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Colorectal cancer remains a significant cause of mortality worldwide. A spiro-acridine derivative, ( E )-1'-((4-bromobenzylidene)amino)-5'-oxo-1',5'-dihydro-10 H -spiro[acridine-9,2'-pyrrole]-4'-carbonitrile (AMTAC-19), showed significant cytotoxicity in HCT-116 colorectal carcinoma cells (half maximal inhibitory concentration, IC50 = 10.35 ± 1.66 µM) and antioxidant effects after 48 h of treatment. In this study, Molegro Virtual Docker v.6.0.1 software was used to investigate the interactions between AMTAC-19 and the Extracellular Signal-Regulated Kinase 1 (ERK1), c-Jun N-terminal Kinase 1 (JNK1), and p38 Mitogen-Activated Protein Kinase α (p38α MAPK). In vitro assays were conducted in HCT-116 cells to evaluate the effect of AMTAC-19 on the modulation of these proteins' activities using flow cytometry. Furthermore, the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay in the presence or absence of ERK1/2, JNK, and p38 MAPK inhibitors was used to evaluate the involvement of these enzymes in AMTAC-19 cytotoxicity. ROS production was assessed using the 2,7-dichlorodihydrofluorescein diacetate (DCFH-DA) assay at various incubation times (30 min, 1 h, 6 h, 12 h, and 24 h), and the MTT assay using N-acetyl-L-cysteine (NAC) was performed. In silico results indicated that AMTAC-19 interacts with ERK1, JNK1, and p38α MAPK. Additionally, AMTAC-19 activated ERK1/2 and JNK1 in HCT-116 cells, and its cytotoxicity was significantly reduced in the presence of ERK1/2 and JNK inhibitors. AMTAC-19 also induced a significant increase in ROS production (30 min and 1 h), while NAC pretreatment reduced its cytotoxicity. These findings support AMTAC-19's in vitro antitumor effect through ROS-dependent activation of ERK and JNK pathways., Competing Interests: The authors declare no conflicts of interest.

Seven new abietane diterpenoids, comprising medusanthol A-G ( 1 - 3 , 5 , 7 - 9 ) and two previously identified analogs ( 4 and 6 ), were isolated from the hexane extract of the aerial parts of Medusantha martiusii. The structures of the compounds were elucidated by HRESIMS, 1D/2D NMR spectroscopic data, IR spectroscopy, NMR calculations with DP4+ probability analysis, and ECD calculations. The anti-neuroinflammatory potential of compounds 1 - 7 was evaluated by determining their ability to inhibit the production of nitric oxide (NO) and the proinflammatory cytokine TNF-α in BV2 microglia stimulated with LPS and IFN-γ. Compounds 1 - 4 and 7 exhibited decreased NO levels at a concentration of 12.5 µM. Compound 1 demonstrated strong activity with an IC 50 of 3.12 µM, and compound 2 had an IC 50 of 15.53 µM; both compounds effectively reduced NO levels compared to the positive control quercetin (IC 50 11.8 µM). Additionally, both compounds significantly decreased TNF-α levels, indicating their potential as promising anti-neuroinflammatory agents.

