Cryptic Biosynthesis of the Berkeleypenostatins from Coculture of Extremophilic Penicillium sp

Abstract

Coculture fermentation of Penicillium fuscum and P. camembertii/clavigerum yielded berkeleypenostatins A-G (1-7) as well as the previously reported berkeleylactones A-H, the known macrolide A26771B, citrinin, and patulin. As was true with the berkeleylactones, there was no evidence of the berkeleypenostatins in either axenic culture. The structures were deduced from analyses of spectral data, and the absolute configuration of berkeleypenostatin A (1) was determined by single-crystal X-ray crystallography. Berkeleypenostatins A (1) and E (5) inhibited migration of human pancreatic carcinoma cells (HPAF-II). Both compounds were tested by the NCI Developmental Therapeutics Program. In the NCI 60 cell five-dose screen, berkeleypenostatin E (5) was the more active of the two, with 1-10 μM total growth inhibition (TGI) of all leukemia cell lines, as well as the majority of colon, CNS, melanoma, ovarian, prostate, renal, and breast cancer cell lines.

Figure 1.

Selected HMBC correlations for berkeleypenostatin A (1). Spin systems A (blue), B (red), C (green), and D (pink) were established by ¹H-¹H-COSY.

Figure 2.

X-ray structure of berkeleypenostatin A (1).

Figure 3.

Proposed Claisen rearrangement of berkeleypenostatin A (1) to generate compound 4.

Figure 4.

Comparison of LC-MS spectral data of pure berkeleypenostatin A (1) with crude extracts of PW2A/PW2B coculture and axenic cultures of PW2A and PW2B. Under these conditions, three peaks were diagnostic for the detection of berkeleypenostatin A: m/z 551 [M+1]⁺; m/z 568 [M+18]⁺; and m/z 1118 [2M+18]⁺.

Figure 5.

Cancer cell migration inhibition assay of compounds 1 and 5 (1.25 μM) with HPAF-II pancreatic cancer cells. NNGH was used as a positive control and untreated cancer cells were the control.