Bioactive Novel Indole Alkaloids and Steroids from Deep Sea-Derived Fungus Aspergillus fumigatus SCSIO 41012

Abstract

Two new alkaloids, fumigatosides E (1) and F (2), and a new natural product, 3, 7-diketo-cephalosporin P1 (6) along with five known compounds (3–5, 7, 8) were isolated from deep-sea derived fungal Aspergillus fumigatus SCSIO 41012. Their structures were determined by extensive spectroscopic data analysis, including 1D, 2D nuclear magnetic resonance (NMR) and mass spectrometry (MS), and comparison between the calculated and experimental electronic circular dichroism (ECD) spectra. In addition, all compounds were tested for antibacterial and antifungal inhibitory activities. Compound 1 showed significant antifungal activity against Fusarium oxysporum f. sp. momordicae with MIC at 1.56 µg/mL. Compound 4 exhibited significant higher activity against S. aureus (16,339 and 29,213) with MIC values of 1.56 and 0.78 µg/mL, respectively, and compound 2 exhibited significant activity against A. baumanii ATCC 19606 with a MIC value of 6.25 µg/mL.

Recent Discovery of Heterocyclic Alkaloids from Marine-Derived Aspergillus Species

“…This compound also showed excellent antifungal activity against F. oxysporum with an MIC of 1.5 µg/mL. Compound 60 exhibited high activity against S. aureus (16339 and 29213), with MIC values of 1.565 µg/mL and 0.78 µg/mL, respectively, while compound 61 exhibited significant activity against A. baumanii ATCC 19606 with an MIC of 6.25 µg/mL [46]. Although compounds 83 and 123 showed non-significant antimicrobial activity against two common bacterial strains (S. aureus and P. aeruginosa) and three marine-derived bacteria (P. nigrifaciens, B. amyloliquefaciens, and B. stearothermophilus), they increased the growth of S. aureus one-fold at 100 µg/mL, and 123 increased the biofilm formation of S. aureus 1.3-fold at 25 µg/mL [49].…”

“…A quinazoline moiety was found in all these alkaloids, which might provide insights into the biogenetic relationships of quinazoline-containing indole alkaloids. Compounds 59-61 were characterized as two new quinazoline alkaloids and they were isolated from a culture of the deep-sea-derived fungus A. fumigatus SCSIO 41012 [46]. Compound 62 originated from a culture of the Australian marine sediment-derived A. sp.…”

“…Marine-derived fungi could be isolated from every possible marine habitat, such as marine sediments, marine invertebrates (sponges, corals, ascidians, and holothurians), and vertebrates (mainly fish), as well as marine plants (algae, driftwood, and mangrove plants) [74,75]. As shown in Table 1 [46,56,64], while the other strains were collected from marine sediments at depths above 100 m or even tideland mud [28,35,36,40,42,57,65,69,70]. Unfortunately, the source of the producing strain of 31-35 (A. sulphureus KMM 4640 and I. felina KMM 4639) was not described [39].…”

Alkaloids from Marine Fungi: Promising Antimicrobials

“…In 2018, Limbadri et al [26] discovered two new antimicrobial indole alkaloids in the deep-sea sediment-derived fungus Aspergillus fumigatus SCSIO41012 in the Indian Ocean and named them fumigatoside E (19) and fumigatoside F (20). Although they are very similar, they displayed different antimicrobial activities.…”

“…In 2017, Pan et al [30] discovered a new antimicrobial quinoline derivative, 9-hydroxy-3-methoxyviridicatin (24), alongside its two precursors 7-methoxycyclopeptin (25) and 7-methoxycyclopenin (26). All compounds were found in the hydrovental crab-associated Aspergillus versicolor XZ-4 strain in Taiwan.…”