The critical enzyme dihydrofolate reductase-thymidylate synthase in Leishmania major ( Lm DHFR-TS) serves a dual-purpose role and is essential for DNA synthesis, a cornerstone of the parasite's reproductive processes. Consequently, the development of inhibitors against Lm DHFR-TS is crucial for the creation of novel anti- Leishmania chemotherapies. In this study, we employed an in-house database containing 314 secondary metabolites derived from cinnamic acid that occurred in the Asteraceae family. We conducted a combined ligand/structure-based virtual screening to identify potential inhibitors against Lm DHFR-TS. Through consensus analysis of both approaches, we identified three compounds, i.e., lithospermic acid ( 237 ), diarctigenin ( 306 ), and isolappaol A ( 308 ), that exhibited a high probability of being inhibitors according to both approaches and were consequently classified as promising hits. Subsequently, we expanded the binding mode examination of these compounds within the active site of the test enzyme through molecular dynamics simulations, revealing a high degree of structural stability and minimal fluctuations in its tertiary structure. The in silico predictions were then validated through in vitro assays to examine the inhibitory capacity of the top-ranked naturally occurring compounds against Lm DHFR-TS recombinant protein. The test compounds effectively inhibited the enzyme with IC 50 values ranging from 6.1 to 10.1 μM. In contrast, other common cinnamic acid derivatives (i.e., flavonoid glycosides) from the Asteraceae family, such as hesperidin, isovitexin 4'- O -glucoside, and rutin, exhibited low activity against this target. The selective index (SI) for all tested compounds was determined using Hs DHFR with moderate inhibitory effect. Among these hits, lignans 306 and 308 demonstrated the highest selectivity, displaying superior SI values compared to methotrexate, the reference inhibitor of DHFR-TS. Therefore, continued research into the anti-leishmanial potential of these C6C3-hybrid butyrolactone lignans may offer a brighter outlook for combating this neglected tropical disease.

Cancer is a multifactorial disease that continues to increase. Lignans are known to be important anticancer agents. However, due to the structural diversity of lignans, it is difficult to associate anticancer activity with a particular subclass. Therefore, the present study sought to evaluate the association of lignan subclasses with antitumor activity, considering the genetic profile of the variants of the selected targets. To do so, predictive models were built against the targets tyrosine-protein kinase ABL (ABL), epidermal growth factor receptor erbB1 (EGFR), histone deacetylase (HDAC), serine/threonine-protein kinase mTOR (mTOR) and poly [ADP-ribose] polymerase-1 (PARP1). Then, single nucleotide polymorphisms were mapped, target mutations were designed, and molecular docking was performed with the lignans with the best predicted biological activity. The results showed more anticancer activity in the dibenzocyclooctadiene, furofuran and aryltetralin subclasses. The lignans with the best predictive values of biological activity showed varying binding energy results in the presence of certain genetic variants.

Chalcones are direct precursors in the biosynthesis of flavonoids. They have an α,β-unsaturated carbonyl system which gives them broad biological properties. Among the biological properties exerted by chalcones, their ability to suppress tumors stands out, in addition to their low toxicity. In this perspective, the present work explores the role of natural and synthetic chalcones and their anticancer activity in vitro reported in the last four years from 2019 to 2023. Moreover, we carried out a partial least square (PLS) analysis of the biologic data reported for colon adenocarcinoma lineage HCT-116. Information was obtained from the Web of Science database. Our in silico analysis identified that the presence of polar radicals such as hydroxyl and methoxyl contributed to the anticancer activity of chalcones derivatives. We hope that the data presented in this work will help researchers to develop effective drugs to inhibit colon adenocarcinoma in future works.

Sesquiterpene lactone (SL) subtypes including hirsutinolide and cadinanolide have a controversial genesis. Metabolites of these classes are either described as natural products or as artifacts produced via the influence of solvents, chromatographic mobile phases, and adsorbents used in phytochemical studies. Based on this divergence, and to better understand the sensibility of these metabolites, different pH conditions were used to prepare semisynthetic SLs and evaluate the anti-inflammatory and antiproliferative activities. Therefore, glaucolide B ( 1 ) was treated with various Brønsted-Lowry and Lewis acids and bases-the same approach was applied to some of its derivatives-allowing us to obtain 14 semisynthetic SL derivatives, 10 of which are hereby reported for the first time. Hirsutinolide derivatives 7a (CC 50 = 5.0 µM; SI = 2.5) and 7b (CC 50 = 11.2 µM; SI = 2.5) and the germacranolide derivative 8a (CC 50 = 3.1 µM; SI = 3.0) revealed significant cytotoxic activity and selectivity against human melanoma SK-MEL-28 cells when compared with that against non-tumoral HUVEC cells. Additionally, compounds 7a and 7c.1 showed strongly reduced interleukin-6 (IL-6) and nitrite (NOx) release in pre-treated M1 macrophages J774A.1 when stimulated with lipopolysaccharide. Despite the fact that hirsutinolide and cadinanolide SLs may be produced via plant metabolism, this study shows that acidic and alkaline extraction and solid-phase purification processes can promote their formation., Competing Interests: The authors declare no conflicts of interest.

