Analgesic effects of lappaconitine in leukemia bone pain in a mouse model

Traditional processing, uses, phytochemistry, pharmacology and toxicology of Aconitum sinomontanum Nakai: A comprehensive review

ETHNOPHARMACOLOGICAL RELEVANCE

As a folk medicine, Aconitum sinomontanum Nakai (Ranunculaceae) a perennial herbaceous flowering plant, is a widely used traditional Chinese medicine. Its rhizomes and roots are known as 'Gaowutou' in China, and it has been traditionally used for the treatment of rheumatoid arthritis, painful swelling of joints, bruises and injuries and has been known to grow well in regions of high altitude such as Gansu, Tibet etc. THE AIM OF THE REVIEW: This systematic review the comprehensive knowledge of the A. sinomontanum, including its traditional processing and uses, chemical constituents, pharmacological activities, toxicity assessment, pharmacokinetics and metabolism, and its use in clinical settings to emphasize the benefits of this species. We also discuss expectations for prospective research and implementation of this herb. This work lays a solid foundation for further development of A. sinomontanum.

MATERIALS AND METHOD

Information on the studies of A. sinomontanum was collected from scientific journals, books, and reports via library and electronic data search (PubMed, Elsevier, Scopus, Google Scholar, Springer, Science Direct, Wiley, ACS, EMBASE, Web of Science and CNKI). Meanwhile, it was also obtained from published works of material medica, folk records, ethnopharmacological literatures, Ph.D. and Masters dissertation.

RESULTS

As a member of the Ranunculaceae family, A. sinomontanum possesses its up-and-coming biological characteristics. It is widely reported for treating rheumatoid arthritis, painful swelling of joints, bruises and injuries. Currently, over 71 phytochemical ingredients have been obtained and identified from different parts of A. sinomontanum. Among them, alkaloids, flavonoids, steroids, glycosides are the major bioactive constituents. Activities such as antinociceptive, anti-inflammatory, antitumor, antiarrhythmic, local anesthetic, antipyretic, antimicrobial, insecticidal and others have been corroborated in vivo and in vitro. These properties are attributed to different alkaloids. In addition, many of the active ingredients, such as lappaconitine, ranaconitine and total alkaloids have been used as quality markers.

CONCLUSION

This work contributes to update the ethnopharmacological uses, chemical constituents, pharmacological activities, toxicity assessment, pharmacokinetics and metabolism, and clinical settings information for A. sinomontanum, which provide basic information to help better understand the pharmacological and toxicological activities of A. sinomontanum in human. However, further in-depth studies are needed to determine the medical uses of this herb and its chemical constituents, pharmacological activities, clinical applications and toxicology.

The diterpenoid alkaloids

The diterpenoid alkaloids are a family of extremely important natural products that have long been a research hotspot due to their myriad of intricate structures and diverse biological properties. This chapter systematically summarizes the past 11 years (2009-2019) of studies on the diterpenoid alkaloids, including the "so-called" atypical ones, covering the classification and biogenetic relationships, phytochemistry together with 444 new alkaloids covering 32 novel skeletons and the corrected structures, chemical reactions including conversion toward toxoids, synthetic studies, as well as biological activities. It should be noted that the synthetic studies, especially the total syntheses of various diterpenoid alkaloids, are for the first time reviewed in this treatise. This chapter, in combination with our four previous reviews in volumes 42, 59, 67, and 69, will present to the readers a more completed and updated profile of the diterpenoid alkaloids.

Quantitative Electrophysiological Evaluation of the Analgesic Efficacy of Two Lappaconitine Derivatives: A Window into Antinociceptive Drug Mechanisms

Quantitative evaluation of analgesic efficacy improves understanding of the antinociceptive mechanisms of new analgesics and provides important guidance for their development. Lappaconitine (LA), a potent analgesic drug extracted from the root of natural Aconitum species, has been clinically used for years because of its effective analgesic and non-addictive properties. However, being limited to ethological experiments, previous studies have mainly investigated the analgesic effect of LA at the behavioral level, and the associated antinociceptive mechanisms are still unclear. In this study, electrocorticogram (ECoG) technology was used to investigate the analgesic effects of two homologous derivatives of LA, Lappaconitine hydrobromide (LAH) and Lappaconitine trifluoroacetate (LAF), on Sprague-Dawley rats subjected to nociceptive laser stimuli, and to further explore their antinociceptive mechanisms. We found that both LAH and LAF were effective in reducing pain, as manifested in the remarkable reduction of nocifensive behaviors and laser-evoked potentials (LEPs) amplitudes (N2 and P2 waves, and gamma-band oscillations), and significantly prolonged latencies of the LEP-N2/P2. These changes in LEPs reflect the similar antinociceptive mechanism of LAF and LAH, i.e., inhibition of the fast signaling pathways. In addition, there were no changes in the auditory-evoked potential (AEP-N1 component) before and after LAF or LAH treatment, suggesting that neither drug had a central anesthetic effect. Importantly, compared with LAH, LAF was superior in its effects on the magnitudes of gamma-band oscillations and the resting-state spectra, which may be associated with their differences in the octanol/water partition coefficient, degree of dissociation, toxicity, and glycine receptor regulation. Altogether, jointly applying nociceptive laser stimuli and ECoG recordings in rats, we provide solid neural evidence for the analgesic efficacy and antinociceptive mechanisms of derivatives of LA.

