Enhancing the potency of lithospermate B for inhibiting Na+/K+-ATPase activity by forming transition metal ion complexes

Therapeutic Effects of Lithospermate B Complexed with Mg2+ or Zn2+ on Metabolic Syndrome Induced in Rats Fed with High-Fat Diet

Excessive food consumption and insufficient exercise lead to the prevalence of metabolic syndrome in modern life, which consequently increases the risk of many chronic diseases. Magnesium lithospermate B (MLB) from Danshen has been demonstrated to improve metabolic changes in high-fat diet–fed rats with metabolic syndrome. In this study, Mg²⁺ in MLB was successfully replaced with Zn²⁺ to form zinc lithospermate B (ZLB) complex. MLB (10 mg/kg /day) and ZLB of various concentrations (1, 2.5, 5, and 10 mg/kg/day) were prepared and examined for their therapeutic effects on metabolic syndrome induced in rats fed with a high-fat diet. The results showed that both MLB and ZLB were able to recover or alleviate the abnormal physiological states of high-fat diet–fed rats including weight gain, epididymal fat accumulation, fatty liver, retarded blood lipid and glucose metabolism putatively caused by insulin resistance, and elevated levels of proinflammatory cytokine, leptin, and oxidative stress. In an overall view of the animal study, the effectiveness of ZLB supplementation seemed to be better than that of MLB supplementation for the recovery of high-fat-fed rats from metabolic syndrome.

Development of Indirect Competitive ELISA for Lithospermic Acid B of Salvia miltiorrhiza with Its Specific Antibodies Generated via Artificial Oil Bodies

Lithospermic acid B (LSB), the major water-soluble ingredient of Salvia miltiorrhiza (Danshen), has been shown to be an active ingredient responsible for the therapeutic effects of this traditional Chinese herb used to treat cardiac disorders. This study aimed to develop an indirect competitive enzyme linked immunosorbent assay (ELISA) for the detection of LSB. Firstly, LSB was chemically conjugated to a modified oil-body protein, lysine-enriched caleosin, recombinantly expressed in Escherichia coli. Antibodies against LSB (Ab-LSB) were successfully generated by immunizing hens with artificial oil bodies constituted with the LSB-conjugated caleosin. Western blotting showed that Ab-LSB specifically recognized LSB, but not the carrier protein, lysine-enriched caleosin. To detect LSB via indirect competitive ELISA, LSB was conjugated with bovine serum albumin (LSB-BSA) and coated on a microplate. The binding between Ab-LSB and LSB-BSA on the microplate was competed dose-dependently in the presence of free LSB with a concentration ranging from 5 to 5 × 10⁴ ng/mL. The IC₅₀ value was approximately determined to be 120 ng/mL for LSB regardless of its complex with a metal ion of Na⁺, K⁺ or Mg²⁺.

Characterization of Vasorelaxant Principles from the Needles of Pinus morrisonicola Hayata

Pinus morrisonicola Hayata, usually called Taiwan five-leaf pine (5LP), is an endemic species in Taiwan and is traditionally used to relieve hypertension symptoms and improve cardiovascular function. In this study, the needle extract of 5LP was fractionated and analyzed by LC/MS/MS to search for possible antihypertensive candidates. In addition, bioassay-guided purification of the bioactive components was performed by Ca²⁺ fluorescent signal (Fluo 4-AM) assays. Two dihydrobenzofuran lignans, pinumorrisonide A (1) and icariside E4 (2), and one acylated flavonoid glycoside, kaempferol 3-O-α-(6‴-p-coumaroylglucosyl-β-1,4-rhamnoside) (3) were characterized from the active fractions. The structure of a new compound 1 was established on the basis of 2D NMR spectroscopic and mass spectrometric analyses, and the known compounds 2 and 3 were identified by comparison of their physical and spectroscopic data with those reported in the literature. The purified compounds 1–3 exhibited significant inhibition of Ca²⁺ fluorescence with IC₅₀ values of 0.71, 0.36, and 0.20 mM, respectively. A mechanism study showed that these compounds showed vasorelaxant effects by blocking the voltage-operated Ca²⁺ channel (VOCC) and inhibiting Ca²⁺ influx to the cytoplasmic. These results suggested that 5LP and the three characterized components could be promising antihypertensive candidates for the use as VOCC blockers.

