Abstract
Rehmannia glutinosa is an important medicinal plant that has long been used in Chinese traditional medicine. Acteoside, one of the bioactive components from R. glutinosa, possessed various pharmacological activities for human health; however, the molecular mechanism of acteoside formation is not fully understood. In the current study, a novel tyrosine decarboxylase (designated as RgTyDC2) was identified from the R. glutinosa transcriptome. Biochemical analysis of RgTyDC2 showed RgTyDC2 uses tyrosine and dopa as the substrate to produce tyramine and dopamine, respectively, and it displays higher catalytic efficiency toward tyrosine than dopa. Moreover, the transcript level of RgTyDC2 was consistent with the accumulation pattern of acteoside in R. glutinosa, supporting its possible role in the biosynthesis of acteoside in vivo.
Highlights
Rehmannia glutinosa Libosch. (Dihuang), a medicinal herb from the Scrophulariaceae family was widely used in traditional Chinese medicine for thousands of years
RgTyDC2 was amplified from leaves of the R. glutinosa Beijing No.3 cultivar by polymerase chain reaction (PCR) with gene-specific primers, and the sequence of RgTyDC2 was deposited in the NCBI database (GenBank accession number OL744234)
Tyrosine decarboxylase (TyDC) together with tryptophan decarboxylases (TDCs) and aromatic acetaldehyde synthases (AASs) encompassed the aromatic amino acid decarboxylase (AAAD) family which was responsible for discrete decarboxylation or decarboxylation-deamination reactions of different aromatic amino acids
Summary
Rehmannia glutinosa Libosch. (Dihuang), a medicinal herb from the Scrophulariaceae family was widely used in traditional Chinese medicine for thousands of years. Acteoside was generated from the precursor phenylalanine and tyrosine which were produced via the shikimate pathway. The production of caffeoyl moiety was well studied, and feeding experiments revealed that L-phenylalanine is converted to the caffeoyl group via several intermediates, including cinnamic acid, coumaric acid, caffeic acid, and caffeoyl CoA under series enzymes [15]; whereas the hydroxytyrosol group might be generated by alternative pathways. Saimaru’s studies about Olea europaea showed that dopa produced from tyrosine is the main precursor for generating acteoside; dopa is converted to dopamine by dopa decarboxylase and oxidated to aldehyde, reduced to hydroxytyrosol, and glycosylated to form acteoside in order [17]. The study about Rhodiola revealed that tyrosine can be converted to form 4-hydroxy-phenylacetaldehyde directly without the intermediate tyramine [18] and further reduced to tyrosol, which may be used to generate acteoside via hydroxytyrosol. The biosynthetic pathway of acteoside with key genes remains to be studied
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
