Study on optimal harvesting period and rational medicinal parts of Zanthoxylum nitidum based on statistics of main effective components

Abstract

To determine the optimal harvesting period and rational medicinal parts of Zanthoxylum nitidum, the main effective components of cultivated Z. nitidum samples, which originate from various growth years, harvesting months, and different parts were analyzed and compared with the wild samples. HPLC was performed on a Kinetex C18 column(4. 6 mm×100 mm, 2. 6 μm) with the gradient elution of 0. 3% phosphoric acid solution-acetonitrile(80 ∶ 20) containing 0. 2% triethylamine. The flow rate was 1. 0 m L·min-1, and the detection wavelength was 273 nm. The column temperature was 30 ℃. Nitidine chloride and chelerythrine, the main effective components, were determined as the markers. The results showed there was no significant difference in the contents of the main effective components among the roots of wild and cultivated Z. nitidum, as well as the roots and roots + stems of cultivated Z. nitidum. The statistical results of HCA and PCA indicated that the roots and stems could be clearly distinguished, but no distinction could be made between wild and cultivated products, which was consistent with the results of the significance analysis. The total contents of nitidine chloride and chelerythrine in roots and stems of Z. nitidum of 1-6 years old were 0. 114%-0. 256% and 0. 030%-0. 133%, respectively. These results suggested a positive correlation between the content of the main effective components and the growth years. No significant difference was observed between the contents of samples harvested in different seasons, indicating that the harvest season had no effect on the content of the main effective components of the Z. nitidum samples. The total contents of nitidine chloride and chelerythrine of the dried Z. nitidum samples(excluding branches) from three plantation bases were 0. 308%±0. 123% in Yunfu, 0. 192%±0. 025% in Maoming, and 0. 197%±0. 052% in Nanning, respectively, and they were all not less than 0. 15%, or in other words, the roots(including fibrous roots, taproots, and underground stems) and stems(aboveground stems) of Z. nitidum transplanted for more than 2. 5 years can meet the medical requirements. This study demonstrates that the cultivated Z. nitidum could be used as a valid substitute for the wild Z. nitidum, which provides a guarantee for the sustainable development and the application of Z. nitidum resources. The stems and roots could be considered medicinal parts of Z. nitidum. It is recommended to revise the medicinal parts of Z. nitidum to dried roots and stems in the next edition of Chinese Pharmacopoeia, and the medicinal parts can be harvested all year round. In order to ensure the content of effective components and clinical effectiveness, the root and stem should be harvested for medical use after the seedlings of Z. nitidum have been transplanted for more than three years.