Tetrandrine inhibits aldosterone synthesis by covalently targeting CYP11A1 to attenuate hypertension.

Introduction: Tetrandrine (Tet) is the main pharmacological component of Stephania tetrandra S. Moore, which is a well-documented traditional Chinese medicine known for its diuretic and antihypertensive properties. Unraveling the specific targets and mechanisms of Tet involved in inducing diuresis and mitigating hypertension can provide valuable insights into its therapeutic effects. This study aimed to explore the diuretic and antihypertensive targets and mechanisms of Tet using chemical biology coupled with activity analyses in vivo and in vitro. Methods: The diuretic effects of Tet were evaluated using a water-loaded mouse model. The direct target proteins for the diuretic and antihypertensive effects of Tet were determined using chemical biology. Furthermore, the molecular mechanism of Tet binding to target proteins was analyzed using a multidisciplinary approach based on the structure and function of the proteins. Finally, the effects of the Tet-targeted protein on downstream signaling pathways and blood pressure were evaluated in hypertensive model rats. Results: Tet exhibited significant antihypertensive and potassium-preserving diuretic effects. The mechanism underlying these effects involves the modulation of the enzyme activity by covalent binding of Tet to Cys423 of CYP11A1. This interaction alters the stability of heme within CYP11A1, subsequently impeding electron transfer and inhibiting aldosterone biosynthesis. Discussion: This study not only revealed the mechanism of the diuretic and antihypertensive effects of Tet but also discovered a novel covalent inhibitor of CYP11A1. These findings contribute significantly to our understanding of the therapeutic potential of Tet and provide a foundation for future research in the development of targeted treatments for hypertension.

Sinapine targeting PLCß3 EF hands disrupts Gαq-PLCß3 interaction and ameliorates cardiovascular diseases.

BACKGROUND: The renin-angiotensin-aldosterone system (RAAS) over-activation is highly involved in cardiovascular diseases (CVDs), with the Gαq-PLCß3 axis acting as a core node of RAAS. PLCß3 is a potential target of CVDs, and the lack of inhibitors has limited its drug development. PURPOSE: Sinapine (SP) is a potential leading compound for treating CVDs. Thus, we aimed to elucidate the regulation of SP towards the Gαq-PLCß3 axis and its molecular mechanism. STUDY DESIGN: Aldosteronism and hypertension animal models were employed to investigate SP's inhibitory effect on the abnormal activation of the RAAS through the Gαq-PLCß3 axis. We used chemical biology methods to identify potential targets and elucidate the underlying molecular mechanisms. METHODS: The effects of SP on aldosteronism and hypertension were evaluated using an established animal model in our laboratory. Target identification and underlying molecular mechanism research were performed using activity-based protein profiling with a bio-orthogonal click chemistry reaction and other biochemical methods. RESULTS: SP alleviated aldosteronism and hypertension in animal models by targeting PLCß3. The underlying mechanism for blocking the Gαq-PLCß3 interaction involves targeting the EF hands through the Asn-260 amino acid residue. SP regulated the Gαq-PLCß3 axis more precisely than the Gαq-GEFT or Gαq-PKCζ axis in the cardiovascular system. CONCLUSION: SP alleviated RAAS over-activation via Gαq-PLCß3 interaction blockade by targeting the PLCß3 EF hands domain, which provided a novel PLC inhibitor for treating CVDs. Unlike selective Gαq inhibitors, SP reduced the risk of side effects compared to Gαq inhibitors in treating CVDs.

Ursolic acid alleviates tetrandrine-induced hepatotoxicity by competitively binding to the substrate-binding site of glutathione S-transferases.

BACKGROUND: Tetrandrine (TET), a bisbenzylisoquinoline alkaloid isolated from Stephania tetrandra S. Moore, is the only approved medicine in China for silicosis. However, TET-induced hepatotoxicity has raised safety concerns. The underlying toxic targets and mechanism induced by TET remain unclear; there are no targeted detoxification strategies developed for TET-induced hepatotoxicity. Ursolic acid (UA), a pentacyclic triterpene with liver protective effects, may have detoxification effects on TET-induced hepatotoxicity. PURPOSE: This study aims to explore toxic targets and mechanism of TET and present UA as a potential targeted therapy for alleviating TET-induced hepatotoxicity. METHODS: A TET-induced liver-injury model was established to evaluate TET toxicity and the potential UA detoxification effect. Alkenyl-modified TET and UA probes were designed to identify potential liver targets. Pharmacological and molecular biology methods were used to explore the underlying toxicity/detoxification mechanism. RESULTS: TET induced liver injury by covalently binding to the substrate-binding pocket (H-site) of glutathione S-transferases (GSTs) and inhibiting GST activity. The covalent binding led to toxic metabolite accumulation and caused redox imbalance and liver injury. UA protected the liver from TET-induced damage by competitively binding to the GST H-site. CONCLUSION: The mechanism of TET-induced hepatotoxicity is related to irreversible binding with the GST H-site and GST-activity inhibition. UA, a natural antidote, competed with TET on H-site binding and reversed the redox imbalance. This study revealed the hepatotoxic mechanism of TET and provided a targeted detoxifying agent, UA, to alleviate hepatotoxicity caused by GST inhibition.

