Capsaicinoids and Their Effects on Cancer: The "Double-Edged Sword" Postulate from the Molecular Scale.

Capsaicinoids are a unique chemical species resulting from a particular biosynthesis pathway of hot chilies (Capsicum spp.) that gives rise to 22 analogous compounds, all of which are TRPV1 agonists and, therefore, responsible for the pungency of Capsicum fruits. In addition to their human consumption, numerous ethnopharmacological uses of chili have emerged throughout history. Today, more than 25 years of basic research accredit a multifaceted bioactivity mainly to capsaicin, highlighting its antitumor properties mediated by cytotoxicity and immunological adjuvancy against at least 74 varieties of cancer, while non-cancer cells tend to have greater tolerance. However, despite the progress regarding the understanding of its mechanisms of action, the benefit and safety of capsaicinoids' pharmacological use remain subjects of discussion, since CAP also promotes epithelial-mesenchymal transition, in an ambivalence that has been referred to as "the double-edge sword". Here, we update the comparative discussion of relevant reports about capsaicinoids' bioactivity in a plethora of experimental models of cancer in terms of selectivity, efficacy, and safety. Through an integration of the underlying mechanisms, as well as inherent aspects of cancer biology, we propose mechanistic models regarding the dichotomy of their effects. Finally, we discuss a selection of in vivo evidence concerning capsaicinoids' immunomodulatory properties against cancer.

Impact of Drying Process on the Phenolic Profile and Antioxidant Capacity of Raw and Boiled Leaves and Inflorescences of Chenopodium berlandieri ssp. berlandieri.

C. berlandieri ssp. berlandieri (C. berlandieri) is one of the most common members of the group of plants known as quelites, which are dark leafy greens widely consumed in Mexico. This study aimed to evaluate the impact of two drying procedures (oven drying and freeze-drying/lyophilization) on the polyphenolic composition, antioxidant capacity, and proximal chemical analysis of C. berlandieri leaves and inflorescences (raw or boiled). The results indicated that the raw freeze-dried samples had higher amounts (p < 0.05) of total phenolic compounds, total flavonoids, and antioxidant capacity, mainly in the inflorescence. The oven-dried samples showed an increased concentration of polyphenols after boiling, while the lyophilized samples showed a slightly decreased concentration. The drying process was observed to have little impact on the proximal chemical composition. Quantification by UPLC-DAD-ESI-QToF/MS identified up to 23 individual phenolic compounds, with freeze-dried samples showing higher amounts of individual compounds compared with oven-dried. Procyanidin B2 was found exclusively in the inflorescences. The inflorescences have a higher content of phenolic compounds and greater antioxidant capacity than the leaves. Regardless of the drying process, the leaves and inflorescences of C. berlandieri contain an interesting variety of phenolic compounds that may have beneficial effects on health.

Comparison of Phenolic Compounds and Evaluation of Antioxidant Properties of Porophyllum ruderale (Jacq.) Cass (Asteraceae) from Different Geographical Areas of Queretaro (Mexico).

Porophyllum ruderale (P. ruderale) is a well-known Mexican plant from the group of "Quelites", widely consumed plant species used for several food and medicinal purposes. As the production is very heterogeneous and the diverse agroclimatic conditions significantly impact the plant's phytochemical composition, this research aimed to compare the phenolic compound composition and the antioxidant capacity of the P. ruderale plant from three different collection sites (Queretaro, Landa de Matamoros, and Arroyo Seco) in the State of Queretaro (Mexico). Plants collected from Queretaro displayed the lowest total phenolic compounds, flavonoids, and condensed tannins, reflected in a lower antioxidant capacity (DPPH, FRAP, ABTS), compared to the other collection places. Flavones (epicatechin and epigallocatechin gallate) were the most abundant (36.1-195.2 µg equivalents/g) phenolics quantified by HPLC-DAD, while 31 compounds were identified by UHPLC-DAD-QToF/MS-ESI. Most compounds were linked to biological mechanisms related to the antioxidant properties of the leaves. A PCA analysis clustered Landa de Matamoros and Arroyo Seco into two groups based on flavones, hydroxybenzoic acids, the antioxidant capacity (ABTS and DPPH), and total phenolic compounds, the main contributors to its variation. The results indicated contrasting differences in the polyphenolic composition of collected P. ruderale in Queretaro, suggesting the need to standardize and select plants with favorable agroclimatic conditions to obtain desirable polyphenolic compositions while displaying potential health benefits.

Comparison of Phytochemical Composition and Untargeted Metabolomic Analysis of an Extract from Cnidoscolus aconitifolius (Mill.) I. I. Johnst and Porophyllum ruderale (Jacq.) Cass. and Biological Cytotoxic and Antiproliferative Activity In Vitro.

Cnidoscolus aconitifolius (CA) and Porophyllum ruderale (PR) are representative edible plants that are a traditional food source in Mexico. This research aimed to analyze the phytochemical composition and untargeted metabolomics analysis of CA and PR and evaluate their antiproliferative effect in vitro. The phytochemical composition (UPLC-DAD-QToF/MS-ESI) identified up to 38 polyphenols and selected organic acids that were clustered by the untargeted metabolomics in functional activities linked to indolizidines, pyridines, and organic acids. Compared with PR, CA displayed a higher reduction in the metabolic activity of human SW480 colon adenocarcinoma cells (LC50: 10.65 mg/mL), and both extracts increased the total apoptotic cells and arrested cell cycle at G0/G1 phase. PR increased mRNA Apc gene expression, whereas both extracts reduced mRNA Kras expression. Rutin/epigallocatechin gallate displayed the highest affinity to APC and K-RAS proteins in silico. Further research is needed to experiment on other cell lines. Results suggested that CA and PR are polyphenol-rich plant sources exhibiting antiproliferative effects in vitro.

