dissolved in dimethyl sulfoxide before UV–Vis spectrophotometric (Spectroquant® Pharo 100 M) analysis. Three replicates were performed in each extraction.
Quantification of the total xanthones by colorimetric method
Colorimetric method followed by visible spectroscopy technique is one of the common analytical techniques used for the determination of a group of components in a mixture. This method is especially useful for the analysis of natural products which are very complicated mixtures [8]. Thus, this method may provide a solution for the quantification of the xanthones the S. longepedunculata extracts. The principle of this analysis was based on the oxidation of xanthones by the sodium acetate [9], which leads to the formation of yellow complex absorbing at 410 nm. 250 μL microwave extract and 75 μL of sodium acetate (5%) were mixed. This mixture was kept at ambient temperature for 30 min in order to gain a maximum of yellow color. The absorbance of the upper phase was read at 400 nm on an UV/Vis spectrophotometer (Spectroquant® Pharo 100 M) using glass cuvettes against blank in the number one test tube. Calibration curve was developed from 0 to 0.08 μL with an interval of 0.02 μL in different test tube with standard solution standard of 2hydroxy1,7diméthoxyxanthone. Total xanthone were expressed as mg 2hydroxy1,7diméthoxyxanthone equivalent per gram of dry weight extract (EDMX/gP).
Empirical kinetic models
in this study, kinetics of microwaveassistedextraction of xanthones from S. longepedunculata roots is performed using firstorder and secondorder models, it could be known rate of extraction from xanthones.
Hervas et al. model [10]
The kinetics mechanism proposed by Hervas et al. was used to study the extraction process under equilibrium conditions, as shown in Eq. (1)
where C is the concentration of xanthones (µg EDMX/mL) produced at any time t, C_{0} is the initial concentration of xanthones (µg EDMX/mL) present, and k is the effective diffusion coefficient (µL/µg EDMX s).
Integrating Eq. (1) between the initial moment and a given point at time t gives Eq. (2) with the boundary conditions as Ctt = 0 = 0 and Ctt = t = Ct
Peleg model [11]
The model proposed by Peleg was adapted for the extraction and used in the form:
where C(t) is the concentration of xanthones at time t (µg EDMX/g), t is the extraction time (s), K_{1} is the Peleg rate constant (s g/µg EDMX), and K_{2} is the Peleg’s capacity constant (g/µg EDMX).
The Peleg rate constant K_{1} relates to the extraction rate (B_{0}) at the very beginning (t = t_{0})
The Peleg capacity constant K_{2} relates to maximum extraction yield, i.e., equilibrium concentration of xanthones extracted (ce) when t → ∞. Equation (5) gives the relation between equilibrium concentration and K_{2} constant
Thus, the extraction rate coefficient can be written as in Eq. (6)
Gaussian model
The model proposed by Gauss was adapted for the extraction and used in the form:
Y is the extraction rate, a is the maximum value of the extraction rate, x is the variable studied in the extraction, x_{0} is the variable corresponding to the maximum value of the extraction rate a, and k is the constant of the extraction rate.
Statistical analysis
All analyses were performed in triplicate. The results are presented as average values with standard error and were analyzed statistically using oneway ANOVA. Statistical significance was accepted at a level of p < 0.05 using the statistical program Statgraphics centurion 12.
Results
Effect of extraction time on xanthones extraction yield
Kinetics extraction of xanthones from S. longepedunculata by MAE will be studied. Figure 1 shows the curve of xanthones concentration extracts with the extraction time. In this figure, we can observe rapid augmentation of xanthones concentration during eighty seconds and then more controlled increase during twenty seconds and nearsaturation during later stages of extraction.
Therefore, to understand the extraction kinetics, two mathematical models proposed by Harvest and Peleg were used.

Hervas model
Table 1 presents the extraction kinetics data obtained for the solid–liquid extraction using the Hervas method. The constant, k, C_{S} and correlation of coefficient R^{2} were calculated (Table 1).

