Phaeurus antarcticus and its endophytic fungi: chemical diversity of a hidden pharmacy underneath the Antarctic Ocean

• Main Author: Santos, Gustavo Souza dos
• Other Authors: Debonsi, Hosana Maria, Edrada-ebel, Ru Angelie
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: Biblioteca Digital de Teses e Dissertações da USP 2022
• Subjects: Produtos naturais marinhos; Macroalgas antárticas; Fungos antárticos; Fotoproteção; Doenças negligenciadas; Atividade imunomoduladora; Antimicrobianos; Metabolômica; Neglected diseases; Metabolomics; Photoprotection; Marine natural products; Immunomodulatory activity; Antimicrobials; Antarctic seaweed; Antarctic fungi; Antarctic; The Antarctic; Antarctic Ocean; Sob’; Antarc*; antarcticus
• Online Access: https://www.teses.usp.br/teses/disponiveis/60/60138/tde-20072023-113231/; https://doi.org/10.11606/T.60.2022.tde-20072023-113231

Chapter I: The chemical profile and antibacterial, antiparasitic, and insecticidal activities of the seaweed P. antarcticus were investigated. The hexane extract (HX) and its fractions exhibited selective antibacterial activity against Staphylococcus aureus. Fractions HX-FC and HX-FD showed the highest antiparasitic activity against Leishmania amazonensis and Neospora caninum. The HX extract and the HX-FC fraction presented insecticidal potential against Aedes aegypti larvae. Through GC-MS analysis and the combination of multivariate statistical analyses (OPLS-DA) and the construction of molecular networks (GNPS), it was possible to annotate terpenes, steroids, fatty acids, and alcohols in the bioactive fractions. Chapter II: Using metabolomics techniques (UPLC-HRMS/1H NMR) and multivariate statistical analysis (PCA, OPLS-DA), the spatial variability of secondary metabolites of the seaweed P. antarcticus and the antibiofilm activity of extracts and fractions were evaluated against S. aureus resistant to methicillin-oxacillin (MRSA). The results revealed that the changes in the chemical profile were not site-specific and could be related to different life cycle stages of the collected algae. Porphyrins, terpenes, and carotenoids were annotated as discriminating compounds. Linoleic acid (1) and fucosterol (2) were isolated from the bioactive fractions and showed antibiofilm activity against MRSA. Chapter III: The extract and fractions of the fungus Penicillium purpurogenum were evaluated for antibacterial, antiparasitic, immunomodulatory, and photoprotective activities. The bioguided fractionation led to the isolation of six polyketides: 5,6,8-trihydroxy-4-(1\'-hydroxyethyl) isocoumarin (3), aspergillumarin A (4), aspergillumarin B (5), Berkeleyacetal C (6), sescandelin (7), and vermistatin (8). Compounds 3, 4, 7, and 8 presented photostability and photoprotective activities against UVB-UVA. Compounds 3, 6, 7, and 8 presented immunomodulatory activity by down-regulating the production of reactive oxygen species in ...