Antinociceptive Activities of the Methanolic Extract of the Stem Bark of Boswellia dalzielii Hutch. (Burseraceae) in Rats Are NO/cGMP/ATP-Sensitive-K+ Channel Activation Dependent

A Nutritional Supplement as Adjuvant of Gabapentinoids for Adults with Neuropathic Pain following Spinal Cord Injury and Stroke: Preliminary Results

Gabapentinoids are first choice drugs for central neuropathic pain (CNP) despite limited evidence of efficacy and side effects affecting therapy outcomes. Nutraceuticals could improve their efficacy and tolerability. Our aim is to investigate the effect of NACVAN®, in addition to gabapentinoids, on pain symptomatology in CNP patients. The effect of 6 weeks of treatment of NACVAN® was preliminary observed among 29 adult inpatients with spinal cord injury (SCI) or stroke-related CNP recruited to the experimental group. Pain intensity, neuropathic pain, and quality-of-life were measured at baseline (T0) and after 3 (T1) and 6 weeks (T2). Change in each outcome over time was assessed through a repeated measures analysis of variance or Wilcoxon matched-pairs test. Preliminary results show a significant reduction in pain intensity (T0 → T1, p = 0.021; T0 → T2, p = 0.011; T1 → T2, p = 0.46), neuropathic symptoms (T0 → T1, p = 0.024; T0 → T2, p = 0.003), and evoked pain (T0 → T2, p = 0.048). There were no significant reductions in other neuropathic pain dimensions and in quality-of-life components. No side-effects were detected. NACVAN® could have a beneficial adjuvant effect when used as an add-on to gabapentinoids in patients suffering from CNP due to SCI or stroke, with no adverse effect. Future analysis on a larger sample, compared with a placebo condition, could confirm these preliminary results.

Analgesic effects of medicinal plants and phytochemicals on chemotherapy-induced neuropathic pain through glial modulation

Chemotherapy-induced peripheral neuropathy (CIPN) frequently occurs in cancer patients. This side effect lowers the quality of life of patients and may cause the patients to abandon chemotherapy. Several medications (e.g., duloxetine and gabapentin) are recommended as remedies to treat CIPN; however, usage of these drugs is limited because of low efficacy or side effects such as dizziness, nausea, somnolence, and vomiting. From ancient East Asia, the decoction of medicinal herbal formulas or single herbs have been used to treat pain and could serve as alternative therapeutic option. Recently, the analgesic potency of medicinal plants and their phytochemicals on CIPN has been reported, and a majority of their effects have been shown to be mediated by glial modulation. In this review, we summarize the analgesic efficacy of medicinal plants and their phytochemicals, and discuss their possible mechanisms focusing on glial modulation in animal studies.

The antinociceptive mechanisms of melatonin: role of L-arginine/nitric oxide/cyclic GMP/KATP channel signaling pathway

Pain is one of the most common medical challenges, reducing life quality. Despite the progression in pain management, it has remained a clinical challenge, which raises the need for investigating novel antinociceptive drugs with correspondence signaling pathways. Besides, the precise antinociceptive mechanisms of melatonin are not revealed. Accordingly, owing to the critical role of L-arginine/nitric oxide (NO)/cyclic GMP (cGMP)/KATP in the antinociceptive responses of various analgesics, the role of this signaling pathway is evaluated in the antinociceptive effects of melatonin. Male NMRI mice were intraperitoneally pretreated with the injection of L-arginine (NO precursor, 100 mg/kg), N(gamma)-nitro-L-arginine methyl ester [L-NAME, NO synthase (NOS) inhibitor, 30 mg/kg], S-nitroso-N-acetylpenicillamine (SNAP, NO donor, 1 mg/kg), sildenafil (phosphodiesterase inhibitor, 0.5 mg/kg), and glibenclamide (KATP channel blocker, 10 mg/kg) alone and before the administration of the most effective dose of melatonin amongst the intraperitoneal doses of 50, 100, and 150 mg/kg. The formalin test (2%, 25 µL, intra-plantarly) was done following the melatonin administration, then the nociceptive responses of mice were evaluated during the early phase for 5 min and the late phase for 15 min. The results showed that 100 mg/kg dose of melatonin carried out the most antinociceptive effects. While the antinociceptive effect of melatonin was increased by L-arginine, SNAP, and sildenafil, it was significantly reduced by L-NAME and glibenclamide in both phases of the formalin test, with no relation to the sedative effects of melatonin evaluated by the inclined plane test. In conclusion, the antinociceptive effect of melatonin is mediated through the L-arginine/NO/cGMP/KATP pathway.