Eriocaulaceae is a pantropical family whose main center of biodiversity is in Brazil. In general, the family has about 1200 species, in which phytochemical and biological studies have shown a variety of structures and activities. The aim of this research is to compile the compounds isolated in the Eriocaulaceae family and carry out a computational study on their biological targets. The bibliographic research was carried out on six databases. Tables were built and organized according to the chemical class. In addition, a summary of the methods of isolating the compounds was also made. In the computational study were used ChEMBL platform, DRAGON 7.0, and the KNIME 4.4.0 software. Two hundred and twenty-two different compounds have been isolated in sixty-eight species, divided mainly into flavonoids and naphthopyranones, and minor compounds. The ligand-based virtual screening found promising molecules and molecules with multitarget potential, such as xanthones 194 , 196 , 200 and saponin 202 , with xanthone 194 as the most promising. Several compounds with biological activities were isolated in the family, but the chemical profiles of many species are still unknown. The selected structures are a starting point for further studies to develop new antiparasitic and antiviral compounds based on natural products.

Essential oils (EOs) are a mixture of chemical compounds with a long history of use in food, cosmetics, perfumes, agricultural and pharmaceuticals industries. The main object of this study was to find chemical patterns between 45 EOs and antiprotozoal activity (antiplasmodial, antileishmanial and antitrypanosomal), using different machine learning algorithms. In the analyses, 45 samples of EOs were included, using unsupervised Self-Organizing Maps (SOM) and supervised Random Forest (RF) methodologies. In the generated map, the hit rate was higher than 70% and the results demonstrate that it is possible find chemical patterns using a supervised and unsupervised machine learning approach. A total of 20 compounds were identified (19 are terpenes and one sulfur-containing compound), which was compared with literature reports. These models can be used to investigate and screen for bioactivity of EOs that have antiprotozoal activity more effectively and with less time and financial cost.

The current treatments against Leishmania parasites present high toxicity and multiple side effects, which makes the control and elimination of leishmaniasis challenging. Natural products constitute an interesting and diverse chemical space for the identification of new antileishmanial drugs. To identify new drug options, an in-house database of 360 kauranes (tetracyclic diterpenes) was generated, and a combined ligand- and structure-based virtual screening (VS) approach was performed to select potential inhibitors of Leishmania major ( Lm ) pteridine reductase I (PTR1). The best-ranked kauranes were employed to verify the validity of the VS approach through Lm PTR1 enzyme inhibition assay. The half-maximal inhibitory concentration (IC 50 ) values of selected bioactive compounds were examined using the random forest (RF) model (i.e., 2β-hydroxy-menth-6-en-5β-yl ent -kaurenoate ( 135 ) and 3α-cinnamoyloxy- ent -kaur-16-en-19-oic acid ( 302 )) were below 10 μM. A compound similar to 302 , 3α- p -coumaroyloxy- ent -kaur-16-en-19-oic acid ( 302a ), was also synthesized and showed the highest activity against Lm PTR1. Finally, molecular docking calculations and molecular dynamics simulations were performed for the VS-selected, most-active kauranes within the active sites of PTR1 hybrid models, generated from three Leishmania species that are known to cause cutaneous leishmaniasis in the new world (i.e., L. braziliensis , L. panamensis, and L. amazonensis ) to explore the targeting potential of these kauranes to other species-dependent variants of this enzyme.

