Background and Objective: Lithospermum officinale is a famous medicinal herb in the traditional medicine of
India. However, the medicinal use of its root extract is limited due to the presence of pyrrolizidine alkaloids (PzAl). It was
recently shown that PzAl are not accumulated in the cell culture of L. officinale while the biosynthetic pathway of phenolic
acids remains active so that rosmarinic acid (RsA) is the main product in the proliferated callus. Considering the existing literature on the anti-inflammatory effects of caffeic acid (CfA) and its derivatives, this research was devoted to the evaluation
of the anti-inflammatory capacity of methanolic extracts of L. officinale callus (LoE) on the rat microglial cells as the immune cells of the Central Nervous System, which play an essential role in the responses to neuroinflammation.
Methods: primary microglia were obtained from Wistar rat, then they were subjected to various amounts of CfA and methanolic extracts of 17 and 31-day L. officinale callus prior to stimulation by LPS. In addition to HPLC analysis of the extracts, viability, nitric oxide production, evaluation of the pro-inflammatory genes and cytokines in the inflamed microglia
Results: Methanolic extract of the 17-day old callus of L. officinale exhibited anti-inflammatory effects on the LPS- stimulated microglial cells much higher than that was observed for CfA. The data was further supported by the decreased expression of NOS2, TNF-α, and Cox-2 mRNA and the suppression of TNF-α and IL-1β release in the activated microglial cells
pretreated with the effective dose of LoE (0.8 mg mL-1).
Conclusion: It was assumed that better anti-neuroinflammatory performance of LoE than CfA in LPS-activated primary microglia could be a result of synergism of the components of the extract and the lipophilic nature of RsA as the main phenolic
acid of LoE. Considering the fact that LoE shows high antioxidant capacity and lacks PzAl, it is anticipated that LoE is considered as a reliable substitute to the extract of the natural root of L. officinale and plays a key role in the preparation of neuroprotective pharmaceutical formula.