Peleg model
The same data were analyzed using the model of Peleg. The extraction constant, correlation of coefficient R^{2} and the coefficient (K_{1}, K_{2} and k) for the extraction using the method were calculated and are mentioned in Table 2.
The plot of curve (Fig. 2) shows that kinetics extraction of xanthones of S. longepedunculata can be represented.
Effect of microwave power on xanthones extraction yield
Figure 3 shows the effect of microwave power on xanthone content during extraction. It can be clearly seen in this figure that there is a rapid increase in total xanthone at the power ranged from 200 to 550 W after which it reaches a threshold value. However, at 600 W we observe decrease in total xanthone content. The xanthone content at 200 and 550 W is found to be 1998.712 and 2900.7161 µg EDMX/gP, respectively.
Effect of solidtoliquid ratio on xanthones extraction yield
Figure 4 shows the effect of solidtoliquid ratio on the concentration of xanthones during MAE. It can be clearly seen in these figures that there is a steady increase in xanthone content at the ratio of solid to liquid from 0.25 to 1 g/20 mL after there is a significant decrease in the xanthone content and the yield decreases.
Gaussian model
The microwave power and solid–liquid ratio data were analyzed by using a Gaussian model of extraction. The maximum value of extraction rate, coefficient of determination R^{2} and the coefficient (x_{o} and k) for the extraction using the method were calculated and are mentioned in Table 3.
Discussion
Effect of extraction time on xanthones extraction yield
Kinetics extraction of xanthones from S. longepedunculata by MAE will be studied. Figure 1 shows the curve of xanthones concentration extracts with the extraction time. In this figure, it is observed that xanthones concentration increased rapidly with time during eighty seconds, corresponding to initial phase of MAE, followed by twenty seconds of more controlled increase and nearsaturation during later stages of extraction. This phenomenon may be explained by the rapid dissolution of dissolvable substance on particle area through washing and followed by undesirable element removal by diffusion [12]. The extraction curves (concentration of xanthones versus time) have a similar shape as the sorption curves (moisture content vs. time), and due to that fact, all these curves can be described using mathematical models of the mass transfer. Therefore, to describe the extraction kinetics, two mathematical models proposed by Harvest and Peleg model were used.

Hervas model
Table 1 presents the extraction kinetics data obtained for the solid–liquid extraction using the Hervas method. These results presented low value of correlation coefficients. Thus, the process does not act in accordance with evolution of a firstorder kinetic model of extraction, although the beginning of the extraction agreed with this order. The same data were analyzed by using a Peleg model of extraction. The extraction constant, correlation coefficient R^{2} and the coefficient (K_{1}, K_{2} and k) for the extraction using the method were calculated and are mentioned in Table 2. Compared with the harvest model, Peleg model presents very high coefficients and may be used to explain the microwaveassisted extraction process. During the microwaveassisted extraction of xanthones, an intense dissolution during the initial first stage and a strong scrubbing of the most soluble molecules (normal extraction) in the second stage are observed. The second stage is much slower because of the of transfer phenomenon of other molecules and the modification of the solid structure. This stage corresponds essentially to an external diffusion that concerns the remaining soluble matter [13].
Effect of microwave power on xanthones extraction yield
Figure 3 shows the effect of microwave power on xanthone content with extraction time. It can be clearly seen in these figures that there is a steady increase in xanthone content at the power ranged from 200 to 550 W after which it reaches a threshold value. The xanthone content at 200 and 550 W is found to be 1998.712 and 2900.7161 µg EDMX/gP, respectively. This extraction of xanthones by increasing microwave power can be associated with the direct effects of microwave energy on molecules by ionic conduction and dipole rotation which results in power dissipated in volumetric basis inside the solvent and plant material which generates molecular movement and heating [14]. Microwave irradiation energy can enhance the penetration of solvent into the matrix, and the heat generated in the system could cause softening of plant tissue, disruption of compounds of interests and increase in their solubility [15]. As shown in Fig. 3, the steep decrease at 600 W is due to the degradation of interest compounds at higher microwave power range. As the experiments are conducted in dry matter, as is usually the case, chances of degradation due to drying or evaporation at a higher microwave power intensity are ruled out [16]. Similar results of decrease in extraction yield of astragalosides from Radix astragali at high power due to disorderly molecular interactions have been reported in the optimization study of MAE of four main astragalosides in Radix astragali [17].
