Hymenocrater longiflorus Benth. (Sura-halala) is a pharmaceutical plant with anti-inflammatory, anti-allergic, and sedative impacts on human. Accordingly, the phyto-biochemical responses of Sura-halala to salicylic acid (SA) and simvastatin (SV) under in vitro conditions were investigated, to clarify the cross-relationship and the interaction effects of SA and SV. Four levels of SA (0, 0.5, 1, and 2 mM) and of SV (0, 5, 10, and 20 μM) were assessed during the experiments. The results demonstrated that in vitro production of H. longiflorus is not only achievable, but also commercially applicable. The findings verified the significant impacts of SA and SV on Surahalala growth as well as phyto-biochemical contents. SV was found capable of increasing the contents of most essential oils such as α-pinene and n-decane. Furthermore, multivariate statistical methods, i.e., biplot, heatmap, and canonical correlation, pointed out antagonistic effects of SA and SV on biochemical and phytochemical contents of Sura-halala. Additionally, the analytical methods were able to differentiate the two groups of features: one involving shoot fresh weight and the biochemical parameters and the other one involving the essential oils. SA was more closely related to the former group, and SV was mainly associated with the latter one. In addition, the overall results revealed that the, based on our results, appropriate levels of both SA and SV, i.e., 1 mM SA and 10 mM SV, could obtain higher growth coupled with higher content of suitable phyto-biochemical compounds in Sura-halala under in vitro propagation
