Pharmacokinetics and tissue distribution of Cistanche tubulosa stems in normal and depression comorbid with sexual dysfunction rats.

ETHNOPHARMACOLOGICAL RELEVANCE: Depression, a disorder with high global prevalence, is commonly complicated by sexual dysfunction. However, first-line clinical-antidepressants often induce sexual dysfunction, further complicating treatment outcomes. Our previous studies have demonstrated that Cistanche tubulosa aqueous extract (CTE) ameliorates depression comorbid with sexual dysfunction (DCSD). Nevertheless, the pharmacokinetics profiles and tissue distribution of CTE components under different physiological and pathological conditions remain unclear.

AIM OF THE STUDY: This study aimed to compare the pharmacokinetics and tissue distribution of 8 prototype constituents and 4 active metabolites of CTE in normal and DCSD rats, thereby clarifying the in vivo material basis for the therapeutic effects of CTE in treating DCSD.

MATERIALS AND METHOD: A validated ultra-high performance liquid chromatography coupled with triple quadrupole-linear ion trap mass spectrometry (UHPLC-QTRAP-MS/MS) method was employed to determine the dynamic concentrations of 8 prototypes and 4 metabolites in plasma and multiple tissues. Pharmacokinetics parameters and tissue distribution profiles of the major active components were then analyzed clarified and compared between normal and DCSD rats.

RESULTS: DCSD significantly altered the pharmacokinetic profile of CTE in rats. Compared with normal rats, DCSD rats exhibited higher Cmax and AUC of 2'- acetylverbsacoside, caffeic acid, 3,4-dihydroxyphenylpropionic acid, and 3-hydroxyphenylpropionic acid, with a significant increase in Cmax of geniposidic acid (P < 0.05). Shortened Tmax of tubuloside B and 2'-acetylverbsacoside (P < 0.05) indicated enhanced absorption of these compounds in DCSD rats. In contrast, tubuloside B, 3-hydroxyphenylpropionic acid, and hydroxytyrosol showed accelerated elimination in DCSD rats, as evidenced by shorter t1/2 (P < 0.05). DCSD promoted cerebral distribution of geniposidic acid and 8-epiloganic acid (elevated peak concentrations, P < 0.05), but inhibited the testicular accumulation of echinacoside, verbascoside, and isoverbascoside. Prostatic levels of caffeic acid and geniposidic acid were elevated in DCSD rats, and 2'-acetylverbsacoside was detected in the liver and cerebrum where it was undetectable in normal rats. Notably, the active metabolites including hydroxytyrosol and 3-hydroxyphenylpropionic acid maintained high concentrations in the penises of DCSD rats for up to 24 h, indicating strong penile affinity or targeting capacity. Among these, 3-hydroxyphenylpropionic acid exhibited high exposure levels in both groups. These findings first revealed that the disposition process of C. tubulosa was characterized by intestinal adsorption, hepatic metabolism, and subsequent reproductive system enrichment. As well, DCSD reshaped the multi-component exposure profiles in vivo following CTE treatment, characterized by increased accumulation of geniposidic acid, 8-epiloganic acid, 3-hydroxyphenylpropionic acid, hydroxytyrosol, and caffeic acid in the cerebrum-gonadal axis, potentially representing the direct effectors underlying the anti-DCSD effects of C. tubulosa.

CONCLUSION: This study systematically elucidates the in vivo processes of CTE under different physiological conditions, providing a critical foundation for understanding its mechanism of action and advancing its clinical translation.