1H NMR (300 MHz, acetone-d 6) δ (ppm): 0.87 (t, 6H, J = 6.9 Hz, C-7- and C-4′–OOC(CH2)14–CH3); 1.29 (s, 44H, C-7- and C-4′–OOC(CH2)3(CH2)11–CH3); 1.40 (m, 4H, J = 6.9 Hz, C-7- and C-4′–OOC(CH2)2CH2(CH2)11–CH3);

1.60 (d, 6H, J = 1.3 Hz, CH3-4′′ and CH3-5′′); 1.73 (quintet, 4H, J = 6.9 Hz, C-7- and C-4′–OOCCH2CH2(CH2)12–CH3); 2.60 and 2.64 (two t, 4H, J = 7.4 Hz, C-7- and C-4′–OOCCH2(CH2)13–CH3); 2.96 (dd, 1H, J = 17.2 Hz, J = 3.0 Hz, CH-3); 3.17 (d, 2H, J = 6.8 Hz, CH2-1′′); 3.32 (dd, 1H, J = 17.2 Hz, J = 13.1 Hz, CH-3); 5.07 (t sept, 1H, J = 6.8 Hz, J = 1.3 Hz, CH-2′′); 5.71 (dd, 1H, J = 13.1 Hz, J = 3.0 Hz, CH-2); 6.30 (s, 1H, CH-6); 7.22 (d, 2H, J = 8.5 Hz, CH-3′ and CH-5′); 7.65 (d, 2H, J = 8.5 Hz, CH-2′ and CH-6′); 11.87 (s, 1H, C-5–OH). IR (KBr) cm−1: 3437, 2918, 2850, 1751, 1648, check details 1624, 1592, 1512, 1469, 1379, 1264, 1149, 1077, 840, 722. C52H80O7 (817.21): calcd. C 76.43, H 9.87; found C 76.22, H 10.01. Antiproliferative activity The human cell lines of breast cancer (MCF-7), colon adenocarcinoma (HT-29), and leukemia (CCRF/CEM) were obtained from American Type PD-1/PD-L1 inhibition culture Collection (Rockville, Maryland, USA) and maintained in the Cell

Culture Collection at the Institute of Immunology and Experimental Therapy, Wroclaw, Poland. The cells at the density of 105/ml were cultivated in click here 96-well plates (Sarstedt, Germany) in 100 μl of culture medium at 37°C in humid atmosphere containing 5% CO2. In the case of MCF-7 cell lines, the culture medium consisted of Eagle’s medium (IIET, Wroclaw, Poland) with addition of 10% fetal bovine serum (FBS, Sigma-Aldrich Chemie GmbH, Steinheim, Germany), C-X-C chemokine receptor type 7 (CXCR-7) 100 μg/ml streptomycin (Jelfa, Jelenia Góra, Poland), 100 U/ml penicillin (Jelfa, Jelenia Góra, Poland), 2 mM l-glutamine (Gibco, Warsaw, Poland), 1.0 mM sodium pyruvate, 1% amino acid, and 0.8 mg/l insulin. The cells of HT-29 line were cultured in the RPMI 1640 and Opti-MEM (1:1) (both from Gibco) medium with addition of 5% FBS, 100 μg/ml streptomycin, 100 U/ml penicillin, 1 mM sodium pyruvate,

and 2 mM l-glutamine. CCRF/CEM culture medium consisted RPMI 1640, 10% FBS, 100 μg/ml streptomycin, 100 U/ml penicillin and 2 mM l-glutamine. The compounds were dissolved in acetone (1–4, 8, and 10) or absolute ethanol (5–7, 9, 11–13) to the concentration of 10 mg/ml, stored at 4°C, and diluted in the culture medium to obtain concentrations from 0.1 to 100 μg/ml. The controls contained acetone or ethanol at the appropriate concentrations. The solutions of the synthesized compounds in 100 μl of culture medium were added after 24 h of incubation. The sulphorhodamine B (SRB, Sigma-Aldrich Chemie GmbH, Steinheim, Germany) assay for MCF-7 and HT-29 cells and the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium (MTT) assay (Sigma–Aldrich, Germany) for CCRF/CEM cells were executed.