Mircea Vinatoru

Organic and Medicinal chemistry international Journal is an open access journal that is committed to publish the papers on various topics of chemistry, especially synthetic organic chemistry, and pharmacology and various other biological specialties COVID-19, a virus who already shut down the world! To fight against this virus, most of the countries decided to confine people in their homes, limiting their movements and asking them to stay at least 2 meters away from any other person they may meet. This virus not only starts to destroy socialization but also was negatively impacting the whole economy. What should we do? Nothing else than to rediscover the ancient way of treatments, fights against diseases, by using silver and copper metals or their salts as tools against COVID-19 or other viruses or microbes that will threaten in the future.

In this study, we present a strategy for valorizing lignocellulosic wastes (licorice root and willow bark) that result from industrial extraction of active principles using water as green solvent and aqueous NaOH solution. The wastes were submitted to severe ultrasound (US) and microwave (MW) treatments. The aim of these treatments was to extract the remaining active principles (using water as a solvent) or to prepare them for cellulose enzymatic hydrolysis to hexoses (performed in an NaOH aqueous solution). The content of glycyrrhizic acid and salicin derivatives in licorice root and willow bark wastes, respectively, were determined. The best results for licorice root were achieved by applying the US treatment for 5 min at 25 °C (26.6 mg glycyrrhizic acid/gDM); while, for willow bark, the best results were achieved by applying the MW treatment for 30 min at 120 °C (19.48 mg salicin/gDM). A degradation study of the targeted compounds was also performed and showed good stability of glycyrrhizic acid and salicin derivatives under US and MW treatments. The soluble lignin concentration prior to enzymatic hydrolysis, as well as the saccharide concentration of the hydrolyzed solution, were determined. As compared with the MW treatment, the US treatment resulted in saccharides concentrations that were 5% and 160% higher for licorice root and willow bark, respectively.

Currently there is a drive towards the minimisation and reclamation of valuable materials from the waste products of the food and beverage industry. This can be achieved through the extraction of residual nutraceuticals from such materials. Tomato pomace contains carotenoids and other chemicals which can be extracted directly into edible oils to improve the health-giving properties of such oils. We report here a novel green solvent, fatty acid ethyl esters (FAEE), which is significantly more effective than sunflower oil and hexane for the extraction of lycopene and beta-carotene from tomato skin waste. FAEE are a non-toxic renewable resource that is environmentally friendly and to our knowledge has never been used as a vegetal extraction fluid. The efficiency of FAEE extraction was significantly improved relative to both sunflower oil and hexane under ultrasound-assisted extraction (UAE) conditions. In addition, FAEE have the additional and significant advantage that once enriched with the extracted nutraceuticals can be used directly as a food additive.

Sonochemistry can be broadly defined as the science of chemical and physical transformations produced under the influence of sound. The use of sound energy is rather a young branch of chemistry and does not have the clear definitive rules of other, more established, divisions such as those in cycloaddition reactions or photochemistry. Nevertheless, there are a few guidelines which can help to predict what is going to happen when a reaction mixture is submitted to ultrasonic irradiation. Jean-Louis Luche, formulated some ideas of the mechanistic pathways involved in sonochemistry more than 30 years ago. He introduced the idea of “true” and “false” sonochemical reactions both of which are the result of acoustic cavitation. The difference was that the former involved a free radical component whereas only mechanical effects played a role the latter. The authors of this paper were scientific collaborators and friends of Jean-Louis Luche during those early years and had the chance to discuss and work with him on the mechanisms of sonochemistry. In this paper we will review the original rules (laws) as predicted by Jean-Louis Luche and how they have been further developed and extended in recent years.

The literature related to microwave and ultrasound working simultaneously is rather infrequent. The reason is obvious: microwave irradiation is of electromagnetic origin while ultrasound is a mechanical vibration energy. Moreover, the optimal settings for ultrasound propagation throughout a reaction media do not coincide with the conditions required for application of microwaves. Therefore, the challenge is to find a way to best combination of these sources of energy into one apparatus to allow researchers to take advantage of the features of each technology. The oldest paper describing such a combination – microwave and ultrasound is having just 20 years [1] and describe an apparatus which uses a probe system delivering ultrasound through decalin to a vessel holding the reagents dipped in the MW cavity (fig. 1a). Another possibility using a normal MW oven is described by Peng [2] (fig.1b), but this setup is having radiation leakage problems and needs a proper protection. Ragaini et all proposed another type of setup [3] (fig. 1c), not easy to reproduce, but describing calibration and parameters which show an additive increase of thermal energy delivered when MW and US works simultaneous. Insert here uploaded pictures Figure 1. Some MW-US simultaneous setups Few years ago, Cravotto and Cintas [4], disccussed for the first time the potential of using MW and US in sequential or tandem setups. Their paper discuss all possible setups for using mostly glass probe for devlivery of ultrasonic energy or classical setup (fig. 1a). Slowly the concept gain popularity and the paper of Lionelly and Mason [5] prompts to the potential industrial applications, naming the combination of microwave with ultrasound a hybrid technology. The challenge in using this “hybrid technology” is to find a vesatile and reproducible apparatus able to deliver both microwave and ultrasound at a full controlable parameters. In our laboratory we have and use the setup like in the fig. 1a, but the ultrasonic energy is delivered by an ultrasonic cleaning device attached to microwave device (SAIREM Miniflow 200SS). To achieve the above mentioned outcome launched a project to build a device which could work with MW and US in tandem (as Cravotto mentioned [4]) using an US device able to deliver more than a single ultrasonic frequency at a full controlled power. It is our believe that such a device could significantly contribute to MW-US tandem equipment development. Based on our expertise and potential proposed interaction of US with reagents [6] we will investigate the influence (if any) of ultrasound upon MW field. In this paper we will present the earlier results of “Tandem Microwave Ultrasound” energy influence on chemical reagents. References 1. Lagha, A., et al., Analusis, 1999. 27(5): p. 452-457. 2. Peng, Y. and G. Song, Green Chemistry, 2001. 3(6): p. 302-304. 3. Ragaini, V., et al., Ultrasonics Sonochemistry, 2012. 19(4): p. 872-876. 4. Cravotto, G. and P. Cintas, Chemistry - A European Journal, 2007. 13(7): p. 1902-1909. 5. Leonelli, C. and T.J. Mason, Chemical Engineering and Processing: Process Intensification, 2010. 49(9): p. 885-900. 6. Vinatoru, M. and T.J. Mason, Ultrasonics Sonochemistry, 2018.