Résumé
Tropane alkaloids are anticholinergic drugs widely used clinically. Biosynthesis of tropane alkaloids in planta involves a step of transamination of phenylalanine. Based on the sequenced transcriptomes of lateral roots and leaves of Hyoscyamus niger, we found three annotated aromatic amino acid aminotransferases, which were respectively named HnArAT1, HnArAT2 and HnArAT3. Sequence analysis showed that HnArAT3 had highest similarity with the reported Atropa belladonna AbArAT4, which was involved in tropane alkaloid (TA) to provide the precursor of the phenyllactic acid moiety. Tissue expression pattern analysis indicated that HnArAT3 was specifically expressed in lateral roots, where is the organ synthesizing tropane alkaloids. Then, method of virus induced gene silencing (VIGS) was used to characterize the function of HnArAT3 in H. niger. Gene expression analysis given by real-time quantitative PCR showed that all the transgenic lines had lower expression levels of HnArAT3 than the non-transgenic control, and HPLC analysis of alkaloids demonstrated significant decrease in the contents of hyoscyamine, anisodamine and scopolamine in planta. These results suggested that HnArAT3 was involved in the phenyllactic acid branch of TA biosynthetic pathway. Molecular cloning and functional identification of HnArAT3 laid the foundation for further understanding of TA biosynthesis and metabolic regulation, and also provided a new candidate gene for engineering biosynthetic pathway of tropane alkaloids.
Résumé
Aims: To present the clinical findings and intensive care management of Hyoscyamus niger (HN) intoxication in a 7-year-old patient. Presentation of Case: A seven-year-old girl was admitted to the emergency department who had eaten a plant in large amounts. She had psychomotor agitation, inability to recognize her family, slurred speech, dry mouth, flushing, over-distended urinary bladder, visual and hearing hallucinations. After a nasogastric tube was inserted, gastric lavage was performed and activated charcoal was administered. Symptomatic treatment including oxygen, fluid-electrolyte balance, and gastric protective drugs was established. Physostigmine infusion (0.02 mg/kg) was given due to tachycardia at the second hour of hospitalization. The plant that was responsible for the clinical picture was confirmed as ‘deli bat bat grass’. The clinical symptoms resolved after 2-hours administration of physostigmine. She was transferred to pediatric ward after 24 hours of monitorization in intensive care unit. Discussion: HN is commonly known as black henbane or deli bat bat grass in the Eastern Anatolian Region in Turkey. Oral intake of this plant can cause central and peripheral anti-cholinergic effects. This clinical picture described as ‘central anticholinergic syndrome’ is characterized by thought impairment, hallucinations, hyperpyrexia, ataxia, excitement, drowsiness, coma, dry skin and flushing, tachycardia, mydriasis, and reduction of bowel movements. Diagnosis of HN intoxication is made by clinical symptomatology and ingestion history of the parts of HN. Therapy includes stomach lavage, supportive therapy, and physostigmine as a specific antidote in some cases. Conclusion: Physicians should always keep in mind for plant poisoning in patients with anti-cholinergic symptoms.
Résumé
The reports on chemical constituents of Hyoscyamus niger were summarized. The compounds include alkaloids, saponins, lignans, coumarinolignans, flavonoids, and some other nonalkaloidal compounds. TLC, HPLC, and GC were used for the qualitative and quantitative analyses of some chemical constituents in H. niger. Modern pharmacological experiments showed that H. niger had the analgesic, anti-inflammatory, antipyretic, anticonvulsant, spasmolytic, antidiarrhoeal, antisecretory, bronchodilatory, urinary bladder relaxant, hypotensive, cardiosuppressant, vasodilator, antitumor, and feeding deterrent properties. In addition, the toxicities of this medicinal plant were also described.