Boswellia dalzielii-Mediated Silver Nanoparticles Inhibited Acute Myeloid Leukemia (AML) Kasumi-1 Cells by Inducing Cell Cycle Arrest

BACKGROUND

Acute myeloid leukemia (AML) persists to be a major health problem especially among children as effective chemotherapy to combat the disease is yet to be available. Boswellia dalzielii is a well-known herb that is traditionally used for treatment and management of many diseases including degenerative diseases. In this study, silver nanoparticles were synthesized from the phytochemicals of B. dalzielii stem bark aqueous extract. The silver nanoparticles were characterized by carrying out Fourier Transform Infrared (FTIR) spectroscopy, Energy Filtered Scanning Electron Microscopy (FESEM), X-ray diffraction, and Dynamic Light Scattering (DLS) analyses. Antioxidant capacity of the nanoparticles was evaluated using 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay, and the antiproliferative effect of the nanoparticles on Kasumi-1 leukemia cells was investigated using PrestoBlue assay. Flow cytometry analysis was performed to observe the effect of the nanoparticles on the leukemia cell cycle progression.

RESULTS

Our findings revealed that the synthesized silver nanoparticles were formed from electrons of the plant phytochemicals which include aromatic compounds, ethers, and alkynes. FESEM analysis revealed that the sizes of the nanoparticles range from 12 nm to 101 nm; however, DLS analysis estimated a larger average size of the nanoparticles (108.3 nm) because it measured the hydrodynamic radii of the nanoparticles. The zeta potential of the nanoparticles was -16 nm, and the XRD pattern of the nanoparticles has distinct peaks at 38.02°, 42.94°, 64.45°, 77.20°, and 81.47°, which is typical of face-centered cubic (fcc) structure of silver. The Trolox Equivalence Antioxidant Capacity (TEAC) of the nanoparticles was estimated to be 300.91 μM Trolox/mg silver nanoparticles. The nanoparticles inhibited Kasumi-1 cell proliferation. The half minimal inhibitory concentrations (IC50s) that inhibited Kasumi-1 cell proliferation are 49.5 μg/ml and 13.25 μg/ml at 48 and 72 hours, respectively. The nanoparticles induced cell cycle arrest in the Kasumi-1 cells at S (5% increase) and G2/M (3% increase) phases.

CONCLUSION

The nanoparticles synthesized from the stem bark extract of B. dalzielii inhibit the growth of Kasumi-1 leukemia cells by activating cell cycle arrest; thus, they are potential antileukemic agents.

Toxicological studies and bioactivity-guided identification of antimicrobially active compounds from crude aqueous stem bark extract of Boswellia dalzielii

OBJECTIVE

The main objective of this study is to isolate, identify, and quantify the active antimicrobial compounds present in the crude aqueous stem bark extract of B. dalzielii using some common pathogenic microorganisms as well as toxicological profile.

MATERIAL AND METHODS

Crude aqueous stem bark extract of Boswellia dalzielii (CASEB) was partitioned by preparative thin layer chromatography (PTLC) using chloroform-methanol-water, 8:2:1 (v/v). The resulting bands were extracted using chloroform-methanol (50:50). The extract of each band was evaluated for antimicrobial activity on Streptococcus pyogenes, Staphylococcus aureus, Escherichia coli, Enterococcus faecalis, Klebsiella pneumonia, Pseudomonas aeruginosa, Proteus mirabilis, Salmonella typhi, and Candida albicans by disc diffusion. Compounds in the most antimicrobially bioactive fraction (MAAF) were identified by high performance liquid chromatography (HPLC), Fourier transform infrared spectrophotometry (FT-IR), and gas chromatography-mass spectrometry (GC-MS). Toxicological profile of the CASEB was evaluated by studying its effect in albino Wister rats.

RESULTS

PTLC produced five bands/fractions of which the MAAF was identified as RF2-fraction being active against all the isolates except E. coli and K. pneumoniae. HPLC of the MAAF revealed seven components; FT-IR revealed 17 functional groups; GC-MS revealed five compounds of which 93.18% are Oleic acid (44.88%), Squalene (34.16%), and n-Hexadecanoic acid (14.14%). The acute toxicity showed LD50 > 3,000 mg/kg. Sub-chronic toxicity showed that higher doses of the CASEB caused significant changes in liver function indices and a fatty change with lymphocytic infiltration (sign of acute hepatitis) in the liver tissues, but none of these changes were observed in the kidneys.

