Compound characterization data — Yu Zhou et al., 2026

Yu Zhou, Zhengyao Shao, Xueyi Xue, Li-Qing Chen, Hong Qiao, Yi Lu. “Metabolic competition reshapes the performance of engineered polyketide synthases.” ChemRxiv (2026). https://doi.org/10.26434/chemrxiv.15007623/v1

Aldehyde product
LC–MS	C₉H₈O₂ [M+NH₄]⁺; Theoretical mass: 166.0863; Observed: 166.0864

Analytical HPLC standards
Analytical HPLC, column	Agilent Polaris 180 Å C18-A, 4.6 × 150 mm, 5 µm
Analytical HPLC, mobile phase	Water and acetonitrile (MeCN) containing 1 % acetic acid
Analytical HPLC, flow rate	0.4 mL min⁻¹
Analytical HPLC, column temperature	30 °C
Analytical HPLC, separation program	90 % water for 5 min; 90 % water to 10 % water gradient for 10 min; 10 % water for 5 min; 90 % water for another 5 min
naringenin chalcone, retention time; detection wavelength	15.16 min; 350 nm
naringenin, retention time; detection wavelength	15.54 min; 330 nm
p-hydroxybenzalacetone, retention time; detection wavelength	14.57 min; 330 nm
bisnoryangonin, retention time; detection wavelength	14.09 min; 350 nm
p-coumaroyltriacetic acid lactone, retention time; detection wavelength	13.89 min; 350 nm
p-coumaroyltriacetic acid lactone, product assignment	Assigned based on retention time, LC–MS and comparison with other tetraketide products
p-coumaric acid, retention time; detection wavelength	13.48 min; 330 nm

Tetraketide mass signal
LC–MS extracted ion chromatography (negative mode)	Exact Mass: 272.0685; mass signal: 271.0634

Triketide mass signal
LC–MS extracted ion chromatography (negative mode)	Exact Mass: 230.0597; mass signal: 229.0514

demethoxyyangonin
¹H NMR (400 MHz, Chloroform-d)	δ 7.56 – 7.51 (m, 3H), 7.44 – 7.33 (m, 3H), 6.61 (d, J = 16.1 Hz, 1H), 5.97 (d, J = 2.1 Hz, 1H), 5.53 (d, J = 2.2 Hz, 1H), 3.86 (s, 3H)
¹³C NMR (101 MHz, CDCl₃)	δ 171.09, 164.02, 158.66, 135.84, 135.25, 129.46, 128.92, 127.47, 118.64, 101.35, 88.89, 55.95
HRMS	m/z calculated for C₁₄H₁₃O₃ [M+H]⁺: 229.0859; found: 229.0863

yangonin
¹H NMR (400 MHz, Chloroform-d)	δ 7.38 (d, J = 8.5 Hz, 2H), 6.84 (d, J = 8.7 Hz, 2H), 6.38 (d, J = 15.9 Hz, 1H), 5.83 (d, J = 2.1 Hz, 1H), 5.40 (d, J = 2.2 Hz, 1H), 3.77 (s, 3H), 3.76 (s, 3H)
¹³C NMR (101 MHz, CDCl₃)	δ 171.26, 164.20, 160.78, 159.14, 135.50, 129.00, 128.02, 116.39, 114.40, 100.47, 88.39, 55.90, 55.39
HRMS	m/z calculated for C₁₅H₁₅O₄ [M+H]⁺: 259.0965; found: 259.0966

(E)-4-methoxy-6-(4-methylstyryl)-2H-pyran-2-one
¹H NMR (400 MHz, Chloroform-d)	δ 7.41 (d, J = 16.0 Hz, 1H), 7.33 (d, J = 7.9 Hz, 2H), 7.11 (d, J = 7.8 Hz, 2H), 6.47 (d, J = 15.9 Hz, 1H), 5.85 (d, J = 2.2 Hz, 1H), 5.41 (d, J = 2.1 Hz, 1H), 3.76 (s, 3H), 2.30 (s, 3H)
¹³C NMR (101 MHz, CDCl₃)	δ 171.17, 164.12, 158.93, 139.79, 135.85, 132.50, 129.65, 127.44, 117.65, 100.93, 88.65, 55.92, 21.42
HRMS	m/z calculated for C₁₅H₁₅O₃ [M+H]⁺: 243.1016; found: 243.1019

(E)-6-(4-fluorostyryl)-4-methoxy-2H-pyran-2-one
¹H NMR (400 MHz, Chloroform-d)	δ 7.42 (t, J = 4.3 Hz, 3H), 7.39 (d, J = 7.0 Hz, 1H), 7.00 (t, J = 8.5 Hz, 3H), 6.43 (d, J = 15.9 Hz, 1H), 5.87 (d, J = 2.2 Hz, 1H), 5.43 (d, J = 2.2 Hz, 1H), 3.76 (s, 4H)
¹³C NMR (101 MHz, CDCl₃)	δ 171.07, 163.96, 158.48, 134.55, 131.48, 129.19 (d, J = 8.3 Hz), 118.39 (d, J = 2.5 Hz), 116.04, 115.93, 101.36, 88.90, 55.97
¹⁹F NMR (376 MHz, Chloroform-d)	δ −110.87 (m)
HRMS	m/z calculated for C₁₄H₁₃FO₃ [M+H]⁺: 247.0765; found: 247.0769

7,8-dihydroyangonin
¹H NMR (400 MHz, Chloroform-d)	δ 7.01 (d, J = 8.5 Hz, 2H), 6.76 (d, J = 8.6 Hz, 1H), 5.64 (d, J = 2.2 Hz, 1H), 5.34 (d, J = 2.2 Hz, 1H), 3.72 (s, 4H), 3.71 (s, 3H), 2.84 (dd, J = 9.0, 6.6 Hz, 2H), 2.64 (dd, J = 9.0, 6.6 Hz, 2H)
¹³C NMR (101 MHz, CDCl₃)	δ 171.19, 164.97, 164.49, 158.18, 131.92, 129.27, 114.00, 100.28, 87.69, 55.81, 55.27, 35.75, 31.98
HRMS	m/z calculated for C₁₅H₁₇O₄ [M+H]⁺: 261.1121; found: 261.1124