Study on a Chinese herbal Flos Magnoliae (Xin-Yi) – identification and pharmacological actions

Flos Magnoliae (FM), one of the commonly used Chinese herbal medicines (CHM), has a long history of clinical application for rhinitis, sinusitis and headache. More than 20 different FM species can be found in the market. Thus, a systematic evaluation of the authentic species and quality assessment of FM from different botanic sources could be a complicated process. The major aim of this thesis was to study the molecular, chemical and pharmacological profiles of different FM species and varieties, as well as different FM products.

Firstly, DNA-based techniques were used to identify the genetic relationships between six Magnolia spp. The distinct genetic distances of their molecular profiles from six FM species were firstly demonstrated using RAPD by 10 random primers and PCR-RFLP by 5s-rRNA gene after digestion by restriction enzymes (HhaI, PstI, SmaI, and EcoRV). Secondly, magnolin and fargesin were qualitatively and quantitatively determined from all M. biondii batches and M. kobus, but not fargesin was detected from M. liliflora, using optimised and validated TLC and RP-HPLC method. The significant differences of the content of magnolin and fargesin were observed in samples from different FM sources. Furthermore, no magnolin and fargesin were found in other FM species. Then, the distinguished HPLC fingerprinting profiles of different FM species and M. biondii varieties were evaluated using various parameters, including the retention time, the relative retention time, the peak area, the relative peak area, the total peak area of 13 common peaks and the overlapping ratio. In addition, the FM products and the M. biondii batches grown in different cultivation sites were clearly identified and authenticated by their HPLC fingerprinting features.

Finally, the effects of different samples on mast cell derived histamine release induced by compound 48/80 in rat peritoneal mast cells were studied, using HPLC with post-derivatization. The significant differences in inhibition of histamine release were observed among various species or varieties. Moreover, the inhibitory effects of the FM sources from different herbal suppliers and cultivation sites on compound 48/80 induced histamine release were evaluated. To the best knowledge, it is also the first report of the anti-histamine release effects by the bioactive lignan, magnolin, and volatile oil from M. biondii.

In conclusion, the present study verified that the variations of botanic species and varieties, cultivation environments, and manufacturer process might cause the differences of the chemical compositions and pharmacological actions of FM products. Local grown FM species may be used for anti-allergic and anti-inflammatory applications. For the future direction, it would have been interesting to characterize the chemical structures of these components, which may contribute to the anti-allergic effects of FM. Assays on mediators involved in the anti-allergic actions may provide additional evidences of FM on the clinical application for rhinitis and sinusitis. Further to that, assays on anti-allergic effects of the major chemical compounds from FM on these mediators may apply chances to discover new therapeutic agents.