| Abstrakt: |
Introduction: One of the most widely used conventional methods for bioactive compounds recovery from natural sources is Soxhlet extraction. But this process showed different disadvantages such as longer extraction time and large consumption of solvent, which limited its application for bioactive compounds recovery. One of the green and new emerging technologies for plant extractions is microwave-assisted extraction (MAE). This technology has recently received much attention as an alternative means to extract bioactive compounds from plant materials. MAE has noted to possess a number of advantages over a more traditional solvent extraction, including rapid extraction and less consumption of an extraction solvent. Parvansh with the scientific name Catharanthus roseus L. is native to the island of Madagascar. This plant is cultivated in many tropical and subtropical regions. C. roseus is an evergreen plant and has flowers with beautiful and varied colors from pink to purple. Parvansh has medicinal uses in Spain, United States, China, Africa, India and Southern Europe and in Iran. Parvansh cultivated in Khuzestan, Bushehr, Hormozgan, sistan and Baluchestan provinces and rarely in Tehran. This study aimed to optimize the MAE conditions for maximum recovery of bioactive compounds from C. roseus using response surface methodology (RSM). Furthermore, a comparative study was carried out between MAE and Soxhlet methods to determine the most preferable process for bioactive compounds recovery from C. roseus aerial parts. Materials and methods: A microwave-assisted extractor apparatus with maximal microwave power of 1000 W at a frequency of 2450 MHz was used for extraction of bioactive compounds from C. roseus aerial parts. Microwave power (100-300 W), sample to solvent ratio (1:20-1:40 w/v) and microwave irradiation time (9-14 min) were independent variables. Optimization was performed using numerical technique with the aim of maximizing the extraction yield and total phenolic content. A binary solvent composed of ethanol (EtOH) and water (H2O) was selected as an efficient and safe extraction solvent. For performing Soxhlet extraction, About 5 gram of ground sample were put in a thimble holder and covered with wool. Thimble was transferred into a Soxhlet apparatus. Approximately, 200 mL of binary ethanol was added to extraction flask which was connected to the extractor. During extraction, the thimble holder was gradually filled with condensed fresh solvent used for extraction from a distillation flask. Each extraction was performed for 6 h in triplicate. The responses were considered as crude extraction yield and total phenolic compounds for numerical optimization process. However, the free radical scavenging activity of extracts obtained using optimized conditions were determined in terms of DPPH and HO free radical scavenging capacity (%DPPHsc and %HOsc). Box–Behnken design (BBD; Design Expert Software, Trial version 12, Stat-Ease Inc., Minneapolis, MN, USA) of Response Surface Methodology (RSM) was conducted to optimize the three independent variables, namely, microwave power (X1), solid to solvent ration (X2), and irradiation time (X3), with low (-1), medium (0), and high levels (+1) for each independent variable. Results and discussion: In the present study, the effect of MAE independent variables including microwave power, sample-to-solvent ratio, and irradiation time were investigated and optimized for efficient recovery of bioactive compounds from C. roseus aerial parts. The model p-value was less than 0.05 indicating that the models were statistically significant. The Analysis of variance (ANOVA) results and regression coefficients of linear, quadratic, and interaction terms of independent variables showed that all independent variables studied had significant (p<0.05) effect on responses. According to the results, the obtained quadratic polynomial model fits well with the experimental data with a high coefficient of determination (0.99). In a desirable and acceptable statistical model, the adjusted coefficient of determination (R²adj) is close to the coefficient of determination, which is obvious in the present study. The lack of fit test is non-significant (p>0.05) in the case of pure error. Also, the coefficient of variation (CV) in low values indicates a small difference between experimental and predicted values, as well as high accuracy and reliability of experimental data. Therefore, the fitted quadratic polynomial model is suitable for predicting the response within the range of the studied variables). The optimum MAE conditions were determined as 250 W microwave power, 11 min microwave irradiation time and (1:33 w/v) ratio of sample to solvent. Under these conditions, TPC and yield were determined as 118.40 mg GAE/g and 18.21%, respectively. There was no significant difference between experimental and predicted values of the responses, which showed the accuracy of the optimization process. The traditional Soxhlet method was used to evaluate the efficiency of MAE technology. According to the results, the yield obtained under the optimal conditions of MAE was around 60% related to the results from Soxhlet. However, in terms of free radical scavenging activity and total phenolic compounds the MAE extract was significantly better than those obtained using Soxhlet extraction (p<0.05). Conclusions: In this study, it was shown that C. roseus aerial part is a potential source of valuable bioactive compounds, which highlighted its importance for further utilization in food applications. Furthermore, MAE process was successfully optimized using RSM based on BBD to obtain the highest values of TPC and crude extraction yield simultaneously. A comparative study was also carried out between MAE and Soxhlet extraction to determine the efficiency of MAE process. It was revealed that lower quantity of extracts could be obtained using MAE compared with Soxhlet process while; the TPC and free radical scavenging activity of bioactive compounds was considerably better. Therefore, it could be stated that MAE is an efficient green technology for successful recovery of bioactive compounds from C. roseus aerial part. [ABSTRACT FROM AUTHOR] |
