Natural product rhynchophylline prevents stress-induced hair graying by preserving melanocyte stem cells via theβ2 adrenergic pathway suppression

Norepinephrine(NA),a stress hormone,can accelerate hair graying by binding toβ2 adrenergic receptors(β_(2)AR)on melanocyte stem cells(McSCs).From this,NA-β_(2)AR axis could be a potential target for preventing the stress effect.However,identifying selective blockers forβ_(2)AR has been a key challenge.Therefore,in this study,advanced computer-aided drug design(CADD)techniques were harnessed to screen natural molecules,leading to the discovery of rhynchophylline as a promising compound.Rhynchophylline exhibited strong and stable binding within the active site ofβ_(2)AR,as verified by molecular docking and dynamic simulation assays.When administered to cells,rhyncho-phylline effectively inhibited NA-β_(2)AR signaling.This intervention resulted in a significant reduction of hair graying in a stress-induced mouse model,from 28.5%to 8.2%.To gain a deeper understanding of the underlying mechanisms,transcriptome sequencing was employed,which revealed that NA might disrupt melanogenesis by affecting intracellular calcium balance and promoting cell apoptosis.Importantly,rhynchophylline acted as a potent inhibitor of these downstream pathways.In conclusion,the study demonstrated that rhynchophylline has the potential to mitigate the negative impact of NA on melanogenesis by targetingβ_(2)AR,thus offering a promising solution for preventing stress-induced hair graying.

Effects of Rhynchophylline on Guinea Pig Atria

本实验观察钩藤碱对豚鼠左右心房的作用。对自发节律右心房，钩藤碱具有负性变时作用，此作用在１５－２００μｍｏｌ／Ｌ范围内呈浓度效应依赖关系。对电驱动离体左心房，钩藤碱在浓度大于２００μｍｏｌ／Ｌ时产生负性肌力作用。２００μｍｏｌ／Ｌ钩藤碱使阈刺激波宽─强度曲线上移，表明心肌兴奋性下降。钩藤碱抑制肾上腺素诱发的心肌自律性，延长功能性不应期，显著抑制正阶梯现象。上述作用对抗心律失常有益，作用原理可能同其抑制钙内流有关。

Effects of Rhynchophylline on L type Calcium Channels in Isolated Rat Cortical Neurons During Acute Hypoxia

Aim: To study the effects of rhynchophylline (Rhy) on the L type calcium channels in freshly dissociated cortical neurons of Wistar rats during acute hypoxia. Methods: Cell attached configuration of patch clamp technique. L type calcium channel was activated by stepping from 40 mV to 0 mV. Results: The results showed that the L type calcium channels of cortical neurons were activated by acute hypoxia. The mean open time of the channel was increased, the mean close time decreased and the open state probability raised during acute hypoxia. Rhy (15 and 30μmol·L -1 ) in concentration dependent manner blocked activity of the channels. The drug shortened the mean open time of the channels from 8 87 ms to 3 03 ms and 2 23 ms ( P 【0 001), prolonged the mean close time from 9 23 ms to 38 84 ms and 54 43 ms ( P 【0 001), and decreased the open state probability from 0 142 to 0 031 and 0 025 ( P 【0 001) under the hypoxia condition, respectively. The effects of Rhy were similar to but weaker than those of verapamil (15 μmol·L -1 ). Conclusion: The study confirmed that Rhy has the blockade effects on L type calcium channels in cortical neurons of rats during hypoxia, by which it protects the brain from hypoxic injury.

Determination of rhynchophylline,isorhynchophylline,prim-O-glucosylcimifugin and 5-O-methylvisammioside in Babaojingfeng San by HPLC

OBJECTIVE: To develop an HPLC method for the simultaneous determination of rhynchophylline, isorhynchophylline,prim-O-glucosylcimifugin and 5-O-methylvisammioside in Babaojingfeng San.METHODS: The chromatograhic separation was performed on C_(18) column(4.6 mm×200 mm, 5 μm), a linear elution of acetonitrile-methanol(1:4) and 0.1% triethylamine solution was adopted at the flow rate of 0.7 mL·min^(-1). The detection wavelength was 254 nm and the column temperature was 30 ℃.RESULTS: Rhynchophylline, isorhynchophylline, prim-Oglucosylcimifugin and 5-O-methylvisammioside had a good linearity at 5.10 to 102.00 μg·mL^(-1)(r=0.9994), 5.95 to 119.00μg·mL^(-1)(r=0.9996), 6.10 to 122.00 μg·mL^(-1)(r=0.9999), 5.65 to113.00 μg·mL^(-1)(r=0.9998), respectively. The average recoveries and RSD were 97.66%(1.32%), 96.72%(0.52%), 98.99%(0.78%) and 99.16%(1.56%), respectively.CONCLUSION: The method was simple, convenience and may be used in the determination of rhynchophylline, isorhynchophylline, prim-O-glucosylcimifugin and 5-O-methylvisammioside in Babaojingfeng San.

