Fernando Díaz de León-Sánchez

Prickly pear (Opuntia ficus-indica) fruits are recognized as valuable sources of bioactive compounds with potential health-promoting properties. However, the relationship between phytochemical composition and antidiabetic activity among different cultivars remains insufficiently characterized. This study evaluated the chemical composition, antioxidant capacity, and anti-hyperglycemic effects of juices obtained from three Mexican prickly pear cultivars (San Martín, Mandarina, and Vigor). Organic acids, sugars, total phenolic and total flavonoid content, betalains, and antioxidant capacity were determined using chromatographic and spectrophotometric methods. The antihyperglycemic activity of the juices was evaluated in healthy Wistar rats using oral glucose tolerance tests (OGTT), and the antidiabetic potential of the San Martín cultivar was assessed in a neonatal streptozotocin-induced type 2 diabetes (T2D) model. Ascorbic acid, oxalic acid, and malic acid were identified in all cultivars, with ascorbic acid being the predominant organic acid in San Martín and Mandarina cultivars juices. Mandarina cultivar exhibited the highest concentration of total phenolic compounds, whereas San Martín cultivar contained significantly greater levels of flavonoids and betalains. Antioxidant activity assessed by ABTS and FRAP assays confirmed the presence of highly active hydrophilic antioxidant compounds. Among the cultivars evaluated, only Mandarina and San Martín juices significantly attenuated postprandial hyperglycemia in healthy animals. Interestingly, freeze-drying abolished the antihyperglycemic effect of San Martín cultivar juice, suggesting degradation or modification of bioactive constituents during processing. In diabetic rats, sub-chronic administration of fresh San Martín cultivar juice significantly reduced blood glucose levels but failed to restore glucose tolerance. Altogether, these findings demonstrate that San Martín prickly pear cultivar juice represents a promising source of bioactive compounds with antihyperglycemic activity. The observed effects are likely associated with the synergistic action of flavonoids, betalains, phenolic compounds, and ascorbic acid. Further mechanistic studies and clinical investigations are warranted to elucidate the molecular pathways involved and evaluate its potential as a functional food for the management of T2D.

Background: Prediabetes and type 2 diabetes (T2D) are characterized by progressive impairment of glucose homeostasis. This study aimed to expand the phytochemical profile of freeze-dried Stenocereus stellatus (red tunillo) seeds and evaluate their antihyperglycemic activity in experimental models of prediabetes (PDB) and T2D. Results: Phytochemical screening and UPLC-QTOF-MSE revealed a chemically diverse profile. Six chromatographic features were putatively annotated on the basis of accurate mass, elemental composition, isotopic pattern, and high-energy data; the confidence of these annotations varied among features because authentic standards were not analyzed. Fourteen-day oral administration of freeze-dried seeds reduced blood glucose and improved glucose tolerance in prediabetic rats. In T2D rats, treatment reduced hyperglycemia and enhanced the glucose-lowering response to exogenous insulin, although the overall glucose excursion during the OGTT was not significantly improved. Methods: Female rats with PDB and male rats with T2D were fed freeze-dried S. stellatus seeds at 100 and 200 mg kg⁻¹, respectively, for 14 consecutive days. Conclusions: Freeze-dried S. stellatus seeds showed antihyperglycemic activity in both experimental models. Further quantitative, mechanistic, and long-term studies are required to define the contribution of individual metabolites and assess translational relevance.

Myocardial oxidative stress increases under conditions of hyperglycemia and ischemia/reperfusion (I/R) injury, leading to cellular damage. Inhibition of oxidative stress is involved in the cardioprotective effects of hydrogen sulfide (H₂S) during I/R and diabetes, and H₂S has the potential to protect the heart. However, the mechanism by which H₂S regulates the level of cardiac reactive oxygen species (ROS) during I/R and hyperglycemic conditions remains unclear. Therefore, the objective of this study was to evaluate the cytoprotective effect of H₂S in primary cardiomyocyte cultures subjected to hyperglycemia, hypoxia–reoxygenation (HR), or both conditions, by assessing the PPAR-α/Keap1/Nrf2/p47phox/NOX4/p-eNOS/CAT/SOD and the PPAR-γ/PGC-1α/AMPK/GLUT4 signaling pathways. Treatment with NaHS (100 μM) as an H₂S donor in cardiomyocytes subjected to hyperglycemia, HR, or a combination of both increased cell viability, total antioxidant capacity, and tetrahydrobiopterin (BH₄) concentrations, while reducing ROS production, malondialdehyde concentrations, 8-hydroxy-2′-deoxyguanosine, and dihydrobiopterin (BH₂) concentrations. Additionally, the H₂S donor treatment increased the expression and activity of PPAR-α, reversed the reduction in the expression of PPAR-γ, PGC-1α, AMPK, GLUT4, Nrf2, p-eNOS, SOD, and CAT, and decreased the expression of Keap1, p47phox and NOX4. Therefore, the treatment with the H₂S donor protects cardiomyocytes from damage caused by hyperglycemia, HR, or both conditions by reducing oxidative stress markers and improving antioxidant mechanisms, thereby increasing cell viability and “cardiomyocyte ultrastructure”.

