The aim of this work was to evaluate the vasorelaxant and antihypertensive effects of a standardized precipitate of the hydroalcoholic extract from Agastache mexicana (PPAm), comprising ursolic acid, oleanolic acid, acacetin, luteolin and tilianin, among others. In the ex vivo experiments, preincubation with L-NAME (nonspecific inhibitor of nitric oxide synthases) reduced the relaxation induced by PPAm; nevertheless, preincubation with indomethacin (nonspecific inhibitor of cyclooxygenases) did not generate any change in the vasorelaxation, and an opposed effect was observed to the contraction generated by CaCl₂ addition. Oral administration of 100 mg/kg of PPAm induced a significant acute decrease in diastolic (DBP) and systolic (SBP) blood pressure in spontaneously hypertensive rats, without changes in heart rate. Additionally, PPAm showed a sustained antihypertensive subacute effect on both DBP and SBP for 10 days compared to the control group. On the other hand, human umbilical vein cells treated with 10 µg/mL of PPAm showed a significant reduction (p < 0.05) in intracellular adhesion molecule-1, compared to the control, but not on vascular cell adhesion molecule-1. In conclusion, PPAm induces a significant antihypertensive effect in acute- and subacute-period treatments, due to its direct vasorelaxant action on rat aortic rings through NO production and Ca²⁺ channel blockade.

Background: Casimiroa edulis La Llave (Rutaceae), commonly known as “zapote blanco”, is a tree widely distributed in the tropical and subtropical areas of Mexico. The decoction of its leaves is traditionally used as a natural remedy to treat hypertension and anxiety. Objective: The present study aimed to determine the vasorelaxant and antihypertensive effects of C. edulis extracts and evaluate the acute and sub-acute toxicity of one of the most active extracts. Methods: The hydro-alcohol and organic (hexane, dichloromethane, and methanol) extracts, obtained from the leaves of C. edulis, were evaluated on isolated aorta rat rings in the presence and absence of endothelium to determine their vasorelaxant effect. Then, most active extracts were studied to evaluate the functional mechanism of their vasorelaxant action and antihypertensive effect on spontaneously hypertensive rats (SHR). The acute and sub-acute toxicity of dichloromethane extract was evaluated following the OECD 423 and 407 protocols. Results: The hexane (HE) and dichloromethane (DE) extracts from Casimiroa edulis induced significant vasorelaxant action on isolated rat aortic rings with (Emax 104.7 ± 1.4% and Emax 97.3 ± 6.7%, respectively) and without (Emax 94.9 ± 3.5% and Emax 67.4 ± 1.0%, respectively) endothelium, and this effect was partially endothelium-dependent. Their vasorelaxant action was modified by L-NAME (nitric oxide synthase inhibitor) and ODQ (soluble guanylyl cyclase inhibitor); however, indomethacin did not modify the effect. Also, both HE and DE significantly decreased the contraction induced by KCl in a concentration-dependent manner and the maximal effect induced by CaCl2. Moreover, DE showed a significant decrease in systolic and diastolic blood pressure in SHR at 7 hours and 15 days after treatment, respectively. Finally, the toxicity test of DE allowed classifying it in category 5, indicating it to be a non-toxic extract based on OECD guideline 423; the LD50 value was estimated to be greater than 2,000 mg/Kg and smaller than 5,000 mg/Kg in Wistar rats. Conclusion: The results demonstrated hexane and dichloromethane extracts to exert a vasorelaxant effect through endothelium-dependent NO release and cGMP increase, as well as by calcium channel blockade. Also, dichloromethane extract showed efficacy and security as a potential antihypertensive agent.

Objective: The aim of this study was to determine the vasorelaxant effect of semisynthetic derivatives of ursolic acid, establish the mode of action, and determine the antihypertensive effect of the most active compound.Methods: Isolated aorta rat rings (ex vivo assay), with and without endothelium, were used to determine the vasorelaxant effect of seven semisynthetic derivatives of ursolic acid (UA-01 to UA-07). Then, the effect of the most active compound was studied in ex vivo assay using L-NAME, ODQ and indomethacin to determine its mode action. Finally, the in vivo cardiovascular effect and molecular docking of the most active compound were determined.Results: UA-07 was the most potent compound of the derivatives, since UA-07 induced significant relaxant effect in concentration- and endothelium-dependent manners (Emax = 79.09% and EC50 = 110 μM) on aortic rat rings pre-contracted with noradrenaline (NA, 0.1 μM). Also, endothelium-derived nitric oxide seems to be involved in the mechanism of action of UA-07, because pre-incubation with L-NAME (a NOS inhibitor) and ODQ (a soluble guanylate cyclase inhibitor) significantly reduced its vasorelaxant effect. Further, UA-07 showed a similar binding affinity as ursolic acid on eNOS C1 binding pocket in in silico studies. Finally, treatment with UA-07 (50 mg/Kg) on spontaneously hypertensive rats (SHR) significantly decreased diastolic blood pressure for seven hours.Conclusion: These results demonstrate the significant antihypertensive effect of UA-07, possibly through the NO/cGMP system.

