Currently, I am working with some plants that offer antimicrobial and antiviral activity, but nonetheless, I need some other plants that are best for these two activities.
If anyone has any thoughts on this please let me know.
Yet about your wish, if such plants exist keep in your mind that is all about "luck". Plants activities depend on their content of secondary metabolite ( Alcaloides, flavonoides, tanins, phenols, terpenoides etc.) so depending on the presence, the quantity and the nature of these secondary metabolite you might have high or low activity.
Did you tried to fractionnate those plants extracts you have? Before looking for new plants fractionnate your extracts and test each fraction and at the end associate the best fraction and test.
Research is not all about looking for new plants but also how you are exploiting what you have already. So please if possible do fraction mat be you might have the best ever tested antiviral and antimicrobial.
As Dr. Ekon said, the functional element is extract composition, not so much the "plant." Qualitatively, extracts generally include the same compounds and differential efficacy is based on quantitative composition.
I strongly recommend you complete your scholarship - an adequate review of the literature.
Your question is too general. Please be more specific. For instance, describe what is your research about, what do you want to achieve, on which plant species you're working, etc.
Maybe I could help you. In the meantime, please check my references on my ResearchGate profile, and if you want, I can send my personal author’s copies of the papers you’re interested in. Off course, we can also continue our conversation when you’ will send me some required information I requested above. Thank you.