Effects of Rhynchophylline on Learning and Memory of Alzheimer's Disease Zebrafish

[Objectives]To investigate the effect of rhynchophylline on the behavior of Alzheimer's disease zebrafish induced by aluminum trichloride(AlCl3),to provide theoretical basis for the development and application of rhynchophylline in the field of Alzheimer's disease.[Methods]The video recording was made on zebrafish before training,so as to judge whether zebrafish training was successful or not.After training zebrafish for 7 d,60 zebrafish were randomly divided into 6 groups:blank group,model group,positive group,low-dose rhynchophylline group,medium-dose rhynchophylline group and high-dose rhynchophylline group.The blank group was video-recorded,while the model group,positive group,low-dose group,medium-dose group and high-dose group were exposed to AlCl3 for modelling.After the end,the model group was video-recorded,and the other groups were given drug intervention.Both the positive group and the rhynchophylline group were given drug for 6 d,and finally all the groups were video-recorded.After all the videos were finished,the behavioral analysis was carried out by using the behavioral record analysis software smart3.0,and the conclusion was drawn by analyzing the data.[Results]The data of length of stay of zebrafish in red short arm area of 6 groups were compared and analyzed:there was a significant difference between blank group and model group(P<0.05),and there was a significant difference between model group and positive group,medium-dose group or high-dose group(P<0.05).The percentage of time spent in the red short arm area of 6 groups of zebrafish was compared and analyzed:there was a significant difference between blank group and model group(P<0.05),and there was a significant difference between model group and positive group,medium-dose group or high-dose group(P<0.05).The data of swimming distance of 6 groups of zebrafish in red short arm area were compared and analyzed:there was no significant difference between the blank group and the model group(P>0.05),but there was only significant difference between the model group and the high-dose group(P<0.05).The percentage of swimming distance of zebrafish in the red short arm area of the six groups was compared and analyzed:there was a significant difference between the blank group and the model group(P<0.05),and there were significant differences between model group and positive group,medium-dose group or high-dose group(P<0.05).[Conclusions]Rhynchophylline can improve the behavior of Alzheimer's disease zebrafish.

Effect of rhynchophylline on behavior of zebrafish with Alzheimer disease

OBJECTIVE To investigate the effect of rhynchophylline on behavior of zebrafish with Alzheimer disease induced by AlCl3.METH⁃ODS Take a video of the zebrafish before train⁃ing,which is convenient for judging whether the zebrafish has been trained successfully.Then,the zebrafish were trained for 7 d.The 60 zebraf⁃ish that were successfully trained were randomly divided into 6 groups:normal group,model group,positive group,low-dose rhynchophylline group,middle-dose group,and high-dose group.The normal group was video-recorded,while the model group,positive group,low-dose group,middle-dose group,and high-dose group were given AlCl3 for modeling.After that,the model group was videotaped,and the other groups were given drug intervention.Both the positive group and the rhynchophylline administration group were administered for 6 d,and finally all the administration groups were videotaped.After all the video is finished,the behavioral analysis software smart 3.0 was used for behavioral anal⁃ysis,and conclusions are drawn by analyzing the data.RESULTS The data of the 6 groups of zebrafish staying in the red short arm area were used for comparative analysis:there was a signif⁃icant difference between the normal group and the model group(P<0.05),the model group and the positive group,and the middle-dose group of rhynchophylline There are significant differences in the high-dose group(P<0.05).Comparative analysis with the data of the percentage of zebraf⁃ish in the red short arm area of the 6 groups:the normal group and the model group are signifi⁃cantly different(P<0.05),There were significant differences between the model group and posi⁃tive group,the dose of the rhynchophylline administration group high-dose group and the middle-dose group(P<0.05).Comparing the data of the swimming distance of the 6 groups of zebrafish in the red short arm area:the normal group and the model group are not significantly different(P>0.05),while the model group is only significantly different from the high-dose group(P<0.05).However,the comparison of the percentage of zebrafish swimming distance in the red short arm area of the 6 groups of data:the normal group and the model group are signifi⁃cantly different(P<0.05),the model group and the positive group,and the rhynchophylline administration group There were significant differ⁃ences between the dose group and the high-dose group(P<0.05).CONCLUSION Rhynchophyl⁃line can improve the behavior of zebrafish with Alzheimer disease.

Effect of rhynchophylline on p38MAPK/N-cadherin in zebrafish with Alzheimer disease

