FIG. 2.

HPLC-DAD-MS analysis of quinone extracts. (A) HPLC profiles. Dashed lines are applied to facilitate the identification of quinone peaks. (B) DAD-UV spectra of UQ₁₀ (λ_max = 275 nm), UQ₁₀H₂ (λ_max = 292 nm), RQ₁₀ (λ_max = 284 nm), and RQ₁₀H₂ (λ_max = 290 nm). (C) MS signals (only the monoisotopic masses are indicated for clarity) obtained with APCI could be attributed to the following ions: for UQ₁₀, m/z 864.6 to [M+H]⁺ and m/z 198.0 to a benzylium ion, a characteristic fragment of the UQ ring structure; for UQ₁₀H₂, m/z 882.4 to [M+NH₄]⁺, m/z 866.4 to [M+H]⁺, and m/z 198.0 to a benzylium ion; for RQ₁₀, m/z 849.6 to [M+H]⁺; and for RQ₁₀H₂, m/z 851.6 to [M+H]⁺. The last compound could be detected only when M2SF was used for cultivation under oxygen-limiting conditions. The signals obtained for UQ₉ (not shown) were m/z 795.6 (M⁺) and m/z 812.8 ([M+NH₄]⁺).