Synergy assessment of fixed combinations of Herba Andrographidis and Radix Eleutherococci extracts by transcriptome-wide microarray profiling.

Background: Generally accepted, but insufficiently proved, the concept of synergy is based on an assumption that combining of two biologically active substances is justified because the combination is more active and less harmful than the ingredients.

Hypothesis: Analysis of RNA microarray of isolated neuroglia cells and the comparison the number of genes deregulated by plant extracts and their fixed herbal formulation might be a useful tool/method for assessment of synergistic and antagonistic interactions of herbal extracts in human organism.

Aim: The primary aim of this study was to extend a new method of assessment of synergistic and antagonistic interactions of herbal extracts in isolated human neuroglia cells when they applied in the form of fixed combinations. The secondary aim of the study was to predict possible effects of Herba Andrographidis (APE), Radix Eleutherococci (ESE) genuine extracts and their fixed combination Kan Jang (KJ) on cellular and physiological functions and associated diseases. The third task of the study was to find evidences that justify the hypothesis that these plants extracts in combination are more useful than the monodrugs.

Methods: Gene expression profiling was performed on the human neuroglia cell line T98G after treatment with APE, ESE, KJ and total number of more than two fold-deregulated genes from all experiments were compared by Venn diagram. Interactive pathways downstream analysis was performed with data sets of significantly up- or down-regulated genes and predicted effects on cellular functions and diseases were identified by Ingenuity IPA database software.

Results: ESE and APE significantly deregulate 207 and 211 genes correspondingly; 36 deregulated genes were common for both extracts. In total of 382 deregulated genes was expected to be deregulated by their fixed combination KJ. However, it was found only 250 genes deregulated by KJ. Among these 250 genes, 111 genes were unique for the KJ combination and not affected by ESE and APE. This is presumably due to synergistic interactions of molecular networks affected by ESE and APE. Meanwhile, 170 genes deregulated by ESE, and 55 genes deregulated by APE when tested alone, were not up- or downregulated by KJ. That is the result of antagonistic integrations of ESE and APE extracts when applied in the combination. Fold change of expression of 18 common genes deregulated by APE, ESE and KJ was not additive when APE and ESE are combined in KJ herbal formula. However, a qualitative difference is observed in the fingerprint of deregulated genes of daughter substance (KJ) compared to fingerprints/signatures of deregulated genes of parent substances (APE and ESE). Specific for KJ and predictable (z-score > 2) were the effects on pathways and networks associated with infectious and chronic inflammatory disorders, namely encephalitis or neurological movement disorders. Noteworthy, Eleutherococcus alone has no effect on those networks, particularly on encephalitis network, while KJ deregulates 11 genes which have predictable inhibitory effect on infection, while APE regulates only 5 genes which are activated in encephalitis. It can be speculated that APE in combination with ESE may have better therapeutic effect, since more targets are affected. Similar suggestion is justified regarding neurological movement, which is associated with chronic inflammation, like arthritis and osteoarthrosis. Though, microarray analysis did not provide final proof that the genes induced by the KJ, APE and ESE are responsible for the physiological effects observed in humans following their oral administration. It provided insights into putative genes and directions for future research and possible implementation into practice. The most significantly affected canonical pathways deregulated by KJ and APE was interferon signaling pathway, indicating the possible effectiveness of KJ and APE in the treatment of severe sepsis, systemic lupus erythematosus and other autoimmune diseases

Conclusion: Analysis of RNA microarray data from isolated neuroglia cells and the comparison the number of genes deregulated by plant extracts and their fixed herbal formulation might be a useful tool/method for assessment of synergistic and antagonistic interactions of herbal extracts in human organism. Combination of APE and ESE in KJ formulation is most likely justified.