## 4 Conclusions  
In the present work, the main parameters of the extraction, i.e., temperature, duration, solvent-to-biomass ratio, and microwave power, were examined during the microwave-assisted extraction of bioactive compounds from _C. vulgaris_ biomass with aq. ethanol 90% \(v/v\). The obtained extracts were subjected to determination of their yield, total phenolic, chlorophyll, and carotenoid content, as well as their antioxidant activity. The correlation between the examined parameters and the determined responses was based on the ANOVA and led to reliable models, except for the total phenolic and selected carotenoid content, which failed to correlate.  
The data correlation proved the significance of the individual influence of temperature and solvent-to-biomass ratio, as well as the combined factor of temperature, power, and duration (T P t) on the extraction yield. The solvent-to-biomass ratio highly affected chlorophyll content, while temperature proved to be the most significant factor affecting the extract's antioxidant activity. Nevertheless, all the responses of phenolic, chlorophyll, carotenoid content, and the extract's antioxidant activity were significantly affected by the combined factor of temperature and microwave power (T P).  
Consequently, MAE was optimized, aiming at the simultaneous maximization of all the correlated responses. The determined optimal extraction conditions of temperature, microwave power, duration, and solvent-to-biomass ratio were 60 \({}^{\circ}\)C, 300 watts, 14 min, and 22 mL\({}_{\text{solv}}\)/g\({}_{\text{biom}}\), respectively.  
Furthermore, the comparison of MAE with SLE and SFE with and without cosolvent (10% \(w/w\) ethanol) also led to important observations. During the use of the same polar solvent, the MAE's bioactive compounds and extract's antioxidant activity were slightly improved compared to SLE. Despite the higher SLE yield, the assistance of microwave power offered a satisfactory extraction yield and an improved extract during an extremely shorter amount of time. Alternatively, the application of SFE with a non-polar solvent proved to be of decisive importance for the greater selectivity towards carotenoids over chlorophylls, and the remarkably improved extract's antioxidant activity, at the expense of extraction yield, which was significantly lower. However, the attempt to address the yield obstacle of SFE through the addition of a polar cosolvent narrowed the gap between MAE and SFE and also led to an overall enhanced extract.  
In conclusion, the two non-conventional time-saving methods of MAE and SFE were considered very promising with competitive extracts compared to the conventional SLE. SFE, with or without the cosolvent presence, offered more limited yet more competing extracts than MAE. However, the products of both methods could be exploited in the demanding industry fields of food, cosmetics, fertilizers, animal feed and health products, according to their characteristics and value.  
Conceptualization, K.M.; methodology, I.G. and S.T.; software, I.G.; validation, I.G., S.T., V.L. and K.M.; investigation, I.G.; data curation, I.G., S.T., V.L. and K.M.; writing--original draft preparation, I.G.; writing--review and editing, V.L., K.M.; supervision, K.M.; project administration, K.M. All authors have read and agreed to the published version of the manuscript.  
The implementation of the doctoral thesis of the author [PERSON] was co-financed by Greece and the European Union (European Social Fund-ESF) through the Operational Programme \"Human Resources Development, Education and Lifelong Learning\" in the context of the Act \"Enhancing Human Resources Research Potential by undertaking a Doctoral Research\" Sub-action 2: IKY Scholarship Programme for PhD candidates in the Greek Universities.  
Not applicable.  
Additional data for this study are not available in any public database. The corresponding author can provide them upon request.  
The authors declare no conflict of interest.