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Ruta graveolens L. is a medicinal plant used in traditional systems of medicine for treatment of psoriasis, vitiligo, leucoderma, and lymphomas with well-known anti-inflammatory and anticancer properties. Therefore antioxidant potential of R. graveolens (in planta and in vitro) was investigated. As antioxidants present in plant extracts are multifunctional, their activity and mechanism depends on the composition and conditions of the test system. Therefore, the total antioxidant capacity was evaluated using assays that detect different antioxidants: free radical scavenging (DPPH and ABTS), transition metal ion reduction (phosphomolybdenum assay), reducing power, and nitric oxide reduction. Content of furanocoumarin-bergapten in the extracts showed good corelation with free radical scavenging, transition metal reduction and reducing power, while total phenolic content showed good corelation with nitric oxide reduction potential. Antioxidant activity of in vitro cultures was significantly higher compared to in vivo plant material. The present study is the first report on comprehensive study of antioxidant activity of R. graveolens and its in vitro cultures.

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Effect of various abiotic (methyl jasmonate, salicylic acid) and biotic (yeast extract, Aspergillus niger) elicitors on furanocoumarin production and in situ product removal was studied using shoot cultures of Ruta graveolens L. Elicitation by yeast extract (1% w/v) on day 15 was most effective. It led to 7.8-fold higher furanocoumarin production that was attained 24 h after elicitation and 43% of the product was released into the medium. Changes in the relative concentration of furanocoumarins produced depend on the elicitor used. Molar ratio of bergapten increased to 93% in response to yeast extract. With the perspective of developing a commercially feasible process, an approach for preserving viability of biomass and its reuse needs to be developed. For this, medium renewal strategy was investigated. Removal of the spent medium 48 h after elicitation allowed in situ product removal and proved effective in revival of cultures, allowing reuse of biomass. A week after medium renewal, the revived biomass was re-elicited and a second furanocoumarin production peak was obtained. A perfusion-based bioprocess optimization approach, employing elicitation coupled with medium renewal with subsequent re-elicitation, as a new strategy for improved furanocoumarin production, has been suggested.

Cell cultures of Ruta graveolens L. were used as a model system to study the relationship between cellular organization and furanocoumarin production. Relative contributions of individual cells were traced using a combination of biochemical and localization techniques in three types of cell cultures: dispersed, aggregated, and organized. The proportion of relative furanocoumarins produced varied with the organization level in cultures. Productive population in dispersed cell culture was 10% which increased to 17% and to 35% in aggregated and organized cell cultures, respectively. Large cell clusters accumulating furanocoumarins were restricted to organized cell cultures. In these lines, sites for psoralen, bergapten, and xanthotoxin accumulation were spatially separated from each other, which has been reported for the first time. Variation in production was due to change in relative size of productive population in the three types of cultures studied. A model has been proposed for differential furanocoumarin producing ability of cells based on differentiation levels.