ABSTRACT
Four pyrazines were isolated from the n-butanol fraction of Hypecoum erectum L. by using various chromatographic methods, including MCI gel, ODS, silica gel and semi-preparative HPLC. The structures of the isolated compounds were identified as hyperectpyrazin A (1), 1′S-(6-methylpyrazin-2-yl)-ethane-1′,2′-diol (2), 2-hydroxymethyl-6-methylpyrazin (3) and pyrazine-2-carboxylic acid (4) by spectroscopy methods (1D NMR, 2D NMR, UV, IR, MS, etc.). The absolute configuration of compound 2 was determined by using the Mo2(OAc)4 induced CD analysis for the first time. Compound 1 was a new compound, compounds 2-4 were isolated from H. erectum for the first time. Compounds 1-4 were evaluated for their inhibition against acetylcholinesterase and nitric oxide generation induced by lipopolysaccharide-RAW264.7 macrophage cells. At a concentration of 50 μmol·L-1, compounds 2 and 4 displayed inhibitory effects on acetylcholinesterase with the inhibition rates of 44.40% and 43.99%, respectively.
ABSTRACT
Hippeastrum puniceum is a species that belongs to the Amaryllidaceae family. A particular characteristic of this family is the consistent and very specific presence of isoquinoline alkaloids, which have demonstrated a wide range of biological activities such as antioxidant, antiviral, antifungal, antiparasitic, and acetylcholinesterase inhibitory activity, among others. In the present work, fifteen alkaloids were identified from the bulbs of Hippeastrum puniceum (Lam.) Kuntz using a GC-MS approach. The alkaloids 9-O-demethyllycoramine, 9-demethyl-2α-hydroxyhomolycorine, lycorine and tazettine were isolated through chromatographic techniques. The typical Amaryllidaceae alkaloids lycorine and tazettine, along with the crude and ethyl acetate extract from bulbs of the species were evaluated for their inhibitory potential on α-amylase, α-glucosidase, tyrosinase and acetylcholinesterase activity. Although no significant inhibition activity was observed against α-amylase, α-glucosidase and tyrosinase from the tested samples, the crude and ethyl acetate extracts showed remarkable acetylcholinesterase inhibitory activity. The biological activity results that correlated to the alkaloid chemical profile by GC-MS are discussed herein. Therefore, this study contributed to the knowledge of the chemical and biological properties of Hippeastrum puniceum (Lam.) and can subsidize future studies of this species
Subject(s)
Amaryllidaceae Alkaloids/analysis , Amaryllidaceae/classification , Acetylcholinesterase/adverse effects , Cholinesterase Inhibitors/pharmacology , Acetates/agonists , Antioxidants/pharmacologyABSTRACT
Objective: To study the secondary metabolites of endophytic fungus Aspergillus ochraceus SX-C7 from Setaginella stauntoniana. Methods: The compounds were isolated and purified by silica gel, Sephadex LH-20, C-18 reversed phase column chromatography, and their structures were identified by MS and NMR analyses. Antibacterial activity and inhibitory activity against acetylcholinesterase were studied by doubling dilution and Ellman methods. Results: Ten known compounds were isolated from the secondary metabolites of A. ochrateus SX-C7, and identified as: semivioxanthin (1), 6-hydroxy-p-menth-4 (5)-en-3-one (2), flavacol (3), magnolin (4), preussin B (5), circumdatins D (6), isofucosterol (7), sclerotiamide (8), 3β-hydroxyergosta-8,24(28)-dien-7-one (9), and 3-O-β-D-glucopyranosyl stigmasta-5(6),24(28)-diene (10). Conclusion: Compounds 1, 2, 4, 7, and 10 were isolated from A. ochraceus SX-C7 for the first time. The results of the bioactivity assay showed that compound 10 possessed obvious inhibitory activity against Bacillus subtilis with a MIC value of 2 μg/mL, which was at the same grade with positive control. Compound 1 exhibited potent inhibitory activity against acetylcholinesterase with an inhibitory rate of 62.3% (the final concentration was 50 μmol/L.
ABSTRACT
Three new phenazine-type compounds, named phenazines SA-SC (1-3), together with four new natural products (4-7), were isolated from the fermentation broth of an earwig-associated Streptomyces sp. NA04227. The structures of these compounds were determined by extensive analyses of NMR, high resolution mass spectroscopic data, as well as single-crystal X-ray diffraction measurement. Sequencing and analysis of the genome data allowed us to identify the gene cluster (spz) and propose a biosynthetic pathway for these phenazine-type compounds. Additionally, compounds 1-5 exhibited moderate inhibitory activity against acetylcholinesterase (AChE), and compound 3 showed antimicrobial activities against Micrococcus luteus.