## 3 Results and Discussion
### Green Corrosion Inhibitors Derived from Plant Extracts  
The combination of group C descriptors (corros* AND (inhib* or inib*) AND (green OR environmental sustainable OR eco-friendly) AND plant* AND extract) recovered 333 articles from the Web of Science database. Figure 5 shows its distribution over the years. Publications have grown significantly, especially in the last 10 years, indicating that interest in plant extract derivatives such as green corrosion inhibitors is on the rise. When analyzing the articles, it was found that 285 were directly related to the theme of interest. Then, a survey was conducted regarding the part of the plant used, the type of metal that should be protected, the aggressive/corrosive medium tested and the type of inhibitor that these studies reported. This data is shown in Figure 6. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Code** & **Title** & **IPC Classification** & **Year of Filing** & **Status** \\ \hline \multirow{3}{*}{BR 10 2020 000691 6} & Use of ethanolic extract of red propolis from Alagoas as an environmentally friendly metal corrosion inhibitor & C23F 11/10; C23F 11/08 & 2020 & A2 \\ \cline{1-1}  & & corrosion inhibitor & C23F 11/08 & 2019 & A2 \\ \hline \multirow{3}{*}{BR 10 2019 006077 8} & Corrosion inhibitor powder obtained from cocoa bean shell & C23F 11/10; C23F 11/04 & 2019 & A2 \\ \cline{1-1}  & & Process for obtaining and using glycoprotein secretion from terrestrial gastropod mollusks as an environmentally friendly metal corrosion inhibitor & C23F 11/12; C08B 37/00 & 2017 & A2 \\ \cline{1-1}  & & corrosion inhibitor & & & \\ \hline \multirow{3}{*}{BR 10 2017 023566 1} & Powdered corrosion inhibitor obtained from palm kernel cake & C23F 11/10 & 2017 & A2 \\ \cline{1-1}  & & Process for the production and application of macerated barley residue extract as a green inhibitor for acid pickling of ferrous materials & C23F 11/04; C23F 11/06; C23F 11/08 & 2016 & A2 \\ \hline \multirow{3}{*}{BR 10 2016 017142 3} & Protector of biodegradable metallic material based on microemulsion containing the surfactant OCS added with DBS for commercial application in oil pipelines & C10M 141/08 & 2016 & A2 \\ \cline{1-1}  & & Green corrosion inhibitor based on Phylanthus amarus Schum hydroalcoholic extract. \& [PERSON] & C09D 5/14; C09D 5/08 & 2016 & A2 \\ \cline{1-1}  & & Composition & C09D 5/08; C09D 5/18; C09D 1/00 & 2014 & A2 \\ \hline \multirow{3}{*}{BR 10 2014 031459 8} & Auto-micro-emulsifying system containing industrialized copaiba oil for application in green chemistry & B01F 17/00; C23F 11/00 & 2014 & A2 \\ \cline{1-1}  & & Obtaining nano-self-emulsifying systems using oil from the seeds of azadirachta indica a. Juss for application as a corrosion inhibitor & B01F 17/00; C23F 11/00 & 2014 & A2 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Main information on the patents recovered from the PTO basis for group B descriptors. Plants are rich sources of organic matter and present variations in availability and types of compounds according to the parts analyzed. Most of the articles analyzed are concerned with the leaves (63.38%), as shown in Figure 6a. This choice is related to its bioavailability, easy extraction by low-cost methodologies and the fact that in most species it is the part where significant amounts of antioxidant compounds are found. This is mainly due to the fact that phytochemicals are produced mainly in the leaves, where they  
Figure 5: Distribution over the years for articles retrieved from the Web of Science with group C descriptors. Figure 6: Information from the articles retrieved from the Web of Science with group C descriptors referring to (**a**) part of the plant used, (**b**) metallic material to be protected researched, (**c**) aggressive/corrosive medium tested and (**d**) type of action of the proposed inhibitor. are synthesized in the presence of sunlight, water and CO\({}_{2}\).