Carbazoles and imidazole represent two important classes of heterocycles which exhibit diverse biological activities such as antitumor properties. In this study, imidazole (C1-C3) and carbazole (C4 and C5) derivatives were evaluated for their cytotoxic activity against three human cancer cell lines namely, MCF7 (human breast cancer), HT29 (human colon cancer), and HeLa (human cervical cancer). Carbazole derivatives (C4 and C5) with IC50 < 10 µM showed greater cytotoxic effect than imidazole derivatives (C1-C3). Furthermore, all compounds exhibited better anticancer activity against MCF-7 than other two cell lines (HT-29, HeLa) and compound C4 was the most potent compound with the IC50 values of 2.5, 5.4 and 4.0 µM, against MCF-7, Hela and HT-29 cell lines, respectively. Physicochemical properties of compounds were calculated and their correlation with the IC50 values on MCF-7 cell line investigated. Surface area and polarizability of compounds showed good correlation by R2 = 0.8396 and R2 = 0.834, respectively. Docking studies of these compounds were also performed on the DNA as proposed target to comprehend their binding interactions and binding energies. The docking energy of compounds ranged from - 11.32 to -13.48 kcal/mol. Compound C3 with energy of -13.48 kcal/mol had the highest docking energy. Docking results indicated that these compounds (C1-C5) had strong affinity in binding to the DNA.                     KEY WORDS: Imidazole, Carbazole, Molecular docking, Cancer, MTT assay   Bull. Chem. Soc. Ethiop. 2020, 34(2), 377-384 DOI: https://dx.doi.org/10.4314/bcse.v34i2.14

Chenopodium album polcalcin (Che a 3) is characterized as a major cause of cross-reactivity inallergic patients to the Chenopodiaceae family. Therefore, the present study was conducted to develop a hypoallergenic Che a 3 derivatives as the candidate vaccine for type 1 allergy. Four derivatives were generated from Che a 3. The first was a mosaic peptide derivative computationally identified in Che a 3 which was coupled to keyhole limpet hemocyanin (KLH). The second one was a mutant Che a 3, and the other two derivatives included N- and C-terminal halves of Che a 3 that both coupled to KLH. The IgE-binding capacity of Che a 3 and its derivatives and also their ability to induce there combinant Che a 3 (rChe a 3)-specific IgG antibody, were determined using the enzyme-linked immune sorbent assay (ELISA). Moreover, the lymphopro liferative capacity of rChe a 3 or its derivatives and their pro-inflammatory cytokine response interleukin (IL)-5 and IL-13 were measured in the human peripheral blood mononuclear cells (PBMCs). Among all derivatives, the N-terminal half peptide and mosaic peptide exhibited the lowest IgE-binding capacity. In addition, in comparison to other antigens, KLH-coupled mosaic peptide induced the highest level of the recombinant Che a 3 (rChe a 3)-specific IgG antibody and ther Che a 3 specific-blocking IgG antibody in mice. Moreover, the mosaic peptide lacked lymphopro liferative capacity and down-regulated expression of pro-allergic IL-5 and IL-13 cytokines. Therefore, a peptide-carrier fusion vaccine, composed of the B-cell epitope coupled to the carrier, could be considered as one of the promising hypoallergenic vaccines to treat patients with allergy to low molecular weight allergens such as Che a 3.