Atractylenolide-I covalently binds to CYP11B2, selectively inhibits aldosterone synthesis, and improves hyperaldosteronism.

Hyperaldosteronism is a common disease that is closely related to endocrine hypertension and other cardiovascular diseases. Cytochrome P450 11B2 (CYP11B2), an important enzyme in aldosterone (ALD) synthesis, is a promising target for the treatment of hyperaldosteronism. However, selective inhibitors targeting CYP11B2 are still lacking due to the high similarity with CYP11B1. In this study, atractylenolide-I (AT-I) was found to significantly reduce the production of ALD but had no effect on cortisol synthesis, which is catalyzed by CYP11B1. Chemical biology studies revealed that due to the presence of Ala320, AT-I is selectively bound to the catalytic pocket of CYP11B2, and the C8/C9 double bond of AT-I can be epoxidized, which then undergoes nucleophilic addition with the sulfhydryl group of Cys450 in CYP11B2. The covalent binding of AT-I disrupts the interaction between heme and CYP11B2 and inactivates CYP11B2, leading to the suppression of ALD synthesis; AT-I shows a significant therapeutic effect for improving hyperaldosteronism.

Sinigrin Enhanced Antiasthmatic Effects of Beta Adrenergic Receptors Agonists by Regulating cAMP-Mediated Pathways.

Millions of patients suffer from asthma worldwide. However, the first-line drugs used to treat asthma, namely, the beta-adrenergic receptors agonists (ß-agonists), are not recommended for use as monotherapy because of their severe dose-related side effects. This limitation has prompted the search for new therapies, which can be used in conjunction with ß--agonists so that lower doses can be administered. Sinigrin is a major compound found in many antiasthmatic medicinal plants. In this study, we explored the antiasthmatic activity of sinigrin when used in combination with ß-agonists and its underlying mechanism. Sinigrin enhanced the asthma-relieving effects of isoproterenol and reduced the effective isoproterenol dose in an acute-asthma model in guinea pigs. Mechanistically, sinigrin enhanced the cAMP levels induced by ß-agonists by inhibiting PDE4. The resulting increase in cAMP levels stimulated the activity of the downstream effector protein kinase A, which would be expected to ultimately induce the relaxation of airway smooth muscle. In conclusion, sinigrin enhances the asthma-relieving effects of ß-agonists by regulating the cAMP signaling pathway and represents a potential add-on drug to ß-agonists for the treatment of asthma.

Lepidiline A Improves the Balance of Endogenous Sex Hormones and Increases Fecundity by Targeting HSD17B1.

SCOPE: Maca (Lepidium meyenii), a well-known plant from the Andean highlands of Peru, has been used widely as a nutritional supplement to increase sexual function and fecundity. However, the identity of its active ingredients and how they function remain unknown. METHODS AND RESULTS: Chemical substances in maca are identified by UPLC-Q-TOF, and the active ingredients are screened through HotMap coupled with an artificial neural network. Lepidiline A (LA), an imidazole alkaloid, is identified as the key active compound. LA affects the balance of endogenous sex hormones in mice and improves fecundity in Drosophila. Using a molecular LA probe, 17ß-hydroxysteroid dehydrogenase type 1 (HSD17B1) is revealed to be the potential target of LA using a fishing-rod strategy. It is demonstrated with experimental data that LA targets HSD17B1 to enhance the enzyme's activity and increases its bioconversion efficiency of actively formed sex hormones including estrogen to 17ß-estradiol and 4-androsten-3,7-dione to testosterone, which ultimately improves reproductive activity. CONCLUSION: LA improves the balance of endogenous sex hormones and increases fecundity by targeting HSD17B1. This underlying mechanism of action provides a useful insight into the application of maca in the regulation of dietary nutrition and healthy fertility.