*3.4. Procedure for the Semisynthesis of Compound* **11**

Compound **4** (15 mg, 0.03 mmol) in dry CH2Cl2 (20 mL) was irradiated by a 4 W LED lamp (blue light) at room temperature under a nitrogen atmosphere for 24 h. The reaction was monitored by TLC using a hexane and ethyl acetate solution (1:1 *v*/*v*) as the mobile phase. After the completion of the reaction, the solvent was removed under reduced pressure. The crude product was precipitated using hexane, affording **7** as a yellow amorphous solid. Compound **7** was employed in the next step without further purification. Next, compound **7** (21 mg, 0.04 mmol), 4-dimethylaminopyridine (DMAP) (5 mg, 0.04 mmol), 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride (EDCI) (8 mg, 0.04 mmol), and isonicotinoyl chloride hydrochloride (32 mg, 0.18 mmol) were dissolved in CH2Cl2 (20 mL). The mixture was stirred for 24 h at room temperature under a nitrogen atmosphere. After the completion of the reaction, as determined by TLC, the reaction mixture was quenched by adding distilled H2O (20 mL) and extracted with CH2Cl2 (20 mL, three times). The organic layers were combined and dried over anhydrous magnesium sulfate (MgSO4), filtered, and concentrated under reduced pressure. After purification by silica gel flash chromatography using the hexane and ethyl acetate solution as the eluent, 5-*O*-(4- -pyridinecarbonyl) renieramycin T (**11**) was obtained in 20% yield as a yellow amorphous powder.

#### *3.5. Procedure for the Semisynthesis of Compound* **12**

Jorunnamycin A (**3**) (25 mg, 0.05 mmol) was placed into an oven-dried, roundbottomed flask and dissolved in dry CH2Cl2 (10 mL). Thereafter, DMAP (31 mg, 0.25 mmol), EDCI (49 mg, 0.25 mmol), and isonicotinoyl chloride hydrochloride (45 mg, 0.25 mmol)

were added. The mixture was stirred for 24 h at room temperature under a nitrogen atmosphere and monitored by TLC using a mixture solvent of ethyl acetate and hexane (1:1 *v*/*v*) as the mobile phase. After completion, the solution was concentrated under reduced pressure. Next, the resultant crude product was purified by flash column chromatography using silica gel as the stationary phase and the mixed solvent of ethyl acetate and hexane as the mobile phase to yield a yellow product (**9**) in 72% yield. Subsequently, compound **9** (6 mg, 0.01 mmol) was dissolved in CH2Cl2 (15 mL) and irradiated by a 4 W LED lamp (blue light) at room temperature under a nitrogen atmosphere for 24 h. The reaction mixture was monitored by TLC and further purified following the procedure described above to obtain 22-*O*-(4- -pyridinecarbonyl) renieramycin T (**12**) as an amorphous yellow powder in 83% yield.

#### *3.6. Cytotoxic Evaluations against NSCLC Cell Lines*

The in vitro cytotoxicity of compounds **3**–**12** against H292 and H460 NSCLC cell lines was determined by MTT colorimetric assay. The H292 and H460 cultured cell lines were obtained from the American Type Culture Collection (Manassas, VA, USA). The Roswell Park Memorial Institute (RPMI) medium 1640, fetal bovine serum (FBS), L-glutamine, a penicillin/streptomycin solution, and Albumax I were purchased from Gibco (Gaithersburg, MA, USA). Dimethyl sulfoxide (DMSO) was acquired from Merck Millipore (Billerica, MA, USA) or Sigma-Aldrich. All cell lines were cultured in the RPMI 1640 medium, supplemented with 10% FBS, 2 mM L-glutamine, and 100 units/mL of penicillin/streptomycin, and the temperature was maintained at 37 ◦C under 5% CO2. Cells were trypsinized and seeded at a density of 5000 cells/well with the RPMI media for 24 h in a 96-well plate. A 10 mm stock solution of each test compound in DMSO was prepared and diluted into the serial concentrations at 1–250 nM, with a DMSO concentration of less than 0.2% *v*/*v*. The cells were treated with various concentrations of each derivative for 72 h. Next, the cells were incubated with 0.5 mg/mL of MTT for 2 h. After solubilizing the resulting formazan salt with 100 μL of DMSO, the absorbance of the formed formazan was measured by a spectrophotometric microtiter plate reader (Perkin Elmer Victor 3 1420 Multilabel Plate Counter, Massachusetts, MA, USA) at 570 nm. The experiment was performed in three replicate wells with at least five concentrations of the tested compounds. The cell viability was determined using the GraphPad Prism software (version 5), calculated as a percentage of non-treated control cells and the mean of the half-maximal inhibitory concentration (IC50) values. Cisplatin and doxorubicin were used as the positive controls, and 0.2% DMSO was used as the negative control.