Background: Mexico, one of the world’s most biodiverse countries, holds a rich tradition of using medicinal plants to manage chronic diseases such as type 2 diabetes and hypertension. Despite their historical significance, the scientific validation of these plants’ mechanisms and safety remains limited. Natural products have shown potential in improving insulin sensitivity, reducing insulin resistance, and promoting vasodilation. Prostachea livida (Lindl.) W.E.Higgins, a native orchid, is believed to possess therapeutic properties, yet its pharmacological effects are unexplored. Objective: The current investigation is aimed to bridge traditional knowledge and scientific evidence by investigating the antidiabetic, vasodilatory and antihypertensive activities of a 1:1 dichloromethane and methanol extract from Prosthechea livida bulbs, alongside an evaluation of its pharmacological safety. Methods: Antidiabetic effects of the extract were evaluated in a non-insulin-dependent mouse model using a 100 mg/kg dose. Vasodilatory activity was assessed ex vivo using rat aortic rings, exploring its mechanism through calcium channel blockade. Antihypertensive effects were evaluated in spontaneously hypertensive rats, while acute and subacute toxicity tests were conducted in a murine model. Results: The extract significantly reduced glycemia between 1, 3, 5, and 7 h compared to the positive control (* p = 0.04, *** p < 0.001) and induced vasorelaxation but showed no antihypertensive effects in vivo. Toxicity tests indicated no severe damage, though elevated transaminase activity and increased liver weight were observed. Histopathological analysis revealed minimal hepatocellular lesions with active regeneration. Conclusions: Prosthechea livida demonstrates potential in the discovery of active metabolites to treat diabetes, with significant hypoglycemic and vasorelaxant effects and promising pharmacological safety. Further research is needed to fully understand its therapeutic applications and ensure its safe integration.

Background/Objectives: Achillea millefolium is a well-known plant used in traditional medicine for the treatment of inflammation, gastrointestinal disorders, respiratory diseases, hypertension, and diabetes, among others. These effects are attributed to the metabolite content of flavonoids and terpenes such as achillin (1) and leucodin (2). Thus, the current investigation aims to standardize the extracts from A. millefollium based on the presence of 1 and 2 and relate them to their relaxant effect in ex vivo assays. Methods: A validated High-Performance Liquid Chromatography (HPLC) method was used to determine the concentration of the main compounds, employing standard molecules previously isolated from the same species and characterized by nuclear magnetic resonance (NMR) and X-ray diffraction. Also, the relaxant effects of both compounds and their combinations were assayed on aortic and tracheal rat rings in an organ bath. Results: Compounds (1) and (2) are the main compounds in hexane, dichloromethane, and hydroalcoholic extracts, present in different proportions. The relaxant effects in ex vivo models of the aorta and trachea showed that the sesquiterpene lactones achillin (1) [Trachea, maximum effect (Emax): 67.67 ± 5.01%, medium effective concentration (EC50): 304.44 ± 2.61 µM; Aorta: Emax: 63.94 ± 6.28%, EC50: 225.73 ± 4.49 µM)] and leucodin (2) (Trachea: Emax: 76.71 ± 4.73%, EC50: 266.40 ± 2.05 µM; Aorta, Emax: 72.96 ± 1.73%, EC50: 163.29 ± 2.99 µM) are responsible for the relaxant effects shown by the extracts. The observed effect is proportional to the concentration of these molecules, with hexane extracts being more active. Additionally, we demonstrate the safety of molecules 1 and 2 through toxicological studies recommended by the OECD. Conclusions: The isolated compounds achillin and leucodin are the primary constituents in the flowers of A. millefolium, with higher concentrations found in hexane extracts, particularly of achillin, which shows a correlation of 2.33 with respect to leucodin. This correlation is closely related to their relaxant effect, as these compounds are the main contributors to the relaxant response in the trachea and aorta, being more effective when used together.