Biomolecules

Cardiolipin (CL), a unique dimeric phospholipid predominantly enriched in the inner mitochondrial membrane, is a crucial determinant of mitochondrial structure and function. Its content, fatty acyl composition, and oxidation state are associated with mitochondrial bioenergetics, dynamics, and cellular signaling. Disruptions in CL metabolism are increasingly implicated in the pathogenesis of various central nervous system (CNS) disorders, including Alzheimer’s disease, Parkinson’s disease, amyotrophic lateral sclerosis, epilepsy, and traumatic brain injury. This narrative review summarizes recent advances in the analytical techniques employed for CL analysis. The principles and applications of mass spectrometry-based platforms, nuclear magnetic resonance, Fourier-transform infrared spectroscopy, atomic force microscopy-infrared spectroscopy, and fluorescent probes were discussed, with an emphasis on their strengths in revealing the structure, composition, dynamics, and spatial distribution of CL. Furthermore, the evidence of CL abnormalities in various CNS disorders was assessed, often showing decreased CL levels, loss of polyunsaturated species, and increased oxidation associated with mitochondrial dysfunction and neuronal apoptosis. Furthermore, the nutritional interventions for CL modulation were discussed, such as polyunsaturated fatty acids, polyphenols, carotenoids, retinoids, alkaloids, and triterpenoids, which summarize their potential health-beneficial effects in remodeling the CL acyl chain, preventing oxidation, and regulating mitochondrial homeostasis. Overall, this review provided insight into integrating CL analysis and dietary modulation in understanding CL-related pathologies in CNS disorders.

Treatment-resistant depression (TRD) is a subtype of major depressive disorder (MDD) that fails to respond to first-line pharmacotherapy. This cross-sectional study compared blood concentrations of folic acid, vitamin B12, and homocysteine between female depressed patients with or without TRD, and examined the association of these parameters with the severity of depression. It included 116 female patients treated for MDD, of whom 59 (51%) developed TRD. The diagnosis of MDD was established via a structured clinical interview, while the severity of depression was measured with the Montgomery–Asberg Depression Rating Scale. Blood samples were taken at the initial psychiatric examination to determine the serum levels of folic acid and vitamin B12 and plasma levels of homocysteine. Folic acid levels were significantly lower in the female TRD group (p < 0.001), whereas homocysteine levels were significantly higher in the female TRD group (p < 0.001), compared to the female depressed group without TRD. In the regression analyses, higher levels of homocysteine (p < 0.001) were associated with TRD, while lower levels of folic acid (p = 0.036) were related to higher severity of depression, independently of sociodemographic and clinical parameters. Our findings showed that folate correlated with symptom severity, while homocysteine correlated with the TRD status in female MDD patients.

α-L-Rhamnosidase can specifically hydrolyze plant natural glycosides and holds significant potential for biocatalytic applications in functional foods, healthy products, and pharmaceutical industries. Herein, a novel thermophilic and acidophilic α-L-rhamnosidase TsRha from Thermotoga sp. 2812B belonging to glycoside hydrolase family 78 was identified by genome mining and comprehensively characterized by bioinformatics, computer-aided structural analysis, and biochemical characterization. TsRha possesses a domain architecture comprising one catalytic (α/α)₆-barrel domain and four β-sheet domains. TsRha displayed optimal activity at 90 °C and pH 5.0, remarkable thermostability at 80 °C, and considerable tolerance to organic solvents. TsRha exhibited broad substrate selectivity and might efficiently hydrolyze a series of natural flavonoid glycosides with various glycosidic bonds (α-1, α-1, 2, α-1, 6) from different aglycone subgroups (flavanone, flavone, flavonol, and dihydrochalcone). Moreover, it demonstrated high conversion efficiencies toward a variety of natural flavonoid diglycosides rutin, naringin, naringin dihydrochalcone, hesperidin, and troxerutin, achieving ≥99.1% conversion within 20~100 min. The excellent properties including high activity, thermophilicity, acidophilicity, good thermostability, broad substrate spectrum will make the α-L-rhamnosidase TsRha a promising biocatalyst for the efficient production of rare and high-value flavonoid glucosides with improved bioavailability and bioactivity.