Development and optimization of a method for the analysis of Brazilein by HPLC with electrochemical detection

Sappanone A: A natural PDE4 inhibitor with dual anti-inflammatory and antioxidant activities from the heartwood of Caesalpinia sappan L

ETHNOPHARMACOLOGICAL RELEVANCE

Sumu (Lignum sappan), the dry heartwood of Caesalpinia sappan L., is a traditional Chinese medicine used as an analgesic and anti-inflammatory agent.

AIM OF THE STUDY

The study aspired to discover natural phosphodiesterase 4 (PDE4) inhibitors with dual anti-inflammatory and antioxidant activities from Sumu for the treatment of chronic obstructive pulmonary disease (COPD).

MATERIALS AND METHODS

To accurately and efficiently identify natural PDE4 inhibitors from Sumu, molecular docking and molecular dynamics (MD) analysis methods were used for structure-based virtual screening of a self-built database of primary polyphenols in Sumu. According to the previous studies of Sumu and the free radical scavenging mechanism of polyphenols, the reported antioxidant components from Sumu and the potential antioxidants with the antioxidant pharmacophore of catechol and π-conjugated moieties were selected from the potential PDE4 inhibitors predicted by docking. Sappanone A, a potential PDE4 inhibitor with antioxidant activity from Sumu, was selected, calculated and synthesized to evaluate its dual anti-inflammatory and antioxidant functions in vitro and in vivo studies. Herein sappanone A was assayed for its inhibitory effects against PDE4 enzyme activity, tumor necrosis factor-alpha (TNF-α) production induced by lipopolysaccharide (LPS) in RAW264.7 macrophages and malondialdehyde (MDA) production induced by Fe²⁺ in mouse lung homogenate; sappanone A was also assayed for its abilities of radical (DPPH) scavenging, reducing Fe³⁺ and complexing Fe²⁺ in vitro. Additionally, LPS-induced acute lung injury (ALI) in mice was used to evaluate its anti-inflammatory activity as a PDE4 inhibitor in vivo, and the levels of TNF-α and total protein in bronchoalveolar lavage fluid (BALF) and myeloperoxidase (MPO) activity in the lung were assayed.

RESULTS

The present study predicted and validated that sappanone A was a promising PDE4 inhibitor from Sumu with dual anti-inflammation and antioxidant activities from Sumu. In vitro, sappanone A remarkably inhibited PDE4 enzyme activity and reduced TNF-α production induced by LPS in RAW264.7 macrophages and MDA production induced by Fe²⁺ in mouse lung homogenate. Meanwhile, it showed outstanding abilities of scavenging DPPH radicals, reducing Fe³⁺ and complexing Fe²⁺. In vivo, sappanone A (25 mg/kg and 50 mg/kg, i.p., twice daily for 7 days) distinctly prevented LPS-induced ALI in mice by reducing the levels of TNF-α and total protein in BALF and MPO activity in the lung.

CONCLUSION

Sappanone A is a natural PDE4 inhibitor with dual anti-inflammatory and antioxidant activities from the traditional Chinese medicine Sumu, which may be a promising therapeutic agent to prevent the vicious cycle of COPD inflammation and oxidative stress.

Analysis of brazilin and protosappanin B in sappan lignum by capillary zone electrophoresis with acid barrage stacking

A method was developed to determine brazilin and protosappanin B in natural products by CE after acid barrage stacking. The optimum conditions were as follows: a BGE of 20 mM sodium tetraborate (pH 9.2) containing 6% v/v of methanol, hydrodynamic injection (0.5 psi, 65 s) followed by hydrodynamic injection of 150 mM citric acid (pH 2.3; 0.5 psi, 22 s), and separated with +25 kV. Under these conditions, brazilin and protosappanin B were separated with a sample-to-sample time less than 13 min and detection limits of 0.28 μg/mL and 0.15 μg/mL, respectively. The applicability of the developed method was demonstrated by the detection of brazilin and protosappanin in methanol extract of sappan lignum.

Brazilein from Caesalpinia sappan L. Antioxidant Inhibits Adipocyte Differentiation and Induces Apoptosis through Caspase-3 Activity and Anthelmintic Activities against Hymenolepis nana and Anisakis simplex

