title: Structure-Bioactivity Relationships of Methylxanthines: Trying to Make Sense of All the Promises and the Drawbacks.
abstract: Methylxanthines are a group of phytochemicals derived from the purine base xanthine and obtained from plant secondary metabolism. They are unobtrusively included in daily diet in common products as coffee, tea, energetic drinks, or chocolate. Caffeine is by far the most studied methylxanthine either in animal or epidemiologic studies. Theophylline and theobromine are other relevant methylxanthines also commonly available in the aforementioned sources. There are many disseminated myths about methylxanthines but there is increased scientific knowledge to discuss all the controversy and promise shown by these intriguing phytochemicals. In fact, many beneficial physiologic outcomes have been suggested for methylxanthines in areas as important and diverse as neurodegenerative and respiratory diseases, diabetes or cancer. However, there have always been toxicity concerns with methylxanthine (over)consumption and pharmacologic applications. Herein, we explore the structure-bioactivity relationships to bring light those enumerated effects. The potential shown by methylxanthines in such a wide range of conditions should substantiate many other scientific endeavors that may highlight their adequacy as adjuvant therapy agents and may contribute to the advent of functional foods. Newly designed targeted molecules based on methylxanthine structure may originate more specific and effective outcomes.
authors.affiliation: Laboratory of Cell Biology and Unit for Multidisciplinary Research in Biomedicine (UMIB), Department of Microscopy, Institute of Biomedical Sciences Abel Salazar (ICBAS), University of Porto, 4050-313 Porto, Portugal. jpspmonteiro@yahoo.com.
authors.forename: João P
authors.initials: JP
authors.lastname: Monteiro
authors.affiliation: Health Sciences Research Centre (CICS-UBI), University of Beira Interior, 6201-506 Covilh&#227;, Portugal. alvesmarc@gmail.com.
authors.forename: Marco G
authors.initials: MG
authors.lastname: Alves
authors.affiliation: Laboratory of Cell Biology and Unit for Multidisciplinary Research in Biomedicine (UMIB), Department of Microscopy, Institute of Biomedical Sciences Abel Salazar (ICBAS), University of Porto, 4050-313 Porto, Portugal. pfobox@gmail.com.|Institute of Health Research an Innovation, University of Porto, 4200-135 Porto, Portugal. pfobox@gmail.com.
authors.forename: Pedro F
authors.initials: PF
authors.lastname: Oliveira
authors.affiliation: Health Sciences Research Centre (CICS-UBI), University of Beira Interior, 6201-506 Covilh&#227;, Portugal. bmcms@ubi.pt.
authors.forename: Branca M
authors.initials: BM
authors.lastname: Silva
mesh_terms: D000818:Animals; D002099:Cacao / Q000737:chemistry; D002110:Caffeine / Q000737:chemistry / Q000494:pharmacology; D006801:Humans; D015394:Molecular Structure; D064209:Phytochemicals / Q000737:chemistry* / Q000494:pharmacology*; D064210:Secondary Metabolism; D013329:Structure-Activity Relationship; D013805:Theobromine / Q000737:chemistry / Q000494:pharmacology; D013806:Theophylline / Q000737:chemistry / Q000494:pharmacology; D014970:Xanthines / Q000737:chemistry* / Q000494:pharmacology*
chemical_list: D064209:Phytochemicals; D014970:Xanthines; C008514:methylxanthine; D002110:Caffeine; D013806:Theophylline; D013805:Theobromine
keywords: caffeine; cancer; diabetes; methylxanthine; neurodegenerative diseases; structure-activity relationship; theobromine; theophylline