Julio Montes-Avila

Solution-phase parallel synthesis of substituted chalcones and their antiparasitary activity against Giardia lamblia

A library of 25-membered chalcones was prepared by parallel synthesis. Substituted acetophenones and benzaldehydes were condensed using the Claisen-Schmidt base-catalyzed aldol condensation. Several chalcones showed in vitro antiparasitic activity against Giardia lamblia. The highest activity observed for the IC(50) values were 12.72, 15.05 and 15.31 microg/mL, respectively; these are potential leads for the development of antigiardial compounds.

Microwave-assisted synthesis of hydropyridines and study of the DPPH-scavenging activity

A series of hydropyridines (HPs) were synthesized using dimedones, ethyl acetoacetate, ammonium acetate and appropriate aldehydes under solvent-free conditions and microwave-irradiation through Hantzsch reaction. All the synthesized HPs were tested in vitro for the 1,1-diphenyl-2-picrylhydrazyl (DPPH) scavenging activity and structure–activity relationship was discussed; only 12 out of the 36 HPs showed antioxidant activity. Polyhydroquinolines (PHQs) were the most active compounds among the studied HPs, they were characterized by the lack of an ester-like structure substituent at carbon 5.

Synthesis of 1H-benzoxazine-2,4-diones from heterocyclic anhydrides: evaluation of antioxidant and antimicrobial activities

A facile one-step synthesis of 1H-benzoxazine-2,4-diones from heterocyclic anhydrides and TMSA was described. This paper determines their antimicrobial activity against nine human bacterial pathogens by the broth microdilution method; antioxidant activity by DPPH• inactivation and a ferric-reducing power assay; and toxicity by a brine shrimp, Artemia salina, assay. The 1H-benzoxazine-2,4-dione yields were in the range of 57 to 98%. The novel compound 1H-pyrazino[2,3-][1,3]oxazine-2,4-dione 4c showed the highest antioxidant capacity (DPPH 35.4% and FRAP 0.063 µmol TEs/µmol).

Antibacterial activity of new oxazolidin-2-one analogues in methicillin-resistant Staphylococcus aureus strains.

Staphylococcus aureus is one of the most common causes of nosocomial infections. The purpose of this study was the synthesis and in vitro evaluation of antimicrobial activity of 10 new 3-oxazolidin-2-one analogues on 12 methicillin resistant S. aureus (MRSA) clinical isolates. S. aureus confirmation was achieved via catalase and coagulase test. Molecular characterization of MRSA was performed by amplification of the mecA gene. Antimicrobial susceptibility was evaluated via the Kirby-Bauer disc diffusion susceptibility test protocol, using commonly applied antibiotics and the oxazolidinone analogues. Only (R)-5-((S)-1-dibenzylaminoethyl)-1,3-oxazolidin-2-one (7a) exhibited antibacterial activity at 6.6 μg. These results, allow us to infer that molecules such as 7a can be potentially used to treat infections caused by MRSA strains.

Antioxidant activity and antimicrobial evaluation of 1-benzyl-1,2,3-triazole

Este articulo reporta las actividades biologicas de 1-bencil-1,2,3-triazoles: antibacteriana por el metodo de microdilucion en caldo, antioxidante por el metodo de inactivacion del DPPH (2,2-difenil-1-picrilhidrazil•) y la toxicidad en el ensayo de artemia (Artemia salina). El compuesto 1-(1-bencil-1H-1,2,3-triazol-4-il) ciclopentanol (50 µg/mL a 200 µg/mL) presento inhibicion selectiva y moderada contra el crecimiento de Staphylococcus aureus 3, mientras que el mismo efecto se registro para el 3-(1-bencil-1H-1,2,3-triazol-4-il)-1-propanol contra E. coli AO11, E. coli AO15 y Salmonella enterica serovar Typhi. Los compuestos 5g-i mostraron la mas alta inactivacion del DPPH•. Los compuestos sinteticos 1,2,3-triazoles evaluados se clasificaron en el intervalo de moderadamente toxico a no toxico. Asi, basados en la informacion publicada actualmente, estos podrian ser una fuente de compuestos con actividades biologicas de importancia para la salud humana

Anthocyanins of Pithecellobium dulce (Roxb.) Benth. Fruit Associated with High Antioxidant and α-Glucosidase Inhibitory Activities

Red arils of Pithecellobium dulce fruit, commonly known as guamuchil, show high antioxidant (AOx) and α-glucosidase inhibitory (IαG) activities, which have been mainly associated with the content of unknown anthocyanins. In this study, the AOx (i.e., DPPH and ABTS as Trolox equivalents, μmol TE/g) and IαG (as half-maximal inhibitory concentration, IC50, mg/mL) activities of the anthocyanin-rich fraction (ARF) obtained from red arils were contrasted with those of the methanol extract (ME), and the main ARF anthocyanins were characterized by HPLC-DAD-ESI-MS, GC-MS and 1H-NMR. The AOx and IαG values of the ARF (DPPH = 597.8; ABTS = 884.01; IαG = 0.06) were better than those of the ME (DPPH = 41.5; ABTS = 142.3; IαG = 17.5); remarkably, the ARF IαG value was about 42 times lower than that of acarbose. The main anthocyanins in ARF were pelargonidin 3-O-glucoside and cyanidin 3-O-glucoside. Thus, the consumption of red P. dulce arils could provide health benefits for prevention/treatment of chronic degenerative diseases such as diabetes.