OBJECTIVE To investigate the effect of rhynchophylline on zebrafish with Alzheimer disease induced by AlCl3.METHODS Zebrafish were trained in T maze for 7 d.60 zebrafish were selected and divided into 6 groups:blank group,model group,positive group,low-dose group,medium-dose group and high-dose group,with 10 in each group.Feeding zebrafish adaptively for 2 d,starting training on the third day,and recording its movement track;Except the blank group,the other five groups were modeled and their motion trajectories were recorded.After modeling,the drug group was giv⁃en rhynchophylline,while the positive group was given huperzine A,and the movement track was recorded.The recorded movement track was analyzed by behavioral record analysis software smart 3.0.The expression levels of P38,p-P38 protein and N-cadherin protein in zebrafish brain tissue were detected by Western blotting.RESULTS The data of time spent in the green short arm area of six groups of zebrafish were compared and analyzed:there was significant dif⁃ference between blank group and model group(P<0.05),and there was significant difference between model group and positive group,low dose group,middle dose group and high dose group(P<0.05).Comparative analysis of the time percentage of zebrafish in the green arm area of six groups:there was significant differ⁃ence between the blank group and the model group(P<0.05),and there was significant differ⁃ence between the model group and the positive group,the rhynchophylline administration group,low dose group,middle dose group and high dose group(P<0.05).The protein was detected by Western blotting.Compared with the model group,the expression level of N-cadherin protein was up-regulated(P<0.05).Compared with the model group,the expression levels of p-P38 pro⁃tein in blank group,positive group and rhyncho⁃phylline administration group were down-regulat⁃ed(P<0.05).CONCLUSION Uncaria rhyncho⁃phylline can down-regulate the ratio of p-P38/P38 and up-regulate N-cadherin,thus improving the learning and memory ability of zebrafish with Alzheimer disease.

Quantification of rhynchophylline in rabbit plasma by UPLC-MS/MS and its application in a pharmacokinetic study

It was recently revealed that Rhynchophylline （Rhy）, an important constituent of Uncaria rhynchophylla, possessed antihypertensive and neuroprotective effects. However, no information about the pharmacoldnetics of Rhy in a herbivorous species such as rabbit is available. Allometric scaling is valuable in designing human pharmacokinetic parameters from preclinical species. To investigate the characteristics of Rhy in vivo, a rapid and sensitive ultra performance liquid chromatography-tandem mass spectrometry （UPLC-MS/MS） method was developed and validated for the measurement of Rhy concentrations in rabbit plasma. The method was linear over the concentration range of 0.01-10.24 μg/mL. Intra-day and inter-day precision and accuracy were less than 8.0%. The recoveries were in the range of 94.17%-103.32%. Matrix effects （ME） were minor. After oral administration of Rhy at 20, 40 and 80 mg/kg, the mean elimination half-life （h/E） for these doses were 1.19, 1.49 and 1.37 h in rabbits, respectively. There was a proportionate increase in the maximum concentration （Cmax） and the area under the blood concentration-time curve （AUC∞） for three doses. The developed method was suitable for the study on pharmacokinetics of Rhy after oral administration and it may provide a valuable basis for clinical application of such a bioactive compound of herbal medicines.

Acute oral toxicity test and assessment of rhynchophylline in mice

As the main alkaloid constituent of Uncaria species,rhynchophylline has drawn extensive attention in recent years for its antihypertensive and neuroprotective activities.However,toxicity study of the rhynchophylline is still lacking.In the present study,oral acute toxicity of rhynchophylline was conducted in Kunming mice.The mice were orally treated with 520.00,442.00,375.70,319.34 and 271.44 mg/kg of rhynchophylline for 14 d.The general behavior,body weight changes,toxic reaction,and death were recorded,and histopathological analyses were performed.The acute toxicity was evaluated by the assessment of the median lethal dose(LD50).The acute toxicity study showed that no significant difference was found in the body weight of the mice in the control group and those in the drug group.However,the mice treated with rhynchophylline showed obvious abnormal symptoms and mortality.The median lethal dose(LD50)of orally administered rhynchophylline was 308.08 mg/kg.The histopathological results showed that the mice in the high-dose rhynchophylline group displayed toxic effects in the brain,liver,lung,and kidney.The results of the current study indicated that rhynchophylline could not be taken at a high dose.Collectively,our current findings provided a strong basis for further clinical investigation.

Activation of PXR causes drug interactions with Paxlovid in transgenic mice

Paxlovid is a nirmatrelvir(NMV)and ritonavir(RTV)co-packaged medication used for the treatment of coronavirus disease 2019(COVID-19).The active component of Paxlovid is NMV and RTV is a pharmacokinetic booster.Our work aimed to investigate the drug/herb-drug interactions associated with Paxlovid and provide mechanism-based guidance for the clinical use of Paxlovid.By using recombinant human cytochrome P450s(CYPs),we confirmed that CYP3A4 and 3A5 are the major enzymes responsible for NMV metabolism.The role of CYP3A in Paxlovid metabolism were further verified in Cyp3a-null mice,which showed that the deficiency of CYP3A significantly suppressed the metabolism of NMV and RTV.Pregnane X receptor(PXR)is a ligand-dependent transcription factor that upregulates CYP3A4/5 expression.We next explored the impact of drug-and herb-mediated PXR activation on Paxlovid metabolism in a transgenic mouse model expressing human PXR and CYP3A4/5.We found that PXR activation increased CYP3A4/5 expression,accelerated NMV metabolism,and reduced the systemic exposure of NMV.In summary,our work demonstrated that PXR activation can cause drug interactions with Paxlovid,suggesting that PXR-activating drugs and herbs should be used cautiously in COVID-19 patients receiving Paxlovid.