Lamiophlomis rotata, an orally available Tibetan herbal painkiller, specifically reduces pain hypersensitivity states through the activation of spinal glucagon-like peptide-1 receptors.

BACKGROUND: Lamiophlomis rotata is an orally available Tibetan herb prescribed for the management of pain, with shanzhiside methylester (SM) and 8-O-acetyl-SM as quality control ingredients. This study aimed to evaluate the antinociceptive properties of L. rotata, determine whether SM and 8-O-acetyl-SM are principle effective ingredients, and explore whether L. rotata produces antinociception through activation of spinal glucagon-like peptide-1 receptors (GLP-1Rs). METHODS: Formalin test, neuropathic pain, and bone cancer pain models were used, and the animal sample size was 5 to 6 in each group. Hydrogen peroxide-induced oxidative damage was also assayed. RESULTS: The L. rotata aqueous extract blocked formalin-induced tonic hyperalgesia and peripheral nerve injury- and bone cancer-induced mechanical allodynia by 50 to 80%, with half-effective doses of 130 to 250 mg/kg, close to the human dosage. The herb was not effective in alleviating acute nociceptive pain. A 7-day gavage with L. rotata aqueous extract did not lead to antiallodynic tolerance. Total iridoid glycosides, rather than total flavonoids, were identified by the activity-tracking method as effective ingredients for antihyperalgesia, whereas both SM and 8-O-acetyl-SM were principal components. Further demonstrations using the GLP-1R antagonist and gene silencer against GLP-1R at both the spinal and the cellular levels indicated that L. rotata inhibited pain hyperactivity by activation of spinal GLP-1Rs, and SM and 8-O-acetyl-SM appeared to be orthosteric, reversible, and fully intrinsic agonists of both rat and human GLP-1Rs. CONCLUSIONS: Results support the notion that the activation of spinal GLP-1Rs leads to specific antinociception in pain hypersensitivity and further suggest that GLP-1R is a human-validated target molecule for the treatment of chronic pain.

Salidroside can target both P4HB-mediated inflammation and melanogenesis of the skin.

Rationale: Many external factors can induce the melanogenesis and inflammation of the skin. Salidroside (SAL) is the main active ingredient of Rhodiola, which is a perennial grass plant of the Family Crassulaceae. This study evaluated the effect and molecular mechanism of SAL on skin inflammation and melanin production. It then explored the molecular mechanism of melanin production under ultraviolet (UV) and inflammatory stimulation. Methods: VISIA skin analysis imaging system and DermaLab instruments were used to detect the melanin reduction and skin brightness improvement rate of the volunteers. UV-treated Kunming mice were used to detect the effect of SAL on skin inflammation and melanin production. Molecular docking and Biacore were used to verify the target of SAL. Immunofluorescence, luciferase reporter assay, CO-IP, pull-down, Western blot, proximity ligation assay (PLA), and qPCR were used to investigate the molecular mechanism by which SAL regulates skin inflammation and melanin production. Results: SAL can inhibit the inflammation and melanin production of the volunteers. SAL also exerted a protective effect on the UV-treated Kunming mice. SAL can inhibit the tyrosinase (TYR) activity and TYR mRNA expression in A375 cells. SAL can also regulate the ubiquitination degradation of interferon regulatory factor 1 (IRF1) by targeting prolyl 4-hydroxylase beta polypeptide (P4HB) to mediate inflammation and melanin production. This study also revealed that IRF1 and upstream stimulatory factor 1 (USF1) can form a transcription complex to regulate TYR mRNA expression. IRF1 also mediated inflammatory reaction and TYR expression under UV- and lipopolysaccharide-induced conditions. Moreover, SAL derivative SAL-plus (1-(3,5-dihydroxyphenyl) ethyl-ß-d-glucoside) showed better effect on inflammation and melanin production than SAL. Conclusion: SAL can inhibit the inflammation and melanogenesis of the skin by targeting P4HB and regulating the formation of the IRF1/USF1 transcription complex. In addition, SAL-plus may be a new melanin production and inflammatory inhibitor.