Under conditions of hyperglycemia and ischemia/reperfusion (I/R) injury, myocardial oxidative stress increases, leading to cellular damage. Inhibition of oxidative stress has been reported to be involved in the cardioprotective effects of hydrogen sulfide (H2S) during I/R and diabetes. Recent studies have shown that H2S has the potential to protect the heart. However, the mechanism by which H2S regulates the level of cardiac reactive oxygen species (ROS) during I/R and hyperglycemic conditions remains unclear. Therefore, the objective of this study was to evaluate the cytoprotective effect of H2S in primary cardiomyocyte cultures subjected to hyperglycemia, hypoxia/reoxygenation (HR), or both conditions, by assessing the PPAR-α/Keap1/Nrf2/p47phox/NOX4/p-eNOS/CAT/SOD signaling pathway and the PPAR-γ/PGC1α/AMPK/GLUT4 signaling pathway. Treatment with NaHS (100 μM) as an H2S donor in cardiomyocytes subjected to hyperglycemia, HR, or a combination of both experimental conditions increased cell viability, total antioxidant capacity, and tetrahydrobiopterin (BH4) concentrations, while reducing ROS production, malondialdehyde concentrations, 8-hydroxy-2´-deoxyguanosine, and dihydrobiopterin (BH2) concentrations. Additionally, H2S donor treatment increased the expression and activity of PPAR-α, reversed the reduction in the expression of PPAR-γ, PGC1α, AMPK, GLUT4, Nrf2, p-eNOS, SOD and CAT, and decreased the expression of Keap1, p47phox y NOX4. Treatment with the H2S donor protects cardiomyocytes from damage caused by hyperglycemia, HR, or both conditions by reducing oxidative stress markers and improving antioxidant mechanisms, thereby increasing cell viability and cardiomyocyte ultrastructure.

Prediabetes is defined as a state of moderate hyperglycemia. Here, we used freeze-dried seeds of Stenocereus stellatus (white tunillo) as a possible therapeutic strategy for the treatment of prediabetes. In the aqueous extract of freeze-dried seeds of white tunillo, polyphenols were identified using the Folin–Ciocalteu technique, separated by UPLC and analyzed by infrared spectrophotometry. Five well-defined peaks with good resolution were observed in the chromatogram of the aqueous extract obtained by UPLC. Two of these peaks corresponded to polyphenols with similarity to quercetin and rutin. The subchronic oral administration of freeze-dried seeds of white tunillo for 14 days in a prediabetes model in female Wistar rats reversed hyperglycemia and glucose intolerance. Treatment with the freeze-dried seeds reversed the decrease in the hepatic expression of Akt, eNOS, and p-eNOSSer¹¹⁷⁷ but did not reverse the decrease in MnSOD, catalase, and GPx1. No changes in the expression of GPx4 and p-AktSer⁴⁷³ were observed in the pathological state or with the treatment but there was an increase in the expression and activity of eNOS. The bioactive compounds present in the freeze-dried seeds of Stenocereus stellatus could provide guidelines for studying the mechanisms of action through which they reverse signs of prediabetes.

Lychee is a fruit of Asian origin with an exquisite flavor and an attractive reddish color. However, according to recent reports, the consumption of this fruit reduces the levels of blood glucose with adverse effects on human health such as encephalopathy and hypoglycemic. The objective of this work was to determine if the peel, pulp, and seed of “Brewster” lychee fruits harvested at two stages of maturity had antihyperglycemic effect. This effect was determined by an oral glucose tolerance test using Wistar rats. In addition, ultraviolet-visible spectrophotometry and high-resolution liquid chromatography were used to quantify phenolic compounds, flavonoids, organic acids (OAs), sugars, and antioxidant activity. Results indicated that stage I pulp (immature fruits) and stage II peel and seed (export mature fruits) reduced blood glucose levels, and the effects of the former two were synergistic with metformin. The pulp of mature fruits (stage II), however, lacked a hypoglycemic effect. Additionally, the peel and the seeds of these fruits presented a high antioxidant activity (as determined by DPPH [2,2-diphenyl-2-picryl-hydracyl] and ABTS ⁺ [2,2-azino-bis-(3-ethylbenzothiazoline)-6-sulfonic acid] methods), which correlated well with the total content of phenolic compounds. The highest content of polyphenolics, flavonoids, and OAs was found in the extracts of the peel and seeds of both stages of maturity. It was therefore concluded that “Brewster” mature lychees are safe for human consumption, and both the seed and the peel can be useful sources for obtaining new compounds with antihyperglycemic activity.

