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In this study, Astragalus membranaceus hairy root cultures (AMHRCs) were established as an attractive alternative source for the efficient production of isoflavonoids (IF). A. membranaceus hairy root line II was screened as the most efficient line and was confirmed by PCR amplification of rolB, rolC and aux1 genes. Culture parameters of AMHRCs were systematically optimized, and five main IF constituents were quali-quantitatively determined by LC-MS/MS. Under optimal conditions, the total IF accumulation of 34 day old AMHRCs was 234.77 μg/g dry weight (DW). This yield was significantly higher compared to that of 3 year old field grown roots (187.38 μg/g DW). Additionally, in vitro antioxidant assays demonstrated that AMHRC extracts exhibited antioxidant activities with lower IC50 values (1.40 and 1.73 mg/mL) as compared to those of field grown roots (1.96 and 2.17 mg/mL). Overall, AMHRCs may offer a promising and continuous product platform for naturally derived, high quality and valuable nutraceuticals.

In this work, Isatis tinctoria hairy root cultures (ITHRCs) were established as an alternative source for flavonoids (FL) production. I. tinctoria hairy root line V was found to be the most efficient line and was further confirmed by the PCR amplification of rolB, rolC and aux1 genes. Culture parameters of ITHRCs were optimized by Box-Behnken design (BBD), and eight bioactive FL constituents (rutin, neohesperidin, buddleoside, liquiritigenin, quercetin, isorhamnetin, kaempferol and isoliquiritigenin) were quali-quantitatively determined by LC-MS/MS. Under optimal conditions, the total FL accumulation of ITHRCs (24 day-old) achieved was 438.10 μg/g dry weight (DW), which exhibited significant superiority as against that of 2 year-old field grown roots (341.73 μg/g DW). Additionally, in vitro antioxidant assays demonstrated that ITHRCs extracts exhibited better antioxidant activities with lower IC50 values (0.41 and 0.39, mg/mL) as compared to those of field grown roots (0.56 and 0.48, mg/mL). To the best of our knowledge, this is the first report describing FL production and antioxidant activities from ITHRCs.

In this work, Astragalus membranaceus hairy root cultures (AMHRCs) were exposed to ultraviolet radiation (UV-A, UV-B, and UV-C) for promoting isoflavonoid accumulation. The optimum enhancement for isoflavonoid production was achieved in 34-day-old AMHRCs elicited by 86.4 kJ/m(2) of UV-B. The resulting isoflavonoid yield was 533.54 ± 13.61 μg/g dry weight (DW), which was 2.29-fold higher relative to control (232.93 ± 3.08 μg/g DW). UV-B up-regulated the transcriptional expressions of all investigated genes involved in isoflavonoid biosynthetic pathway. PAL and C4H were found to be two potential key genes that controlled isoflavonoid biosynthesis. Moreover, a significant increase was noted in antioxidant activity of extracts from UV-B-elicited AMHRCs (IC50 values = 0.85 and 1.08 mg/mL) in comparison with control (1.38 and 1.71 mg/mL). Overall, this study offered a feasible elicitation strategy to enhance isoflavonoid accumulation in AMHRCs and also provided a basis for metabolic engineering of isoflavonoid biosynthesis in the future.

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