CONCLUSION

The antimicrobially active compounds in CASEB were Oleic acid, Squalene, and n-Hexadecanoic acid. These can be further purified and used as precursors of new antimicrobial agents for treating infections especially those due to fungi and Pseudomonas spp. that are known to resist wide array of antimicrobial agents. The LD50 of CASEB is >3,000 mg/kg in rats. However, long-term consumption of CASEB is associated with significant liver damage.

Curcumin downregulates expression of opioid-related nociceptin receptor gene (OPRL1) in isolated neuroglia cells

BACKGROUND

Curcumin (CC) exerts polyvalent pharmacological actions and multi-target effects, including pain relief and anti-nociceptive activity. In combination with Boswellia serrata extract (BS), curcumin shows greater efficacy in knee osteoarthritis management, presumably due to synergistic interaction of the ingredients.

AIM

To elucidate the molecular mechanisms underlying the analgesic activity of curcumin and its synergistic interaction with BS.

METHODS

We performed gene expression profiling by transcriptome-wide mRNA sequencing in human T98G neuroglia cells treated with CC (Curamed), BS, and the combination of CC and BS (CC-BS; Curamin), followed by interactive pathways analysis of the regulated genes.

RESULTS

Treatment with CC and with CC-BS selectively downregulated opioid-related nociceptin receptor 1 gene (OPRL1) expression by 5.9-fold and 7.2-fold, respectively. No changes were detected in the other canonical opioid receptor genes: OPRK1, OPRD1, and OPRM1. Nociceptin reportedly increases the sensation of pain in supra-spinal pain transduction pathways. Thus, CC and CC-BS may downregulate OPRL1, consequently inhibiting production of the nociception receptor NOP, leading to pain relief. In neuroglia cells, CC and CC-BS inhibited signaling pathways related to opioids, neuropathic pain, neuroinflammation, osteoarthritis, and rheumatoid diseases. CC and CC-BS also downregulated ADAM metallopeptidase gene ADAMTS5 expression by 11.2-fold and 13.5-fold, respectively. ADAMTS5 encodes a peptidase that plays a crucial role in osteoarthritis development via inhibition of a corresponding signaling pathway.

CONCLUSION

Here, we report for the first time that CC and CC-BS act as nociceptin receptor antagonists, selectively downregulating opioid-related nociceptin receptor 1 gene (OPRL1) expression, which is associated with pain relief. BS alone did not affect OPRL1 expression, but rather appears to potentiate the effects of CC via multiple mechanisms, including synergistic interactions of molecular networks.

Evaluation of the antinociceptive and anti-inflammatory activities of piperic acid: Involvement of the cholinergic and vanilloid systems

Piperin is the active compound of black pepper (Piper nigrum). From the piperine was obtained the molecule of the piperic acid (PAC). The objective of this study was to evaluate the antinociceptive and anti-inflammatory of the compound. The antinociceptive effects of PAC were evaluated by abdominal writhing, formalin, capsaicin and tail-flick tests; while the anti-inflammatory effects were evaluated by paw oedema and air pouch tests, and in vitro COX inhibition assay. The possible action mechanism of PAC was evaluated using naloxone, L-NAME, glibenclamide and atropine in tail flick test and by Cholinesterase activity assay and production of TNF-α and IL-1β. PAC significantly reduced the nociceptive effects induced by acetic acid or formalin in mice. PAC also demonstrated an antinociceptive effect in the tail-flick model. The muscarinic receptor antagonist, atropine reduced the antinociceptive effect of PAC in the tail-flick model. PAC was able to inhibit capsaicin-induced nociception, showing involvement of TRPV1. The compound did not alter the motor capacity of the animals, not interfering in the nociceptive response. PAC also showed anti- inflammatory activity by inhibiting the formation of carrageenan-induced paw oedema, leukocyte migration, and cytokine production / release. Atropine reduced the activity of PAC on leukocyte migration, and cytokine production. The compound showed to be able to reduce the cytokine production stimulated by capsaicin. PAC inhibited the COX activity. The results presented suggest that the possible cholinomimetic action and vanilloid agonist of the piperic acid may be responsible by antinociceptive and anti- inflammatory effects; these effects are devoid of toxicity.