Growth patterns and biological activities of Pelargonium sidoides DC. hairy root cultures: A commercially-feasible industrial scale-up to improve yields

Abstract

Pelargonium sidoides DC. (Geraniaceae), a broadly investigated perennial herb native to South Africa, contains numerous medicinal coumarins in its roots with confirmed anti-viral properties in both clinical and in vitro studies. Transgenic hairy root lines (HRLs) of P. sidoides mediated by Agrobacterium tumefaciens strain C58C1 (pRiA4) were established in the present study. The established hairy root cultures (HRCs) were treated with different subculture cycles during culture growth (35 days). The maximum specific growth rate (μ = 0.091) of HRCs was recorded on day 14, corresponding to doubling times (tD= 9.17 days) based on the exponential growth model. The harvested times were then considered to test the efficiency of biological and antioxidant activities of hairy root (HR) extracts for functional and correlation analysis. Among the three selected HRLs, HRL4 significantly showed higher content of total phenols (474.80 ± 22.34 mg GAE/g FW) and total flavonoids (0.323 ± 0.036 mg QE/g FW) on day 19 of culture. The maximum malondialdehyde (MDA) content was achieved by all studied HRLs at the end of the culture period (21–35 days). The potential of the HRL extracts to scavenge DPPH (2,2-diphenyl-1-picrylhydrazyl) radicals was measured in the range from 25.46 ± 3.13% to 48.56 ± 1.50%. The greatest β-carotene/linoleic acid (β-car) bleaching activity was found in HRL10 (94.52 ± 3.14%) on day 28 of culture. A significant positive correlation between antioxidant activity and total flavonoid content was observed in HRLs. These findings can be considered for the commercial production of pharmaceutically important compounds of P. sidoides through the selection of high-yielding HRLs in biotechnological production systems.