Virtual screening is a well-known computational approach used to select promising compounds for drug discovery. It consists of medium-precision dockings of a compound library against a protein, in order to identify ligands with high affinity. In this study, the virtual screening was carried out using PyRx v0.8 (The scripps Research Institute, La Jolla, San Diego, CA, USA) [19]. It selected 17 of the most abundant compounds of Boswellia carterii resin and screened them against collagenase and elastase.The tridimensional structures of the selected ligands were downloaded from PubChem (http://pubchem.ncbi.nlm.nih.gov, accessed 6 October, 2022), namely 11-keto-beta-boswellic acid (1) (PubChem CID: 6918114), acetyl-11-keto-beta-boswellic acid (2) (PubChem CID: 71463896), beta-boswellic acid (3) (PubChem CID: 168928), alpha-boswellic acid (4) (PubChem CID: 637234), alpha-acetyl boswellic acid (5) (PubChem CID: 117072585), beta-acetyl boswellic acid (6) (PubChem CID: 11386458), 3-oxotirucallic acid (7) (PubChem CID: 134693088), elemonic acid (8) (PubChem CID: 15559100), 3-beta-hydroxytirucallic acid (9) (PubChem CID: 441677), palmitic acid (10) (PubChem CID: 985), lupeol (11) (PubChem CID: 259846), incensole (12) (PubChem CID: 44583885), incensole acetate (13) (PubChem CID: 73755086), 3alpha-hydroxytirucalla-7,24-dien-21-oic acid (14) (PubChem CID: 158143), lupeolic acid (15) (PubChem CID: 12111950), acetyl-9,11-dehydro-beta-boswellic acid (16) (PubChem CID: 44558899) and 9,11-dehydro-beta-boswellic acid (17) (PubChem CID: 102509765) (Figure 2). Regarding the structures of the collagenase (PDB CID: 1CGL) and elastase (PDB CID: 1BRU), they were downloaded from the RCSB Protein Data Bank (http://www.rcsb.org/, accessed 6 October, 2022).

The proteins were downloaded in PDB format and the ligands in SDF format, the structures were prepared and processed on PyRx using the software internal openbabel and Autodock extension. The ligands that showed the best results were submitted to a molecular docking study.