Metabolites from Aspergillus fumigatus, an Endophytic Fungus Associated with Melia azedarach, and Their Antifungal, Antifeedant, and Toxic Activities

Abstract

Thirty-nine fungal metabolites 1−39, including two new alkaloids, 12β-hydroxy-13α-methoxyverruculogen TR-2 (6) and 3-hydroxyfumiquinazoline A (16), were isolated from the fermentation broth of Aspergillus f umigatus LN-4, an endophytic fungus isolated from the stem bark of Melia azedarach. Their structures were elucidated on the basis of detailed spectroscopic analysis (mass spectrometry and one-and two-dimensional NMR experiments) and by comparison of their NMR data with those reported in the literature. These isolated compounds were evaluated for in vitro antifungal activities against some phytopathogenic fungi, toxicity against brine shrimps, and antifeedant activities against armyworm larvae (Mythimna separata Walker). Among them, sixteen compounds showed potent antifungal activities against phytopathogenic fungi (Botrytis cinerea, Alternaria solani, Alternaria alternata, Colletotrichum gloeosporioides, Fusarium solani, Fusarium oxysporum f. sp. niveum, Fusarium oxysporum f. sp. vasinfectum, and Gibberella saubinettii), and four of them, 12β-hydroxy-13α-methoxyverruculogen TR-2 (6), fumitremorgin B (7), verruculogen (8), and helvolic acid (39), exhibited antifungal activities with MIC values of 6.25−50 μg/ mL, which were comparable to the two positive controls carbendazim and hymexazol. In addition, of eighteen that exerted moderate lethality toward brine shrimps, compounds 7 and 8 both showed significant toxicities with median lethal concentration (LC 50 ) values of 13.6 and 15.8 μg/mL, respectively. Furthermore, among nine metabolites that were found to possess antifeedant activity against armyworm larvae, compounds 7 and 8 gave the best activity with antifeedant indexes (AFI) of 50.0% and 55.0%, respectively. Structure−activity relationships of the metabolites were also discussed.

The essential oils chemical compositions and antimicrobial, antioxidant activities and toxicity of threeHyptisspecies

“…Three repetitions were conducted for each compound. After being incubated at 28 AE 0.5 C for 24 h, dead nauplii and total number of brine shrimp in each microplates well was then examined and counted under the microscope (Li et al, 2012). The mortality rate was calculated according to the following formula:…”

Natural products as sources of new fungicides (I): synthesis and antifungal activity of Kakuol derivatives against phytopathogenic fungi

“…The presence of these compounds in the reaction mixture made the purification of desired ortho-acyl phenols very difficult and in most cases, a further purification by crystallization after flash chromatography was needed. Compound 4 was obtained from kakuol（2b）by methylation with MeI and K 2 CO 3 in acetone [18] (Scheme 2). The synthesis of compound 5 was preparing in 90 % yield by refluxing a solution of 2b in methanol with NaBH 4 [19] for 1 h and 6 was performed by reacting kakuol (2b) with NH 2 OH·HCl [15] and AcONa in MeOH.…”

Synthesis and Biological Evaluation of Norcantharidin Derivatives Possessing an Aromatic Amine Moiety as Antifungal Agents

“…To date, few attempts have been made to develop a biorational fungicide from NCTD via chemical modification. Encouraged by the abovementioned results and in continuation of our program aimed at the discovery and development of natural-product-based fungicidal agents, in this study, thirty six aromatic amine derivatives of NCTD modified in the anhydride ring were synthesized (Scheme 1), and their biological activities against eight phytopathogenic fungi were evaluated using the mycelium growth rate method [27]. Additionally, their preliminary SAR studies were also described.…”