Sulforaphane alleviates hyperalgesia and enhances analgesic potency of morphine in rats with cancer-induced bone pain

Due to the efficacy and tolerability of the available drugs, the current treatment for cancer-induced bone pain (CIBP) is not considered ideal, and new drugs are required for better treatment results. This study investigated whether intrathecal injection of sulforaphane (SFN) can modulates the noxious behavior associated with CIBP and enhances the analgesic effects of morphine and the possible mechanisms related to these effects were investigated. Walker256 breast cancer cells were injected into the bone marrow cavity of rats to establish the CIBP model. When CIBP rats began to exhibit painful behavior (CIBP 6 days), SFN was injected intrathecally for 7 days. The results showed that SFN alleviated the painful behavioral hypersensitivity caused by cancer, accompanied by nuclear factor, erythroid 2 like 2 (Nrf2), Haem oxygenase 1 (HO-1) activation, nuclear factor kappa B (NF-κB) inhibition and inflammation-related factors (tumor necrosis factor-alpha (TNF-α), interleukin-1β (IL-β), interleukin-6 (IL-6), and inducible nitric oxide synthase (iNOS) reduction. In addition, SFN treatment inhibited the proliferation of Walker 256 cells in a dose-dependent manner, promoted mu-opioid receptor (MOR) expression in SH-SY5Y cells and enhanced the antihyperalgesic effects of morphine on CIBP rats by restoring the downregulation of MOR expression in the spinal cord. Interestingly, the antihyperalgesic effects of SFN were partially blocked by opioid receptor antagonists. This study showed that SFN combined with morphine might be a new way to treat CIBP.

The Analgesic Effect of Aconitum Sinomontanum Nakai Pharmacopuncture in Sprague-Dawley Rats

Background: Aconitum sinomontanum Nakai (ASN) has been reported to have analgesic effects. In this study an animal model of pharmacopuncture using ASN (100-500 mg/kg) was examined.Methods: Sprague-Dawley (SD) rats (<i>n</i> = 40) were randomly assigned to ASN-Low (1 mg/mL, 1.8 mL, ASN-L), ASN-Intermediate (5 mg/mL, 1.8 mL, ASN-M), ASN-High (10 mg/mL, 1.8 mL, ASN-H), negative control (0.2 mL normal saline), and positive control (0.2 mL 0.5% lidocaine) groups. All experiments were administered to the rats’ left hind leg. The analgesic response was assessed by monitoring the physical (hot plate, and von Frey test) and chemical (formalin) responses to pain.Results: All ASN pharmacopuncture groups demonstrated significant differences in pain response to the hot plate test, von Frey test, and formalin test, compared to the control group (<i>p</i> < 0.05). The response of the ASN-M group and ASN-H groups to the hot plate, the formalin, and the von Frey tests were significantly different, compared to the lidocaine group (<i>p</i> < 0.05).Conclusion: ASN pharmacopuncture had a significant analgesic effect on SD rats in response to physical and chemical models of pain.

Hybrides of Alkaloid Lappaconitine with Pyrimidine Motif on the Anthranilic Acid Moiety: Design, Synthesis, and Investigation of Antinociceptive Potency

Convenient and efficient routes to construct hybrid molecules containing diterpene alkaloid lappaconitine and pyrimidine fragments are reported. One route takes place via first converting of lappaconitine to 1-ethynyl-lappaconitine, followed by the Sonogashira cross-coupling-cyclocondensation sequences. The other involves the palladium-catalyzed carbonylative Sonogashira reaction of 5'-iodolappaconitine with aryl acetylene and Mo (CO)6 as the CO source in acetonitrile and subsequent cyclocondensation reaction of the generated alkynone with amidines. The reaction proceeded cleanly in the presence of the PdCl2-(1-Ad)2PBn∙HBr catalytic system. The protocol provides mild reaction conditions, high yields, and high atom and step-economy. Pharmacological screening of lappaconitine-pyrimidine hybrids for antinociceptive activity in vivo revealed that these compounds possessed high activity in experimental pain models, which was dependent on the nature of the substituent in the 2 and 6 positions of the pyrimidine nucleus. Docking studies were undertaken to gain insight into the possible binding mode of these compounds with the voltage-gated sodium channel 1.7. The moderate toxicity of the leading compound 12 (50% lethal dose (LD50) value was more than 600 mg/kg in vivo) and cytotoxicity to cancer cell lines in vitro encouraged the further design of therapeutically relevant analogues based on this novel type of lappaconitine-pyrimidine hybrids.

