## 3 Discussion  
Analysis of the biological activity of the 3,4,5-trimethoxybenzoic acid derivatives was performed using the results obtained in the antiparasitic assays (IC\({}_{50}\)). Twenty-three compounds were tested at CC\({}_{50}\) against LLC-MK2 cells, of which five analogs (one ester and four amides) were selected for IC\({}_{50}\) assays. In the evaluation of trypanicidal activity against the trypanastigote form, amides **16**-**18** and **20** were more potent than the ester compound **15**. \(N\)-butyl-3,4,5-trimethoxybenzamide amide (**16**) and \(N\)-iso-butyl-3,4,5-trimethoxybenzamide amide (**17**) presented IC\({}_{50}\) of 6.21 \(\upmu\)M and 2.21 \(\upmu\)M, respectively; and SI = 83.10 and 298.64. The isomerism of these compounds reveals that compound **16** presents a linear side carbon chain as a substituent, while compound **17** presents a branched side carbon chain. The greater volume of this alkyl substituent results in the potentiation of trypanicidal action against the trypanastigote form, in addition to presenting a high selectivity index for this strain. The compound \(N\)-pyrrolidyl-3,4,5-trimethoxybenzamide (**18**) presented an IC\({}_{50}\) of 8.14 \(\upmu\)M, while the analog \(N\)-4-hydroxybenzyl-3,4,5-trimethoxybenzamide amide (**20**) presented an IC\({}_{50}\) of 8.95 \(\upmu\)M. Thus, these compounds showed similar activity, despite having different substituents. The obtained results corroborate with those from [PERSON] and collaborators (2020) [22], who tested piplartine in vitro and in vivo for antiparasitic activity. In the in vivo study, treatment with the highest dose of piplartine (400 mg/kg) significantly reduced the total load of the etiological agent, which for this study was _Schistosoma mansoni_, demonstrating satisfactory results in the tests, and suggesting that piplartine may be useful as a prototype in the development new antiparasitic agents. The ester diphenyl 3,4,5-trimethoxybenzoate (**15**) presented the highest IC\({}_{50}\) (35.30 \(\upmu\)M) of the five bioactive analogs tested, being the least potent compound in the group against the trypanastigote form. In the study by [PERSON] et al. (2019) [10], where piplartine analogs were also tested, the antiparasitic results were better for the ester compounds. For example, benzyl 3,4,5-trimethoxybenzoate (IC\({}_{50}\) = 0.025 \(\pm\) 0.009 \(\upmu\)M, SI > 3.2) presented \begin{table}
\begin{tabular}{l c c} \hline \hline
**Parameter** & **Compound 17** & **Benznidazole** \\ \hline
**Physiochemical properties** & & \\ Molecular weight (g/mol) & 267.32 & 260.25 \\ Rotatable bonds & 7 & 6 \\ H-bond acceptors & 4 & 4 \\ H-bond donors & 1 & 1 \\ Fraction Csp3 & 0.5 & 0.17 \\ TSPA (A\({}^{2}\)) & 56.79 & 92.74 \\ \hline
**Lipophilicity (Log \(P_{\text{o/w}}\))** & & \\ iLOGP & 3.01 & 1.15 \\ XLOBP3 & 2.44 & 0.91 \\ MLOGP & 1.5 & 0.37 \\ Consensus & 2.31 & 0.49 \\ \hline
**Solubility** & & \\ Water solubility & Moderately soluble & Soluble \\ \hline
**Pharmacokine** & & High \\ Gastrointestinal absorption & High & \(-\)6.2 \\ Skin permeability (Log K\({}_{\text{P}}\), cm/s) & \(-\)6.2 & \(-\)7.24 \\ Blood-brain permeability & Yes & No \\ P-gp substrate & No & No \\ CYP1A2 inhibitor & Yes & No \\ CYP2C19 inhibitor & No & No \\ CYP2C9 inhibitor & No & No \\ CYP2D6 inhibitor & Yes & No \\ CYP3A4 inhibitor & No & No \\ \hline \hline \end{tabular}
\end{table} 
Table 4: ADME predictions for compound **17** and the reference drug benznidazole. the best activity against _Leishman amazonensis_. In this study, the results show that the benzamides showed a better antiparasitic profile against _T. cruzi_. Evaluating the results obtained against the epimastigote form, compound **16** presented an IC\({}_{50}\) of 10.66 uM, while compound **17** presented an IC\({}_{50}\) of 8.71 uM, confirming that branched substituents present greater trypanacid activity. Comparing compound **18** with compound **20**, presenting IC\({}_{50}\) of 34.30 uM and 4.06 uM, respectively, compound **20** was about 8.4 times more potent.