Comparison of terpene and phenolic profiles of three wild species of Echeveria (Crassulaceae)

Echeveria species (Crassulaceae) are used in traditional medicine and some of their biological activities are demonstrated (e.g. antimicrobial, anti-inflammatory, anticancer). However, their chemical composition has been scarcely studied. The methanol extracts (ME) of three Echeveria species (E. craigiana, E. kimnachii and E. subrigida) from Mexico were analyzed for the sterol (GC-MS) and phenolic (HPLC-DAD-ESI-MSn) composition. Eleven sterols were identified, E. kimnachii showed the highest total content (7.87 mg/g ME), and the main constituents were γ-sitosterol in E. craigiana (33.9%) and E. subrigida (54.4%), and lupenone in E. kimnachii (28.9%). The phenolic analysis showed differences among the Echeveria species, which contained flavonoids derivatives and tannins as the main components. The main flavonoids in E. craigiana were hexoside derivatives of quercetin and isorhamnetin, both with a 3-hydroxy-3-methylglutaroyl substituent; in E. subrigida hexosides of isorhamnetin, quercetin and kaempferol; and E. kimnachii showed the greatest diversity including proanthocyanidins and less common flavonoid derivatives of kaempferol O,O-disubstituted by acyl derivatives. The characteristic phytochemicals of each studied Echeveria species could be responsible of its specific biological activities and useful as chemotaxonomic markers. The kaempferol derivatives in E. kimnachii are rare in nature and they will be isolated and characterized.

Chemical composition and biological activities of Helicteres vegae and Heliopsis sinaloensis

Abstract Context: Helicteres vegae Cristóbal (Sterculiaceae) (Hv) and Heliopsis sinaloensis B.L. Turner (Asteraceae) (Hs) are endangered and poorly studied plant species; related plants have been used against chronic-degenerative and infectious diseases. Therefore, Hv and Hs could be sources of bioactive compounds against these illnesses. Objective: To determine the chemical composition and biological activities (antioxidant, antimutagenic and antimicrobial) of Hv and Hs leaves (L) and stems (S). Materials and methods: Methanol extracts (ME) of each plant/tissue were evaluated for their phytochemicals; phenolics (HPLC-DAD-ESI-MS); antioxidant activity (AA) (0.125–4 mg/mL) (DPPH, ABTS, ORAC and β-carotene discoloration); antimutagenicity (0.5 and 1 mg/plate) (Ames assay, tester strain Salmonella enterica serovar Typhimurium YG1024, 1-nitropyrene as mutagen); activity against human pathogens (1 mg/mL); and toxicity (0.01–2 mg/mL) (Artemia salina assay). Results: All ME showed flavonoids and triterpenes/steroids. The ME-SHv had the highest content of total phenolics (TP) (2245.82 ± 21.45 mg GAE/100 g d.w.) and condensed tannins (603.71 ± 1.115 mg CE/100 g d.w.). The compounds identified were flavonoids (kaempferol 7-O-coumaroylhexoside, and two kaempferol 7-O-rhamnosylhexosides) and phenolics [rosmarinic acid, and 3′-O-(8″-Z-caffeoyl) rosmarinic acid]. The ME-LHs showed the highest content of flavonoids (357.88 mg RE/g d.w.) and phenolic acids (238.58 mg CAE/g d.w.) by HPLC. The ME-SHv showed the highest AA. All ME were strong antimutagens (63.3-85.7%). Only the Hs extracts were toxic (ME-LHs, LC50 = 94.9 ± 1.7 μg/mL; ME-SHs, LC50 = 89.03 ± 4.42 μg/mL). Discussion and conclusions: Both Hv and Hs are potential sources of preventive and therapeutic agents against chronic-degenerative diseases.

Bioguided study of the in vitro parasitocidal effect on adult Hymenolepis nana of the Psidium sartorianum (O. Berg Nied.) fruit methanol extract

Intestinal parasites have a high prevalence in many developing countries. In particular, Hymenolepis nana affects primarily children and available treatments are not 100% effective. In Mexico, Psidium sartorianum fruit has been used in traditional medicine to cure intestinal worms. In this paper, the in vitro antiparasitic activity of the methanol extract from P. sartorianum fruit was analyzed by a bioguided strategy and through light and electronic microscopy. Chloroform fraction (CF) of the methanol extract and its sub-fraction (F4-sCF) showed the highest activities; the results for the times of paralysis (5 min) and death (20 min) and the ultrastructural damage were better with F4-sCF than those found using the commercially pure compound Praziquantel. The compound identified in the F4-sCF by nuclear magnetic resonance (1H and 13C nuclear magnetic resonance) and gas-chromatography mass-spectrometry was the 2′,6′-dihidroxy-4′-methoxychalcone (pinostrobin chalcone). Accordingly to the literature, this chalcone may be acting by inhibition of tubulin polymerization and apoptosis induction, but future studies must identify what the molecular targets in H. nana are behind the effect of this chalcone.

Microwave-assisted synthesis of benzoxazinediones under solvent-free conditions

ABSTRACT Benzoxazinediones exhibit potential as versatile synthons in the synthesis of wide variety of heterocyclic compounds with biological activity. In this work, an efficient and eco-friendly one-step synthesis of benzoxazine-2,4-diones from phthalic anhydrides derivatives and trimethylsilyl azide using the microwave technique was developed and compared with conventional heating. Microwave irradiation plays a critical role in driving the reaction and providing access to products and/or regioisomers not available from conventional heating. Thus, the regioselectivity of the reaction may be modulated by the irradiation time. Depending on the method employed the benzoxazinediones were isolated with yields in the range of 30–90%. GRAPHICAL ABSTRACT