Acetals (2a-d, 3a-d, and 6a-d) of andrographolide (1), 14-deoxy-12-hydroxyandrographolide (4), and isoandrographolide (5) were synthesized using benzaldehyde and heteroaromatic aldehydes. All the synthesized derivatives were characterized using 1H-NMR, 13C-NMR, mass...

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A series of 22 different 3,5-diarylidenetetrahydro-2H-pyran-4(3H)-ones (DATPs) were synthesized, characterized, and screened for their in vitro antiplasmodial activities against chloroquine (CQ)-sensitive Pf3D7, CQ-resistant PfINDO, and artemisinin-resistant PfMRA-1240 strains of Plasmodium falciparum.DATP 19 (3,5-bis(4-hydroxy-3,5-dimethoxybenzylidene)tetrahydro-2H-pyran-4(3H)-one) was found to be the most potent (IC 50 1.07 μM) against PfMRA-1240, whereas 21(3,5-bis(3,4,5-trimethoxybenzylidene)tetrahydro-2H-pyran-4(3H)-one) showed IC 50 values of 1.72 and 1.44 μM against Pf3D7 and PfINDO, respectively. Resistance indices (RI) as low as 0.2 to 0.5 for 10 (3,5-bis(4-nitrobenzylidene)tetrahydro-2Hpyran-4(3H)-one) and 20 (3,5-bis(3-nitrobenzylidene)tetrahydro-2H-pyran-4(3H)-one), and < 1 for most other DATPs reveals their greater potency against resistant strains than the sensitive one. The single-crystal XRD data for DATP 21 are reported. In silico support was obtained through docking studies. Killing all three strains within 4-8 h, these DATPs showed rapid kill kinetics toward the trophozoite stage. Furthermore, DATP 18 (3,5bis(quinolin-4-ylmethylene)tetrahydro-2H-pyran-4(3H)-one) inhibited PfPdx1 enzyme activity with IC 50 20.34 μM, which is about twofold lower than that (IC 50 43 μM) for an already known inhibitor 4PEHz. At an oral dose of 300 mg/kg body weight, DATPs 19 and 21 were found to be nontoxic to mice, and at 100 mg/kg body weight, DATP 19 was found to suppress parasitaemia, which led to an increase in median survival time by three days relative to untreated control mice in a malaria curative study.

Novel far‐red sensitive symmetrical squaraine dyes aiming towards multifunctional properties such as control of dye aggregation, promotion of molecular self‐assembly and introduction of electrolyte function by alkyl chain terminal modification were designed. Newly designed dye without terminal modification as reference (SQ‐5) along with iodine (SQ‐77) and imidazole (SQ‐79) alkyl terminal‐modified dyes were successfully synthesized, characterized, and subjected to detailed photophysical investigations. Iodine terminal modification (SQ‐77) led to enhanced molar extinction coefficient, dye aggregation, dye loading and binding strength on the TiO2 surface, which was found by just the opposite after the imidazole (SQ‐79) terminal modification. Demonstration of nearly similar photovoltaic performance by SQ‐77 and SQ‐79 in the absence of iodine and chenodeoxycholic acid validates their multi‐functional role as electrolyte function and dye aggregation prevention, respectively, in addition to their main role as photosensitizer. DSSCs fabricated with SQ‐5 as a sensitizer showed efficient far‐red to NIR photo‐sensitization and photon harvesting with short‐circuit current density, open‐circuit voltage and fill factor of 11.98 mA/cm2, 0.61 V, and 0.57, respectively leading to a photoconversion efficiency of 4.2 % under simulated solar irradiation.This article is protected by copyright. All rights reserved.

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