Background: The growing demand for agricultural products has led to the misuse/overuse of insecticides; resulting in the use of higher concentrations and the need for ever more toxic products. Ecologically, bioinsecticides are considered better and safer than synthetic insecticides; they must be toxic to the target organism, yet with low or no toxicity to non-target organisms. Many plant extracts have seen their high insecticide potential confirmed under laboratory conditions, and in the search for plant compounds with bioinsecticidal activity, the Lamiaceae family has yielded satisfactory results., Objective: The aim of our study was to develop computer-assisted predictions for compounds with known insecticidal activity against Aphis gossypii and Drosophila melanogaster ., Results and Conclusion: Structure analysis revealed ent -kaurane, kaurene, and clerodane diterpenes as the most active, showing excellent results. We also found that the interactions formed by these compounds were more stable, or presented similar stability to the commercialized insecticides tested. Overall, we concluded that the compounds bistenuifolin L ( 1836 ) and bistenuifolin K ( 1931 ), were potentially active against A. gossypii enzymes ; and salvisplendin C ( 1086 ) and salvixalapadiene ( 1195 ), are potentially active against D. melanogaster . We observed and highlight that the diterpenes bistenuifolin L ( 1836 ), bistenuifolin K ( 1931 ), salvisplendin C ( 1086 ), and salvixalapadiene ( 1195 ), present a high probability of activity and low toxicity against the species studied.

Objective: This study evaluated the antifungal activity of cinnamaldehyde on Candida spp. In vitro and in situ assays were carried out to test cinnamaldehyde for its anti- Candida effects, antibiofilm activity, effects on fungal micromorphology, antioxidant activity, and toxicity on keratinocytes and human erythrocytes. Statistical analysis was performed considering α = 5%., Results: The minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) of cinnamaldehyde ranged from 18.91 μM to 37.83 μM. MIC values did not change in the presence of 0.8 M sorbitol, whereas an 8-fold increase was observed in the presence of ergosterol, suggesting that cinnamaldehyde may act on the cell membrane, which was subsequently confirmed by docking analysis. The action of cinnamaldehyde likely includes binding to enzymes involved in the formation of the cytoplasmic membrane in yeast cells. Cinnamaldehyde-treated microcultures showed impaired cellular development, with an expression of rare pseudo-hyphae and absence of chlamydoconidia. Cinnamaldehyde reduced biofilm adherence by 64.52% to 33.75% ( p < 0.0001) at low concentrations (378.3-151.3 µM). Cinnamaldehyde did not show antioxidant properties., Conclusions: Cinnamaldehyde showed fungicidal activity through a mechanism of action likely related to ergosterol complexation; it was non-cytotoxic to keratinocytes and human erythrocytes and showed no antioxidant activity.

Leishmaniasis is endemic in at least 98 countries. Due to the high toxicity and resistance associated with the drugs, we chose lignans as an alternative, due to their favorable properties of absorption, distribution, metabolism, excretion, and toxicity (ADMET). To investigate their leishmanicidal potential, the biological activities of a set of 160 lignans were predicted using predictive models that were built using data for Leishmania major and L. (Viannia) braziliensis . A combined analysis, based on ligand and structure, and several other computational approaches were used. The results showed that the combined analysis was able to select 11 lignans with potential activity against L. major and 21 lignans against L. braziliensis , with multitargeting effects and low or no toxicity. Of these compounds, four were isolated from the species Justicia aequilabris (Nees) Lindau. All of the identified compounds were able to inhibit the growth of L. braziliensis promastigotes, with the most active compound, ( 159 ) epipinoresinol-4- O -β-d-glucopyranoside, presenting an IC 50 value of 5.39 µM and IC 50 value of 36.51 µM for L. major . Our findings indicated the potential of computer-aided drug design and development and demonstrated that lignans represent promising prototype compounds for the development of multitarget drugs against leishmaniasis.