Mexico is the fifth largest producer of fresh oranges in the world, and Tepalcingo in Morelos has recently become an important area of cultivation for cv Valencia. The objectives of this work were to assess fruit quality in the oranges from this region, and to determine their commercial life during storage. Significant differences occurred in the juice volume of fruits during all three seasons evaluated; however, no differences were detected in their weight, size, shape, rind thickness, or flavedo color (L*, C*, h). TSS/TA (total soluble solids/titratable acidity) ratios were high (10.3-12.9) in fruits collected during spring and summer. Overall, the oranges met the specifications of both national and international quality standards. Changes during storage indicated that compression force, % weight loss, and sensorial flavor were negatively impacted by storage at 24⁰C while TSS and TA of juice remained unaffected at 11 and 24 ⁰C. The commercial life of oranges was 21 d at 24 ⁰C and > 28 d at 11 ⁰C as determined from changes in the concentrations of certain aroma compounds and from differences in the firmness of their rinds. Such changes correlate well with both weight loss and the sensorial perception of quality attributes. México es el quinto productor de naranjas en el mundo y Tepalcingo en Morelos es considerado como una importante área de cutlivo. El objetivo de este trabajo fue medir la calidad de las naranjas cv Valencia de esta región y determinar la vida comercial durante el almacenamiento. En las tres temporadas de cosecha evaluadas se observaron diferencias significativas en las variables: peso, tamaño, forma, grosor de la cáscara y color del flavedo (L*, C*, h). El cociente SST/AT (sólidos solubles totales/acidez titulable) fue mayor (10.3-12.9)en las cosechas de primavera y verano. Se observó que las naranjas cumplen con las especifícaciones de calidad nacionales e internacionales. El almacenamieto de las naranjas a 24ºC tuvo efecto sobre la firmeza, la pérdida de peso y el sabor, mientras que los SST y la AT del jugo no se vieron afectados durante el almacenamiento a 11 y 24ºC. La vida comercial de las naranjas fue de 21 d a 24°C y >28 d a 11°C, según lo determinan los cambios en las concentraciones de ciertos compuestos aromáticos y la firmeza de sus cáscaras. Dichos cambios se correlacionan bien con la pérdida de peso y la percepción sensorial de los atributos de calidad.

The purpose of this study was to identify visible and microscopic symptoms as well as certain biochemical changes associated with chilling injury (CI) in “Atlixco” cactus stems. Cladodes were harvested, disinfected, minimally processed and stored at 4, 12 and 26C for 14–21 days. Results indicated that cactus stems were sensitive to CI at 4 and 12C and exhibited pitting and bronzing as visible symptoms of this disorder. Confocal microscopy showed that mitochondrial integrity was maintained at 4C whereas a deterioration of these organelles occurred at 12 and 26C. Electrolyte leakage, together with an increase in the levels of Adenosine triphosphate (ATP), glutathione and the reduced form of ascorbic acid were associated with CI. In spite of the presence of CI at 4C, cactus stems were still able to preserve their taste quality and no adverse effects were observed on either firmness or color for 21 days. Practical Applications Minimally processed products should be refrigerated at ≤4C in order to maintain their quality and prevent the growth of harmful microorganisms. However, the refrigeration of cactus stems at suboptimal temperatures causes the appearance of chilling injury (CI). Previous studies have mentioned the general symptoms of this physiological disorder in cactus stems, but no one has described the symptomatology in detail and there is yet to be reported histological and biochemical characterization that might serve to confirm or diagnose its presence. This study describes the symptoms of CI and provides histological and biochemical indicators for its early identification during storage. It also constitutes the preliminary stage to the future application of postharvest technologies that induce tolerance to CI, preventing browning and preserving the quality of minimally processed cactus stems in order to expand their domestic and international markets.