Detection of lithospermate B in rat plasma at the nanogram level by LC/MS in multi reaction monitoring mode

Low bioavailability and high binding affinity to plasma proteins led to the difficulty for the quantitative detection of lithospermate B (LSB) in plasma. This study aimed to develop a protocol for detecting LSB in plasma. A method was employed to quantitatively detect LSB of 5–500 ng/mL by LC/MS spectrometry in multi reaction monitoring mode via monitoring two major fragments with m/z values of 519 and 321 in the MS2 spectrum. To set up an adequate extraction solution to release LSB captured by plasma proteins, recovery yields of LSB extracted from rat plasma acidified by formic acid or HCl in the presence or absence of EDTA and caffeic acid were detected and compared using the above quantitative method. High recovery yield (~90%) was achieved when LSB (5–500 ng/mL) mixed in rat plasma was acidified by HCl (5 M) in the presence of EDTA (0.5 M) and caffeic acid (400 μg/mL). The lower limit of detection and the lower limit of quantification for LSB in the spiked plasma were calculated to be 1.8 and 5.4 ng/mL, respectively. Good accuracy (within ±10%) and precision (less than 10%) of intra- and inter-day quality controlled samples were observed. Oral bioavailability of LSB in rat model was detected via this optimized extraction method, and the maximum plasma concentration (C_max) was found to be 1034.3 ± 510.5 μg/L at t_max around 10 min, and the area under the plasma concentration–time curve (AUC) was 1414.1 ± 851.2 μg·h/L.

Detecting metabolites of different transition metal-lithospermate B complexes after intravenous injection in rats

AIM

Lithospermate B (LSB) isolated from the traditional Chinese medicine danshen (Salvia miltiorrhiza) is an effective Na(+)/K(+)-ATPase inhibitor and used to treat congestive heart failure. The inhibition of LSB on Na(+)/K(+)-ATPase is potentiated by forming complexes with transition metal ions. Here we investigated the safety and metabolites of different transition metal-LSB complexes in rats.

METHODS

LSB complexed with six different transition metal ions (Mg(2+), Zn(2+), Cr(3+), Co(2+), Ni(2+) and Mn(2+)) were prepared. Adult male SD rats were injected with the different metal-LSB complexes (50 mg/kg, iv), and their bile and blood samples were collected. The metabolites of the metal-LSB complexes in the samples were analyzed using mass spectroscopy.

RESULTS

In rats injected with LSB complexed with Mg(2+), Zn(2+), Cr(3+), Ni(2+) or Mn(2+), LSB and its four putative metabolites were equivalently detected in their bile samples. Mn(2+)-LSB exhibited distinct metabolite profiles compared with the other four metal-LSB complexes. The four putative metabolites were identified as 3-monomethyl-LSB, 3,3''-dimethyl-LSB, 3,3'''-dimethyl-LSB and 3,3'',3'''-trimethyl-LSB. The tracking of successive bile samples of rats injected with Mg(2+)-LSB, Zn(2+)-LSB and Mn(2+)-LSB concurrently demonstrated that LSB was firstly methylated at position 3, then at position 3'', and, finally, the 3''' hydroxyl group. All rats injected with Co(2+)-LSB died.

CONCLUSION

Zn(2+)-LSB, Cr(3+)-LSB, Ni(2+)-LSB or Mn(2+)-LSB produces identical four methylated metabolites of LSB in rats, and seemed to be as safe as LSB or Mg(2+)-LSB.