Lamiaceae is one of the largest families of angiosperms and is classified into 12 subfamilies that are composed of 295 genera and 7775 species. It presents a variety of secondary metabolites such as diterpenes that are commonly found in their species, and some of them are known to be chemotaxonomic markers. The aim of this work was to construct a database of diterpenes and to use it to perform a chemotaxonomic analysis among the subfamilies of Lamiaceae, using molecular descriptors and self-organizing maps (SOMs). The 4115 different diterpenes corresponding to 6386 botanical occurrences, which are distributed in eight subfamilies, 66 genera, 639 different species and 4880 geographical locations, were added to SistematX. Molecular descriptors of diterpenes and their respective botanical occurrences were used to generate the SOMs. In all obtained maps, a match rate higher than 80% was observed, demonstrating a separation of the Lamiaceae subfamilies, corroborating with the morphological and molecular data proposed by Li et al. Therefore, through this chemotaxonomic study, we can predict the localization of a diterpene in a subfamily and assist in the search for secondary metabolites with specific structural characteristics, such as compounds with potential biological activity.

Helicteres velutina K. Schum (Sterculiaceae), a member of Malvaceae sensu lato , is a Brazilian endemic plant that has been used by the indigenous tribe Pankarare as an insect repellent. A previous study has reported the isolation of terpenoids, flavonoids and pheophytins, in addition to the larvicidal activity of crude H. velutina extracts derived from the aerial components (leaves, branches/twigs, and flowers). The present study reports the biomonitoring of the effects of fractions and isolated compounds derived from H. velutina against A. aegypti fourth instar larvae. A crude ethanol extract was submitted to liquid-liquid extraction with hexane, dichloromethane, ethyl acetate and n -butanol to obtain their respective fractions. Larvicidal evaluations of the fractions were performed, and the hexane and dichloromethane fractions exhibited greater activities than the other fractions, with LC 50 (50% lethal concentration) values of 3.88 and 5.80 mg/mL, respectively. The phytochemical study of these fractions resulted in the isolation and identification of 17 compounds. The molecules were subjected to a virtual screening protocol, and five molecules presented potential larvicidal activity after analyses of their applicability domains. When molecular docking was analysed, only three of these compounds showed an ability to bind with sterol carrier protein-2 (1PZ4), a protein found in the larval intestine. The compounds tiliroside and 7,4'-di- O -methyl-8- O -sulphate flavone showed in vitro larvicidal activity, with LC 50 values of 0.275 mg/mL after 72 h and 0.182 mg/mL after 24 h of exposure, respectively. This is the first study to demonstrate the larvicidal activity of sulphated flavonoids against A. aegypti . Our results showed that the presence of the OSO 3 H group attached to C-8 of the flavonoid was crucial to the larvicidal activity. This research supports the traditional use of H. velutina as an alternative insecticide for the control of A. aegypti , which is a vector for severe arboviruses, such as dengue and chikungunya.

The traditional work of a natural products researcher consists in large part of time-consuming experimental work, collecting biota to prepare and analyze extracts and to identify innovative metabolites. However, along this long scientific path, much information is lost or restricted to a specific niche. The large amounts of data already produced and the science of metabolomics reveal new questions: Are these compounds known or new? How fast can this information be obtained? To answer these and other relevant questions, an appropriate procedure to correctly store information on the data retrieved from the discovered metabolites is necessary. The SistematX (http://sistematx.ufpb.br) interface is implemented considering the following aspects: (a) the ability to search by structure, SMILES (Simplified Molecular-Input Line-Entry System) code, compound name and species; (b) the ability to save chemical structures found by searching; (c) compound data results include important characteristics for natural products chemistry; and (d) the user can find specific information for taxonomic rank (from family to species) of the plant from which the compound was isolated, the searched-for molecule, and the bibliographic reference and Global Positioning System (GPS) coordinates. The SistematX homepage allows the user to log into the data management area using a login name and password and gain access to administration pages. In this article, we introduced a modern and innovative web interface for the management of a secondary metabolite database. With its multiplatform design, it is able to be properly consulted via the internet and managed from any accredited computer. The interface provided by SistematX contains a wealth of useful information for the scientific community about natural products, highlighting the locations of species from which compounds are isolated., Competing Interests: The authors declare no conflict of interest.

