Hydroxycitric acid inhibits ferroptosis and ameliorates benign prostatic hyperplasia by upregulating the Nrf2/GPX4 pathway

PURPOSE

Benign prostatic hyperplasia (BPH) poses a significant public health challenge, affecting a substantial portion of aging men worldwide. Current therapeutic options offer limited efficacy. The pathogenesis of BPH is multifactorial, involving ferroptosis, oxidative stress, and chronic inflammation. Hydroxycitric acid (HCA) is a natural compound with diverse pharmacological activities, including the inhibition of ferroptosis, anti-inflammatory, anti-oxidative stress, and anti-tumor effects. However, its role in BPH remains unexplored. This study aimed to investigate the effects of HCA on BPH and elucidate the underlying mechanisms, with the goal of providing novel therapeutic insights for BPH treatment.

METHODS

C57BL/6J mice were used to establish a BPH model induced by testosterone propionate (TP). Animals were then randomly assigned to the following groups: Sham, BPH, BPH + Lip-1, BPH + Bru, BPH + HCA + Bru, and BPH + HCA. Prostate index (PI) was determined, and histopathological changes were evaluated by hematoxylin and eosin (HE) staining. Mitochondrial morphology was analyzed by TEM. The levels of Fe2+, MDA, and GSH in prostate tissues were measured. Western blot analysis was performed to assess the protein expression of Nrf2 and GPX4.

RESULTS

Compared to the Sham group, the prostate tissues of the BPH group exhibited typical histopathological features of hyperplasia, including epithelial cell proliferation, increased glandular lumen size. Concurrently, the levels of ferroptosis markers Fe2+ (P < 0.01) and MDA (P < 0.001) were significantly elevated, while the expression of GSH (P < 0.01) and GPX4 (P < 0.05) was downregulated. Furthermore, mitochondrial morphology showed abnormalities. HCA treatment significantly reduced PI (P < 0.01) and attenuated epithelial cell proliferation and glandular lumen enlargement (P < 0.01, P < 0.001, respectively). HCA also reduced the levels of Fe2+ (P < 0.05) and MDA (P < 0.05), and elevated GSH levels (P < 0.01). Furthermore, HCA upregulated the expression of Nrf2 (P < 0.01) and GPX4 (P < 0.01). The Nrf2 inhibitor Brusatol increased the levels of Fe2+ (P < 0.05) and MDA (P < 0.05), and downregulated the expression of Nrf2 (P < 0.05) and GPX4 (P < 0.05), thereby attenuating the protective effects of HCA. However, co-administration of HCA and Brusatol partially reversed changes in Fe2+ (P < 0.05) and MDA (P < 0.05) levels, and increased the expression of Nrf2 (P < 0.05) and GPX4 (P < 0.05), indicating reduction in Brusatol-induced effects. Furthermore, HCA treatment did not significantly affect liver and kidney function markers (AST, ALT, SCR, and UR) (P > 0.05).

CONCLUSION

HCA inhibits ferroptosis by activating the Nrf2/GPX4 pathway, thereby ameliorating the pathological changes in BPH induced by TP. This study suggests a novel therapeutic strategy for BPH.

Caloric Restriction Mimetics in Nutrition and Clinical Trials

The human diet and dietary patterns are closely linked to the health status. High-calorie Western-style diets have increasingly come under scrutiny as their caloric load and composition contribute to the development of non-communicable diseases, such as diabetes, cancer, obesity, and cardiovascular disorders. On the other hand, calorie-reduced and health-promoting diets have shown promising results in maintaining health and reducing disease burden throughout aging. More recently, pharmacological Caloric Restriction Mimetics (CRMs) have gained interest of the public and scientific community as promising candidates that mimic some of the myriad of effects induced by caloric restriction. Importantly, many of the CRM candidates activate autophagy, prolong life- and healthspan in model organisms and ameliorate diverse disease symptoms without the need to cut calories. Among others, glycolytic inhibitors (e.g., D-allulose, D-glucosamine), hydroxycitric acid, NAD+ precursors, polyamines (e.g., spermidine), polyphenols (e.g., resveratrol, dimethoxychalcones, curcumin, EGCG, quercetin) and salicylic acid qualify as CRM candidates, which are naturally available via foods and beverages. However, it is yet unclear how these bioactive substances contribute to the benefits of healthy diets. In this review, we thus discuss dietary sources, availability and intake levels of dietary CRMs. Finally, since translational research on CRMs has entered the clinical stage, we provide a summary of their effects in clinical trials.

Hydroxycitric acid does not promote inflammation or liver toxicity

Garcinia cambogia extract (GC) with its active component consisting of hydroxycitric acid (HCA) is widely utilized for weight loss. Various HCA salts are available, including calcium, magnesium, potassium and mixtures of these. Experimentally, these salts exhibit different properties with some, but not all, improving glucose tolerance and blood pressure. Recently, obesity-prone C57BL/6J mice were fed a high-fat diet (HFD, 45 kcal% fat) with or without GC (1%, w/w) for 16 wk. The active arm reduced visceral fat, adipocyte size and serum glucose, yet purportedly also exhibited hepatic collagen accumulation, lipid peroxidation and increased mRNA levels of genes related to oxidative stress. The latter findings are at odds with a large body of animal and human studies that have been conducted on the safety and efficacy of HCA. This literature shows HCA to be protective against the liver toxicity associated with ethanol and dexamethasone administration, and to maintain serum aspartate aminotransferase, alanine aminotransferase and alkaline phosphatase at near normal levels. In both animal and clinical literature, elevated intakes of HCA per se have not led to signs of inflammation or hepatotoxicity. The compound has been found to reduce markers of inflammation in brain, intestines, kidney and serum.