Promotion of adventitious root growth by coffee extracts

The preliminary screening results on plant growth regulation of the ethanolic extract of reasted coffee indicated that at high concentration the growth inhibition of plant seeds were observed, while at low concentration the growth promotion clearly visualized. In addition, the highest growth promotion of C. atropurpureus (55%) stimulated by the extract from roasted coffee at 100 ppm was observed while that of H. rosa-sinensis was achieved at 1000 ppm (84%). The bioassay-guided fractionation of the ethanolic extract led to the isolation of substances. Their structures were characterized by means of physical properties and spectroscopic data. The major compound was caffeine while the minor one was a mixture whose structure could not be identified. Caffeine showed the highest plant growth activity on C. atropurpureus at 100 ppm (61%) and H. rosa-sinensis at 10 ppm (81%). Plant growth regulation of plant seeds of caffeine exhibited the same the ethanolicextract. Caffeine (61%) enhanced the root growth promotions and stimulated the rooting of stem cuttings more than other compounds in roasted coffee such as chlorogenic acid (5%), theobromine (39%), theophylline (37%) and trigonelline (27%). It may be concluded that the main plant growth regulator of roasted coffee was caffeine针对烘焙咖啡乙醇提取物的植物生长调节活性初筛结果显示：高浓度条件下可观察到对植物种子的生长抑制作用，而低浓度下则呈现出显著的生长促进效果。此外，烘焙咖啡提取物在100 ppm浓度下对朱缨花（C. atropurpureus）的生长促进率最高，达55%；而对朱槿（H. rosa-sinensis）的最高生长促进率则在1000 ppm浓度下实现，为84%。通过生物活性导向分级分离法对该乙醇提取物进行分离纯化，得到多种活性物质，并通过物理性质与光谱数据对其结构进行了表征。其中主要成分为咖啡因（caffeine），次要成分为一种结构尚未明确的混合物。咖啡因在100 ppm浓度下对朱缨花（C. atropurpureus）的生长调节活性最高，达61%；在10 ppm浓度下对朱槿（H. rosa-sinensis）的活性最高，达81%。咖啡因对植物种子的生长调节效果与该乙醇提取物一致。相较于烘焙咖啡中的其他成分，如绿原酸（chlorogenic acid，5%）、可可碱（theobromine，39%）、茶碱（theophylline，37%）及胡芦巴碱（trigonelline，27%），咖啡因（61%）可更有效地促进根系生长，并提升茎插条的生根效果。综上可得出结论：烘焙咖啡中主要的植物生长调节活性成分为咖啡因。