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Six derivatives of guttiferone-A (LFQM-79, 80, 81, 82, 113 and 114) were synthesized and evaluated for their antimicrobial activity against the opportunistic or pathogenic fungi Candida albicans (ATCC 09548), Candida glabrata (ATCC 90030), Candida krusei (ATCC 6258), Candida parapsilosis (ATCC 69548), Candida tropicalis (ATCC 750), Cryptococcus neoformans (ATCC 90012), Trichophyton tonsurans, Microsporum gypseum and also against the opportunistic and pathogenic Gram-positive bacteria Staphylococcus aureus (ATCC 6538), Staphylococcus epidermidis (ATCC 12228), Bacillus cereus (ATCC 11778) and Gram-negative Escherichia coli (ATCC 25922), Pseudomonas aeruginosa (ATCC 9027), Salmonella typhimurium (ATCC 14028), Proteus mirabilis (ATCC 25933). The antimicrobial activities of derivatives were compared with guttiferone-A and they presented to be more potent than the original molecule and sometimes greater than standard drugs established in therapeutics. The current study showed that derivatives of guttiferone-A possess potent antimicrobial activity and are relatively non-cytotoxic, which reveal these new molecules as promising new drug prototype candidates, with innovative structural pattern.

A series of novel benzophenone derivatives containing a thiazole heterocyclic nucleus were designed by molecular hybridization. Molecular docking studies have demonstrated the inhibitory potential of the designed compounds against cyclooxygenase (COX) isoenzymes. These compounds were synthesized, characterized, and evaluated for their anti-inflammatory properties by the croton oil-induced ear edema assay to examine their effect on both prostaglandin (PG) production and neutrophils recruitment. The thiazole derivatives displayed a potent effect in terms of reducing ear edema. The analysis suggested that the presence of 4-phenyl-2-hydrazinothiazole and the absence of C4′-OCH3 on the benzophenone derivative structure are strongly related to the inhibition of PG production. In addition, the derivatives 2e, 3a and 3c concomitantly inhibit PG production and neutrophil recruitment, which may be a mechanism of action better than of common NSAIDs due to their inability to inhibit the neutrophil recruitment. Thus, these compounds can be considered as potential lead compounds toward the development of new anti-inflammatory drugs with an innovating mechanism of action.

This article reports the three biflavonoids isolated from the fruit pericarp of Garcinia brasiliensis Mart. (Clusiaceae): Morelloflavone-4```-glycoside (compound 1), (±)-Fukugiside (compound 2), and Morelloflavone (compound 3). Structural modifications by acylation and alkylation reactions were performed on the natural biflavonoid (±) morelloflavone to obtain three semisynthetic compounds: Morelloflavone-7,4`,7``,3```,4```-penta-O-acetyl (compound 4), Morelloflavone-7,4`,7``,3```,4```-penta-Omethyl (compound 5), and Morelloflavone-7,4`,7``,3```,4```-penta-O-butanoyl (compound 6). The inhibitory effects of these naturally isolated biflavonoid-type compounds and three semisynthetic derivatives on the activity of the cysteine proteases papain and cruzain, and on the serine protease trypsin were investigated. The potential inhibitory IC 50 of natural bioflavonoids compounds 1, 2, and 3 were 11.0 ± 3.0, 23.0 ± 4.0, and 10.5 ± 0.3 µM, respectively, for papain; 0.86 ± 0.12, 106 ± 7, and 3.8 ± 0.1, 50 ± 2, 119.5 ± 5, and 9.6 ± 1.0 µM, respectively, for cruzain. On the other hand, the semisynthetic biflavonoids compounds 4, 5, and 6 were more efficient in the inhibition of enzyme activity with IC 50 values 0.60 ± 0.02 µM (papain) for biflavonoids compound 4, 1.64 ± 0.11 µM (trypsin) for biflavonoids compound 5, and 8.1 ± 0.6 µM (cruzain) for biflavonoids compound 6. Compound 4 is more active owing to the carbonyl group in the structure; perhaps, this modification could favor a higher nucleophilic attack by serine and cysteine proteases. However, the semisynthetic compound 5 (IC 50 = 15.4 ± 0.7 µM for papain), which has no carbonyl group in structure, was less active in the inhibition. Interestingly, structure-activity relationships (SARs) were confirmed by flexible docking simulations. Likewise, the potential usefulness of natural compound 1 as an antioxidant compound was strengthened by our results concerning the antiproteolytic activity.

Considering the promising antitumor effects of compounds with dual anti-inflammatory and antiproliferative activities, thus benzophenones analogs (2-7) were evaluated on in vivo antiinflammatory assay and molecular docking analysis. Those with the best molecular docking results were in vitro evaluated on cyclooxygenase (COX) enzymes and tested regarding antiproliferative activity. All derivatives displayed in vivo anti-inflammatory activity. Among them, the substances 2’-hydroxy-4’-benzoylphenyl-β-D-glucopyranoside (4), 4-hydroxy-4’-methoxybenzophenone (5) and 4’-(4’’-methoxybenzoyl)phenyl-β-D-glucopyranoside (7) showed the best values of Glide Score in COX-2 docking evaluation and 4 and 5 selectively inhibited COX-2 and COX-1 in vitro enzymatic assay, respectively. Thus, 4 and 5 were tested against breast cancer (MCF-7, MDA‑MB-231, Hs578T) and non-small-cell-lung cancer (A549) cell lines. The estrogen-positive MCF-7 cell line was more responsive compared to other tested cell lines. They induced cell cycle arrest at G1/S transition in MCF-7 cell line once there was an increase in G0/G1 population with concomitant reduction of S population. The antiproliferative activity of these substances on MCF-7 was associated with their ability to inhibit cyclin E expression, a critical regulator of G1/S transition. Taken together, the data indicate that 4 and 5 have dual anti-inflammatory and antiproliferative activities and support further studies to evaluate their antitumor potential.

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