Brazilein, a natural, biologically active compound from Caesalpinia sappan L., has been shown to exhibit anti-inflammatory and antioxidant properties and to inhibit the growth of several cancer cells. This study verifies the antioxidant and antitumor characteristics of brazilein in skin cancer cells and is the first time to elucidate the inhibition mechanism of adipocyte differentiation, cestocidal activities against Hymenolepis nana, and reduction of spontaneous movement in Anisakis simplex. Brazilein exhibits an antioxidant capacity as well as the ability to scavenge DPPH^• and ABTS^•+ free radicals and to inhibit lipid peroxidation. Brazilein inhibited intracellular lipid accumulation during adipocyte differentiation in 3T3-L1 cells and suppressed the induction of peroxisome proliferator-activated receptor γ (PPARγ), the master regulator of adipogenesis, suggesting that brazilein presents the antiobesity effects. The toxic effects of brazilein were evaluated in terms of cell viability, induction of apoptosis, and the activity of caspase-3 in BCC cells. The inhibition of the growth of skin cancer cells (A431, BCC, and SCC25) by brazilein is greater than that of human skin malignant melanoma (A375) cells, mouse leukemic monocyte macrophage (RAW 264.7 cells), and noncancerous cells (HaCaT and BNLCL2 cells). The anthelmintic activities of brazilein against Hymenolepis nana are better than those of Anisakis simplex.

A validated LC-MS/MS method for rapid determination of brazilin in rat plasma and its application to a pharmacokinetic study

Brazilin is a major homoisoflavonoid component isolated from the dried heartwood of traditional Chinese medicine Caesalpinia sappan L., which is a natural red pigment used for histological staining. Herein a sensitive, specific and rapid analytical LC-MS/MS method was established and validated for brazilin in rat plasma. After a simple step of protein precipitation using acetonitrile, plasma samples were analyzed using an LC-MS/MS system. Brazilin and the IS (protosappanin B) were separated on a Diamonsil C18 analytical column (150 × 4.6 mm, 5 µm) using a mixture of water and 10 mm ammonium acetate in methanol (20:80, v/v) as mobile phase at a flow rate of 0.6 mL/min. The method was sensitive with a lower limit of quantitation of 10.0 ng/mL, with good linearity (r(2) ≥ 0.99) over the linear range 10.0-5000 ng/mL. All the validation data, such as accuracy and precision, matrix effect, extraction recovery and stability tests were within the required limits. The assay method was successfully applied to evaluate the pharmacokinetics parameters of brazilin after an oral dose of 100 mg/kg brazilin in rats.

Determination of brazilein in rat plasma after intravenous administration by HPLC

Quantification of brazilein in rat plasma following intravenous administration was achieved by reversed-phase high-performance liquid chromatography using a mobile phase of acetonitrile-0.05 m potassium dihydrogen phosphate water (containing 0.5% triethylamine, pH 3.0; 20:80 v/v) and UV detection at 445 nm. The method was linear (determination coefficient, r(2) = 0.9992) within the tested range (0.313-5.0 microg/mL). Intra- and inter-day precision coefficients of variation and accuracy bias were acceptable (maximal CV value was 2.06% for intra-day and 1.71% for inter-day) over the entire range. The recoveries were 81.48, 84.61 and 82.83% for concentrations of 0.313, 1.25 and 5.0 microg/mL, respectively. The concentration-time curve of brazilein after intravenous administration was fitted to the two-compartment model. This is the first time that brazilein in rat plasma was detected by HPLC-UV method and its pharmacokinetic characteristic was comprehensively studied.

Study on cardioactive effects of brazilein

Brazilein (6a,7-dihydro-3,6a,10-trihydroxy-benz[b]indeno[1,2-d]pyran-9(6H)-one) is a compound obtained in a large amount from Caesalpinia sappan ethanol extracts with a high purity of about 98%. In isolated cardiac tissues, we found that brazilein exhibited a positive inotropic action in a concentration-dependent manner with little effect on heart rate and coronary perfusion. To study its possible mode of action, isolated rat hearts were treated with propranolol. This treatment did not alter the cardiotonic effect of brazilein, suggesting that this effect does not involve stimulation of beta-adrenoceptors. On the other hand, an analysis of the interaction between Na(+),K(+)-ATPase and brazilein was carried out. Albino guinea pig erythrocytes (mainly alpha1-Na(+),K(+)-ATPase isoforms) enriched with Na(+),K(+)-ATPase isoforms were utilized to compare the inhibition promoted by brazilein with that of classical inhibitors such as the cardiac glycoside deslanoside. Analysis of inhibition curves revealed that unlike deslanoside, brazilein had a relatively low affinity for erythrocyte isoforms and failed to completely inhibit the Na(+),K(+)-ATPase activity. The extent of the maximum inhibition rate was about 50%. The inhibitory effect of brazilein was not antagonized by 10 mmol/l K(+), as observed with deslanoside. Electrocardiogram research in vivo showed that brazilein did not induce the ventricular arrhythmias observed with deslanoside, suggesting that brazilein might have a less adverse effect and higher therapeutic index than cardiac glycosides. In light of all the above-mentioned observations, it can be concluded that brazilein, a molecule with a non-steroidal skeleton, produced its positive inotropic effect through inhibiting Na(+),K(+)-ATPase and could thus serve as a structural paradigm to develop new inotropic drugs.