Studies On The Herbicidal Constituents In Cephalotaxus Sinensis

Cephalotaxus sinensis Li. which belongs to Cephalotaxus,Cephalotaxaceae is endemic, but widely spread in China. Pharmaceutical chemicals, pharmaceutical activities, toxicity and synthesis of the chemicals were deeply studied in Cephalotaxus plant since alkaloids with anticancer activity were found in the genius in 1960s. C. sinensis was reported to have strong inseccidal and nemaicidal activity, but the studies about which were superficial. When plants collected in northwest China with high herbicidal activity were screened by us, C. sinensis was found having high inhibition to the 4 kinds of crop seeds germination. In order to find new inseccidal chemicals, the herbicidal activity and herbicidal constituents and herbicidal mechanisms in C. sinensis were studied further. The results were listed bellow: 1. The herbicidal activity of 67 families 152 genus 188 species plant samples in the seeds germination of Sorghum vulgare, Cucumis sativus, Triticum aestivum and Brassica campestris were determined. The results showed that the inhibitory rates of Artomisia roxburghiana, Cephalanoplos setosum, Melilotus alba, Atriplex fera, Atriplex sibirica, Kalidium foliatum, Kochia iranica, Chenopodium glaucum, Suaeda salsa, Anemone hupehensis, Phytolacca acinosa, Cephalotaxus sinensis, Datura stramonium, Sabina vulgaris, Macleaya cordata, Cuscuta ja ponica, Brucea javanica not only to young roots, but also to young buds of the 4 crops were more than 70%. The herbicidal activities, resources and researchment of chemicals were all ideal. So the herbicidal constituents in Cephalotaxus sinensis were studied further. 2. The herbicidal activity of ethanol extract from Cephalotaxus sinensis was determined in the seeds germination of 2 kinds of crop seeds, 4 kinds of vegetible seeds, 4 kinds of herbage seeds and 8 kinds of weed seeds. The results showed that the growth inhibition of the extract to the roots of Chenopodium album were more than that of the 7 kinds of crop, vegetable or herbage seeds at 10mg/ml. At 40mg/ml and 80mg/ml, the growth inhibition of the extract to all the plant wre notable. 3. The inhibiting selectivity of extract from Cephalotaxus sinensis to Triticum aestivum and Avena fatua was determined by growing different length roots and stems of the 2 kinds of plants in the soil mixed with the extract. The results showed all the roots of Avena fatua tested were more sensitive than which of Triticum aestivum. The growth inhibition of the extract to 5-10mm long roots of both kinds of the plants were more than that to 0-5mm and 5-10mm long roots. The sensibility of 0-5cm long stems of Triticum aestivum were higher than that of Avena fatua, while the sensibility of 5-10cm long stems of the 2 kinds of plants were the same. 4. Three alkaloids, drupacine , cephalotaxine and 11-hydroxycephalotaxine were isolated from the needles and stems of Cephalotaxus sinensis. The herbicidal activity of drupacine and 11-hydroxycephalotaxine were much higher than cephalotaxine. At 1mg/ml, the inhibitory rates of drupacine and 11-hydroxycephalotaxine to the root and stem of Amaranthus retroflexus were near or more than 80%, while the inhibitory rates of cephalotaxine were less than 35%. 5. Three nonalkaloids, n-hexadecanoic acid, ?-sitosterol and S3 ( chemical structure has not been identified) were isolated from the needles and stems of Cephalotaxus sinensis. The herbicidal activity of the 3 chemicals were weak; The inhibitory rates of them to the root and stem of Amaranthus retroflexus were less than 30%. Hence the non-alkaloid allelochemics in the Cephalotaxus sinensis need to be studied further. 6. Drupacine isolated from Cephalotaxus sinensis could increase the content of soluble carbohydrates, proteins and nucleic acid in the root and stem of seedling of Triticum aestivum. After treated with drupacine for 2 days, the content of soluble carbohydrates in the root and stem of the seedling increased to 5.95 and 1.71 times respectively; the content of soluble proteins in the root and stem of the seedling increased to 3.74 and 1.66 times respectively; the content of nucleic acid in the root and stem of the seedling increased to 7.09 and 1.25 times respectively. The phenomena that drupacine increased the content of soluble carbohydrates, proteins and nucleic acid in the root than that of stem of the seedling were unanimous with that the growth inhibition of root was higher than that of stem. The content of soluble carbohydrates and proteins in endosperm of seedling of Triticum aestivum was not much influenced after treated with drupacine for 2 days. 7. Drupacine could increase the activity of POD, CAT and SOD in the root, stem and endosperm of seedling of Triticum aestivum. After treated with drupacine for 2 days, the activity of POD in the root, stem and endosperm of the seedling increased 52.96%, 12.97% and 36.55% respectively; the activity of CAT in the root, stem and endosperm of the seedling increased 71.14%, 32.86% and 15.05% respectively; the activity of SOD in the root, stem and endosperm of the seedling increased 119.78%, 87.10% and 55.99% respectively. The phenomone that drupacine increased the activity of POD, CAT and SOD in the root than that of stem of the seedling was unanimous with that the growth inhibition of root was higher than that of stem.