Advances in militarine: Pharmacology, synthesis, molecular regulation and regulatory mechanisms

Militarine is the lead member of secondary metabolites found in multiple medicinal plants of the orchid family. It acts as not only an important inhibitor on plant growth, but also functions as the quality marker for medicinal materials. In addition, Militarine has been shown to possess remarkably medicinal value, with a definite potential for finding widespread adoption of treating various diseases, including lung injury, brain nerve injury, cognitive impairment, aging, tumors, inflammation, peptic ulcers, and more. Thus, it can serve as a material carrier for pharmacophore upon, so much so that it probes as natural source of lead compounds in the research and development of medication. The study reported herein makes an overview on the physicochemical properties and pharmacological mechanisms of Militarine compounds, summarizes the biogenic pathways of Militarine and organically integrates the biological characteristics of Militarine with multiple omics techniques. Besides, this review also constructs a regulatory system for the biological accumulation of Militarine around its precursor compounds, characteristic gene elements, key enzymes, important metabolic products, and critical steps and links. Exceptionally, emphasis on the biosynthesis of Militarine under both abiotic and biotic stress, as well as an elaboration of the signaling pathways and critical regulatory mechanisms that govern the metabolic flow of Militarine have been represented accordingly in this paper. These findings are expected to provide reference schemes and theoretical foundations for acquiring high-quality resources of Militarine and advancing its large-scale industrial production, drug development, and clinical applications to comprehensively elucidate the biosynthetic and metabolic pathways.

Effect of light quality on the growth and main chemical composition of Bletilla striata

This study aimed to investigate the effects of light quality on the morphological traits, photosynthetic pigment content, protective enzyme (superoxide dismutase, peroxidase, and catalase) activity, and bioactive compound (BSP, total phenol, and militarine) content in Bletilla striata. Plants of B. striata were grown under light filtered through three differently colored films. The treatments were red film (RF), yellow film (YF), and blue film (BF), and an uncovered treatment was included as a control (CK). Compared with the B. striata plants in the RF, YF, and CK treatment groups, those receiving BF treatment showed significantly promoted growth of the aerial parts. Meanwhile, the total phenol and militarine contents in B. striata tubers were increased without affecting the accumulation of B. striata polysaccharides. These results show that growing B. striata plants under blue film could be a useful technique to improve quality and production. This technique is conducive to achieving large-scale sustainable production of high-quality plant materials.

Role of Militarine in PM2.5-Induced BV-2 Cell Damage

A growing number of studies have shown that air fine particulate matter (PM_2.5) pollution is closely associated with neuroinflammation in humans. Militarine, a glucosyloxybenzyl 2-isobutylmalate compound isolated from Bletilla striata, has been found to exert significant neuroprotective effects. However, the anti-inflammatory, antioxidant and antiapoptotic effects of militarine on PM_2.5-stimulated BV-2 microglial cells have not been reported. This study aimed to investigate the protective effects of militarine against PM_2.5-induced cytotoxicity and its mechanism in BV-2 microglial cells. Our results revealed that pretreatment with 0.31-1.25 μg/mL militarine reversed the morphological changes caused by PM_2.5 and decreased proinflammatory cytokine generation and gene expression in PM_2.5-treated BV-2 cells. In particular, tumor necrosis factor-α and interleukin-6 expression was inhibited in a dose-dependent manner. Notably, militarine markedly inhibited the upregulation of Toll-like receptor 4, Toll-like receptor 2, and cyclo-oxygenase-2 expression at both the mRNA and protein levels and reduced NF-κB pathway-associated protein expression. Immunofluorescence analysis showed that militarine suppressed NF-κB activity through inhibiting p65 nuclear translocation. Our data suggested that militarine alleviated neuroinflammation in BV-2 microglial cells, possibly by inhibiting the expression of neuroinflammatory cytokines through the TLR/NF-κB signaling pathway. Additionally, militarine significantly reduced PM_2.5-mediated reactive oxygen species (ROS) generation and cell apoptosis and restored the mitochondrial membrane potential (MMP; ΔΨm). Collectively, these findings demonstrate that militarine played a protective role against PM_2.5-induced damage in BV-2 cells by exerting anti-inflammatory, antioxidant, and antiapoptotic effects.