Effect of solidtoliquid ratio on xanthones extraction yield
As shown in Fig. 4, the total xanthone increased with increasing liquidtosolid ratio. When the liquidtosolid ratio increased from 0.25 g/20 mL:1 to 1 g/20 mL, the xanthone total also increased, which was probably due to the fact that more solvent could enter cells, while more xanthones compounds could permeate into the solvent under the higher solidtoliquid ratio conditions. With further increase in liquidtosolid ratio, a decline xanthone content was observed. Effect of solidtoliquid ratio on the concentration of xanthones during MAE was investigated. Pompeu et al. have reported that extraction of phenolics compounds was highly liquid–solid ratio dependent [18]. They have reported that liquid–solid ratio of 40:1 (mL/g) was sufficient to extract high quantities of phenolics from fruits of E. oleracea. Gan and Latiff reported that liquid–solid ratio (20 mL/g) played a significant role in the yield of phenolics, while extraction temperature did not make any significant contribution toward total phenolics content [19].
Gaussian model
The microwave power and solid–liquid ratio data were analyzed using a Gaussian model of extraction. The maximum value of extraction rate, coefficient of determination R^{2} and the coefficient ( x_{o} and k) for the extraction using the method were calculated and are mentioned in Table 3. The Gaussian model presents very high coefficients of and may be used to explain the effect of power and solid–liquid ratio from microwaveassisted extraction process. This model with an axis of symmetry shows the increase and decrease in our interesting compounds of interest. The maximum of xanthones were obtained at a microwave power of 600 W and a solid–liquid ratio of 1 g/20 mL. These models which can give us the maxima of xanthones can be used to contain the experimental domain.
Conclusion
The study of kinetic extraction of xanthones from S. longepedunculata using microwaveassisted extraction (MAE) has been done. This study confirms that microwave power and extraction time could affect the microwaveassisted extraction process. Further, the first and secondorder models were evaluated and we have obtained a remarkable fitting between experimental data and predicted model. The secondorder model of kinetics extraction can well represent extraction models. These studies provide knowledge about mechanisms involved in the extraction kinetic of xanthones from S. longepedunculata using microwave. This indicates the potential of utilization of microwave technology for an industrial scale or commercial purposes.
Availability of data and materials
The datasets analyzed during the current study are available from the corresponding author on reasonable request.
References
Booth FEM, Wickens GE (1988) Nontimber uses of selected arid zone trees and shrubs in Africa, No. 19. FAO Conservation Guide. FAO
Flórez NE, Conde HD (2015) Microwave assisted water extraction of plant compounds. J Chem Technol Biotechnol 90(590):607
Jian Z, Yan X, KunJun M, Xiang L, Jianwei C (2014) Xanthonerich dichloromethane fraction of Securidaca inappendiculata, the possible antirheumatic material base with antiinflammatory, analgesic, and immunodepressive effects. Pharm Biol 52(11):1367–1373. https://doi.org/10.3109/13880209.2014.892143
Wang LL, Liu HG and ZhangTJ (2010) Advances in studies on xanthones. Chin Tradit Herb Drugs 41(7):1196–1206
Yang CH, Ma L,Wei ZP, Han F, Gao J (2012) Advances in isolation and synthesis of xanthone derivatives. Chin Herb Med 4(2):87–102
Mandal V, Mohan Y, Hemalatha S (2007) Microwave assisted extraction an innovative and promising extraction tool for medicinal plant research. Pharmacogn Rev 7:18–21
Variyanaa Y, Mahfudb M (2020) Kinetics study using solventfree microwave extraction of essential oil from Allium sativum L. Key Eng Mater 840:186–192