Effect of Induced Mechanical Leaf Damage on the Yield and Content of Bioactive Molecules in Leaves and Seeds of Tepary Beans (Phaseolus acutifolius).

Growing interest has recently been shown in Tepary beans (Phaseolus acutifolius) because they contain lectins and protease inhibitors that have been shown to have a specific cytotoxic effect on human cancer cells. Bean lectins offer protection against biotic and abiotic stress factors, so it is possible that mechanical foliar damage may increase lectin production. This study evaluates the effect of mechanical stress (foliar damage) on lectin and protease inhibitor content in Tepary beans. Seed yield was also analyzed, and phenolic content and antioxidant capacity (DPPH and TEAC) were determined in the leaves. An experimental design with random blocks of three treatments (T1: control group, T2: 50% mechanical foliar damage and T3: 80% mechanical foliar damage) was carried out. Mechanical foliar damage increased the amount of lectin binding units (LBUs) fivefold (from 1280 to 6542 LBUs in T3) but did not affect units of enzymatic activity (UEA) against trypsin (from 60.8 to 51 UEA in T3). Results show that controlled mechanical foliar damage could be used to induce overexpression of lectins in the seeds of Tepary beans. Mechanical foliar damage reduced seed production (-14.6%: from 1890 g to 1615 g in T3) and did not significantly increase phenolic compound levels in leaves.

Hybridization between Crotalus aquilus and Crotalus polystictus Species: A Comparison of Their Venom Toxicity and Enzymatic Activities.

Hybridization is defined as the interbreeding of individuals from two populations distinguishable by one or more heritable characteristics. Snake hybridization represents an interesting opportunity to analyze variability and how genetics affect the venom components between parents and hybrids. Snake venoms exhibit a high degree of variability related to biological and biogeographical factors. The aim of this work is to analyze the protein patterns and enzymatic activity of some of the main hemotoxic enzymes in snake venoms, such as serine proteases (trypsin-like, chymotrypsin-like, and elastase-like), metalloproteases, hyaluronidases, and phospholipase A2. The lethal dose of 50 (LD50) of venom from the Crotalus aquilus (Cabf) and Crotalus polystictus (Cpbm) parents and their hybrids in captivity was determined, and phenetic analysis is also conducted, which showed a high similarity between the hybrids and C. polystictus. The protein banding patterns and enzymatic activity analyze by zymography resulted in a combination of proteins from the parental venoms in the hybrids, with variability among them. In some cases, the enzymatic activity is higher in the hybrids with a lower LD50 than in the parents, indicating higher toxicity. These data show the variability among snake venoms and suggest that hybridization is an important factor in changes in protein concentration, peptide variability, and enzymatic activity that affect toxicity and lethality.

Properties of a Non-canonical Complex Formed Between a Tepary Bean (Phaseolus acutifolius) Protease Inhibitor and α-Chymotrypsin.

Protease inhibitors are crucial for the control of proteolytic activity in different physiological processes. However, some inhibitors do not show canonical enzyme recognition of the enzyme under certain conditions. In this work, we present evidence that indicates the formation of an active complex between the protease bovine α-chymotrypsin and the Tepary bean protease inhibitor (TBPI). The composition of the active chymotrypsin-TBPI complex (AC) was confirmed by three different methods: size-exclusion chromatography, polyacrylamide gel electrophoresis (PAGE), and mass spectrometry. The kinetic parameters for the AC were similar to those of the enzyme alone, indicating that TBPI binding does not produce any large changes in chymotrypsin. The molecular model proposed here postulates that TBPI binds outside the active cleft of the protease, but near enough to hinder the binding of high molecular weight substrates into the active site. This model was experimentally supported by the inhibitory effect on casein as a substrate, and the unaltered protease activity when a small synthetic substrate was used. We also found that the formation of this complex provided the enzyme with extra stability in denaturing conditions or in the presence of a reducing agent. The chymotrypsin-TBPI complex exhibited higher stability, indicating that autolysis can be partially prevented. When the enzyme was first inactivated followed by the addition of the inhibitor, the activity of the protease was restored. We described a possible mechanism where a plant protease inhibitor binds outside the active site of the enzyme while increasing its stability.

Snake Venom Hemotoxic Enzymes: Biochemical Comparison between Crotalus Species from Central Mexico.

Snakebite envenoming is a serious medical problem in different areas of the world. In Latin America, the major prevalence is due to snakes of the family Viperidae, where rattlesnakes (Crotalus) are included. They produce hemotoxic venom which causes bleeding, tissue degradation and necrosis. Each venom has several enzymatic activities, producing different effects in the envenoming, doing its clinical effects difficult to study. Comparison between venom molecules is also difficult when different techniques are used, and therefore, their identification/characterization using the same methodology is necessary. In this work, a general biochemical characterization in snake venom of serine proteases (SVSP), phospholipases A2 (PLA2), metalloproteases (SVMP) and hyaluronidases (SVH) of Crotalus aquilus (Ca), Crotalus polystictus (Cp) and Crotalus molossus nigrescens (Cmn) was done. Differences in protein pattern, enzyme content and enzymatic activities were observed. All the venoms showed high PLA2 activity, high molecular weight SVSP, and a wide variety of SVMP and SVH forms. Ca and Cp showed the highest enzymatic activities of SVMP and SVSP trypsin-like and chymotrypsin-like, whereas Cmn showed the highest SVH and similar PLA2 activity with Ca. All the venoms showed peptides with similar molecular weight to crotamine-like myotoxins. No previous biochemical characterization of C. aquilus has been reported and there are no previous analyses that include these four protein families in these Crotalus venoms.