Inhibition of inflammation-induced injury and cell migration by coelonin and militarine in PM2.5-exposed human lung alveolar epithelial A549 cells

Accumulating studies suggest that fine particulate matter (PM_2.5) pollutants in the air are easily enter into alveoli and even the bloodstream, resulting in an inflammatory response that not only triggers respiratory disorders but also causes permanent damage to various organs. Recent findings suggest that coelonin and militarine enriched in orchids can inhibit inflammation-induced injury against respiratory diseases. Here, we evaluated the anti-inflammatory properties of coelonin and militarine and examined their underlying molecular mechanisms in A549 cells exposed to PM_2.5. PM_2.5 induced significant intracellular reactive oxidative stress accumulation at a concentration of 250 μg/ml, as determined using the dichlorodihydrofluorescein diacetate (DCFH-DA) fluorescence assay. Cell viability was assessed via the MTS assay to determine the concentrations of compounds appropriate for use in subsequent experiments. Data from the enzyme-linked immunosorbent assay (ELISA) showed that both coelonin (10 and 20 μg/ml) and militarine (5 and 10 μg/ml) mitigated PM_2.5-induced inflammation by reducing the generation of inflammatory factors, including interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α). Quantitative real-time PCR (qRT-PCR) analysis revealed a remarkable decrease in IL-6, TNF-α, cyclooxygenase-2 (COX-2) and interleukin-1β (IL-1β) mRNA levels in the coelonin and militarine-pretreated groups. In Western blot analysis, expression of inhibitor of NF-κB (IκBα) protein in the coelonin and militarine pretreatment groups was significantly increased compared with the PM_2.5 (only) treatment group (P < 0.05), concomitant with a significant decrease in phospho-IκB kinase β/IκB kinase β (p-IKKβ/IKKβ), phospho-nuclear factor of kappa B p65/nuclear factor of kappa B p65 (p-NF-κBp65/NF-κBp65) and COX-2 proteins (P < 0.05). Both coelonin and militarine inhibited migration and inflammation by suppressing PM_2.5-induced IKK phosphorylation, and followed by IκBα protein degradation and NF-κB activation. Our collective data strongly supported the utility of coelonin and militarine as novel sources for development of treatments for PM_2.5-induced lung diseases.

Study on evaluation of toxicology and quality control of Yimusake tablet

ETHNOPHARMACOLOGICAL RELEVANCE

The Yimusake tablet (YMSK-T) is a type of Xinjiang Uygur Medicine, which affects curing diseases of impotence and premature ejaculation. It has remarkable pharmacological effects that mainly involve improving the number and shape of smooth muscle cells in the corpus cavernosum and enhancing the relaxation and contraction function of corpus cavernosum smooth muscle.

AIM OF THE STUDY

The YMSK-T prescription, which consists of 11 traditional herbs, has significant pharmacological effects, however the evaluation of toxicology and quality control of the preparation has not yet been reported. Therefore, in this study, we evaluated the toxicology and quality control of YMSK-T to ensure its safety and effectiveness in clinical applications.

MATERIALS AND METHODS

Male rats were divided into three groups and were given continuous gavage administration of high, medium and low concentrations of YMSK-T. To determine hematopoietic parameters, orbital blood was collected at regular intervals. At termination of the experiment, rats were dissected for histopathological examination. According to the function of the prescription medicinal materials, seven active components were selected for content determination under the same chromatographic condition of using 0.2% aqueous phosphoric acid (solvent A) and acetonitrile (solvent B) with a 40 min post time: 0-13 min, 20% →30% B; 13-26 min, 30% →72% B; 26-38 min, 72% →92% B; 38-40 min, 92% →96% B. The column was maintained at 25 °C and the total sample injection was 10 μL.

RESULTS

Our data showed that using a large dose (400X the dosage used in humans) of YMSK-T resulted in myocardium and liver damage, and eventually death of the rats. At sub-chronic toxicity, no significant differences were observed among indexes about relative organ weight, hematology, serum biochemistry and histopathological examination, and rats behaved normally. Our results also demonstrated that the YMSK-T dosage used was not toxic in the normal range. The linearity of each component was sufficient (correlation coefficients>0.9997). Moreover, the relative standard deviations of precision, repeatability, stability, and recovery were less than 2.0%, which showed that the method for determination of content was stable and reliable.

CONCLUSIONS

YMSK-T has been found to be relatively safe in a rat model, and the method of content determination can be used for quality control of YMSK-T. Toxicology and quality control studies indicated that, the drug is safe and effective for clinical application.