Dai J (1999) Microwaveassisted extraction (MAE) of neem and the development of a colorimetric method for the determination of azadirachtin related limonoids (AZRL). M.Sc. Thesis, Mc Gill University Montreal, Canada, p 114
Negi JS, Bisht VK, Singh P, Rawat SM, Joshi GP (2013) Review article naturally occurring xanthones: chemistry and biology. J Appl Chem. https://doi.org/10.1155/2013/621459
Joubert E, Manley M, Botha M (2008) Evaluation of spectrophotometric methods for screening of green rooibos (Aspalathus linearis) and green honeybush (Cyclopia genistoides) extracts for high levels of bioactive compounds. Phytochem Anal 19:169–178
Hervas F, Celma SP, Berlanga TC, Pérez MF, Queraltó G (2006) Study of the extraction kinetic of glycosaminoglycans from raw sheepskin trimmings. In: Proceedings of international United of Environment Commission of IULTCS, Chengdu, China, pp 14–16
Peleg M (1988) An empirical model for the description of moisture sorption curves. J Food Sci 53:1216–1351
Meziane S, Kadi H (2008) Kinetics and thermodynamics of oil extraction from olive cake. J Am Oil Chem Soc 85:391–396. https://doi.org/10.1007/s1174600812052
Kusuma HS, Mahfud M (2017) Comparison of kinetic models of oil extraction from sandalwood by microwaveassisted hydrodistillation. Int Food Res J 24(4):1697–1702
Tsatsop Tsague RK, Kenmogne SB, Djiobie Tchienou GE et al (2020) Sequential extraction of quercetin3Orhamnoside from Piliostigma thonningii Schum. leaves using microwave technology. SN Appl. Sci. 2:1230. https://doi.org/10.1007/s4245202030316
Jeke K, Abhishek D, Denis C, Surabhi C, Debjani D (2014) Experimental and modeling studies on microwaveassisted extraction of mangiferin from Curcuma amada. 3 Biotech 4:107–120
Yang XD, Xu LZ, Yang XL (2010) Xanthones from the stems of securidaca inappendiculata. Phytochemistry 58:1245–1249
Pompeu DR, Silva EM, Rogez H (2009) Optimisation of the solvent extraction of phenolic antioxidants from fruits of Euterpeoleracea using response surface methodology. Biores Technol 600:6067–6082
CheeYuen G, Latiff AA (2011) Optimisation of the solvent extraction of bioactive compounds from Parkia speciosa pod using response surface methodology. Food Chem 124:1277–2128
Acknowledgements
The authors thank the laboratories of University of Ngaoundere for providing the research facilities.
Funding
This research did not receive any specific grant from funding agencies in the public, commercial or notforprofit sectors.
Author information
Authors and Affiliations
Contributions
MBN was involved in conceptualization; GEDT and RKTT contributed to data curation and resources; GEDT was involved in formal analysis, investigation and writing—original draft; and SDS and MBN contributed to project administration and were involved in supervision. All authors read and approved the final manuscript.
Corresponding author
Ethics declarations
Ethical approval and consent to participate
Not applicable.
Consent for publication
Not applicable.
Competing interests
The authors declare that they have no competing interests.
Additional information
Publisher's Note
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Rights and permissions
Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/.
About this article
Cite this article
Djiobie Tchienou, G.E., Tsatsop Tsague, R.K., Dongmo Sokeng, S. et al. Kinetic study in the extraction of xanthones from Securidaca longepedunculata roots by microwaveassistedextraction. BeniSuef Univ J Basic Appl Sci 11, 116 (2022). https://doi.org/10.1186/s4308802200298w
Received:
Accepted:
Published:
DOI: https://doi.org/10.1186/s4308802200298w
Keywords
 Microwaveassisted extraction (MAE)
 Securidaca longepedunculata Fresen
 Xanthones
 Empirical kinetics model