Aspergixanthones I–K, New Anti-Vibrio Prenylxanthones from the Marine-Derived Fungus Aspergillus sp. ZA-01

Abstract

Marine-derived fungi are a rich source of structurally diverse metabolites. Fungi produce an array of compounds when grown under different cultivation conditions. In the present work, different media were used to cultivate the fungus Aspergillus sp. ZA-01, which was previously studied for the production of bioactive compounds, and three new prenylxanthone derivatives, aspergixanthones I–K (1–3), and four known analogues (4–7) were obtained. The absolute configuration of 1 was assigned by ECD experiment and the Mo2(AcO)4 ICD spectrum of its methanolysis derivative (1a). All the compounds (1–7) were evaluated for their anti-Vibrio activities. Aspergixanthone I (1) showed the strongest anti-Vibrio activity against Vibrio parahemolyticus (MIC = 1.56 μM), Vibrio anguillarum (MIC = 1.56 μM), and Vibrio alginolyticus (MIC = 3.12 μM).

Antiproliferative Role of Secondary Metabolites From Aspergillus unguis AG 1.1 (G) Isolated From Marine Macroalgae Enteromorpha sp. by Inducing Intracellular ROS Production and Mitochondrial Membrane Potential Loss Leading to Apoptosis

“…Asperxanthone, a difuraxanthone reported from marine-derived Aspergillus species exhibited moderate activity against tobacco mosaic virus (Wu et al, 2009). Some prenylxanthone analogs with various bioactive functions such as antibacterial, antifungal and cytotoxic activities have been reported from the Aspergillus species (Zhu et al, 2018). Butylidenephthalide, present in many medicinal herbs possesses various bioactivities including antitumor activity (Chang et al, 2020).…”

Benzophenone Derivatives from an Algal-Endophytic Isolate of Penicillium chrysogenum and Their Cytotoxicity

“…When the coupling constant of H-19b and H-20 is small, it is suggested that isopropenyl group is pseudo-axial oriented and the OH-25 group and the isopropenyl group therefore possesses anti stereochemistry. Examples of this kind of situation included shamixanthone ( J H19b–H20 = 2.8 Hz) [10], tajixanthone derivatives ( J H19b–H20 = 2.8 Hz) [12], and aspergixanthones J–K ( J H19b–H20 = 3.0 Hz) [14]. Conversely, if the coupling constant of H-19b and H-20 is a large value, the isopropenyl group on C-20 is oriented equatorial and it means that OH-25 and the isopropenyl group has a syn relationship, such as epitajixanthone hydrate ( J H19b–H20 = 11.8 Hz) [12], aspergixanthone I ( J H19b–H20 = 12.0 Hz) [14], and epishamixanthone ( J H19b–H20 = 11.0 Hz) [16].…”

“…Examples of this kind of situation included shamixanthone ( J H19b–H20 = 2.8 Hz) [10], tajixanthone derivatives ( J H19b–H20 = 2.8 Hz) [12], and aspergixanthones J–K ( J H19b–H20 = 3.0 Hz) [14]. Conversely, if the coupling constant of H-19b and H-20 is a large value, the isopropenyl group on C-20 is oriented equatorial and it means that OH-25 and the isopropenyl group has a syn relationship, such as epitajixanthone hydrate ( J H19b–H20 = 11.8 Hz) [12], aspergixanthone I ( J H19b–H20 = 12.0 Hz) [14], and epishamixanthone ( J H19b–H20 = 11.0 Hz) [16]. In this study, the pattern of the coupling constants of compound 1 was in accordance with the relevant characteristics of previously reported related compounds, and the large coupling constant of H-19b and H-20 ( J = 11.0 Hz) indicated a syn relationship.…”

“…The absolute configuration of compound 1 was determined by comparison of its electronic circular dichroism (ECD spectrum) with that of related compounds. Zhu et al reported that the Cotton effects (CE) at 250–300 nm and 300–350 nm are diagnostic features of a dihydropyran ring system, and the negative CE at approximately 280 nm and positive CE at 310 nm are responsible for the 25 R configuration [13,14]. The ECD spectrum of compound 1 showed positive CE at 282 nm and negative CE at 328 nm, which was contrary to that of aspergixanthones [13,14]; thus, the absolute configuration of compound 1 was proposed as 25 S .…”

“…Both compounds have an unusual dihydropyran ring incorporated in the structure (ring D), which is fused to an aromatic ring and an open ring (ring C) (Figure 1), proving to be unusual members of benzophenone derivatives in structurally related xanthones. To the best of our knowledge, only a few related prenylxanthones, belonging to the families of shamixanthones, tajixanthones, ruguloxanthones, and aspergixanthones, have been previously reported (Figure 1) [10,11,12,13,14]. In this study, we report the details of the isolation, structure elucidation, and cytotoxic activities of these new polyketides, providing a foundation for further exploration of their pharmaceutical properties as novel drug candidates.…”