Anti-mycobacterial nucleoside antibiotics from a marine-derived Streptomyces sp. TPU1236A

Abstract

Five new nucleoside antibiotics, named streptcytosines A-E (1-5), and six known compounds, de-amosaminyl-cytosamine (6), plicacetin (7), bamicetin (8), amicetin (9), collismycin B (10), and SF2738 C (11), were isolated from a culture broth of Streptomyces sp. TPU1236A collected in Okinawa, Japan. The structures of new compounds were elucidated on the basis of their spectroscopic data (HRFABMS, IR, UV, and 2D NMR experiments including 1H-1H COSY, HMQC, HMBC, and NOESY spectra). Streptcytosine A (1) belonged to the amicetin group antibiotics, and streptcytosines B-E (2-5) were derivatives of de-amosaminyl-cytosamine (6), 2,3,6-trideoxyglucopyranosyl cytosine. Compound 1 inhibited the growth of Mycobacterium smegmatis (MIC = 32 µg/mL), while compounds 2-5 were not active at 50 µg/disc. Bamicetin (8) and amicetin (9) showed the MICs of 16 and 8 µg/mL, respectively.

Figure 1

Structures of new compounds 1–5 isolated from Streptomyces sp. TPU1236A.

Figure 2

Structures of known compounds 6–11 isolated from Streptomyces sp. TPU1236A.

Figure 3

¹H-¹H COSY and key HMBC correlations for compound 1.

Figure 4

¹H-¹H COSY and key HMBC correlations for compounds 2–5.