## 5 Conclusions  
The present study reveals that MnTnHex affects NSCLC cells in vitro at different levels. This redox-active drug, per se, markedly reduces the viability of NSCLC cells according to the endpoints explored, displaying very low IC\({}_{50}\) values. It alters the cell cycle distribution and induces cell death. It further increases the cytotoxicity of cisplatin and most so in H1975 cells, suggesting its usefulness for combination therapy. Moreover, MnTnHex per se or combined with cisplatin reduces collective cell migration pointing out to be also effective in this important metastatic feature of malignancy. Finally, concerning the metabolomics, few VCCs associated with oxidative stress, likely resulting from MnTnHex/H\({}_{2}\)O\({}_{2}\)-induced catalysis of peroxidation, were identified in the culture medium of MnTnHex treated cells. Metabolomics deserves further exploration. Overall, this work suggests that MnTnHex should be considered a promising drug candidate for NSCLC. The research on MnTnHex, an analog of clinically-tested Mn porphyrin BMX-001, would also promote further development of Mn porphyrins into clinical trials on other types of tumors, NSCLC included. The following supporting information can be downloaded at: [[https://www.mdpi.com/article/10.3390/antiox11112198/s1](https://www.mdpi.com/article/10.3390/antiox11112198/s1)]([https://www.mdpi.com/article/10.3390/antiox11112198/s1](https://www.mdpi.com/article/10.3390/antiox11112198/s1)), Figure S1: Viability of NSCLC cells when exposed to low concentrations of cisplatin or MnTnHex in culture medium with 2% FBS and assessed by MTS assay; Figure S2: Representative HS-SPME-GC-MS chromatogram of the extracellular culture medium of the H1975 cells with identification of volatile carbonyl compounds (VCCs), as listed in the first column of the Table S1; Figure S3: Principal component analysis (PCA) scores plot of the HS-SPME-GC-MS chromatograms of extracellular media of all samples under study (H1975 and A549 cells exposed to MnTnHex alone and/or combined with cisplatin and controls, \(n=71\), green circles) and the quality control samples (QCs, \(n=12\), red circles) and Figure S4: GC-MS-based metabolomics analysis of the extracellular medium of A549 cells exposed to MnTnHex and cisplatin, alone and combined. Table S1: List of volatile carbonyl compounds (VCCs) identified in the extracellular culture medium of H1975 and A549 cells by HS-SPME-GC-MS. Table S2: IC\({}_{50}\) values for MnTnHex and cisplatin in A549 and H1975 cells. Conceptualization, N.G.O. and P.G.d.P. ; methodology, R.B.S., R.M., S.P.C., N.S., F.A. and J.P.; formal analysis, R.B.S., R.M., J.G.C. and J.P.; writing--original draft preparation, R.B.S., N.G.O., A.S.F., J.P. and N.S. ; writing--review and editing, R.B.S., J.P.M., I.B.-H., N.G., R.R., I.S. and M.C. ; supervision, N.G.O. and P.G.d.P. ; funding acquisition, N.G.O., J.P.M., A.S.F. and P.G.d.P. All authors have read and agreed to the published version of the manuscript. The authors acknowledge Fundacao para a Ciencia e a Tecnologia (FCT) for financial support (PTDC/MED-TOX/29183/2017, UIDB/04138/2020, and UIDP/04138/2020 to iMed.U.Lisboa, 2020.04602.BD to R.M, UIDP/04567/2020 and UIDB/04567/2020 to CBIOS, UIDP/04378/2020 and UIDB/04378/2020 to the Research Unit on Applied Molecular Biosciences--UCIBIO and UI/BD/151313/2021 to F.A. as well as the project LA/P/0140/2020 of the Associate Laboratory Institute for Health and Bioeconomy--i4 HB). Not applicable. Data Availability StatementData is contained within the article or Supplementary Material. The authors would like to thank the Flow Cytometry Facility of iMed.U.Lisboa--Research Institute for Medicines, in particular to [PERSON] for technical support in the cell cycle distribution experiments. The authors also acknowledge COST Action CA20121. I.B.-H., L.S. and Duke University have patent rights and have licensed technologies to BioMimetix JV, LLC. I.B.-H. and I.S. are consultants with BioMimetix JV, LLC. Duke University and I.B.-H. and I.S.