Comparative in vitro study of immunomodulatory activity of two extracts from the aerial part of Limonium gmelinii

Limonium (L.) gmelinii (Willd.) Kuntze is a valuable industrially significant Kazakhstani plant. Its extracts and isolated compounds were proven to display antioxidant, hepatoprotective, antimicrobial, antimutagenic, antitumor, antiviral [1], [2]; antitrypanosomal [3] and neuroprotective effects [4], which may indicate of potential immunomodulatory activity. Extracts obtained by conventional (maceration; CE) and ultrasound-assisted extraction (UAE) with 50% aqueous ethanol from the aerial part of L. gmelinii were compared by their yield, total phenolic and flavonoid content and in vitro immunomodulatory activity. Extract 1 (obtained by UAE) and Extract 2 (obtained by CE) differed slightly by their yield, total phenolic and flavonoid content: 30.25 ± 1.6% and 33.51 ± 2.4%; 378.1 ± 4.5 and 382.2 ± 3.3 mg GAE/g DW; 90.22 ± 2.8 and 94.61 ± 1.9 mg QE/g DW, respectively. ELISA showed that both extracts stimulated cytokines production in LPS-activated and inhibited them in non-activated murine macrophages and lymphocytes. Maximum stimulatory and inhibitory effect on macrophages was at a concentration of 10 µg/mL and 1 mg/mL, and 100 µg/mL for both extracts, respectively. The maximum stimulatory effect on IL-6 and TNF-α production by non-activated lymphocytes was found at 5 µg/mL and 1 µg/mL, respectively. Suppression of TNF-α was observed at all dosages; of IL-6 at 100 µg/mL. The proliferation assay demonstrated stronger suppressive effect of Extract 2; both preparations had a stimulatory effect on the inactivated lymphocytes. L. gmelinii extracts obtained by UAE and CE had similar immunomodulatory activity. The data obtained gives basis for further research into the mechanisms of this activity and active compounds responsible for it.

Publication History

Article published online:
12 December 2022

• References

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