Structure Elucidation, Conformation, and Configuration of Cytotoxic 6‑Heptyl-5,6-dihydro‑2H‑pyran-2-ones from Hyptis Species and Their Molecular Docking to α‑Tubulin Lucero Martínez-Fructuoso, † Rogelio Pereda-Miranda,* ,† Daniel Rosas-Ramírez, † Mabel Fragoso-Serrano, † Carlos M. Cerda-García-Rojas, ‡ Aline Soares da Silva, § Gilda Guimarã es Leitã o, ⊥ and Suzana Guimarã es Leitã o § † Departamento de Farmacia, Facultad de Química, Universidad Nacional Autó noma de Mé xico, Ciudad Universitaria, Mexico City 04510, Mexico ‡ Departamento de Química, Centro de Investigació n y de Estudios Avanzados del Instituto Polité cnico Nacional, A. P. 14-740, Mexico City 07000, Mexico § Faculdade de Farmacia, Universidade Federal do Rio de Janeiro, CCS, Bloco A, Ilha do Fundã o, 21941-902, Rio de Janeiro, Brazil ⊥ Instituto de Pesquisas de Produtos Naturais, Universidade Federal do Rio de Janeiro, CCS, Bloco H, Ilha do Fundã o, 21941-590, Rio de Janeiro, Brazil * S Supporting Information ABSTRACT: Cytotoxic 6-heptyl-5,6-dihydro-2H-pyran-2- ones are chemical markers of Hyptis (Lamiaceae) and are responsible for some of the therapeutic properties of species with relevance to traditional medicine. The present inves- tigation describes the isolation of known pectinolides A-C (1-3), in addition to the new pectinolides I-M(4-8), from two Mexican collections of H. pectinata by HPLC. The novel biosynthetically related monticolides A (9) and B (10) were also isolated by high-speed countercurrent chromatography from H. monticola, an endemic species of the Brazilian southeastern high-altitude regions. A combination of chemical correlations, chiroptical measurements, and Mosher ester NMR analysis was used to confirm their absolute configuration. The utility of DFT-NMR chemical shifts and J H-H calculations was assessed for epimer differentiation. Molecular docking studies indicated that 6-heptyl-5,6-dihydro-2H-pyran-2-ones have a high affinity for the pironetin-binding site of α-tubulin, which may be a possible mechanism contributing to the cytotoxic potential of these small and flexible molecules. T he plants belonging to the genus Hyptis from the mint family (Lamiaceae), commonly known as bushmints, are widespread in the tropical Americas with the Guianan and Brazilian shields as their diversification center. 1 This genus has great relevance for the traditional medicine of Latin America in the treatment of gastrointestinal and respiratory problems and fever. 2-4 H. pectinata (L.) Poit., with a pantropical distribution, has spread as a weed and become naturalized throughout the South American tropics to the Caribbean, Central America, and Mexico. It is considered a noxious weed of cultivated land, pastures, and trailsides. In Mexico and Brazil, it is utilized extensively in ethnomedicine as a decoction, mainly as a natural anti-inflammatory agent for rheumatic pains. Aqueous and organic extracts from leaves have shown antiedematogenic and antinociceptive effects in animal models, 5,6 validating the popular use of this herbal drug. In addition, the antimicrobial activities of its essential oils, with thymol as the major component, are also responsible for a large number of therapeutic applications of this medicinal plant. 7 Additionally, H. monticola Mart. ex Benth. is an endemic species of high- altitude areas (1000-2000 m a.s.l.) at the Brazilian south- eastern region. Its essential oil was characterized predom- inantly by trans-caryophyllene, (E)-methyl cinnamate, germa- crene D, limonene, α-muurolene, and β-pinene. 7c The pharmacological properties of this species have not been studied. Hyptis contains a group of chemical markers possessing the 6-heptyl-5,6-dihydro-2H-pyran-2-one system, which contrib- utes with its antimicrobial 3 and cytotoxic 8 properties. The activity of these compounds is related to the α,β-unsaturated δ- lactone system, a well-known Michael acceptor, which is complemented with the lipophilicity provided by the 6-alkyl substituent to facilitate interaction with cell membranes. 8b Pironetin, isolated from cultures of Streptomyces sp., is a Special Issue: Special Issue in Honor of Drs. Rachel Mata and Barbara Timmermann Received: October 29, 2018 Article pubs.acs.org/jnp Cite This: J. Nat. Prod. XXXX, XXX, XXX-XXX © XXXX American Chemical Society and American Society of Pharmacognosy A DOI: 10.1021/acs.jnatprod.8b00908 J. Nat. Prod. XXXX, XXX, XXX-XXX J. Nat. Prod. Downloaded from pubs.acs.org by LA TROBE UNIV on 01/02/19. For personal use only.