Chalcones belong to the flavonoid class of phenolic compounds. They form one of the largest groups of bioactive natural products. The potential anticancer, anti-inflammatory, antimicrobial, antioxidant, and antiparasitic properties of naturally occurring chalcones, and their unique chemical structural features inspired the synthesis of numerous chalcone derivatives. In fact, structural features of chalcones are easy to construct from simple aromatic compounds, and it is convenient to perform structural modifications to generate functionalized chalcone derivatives. Many of these synthetic analogs were shown to possess similar bioactivities as their natural counterparts, but often with an enhanced potency and reduced toxicity. This review article aims to demonstrate how bioinspired synthesis of chalcone derivatives can potentially introduce a new chemical space for exploitation for new drug discovery, justifying the title of this article. However, the focus remains on critical appraisal of synthesized chalcones and their derivatives for their bioactivities, linking to their interactions at the biomolecular level where appropriate, and revealing their possible mechanisms of action.

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Three biflavonoids [cupressuflavone (1), amentoflavone (2), and sumaflavone (3)], four diterpenoids [13-epi-cupressic acid (4), imbricatholic acid (5), 3-hydroxysandaracopimaric acid (6), and dehydroabietic acid (7)], and one lignan [β-peltatin methyl ether (8)] were isolated from the cytotoxic fractions of the extracts of the leaves of the Libyan Juniperus phoenicea L. The structures of these compounds were elucidated by spectroscopic means. Cytotoxicity of compounds 1-6 were assessed against the human lung cancer cell line A549 using the MTT assay. Compounds 1 and 3 showed cytotoxicity against the A549 cells (IC 50 = 65 and 77 μM, respectively), whereas compound 2 did not show any activity. Diterpenes 4-6 exhibited weak cytotoxicity against the A549 cells with the IC 50 values of 159, 263, and 223 μM, respectively. The cytotoxicity of each compound was compared with the anticancer drug, etoposide (IC 50 = 61 μM). Cupressuflavone (1) was evaluated also for cytotoxicity against both the human PC3 cancer cell line and the normal prostate cell line (PNT2), and this compound revealed a high degree of cytotoxic selectivity towards the prostate cancer cells (PC3), with IC 50 value of 19.9 μM, without any evidence of cytotoxicity towards the normal prostate cell line (PNT2).