Neurokinin-1 receptor is an effective target for treating leukemia by inducing oxidative stress through mitochondrial calcium overload

Substance P (SP) regulates multiple biological processes through its high-affinity neurokinin-1 receptor (NK-1R). While the SP/NK-1R signaling axis is involved in the pathogenesis of solid cancer, the role of this signaling pathway in hematological malignancy remains unknown. Here, we demonstrate that NK-1R expression is markedly elevated in the white blood cells from acute myeloid leukemia patients and a panel of human leukemia cell lines. Blocking NK-1R induces apoptosis in vitro and in vivo via increase of mitochondrial reactive oxygen species. This oxidative stress was triggered by rapid calcium flux from the endoplasmic reticulum into mitochondria and, consequently, impairment of mitochondrial function, a mechanism underlying the cytotoxicity of NK-1R antagonists. Besides anticancer activity, blocking NK-1R produces a potent antinociceptive effect in myeloid leukemia-induced bone pain by alleviating inflammation and inducing apoptosis. These findings thus raise the exciting possibility that the NK-1R antagonists, drugs currently used in the clinic for preventing chemotherapy-induced nausea and vomiting, may provide a therapeutic option for treating human myeloid leukemia.

Bone Metastasis Pain, from the Bench to the Bedside

Bone is the most frequent site of metastasis of the most common cancers in men and women. Bone metastasis incidence has been steadily increasing over the years, mainly because of higher life expectancy in oncologic patients. Although bone metastases are sometimes asymptomatic, their consequences are most often devastating, impairing both life quality and expectancy, due to the occurrence of the skeletal-related events, including bone fractures, hypercalcemia and spinal cord compression. Up to 75% of patients endure crippling cancer-induced bone pain (CIBP), against which we have very few weapons. This review’s purpose is to discuss the molecular and cellular mechanisms that lead to CIBP, including how cancer cells convert the bone “virtuous cycle” into a cancer-fuelling “vicious cycle”, and how this leads to the release of molecular mediators of pain, including protons, neurotrophins, interleukins, chemokines and ATP. Preclinical tests and assays to evaluate CIBP, including the incapacitance tester (in vivo), and neuron/glial activation in the dorsal root ganglia/spinal cord (ex vivo) will also be presented. Furthermore, current therapeutic options for CIBP are quite limited and nonspecific and they will also be discussed, along with up-and-coming options that may render CIBP easier to treat and let patients forget they are patients.

Lappaconitine, a C18-diterpenoid alkaloid, exhibits antihypersensitivity in chronic pain through stimulation of spinal dynorphin A expression

Lappaconitine is a representative C18-diterpenoid alkaloid extracted from Aconitum sinomontanum Nakai and has been prescribed as a pain relief medicine in China for more than 30 years. This study evaluated its antihypersensitivity activity in the rat models of neuropathic and cancer pains and explored its underlying mechanisms. Subcutaneous injection of cumulative doses of lappaconitine produced dose-dependent mechanical antiallodynia and thermal antihyperalgesia in spinal nerve ligation-induced neuropathic rats. The cumulative dose-response analysis exhibited their E_max values of 53.3 and 58.3% MPE, and ED₅₀ values of 1.1 and 1.6 mg/kg. Single intrathecal lappaconitine dose in neuropathy also dose- and time-dependently blocked mechanical allodynia, with an E_max of 66.1% MPE and an ED₅₀ of 0.8 μg. Its multiple twice-daily intrathecal administration over 7 days did not induce mechanical antiallodynic tolerance. Subcutaneous cumulative doses of lappaconitine also produced dose-dependent blockade of mechanical allodynia in the rat bone cancer pain model induced by tibia implantation of cancer cells, with the E_max of 57.9% MPE and ED₅₀ of 2.0 mg/kg. Furthermore, lappaconitine treatment stimulated spinal dynorphin A expression in neuropathic rats, and in primary cultures of microglia but not neurons or astrocytes. Intrathecal pretreatment with the specific microglia depletor liposome-encapsulated clodronate, dynorphin A antibody, and κ-opioid receptor antagonist GNTI totally suppressed intrathecal and subcutaneous lappaconitine-induced mechanical antiallodynia. This study suggests that lappaconitine exhibits antinociception through directly stimulating spinal microglial dynorphin A expression. Graphical Abstract ᅟ.