This review presents an survey to the biological importance of sesquiterpene lactones (SLs) in the fight against four infectious neglected tropical diseases (NTDs)-leishmaniasis, schistosomiasis, Chagas disease, and sleeping sickness-as alternatives to the current chemotherapies that display several problems such as low effectiveness, resistance, and high toxicity. Several studies have demonstrated the great potential of some SLs as therapeutic agents for these NTDs and the relationship between the protozoal activities with their chemical structure. Recently, Computer-Aided Drug Design (CADD) studies have helped increase the knowledge of SLs regarding their mechanisms, the discovery of new lead molecules, the identification of pharmacophore groups and increase the biological activity by employing in silico tools such as molecular docking, virtual screening and Quantitative-Structure Activity Relationship (QSAR) studies.

A collection of 32 structurally related N -(4-halobenzyl)amides were synthesized from cinnamic and benzoic acids through coupling reactions with 4-halobenzylamines, using (benzotriazol-1-yloxy)tris(dimethylamino)phosphonium hexafluorophosphate (BOP) as a coupling agent. The compounds were identified by spectroscopic methods such as infrared, ¹H- and 13 C- Nuclear Magnetic Resonance (NMR) and high-resolution mass spectrometry. The compounds were then submitted to antimicrobial tests by the minimum inhibitory concentration method (MIC) and nystatin was used as a control in the antifungal assays. The purpose of the tests was to evaluate the influence of structural changes in the cinnamic and benzoic acid substructures on the inhibitory activity against strains of Candida albicans , Candida tropicalis , and Candida krusei . A quantitative structure-activity relationship (QSAR) study with KNIME v. 3.1.0 and Volsurf v. 1.0.7 softwares were realized, showing that descriptors DRDRDR, DRDRAC, L4LgS, IW4 and DD2 influence the antifungal activity of the haloamides. In general, 10 benzamides revealed fungal sensitivity, especially a vanillic amide which enjoyed the lowest MIC. The results demonstrate that a hydroxyl group in the para position, and a methoxyl at the meta position enhance antifungal activity for the amide skeletal structure. In addition, the double bond as a spacer group appears to be important for the activity of amide structures.

Leishmaniasis and Chagas are diseases caused by parasitic protozoans that affect the poorest population in the World, causing a high mortality and morbidity. As a result of highly toxic and long-term treatments, the discovery of novel, safe and more efficacious drugs is essential. In this work, the in vitro antiparasitic activity and mammalian cytotoxicity of three natural tirucallane triterpenoids, isolated from leaves of Schinus terebinthifolius (Anacardiaceae), and nine semi-synthetic derivatives were investigated against Leishmania (L.) infantum and Trypanosoma cruzi. Trypomastigotes of T. cruzi were the most susceptible parasites and seven compounds demonstrated a trypanocidal activity with IC50 values in the range between 15 and 58 µg/mL. Four compounds demonstrated selectivity towards the intracellular amastigotes of Leishmania, with IC50 values in the range between 28 and 97 µg/mL. The complete characterization of triterpenoids was afforded after thorough analysis of nuclear magnetic resonance (NMR) data as well as electrospray ionization mass spectrometry (ESI-MS). Additionally, structure-activity relationships were performed using Decision Trees.

