Thiazolo[5,4-b]pyridine Alkaloid and Seven ar-Bisabol Sesquiterpenes Produced by the Endophytic Fungus Penicillium janthinellum

Abstract

We investigated the secondary metabolites present in Penicillium janthinellum MPT-25, an endophytic fungus isolated from Taxus wallichiana var. chinensis (Pilger) Florin. Chemical characterization of the solid cultured extract resulted in the isolation of 11 compounds, including eight previously undescribed metabolites: a thiazolo[5,4- b ]pyridine alkaloid, janthinedine A ( 1 ), and seven ar -bisabol sesquiterpenes, janthinepenes A–G ( 2–8 ). Their structures were elucidated by a combination of extensive spectroscopic methods, including single-crystal X-ray diffraction and ECD spectra. The antimicrobial activities of these compounds were evaluated against seven agricultural pathogenic fungi and eight clinically drug-resistant bacteria.

Penicillium janthinellum: A Potential Producer of Natural Products

“…Compound 5 exhibited the same activity as brefeldin A against secretion of proteins of Acer pseudoplatanus and more effective destruction of the Colgi stacks of sycamore maple cells than brefeldin A [42]. Compound 5 showed antifungal activity against Alternaria fragriae with an MIC value of 25 µg/mL [36]. Compound 20 was first synthesized in 1999 and the spectra data were also reported [43].…”

“…Furthermore, it exhibits a wide pH tolerance range, thriving in pH levels ranging from 2 to 9, with optimal growth observed within the pH range of 3.8 to 6 [5]. It has a wide distribution in terrestrial environments, such as ginseng plants in Jilin Province, China [6], the fruits of Melia azedarach in Brazil [7], gold mine tailings in South Africa [8] and the soils of the Truelove Lowland in Canada [9], as well as many marine areas, such as the Bohai Sea [10], South China Sea [11] and Amursky Bay [12], which fragriae with an MIC value of 25 µg/mL [36]. Compound 20 was first synthesized in 1999 and the spectra data were also reported [43].…”

“…Further chemical investigation of this fungus resulted in the discovery of a novel compound, brefeldin D (10) [35]. 7-dehydrobrefeldin A (5) and brefeldin A (2) were isolated from P. janthinellum MPT-25 [36]. Two new brefeldin A dimers, dibrefeldins A (11) and B (12), six new derivatives, brefeldin F (13), brefeldin G (14), and 14-hydroxy-BFA (15), BFA seco-acid (16), seco-BFA methyl ester (17) and 10,11-epoxy-BFA (18) and four known products, brefeldin A (2), 7-dehydro-BFA seco-acid (19), 4-epi-BFA (20) and 6α-hydroxy-brefeldin C (21), were separated from P. janthinellum, a soil-divided fungus collected in Chongqing, China [37].…”

“…showed significant cytotoxicity against A549, HeLa and HepG2 with IC 50 values of 0.101, 0.171 and 0.239 µM [39]. Compound 2 showed antifungal activity against Alternaria fragriae with an MIC value of 12.5 µg/mL [36]. Compound 4 was synthesized as early as 1983 [40].…”

“…A known lactone, campyrone B (62), was isolated from P. janthinellum MPT-25 [36]. This compound showed weak toxicity against brine shrimp larvae (A. salina) at a concentration of 10 µg/mL [93].…”