# Responses of Medicinal and Aromatic Plants to Engineered Nanoparticles +
## 3 Improved Production of Secondary Metabolites in Presence of NPs  
As mentioned above, NPs exhibit similar effects to their bulk counterparts; however due to their specific properties connected with their nanoscale sizes, their ultimate effects on plants can be amplified or attenuated [80; 109; 110; 111; 112; 113; 114]. By green production of valuable secondary metabolites of medicinal plants elicited by various NPs, using in vitro cultures (Table 1) or HRs (Table 2), higher amounts of these pharmacologically important compounds can be achieved exceeding those observed with corresponding bulk elicitors. These secondary metabolites can be subsequently utilized by the pharmaceutical industry [115; 116; 117; 118; 119; 120]. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**NPs of Elictor** & **Plant** & **Cultivation Mode** & **Elictor Dose** & **SM** & \begin{tabular}{c} **Multiple of SM** \\ **Content in Control** \\ \end{tabular} & **Refs.** \\ \hline \multirow{3}{*}{Ag} & \multirow{3}{*}{_Momordia channtia L._} & & & TPC & 1.40 & \\  & & & & \begin{tabular}{c} TPC \\ 1.56 \\ \end{tabular} & & 1.52 & \\  & & & & \begin{tabular}{c} flavoods \\ hydrooxybenzoic acid \\ \end{tabular} & 1.23 & \\  & & & & \begin{tabular}{c} hydroxycinamic acid \\ \end{tabular} & 1.15 & \\ \hline \multirow{3}{*}{Ag} & \multirow{3}{*}{_Echinaca purpurea L._} & CSC, root derived & & & \\  & Callus (48 h) & 2 mg/L & \multirow{3}{*}{2 mg/L} & \multirow{3}{*}{cichoric acid} & \(\approx\)2.22 & \\  & & CS, leaf derived & & & \begin{tabular}{c} dichroic acid \\ \end{tabular} & \(\approx\)1.80 & \\  & & & & \\ \hline \multirow{3}{*}{Ag} & \multirow{3}{*}{_Istatis constricta L._} & leaves of shoots & & & \\  & & regenerated in MS & (5 days) & & \\ \hline \multirow{3}{*}{Ag} & \multirow{3}{*}{_Caralluma tuberculla L._} & calls culture & & & \begin{tabular}{c} TPC \\ \end{tabular} & \(\approx\)3.75 & \\  & & & & \begin{tabular}{c} TPC \\ \end{tabular} & \(\approx\)3.60 & \\ \hline \multirow{3}{*}{Ag} & \multirow{3}{*}{_Trigonlla_} & \multirow{3}{*}{\begin{tabular}{c} 2\% agar (5 days) and \\ _fromum-gracum_ L \\ \end{tabular} } & \multirow{3}{*}{200 \%/plant} & \multirow{3}{*}{diosemin} & \multirow{3}{*}{1.30} & \multirow{3}{*}{[115]} \\  & & sterile soil & & & \\ \hline \multirow{3}{*}{Ag} & \multirow{3}{*}{_Linum uslatissimum L_} & cell suspension & & & \begin{tabular}{c} secoisolarciesinol \\ diglucoside \\ \end{tabular} & 10.0 & \\  & & & & \begin{tabular}{c} larcinessiol diglicoscoside \\ dehydrodicointery! \\ \end{tabular} & 2.8 & \\  & & & & \begin{tabular}{c} alcohol glucose \\ guasioxide! \\ alcohol ether glucoside \\ \end{tabular} & 5.0 & \\ \hline \multirow{3}{*}{Ag} & \multirow{3}{*}{_Stevia rehudiana L._} & calls culture & & \
\begin{tabular}{c} 45 mg/L, after 2 d \\ 30 mg/L, 45 mg/L, \\ after 6 d \\ \end{tabular} &
\begin{tabular}{c} stevioside \\ \(\approx\)3.26 \\ rehudioside A \\ \end{tabular} & 1.75 & \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Enhanced production of secondary metabolites (SM) of medicinal plants elicited by various NPs using in vitro cultures and plants grown in soil or hydroponic solutions compared to corresponding bulk elicitors. (CSC = cell suspension culture, TPC = total phenolic content, TFC = total flavonoid content, MS = Murnashige and Skoog medium, EO = essential oil)  
Figure 2: Beneficial and adverse effects of NPs on medicinal and aromatic plants. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline  
Elicitors are compounds that are capable of causing stress to the plant, leading to increased synthesis and accumulation of secondary metabolites, or to the induction of new secondary metabolites [116; 167]. In general, secondary metabolites of plants play a role in their communication and adaptation. Plant secondary metabolism utilizes building blocks and biosynthetic enzymes derived from primary metabolic processes, and it produces large number of specialized compounds that are essential for plant survival in its environment [168; 169; 170].