The search of alternative compounds to control tropical diseases such as schistosomiasis has pointed to secondary metabolites derived from natural sources. Piper species are candidates in strategies to control the transmission of schistosomiasis due to their production of molluscicidal compounds. A new benzoic acid derivative and three flavokawains from Piper diospyrifolium, P. cumanense and P. gaudichaudianum displayed significant activities against Biomphalaria glabrata snails. Additionally, "in silico" studies were performed using docking assays and Molecular Interaction Fields to evaluate the physical-chemical differences among the compounds in order to characterize the observed activities of the test compounds against Biomphalaria glabrata snails.

The Asteraceae, one of the largest families among angiosperms, is chemically characterised by the production of sesquiterpene lactones (SLs). A total of 1,111 SLs, which were extracted from 658 species, 161 genera, 63 subtribes and 15 tribes of Asteraceae, were represented and registered in two dimensions in the SISTEMATX, an in-house software system, and were associated with their botanical sources. The respective 11 block of descriptors: Constitutional, Functional groups, BCUT, Atom-centred, 2D autocorrelations, Topological, Geometrical, RDF, 3D-MoRSE, GETAWAY and WHIM were used as input data to separate the botanical occurrences through self-organising maps. Maps that were generated with each descriptor divided the Asteraceae tribes, with total index values between 66.7% and 83.6%. The analysis of the results shows evident similarities among the Heliantheae, Helenieae and Eupatorieae tribes as well as between the Anthemideae and Inuleae tribes. Those observations are in agreement with systematic classifications that were proposed by Bremer, which use mainly morphological and molecular data, therefore chemical markers partially corroborate with these classifications. The results demonstrate that the atom-centred and RDF descriptors can be used as a tool for taxonomic classification in low hierarchical levels, such as tribes. Descriptors obtained through fragments or by the two-dimensional representation of the SL structures were sufficient to obtain significant results, and better results were not achieved by using descriptors derived from three-dimensional representations of SLs. Such models based on physico-chemical properties can project new design SLs, similar structures from literature or even unreported structures in two-dimensional chemical space. Therefore, the generated SOMs can predict the most probable tribe where a biologically active molecule can be found according Bremer classification.

In this study, the antinociceptive properties of 3,4-dihydro-2,6-diaryl-4-oxo-pyrimidine-5-carbonitrile derivatives 5a-i at doses of 25 and 50 mg/kg were evaluated in mice, using the abdominal constriction test. Molecular modeling studies were also performed using density functional theory calculations. These data provided information about the electrostatic and ionization potentials and were used to compare the antinociceptive activity of the title compounds. The most active compounds were 3,4-dihydro-2-(4-chlorophenyl)-6-(4-methoxyphenyl)-4-oxo-pyrimidine-5-carbonitrile (5b) and 3,4-dihydro-2,6-diphenyl-4-oxo-pyrimidine-5-carbonitrile (5i), which inhibited the number of abdominal constrictions, at 50 mg/kg dose, in 88.6% and 88% of the sample, respectively. A preliminary SAR study demonstrated that halogen replacement in the phenyl rings of the compounds under study reduces the antinociceptive activity. DFT calculations showed that there is a high correlation between the ionization potentials and the analgesic properties of the compounds. It was found that compounds with a positive ionization potential (compounds 5b and 5i) were found to be the best analgesic drugs in this series.

Natural products have widespread biological activities, including inhibition of mitochondrial enzyme systems. Some of these activities, for example cytotoxicity, may be the result of alteration of cellular bioenergetics. Based on previous computer-aided drug design (CADD) studies and considering reported data on structure-activity relationships (SAR), an assumption regarding the mechanism of action of natural products against parasitic infections involves the NADH-oxidase inhibition. In this study, chemometric tools, such as: Principal Component Analysis (PCA), Consensus PCA (CPCA), and partial least squares regression (PLS), were applied to a set of forty natural compounds, acting as NADH-oxidase inhibitors. The calculations were performed using the VolSurf+ program. The formalisms employed generated good exploratory and predictive results. The independent variables or descriptors having a hydrophobic profile were strongly correlated to the biological data.