Antioxidant phenolic constituents, antimicrobial and cytotoxic properties of <em>Stachys annua </em>L. from both natural resources and micropropagated plantlets

Abstract

An efficient micropropagation protocol was developed to produce <em>Stachys annua </em>plantlets and the extracts obtained from both micropropagated and naturally growing individuals were evaluated for their possible antimicrobial, antioxidant and cytotoxic activities. Mean number of shoot (4.5 ± 0.54 per explant) and node number (4.56 ± 0.5 per explant) as well as biomass yield based on fresh (0.29 ± 0.02 gm per explant) and dry weight (0.029 ± 0.003 gm per explant) were found to be the highest on MS medium with 6-BA, whilst the highest mean shoot length (36.65 ± 1.58 mm) was obtained from MS medium containing 2iP. Hexane extracts from both sources showed activity against <em>Staphylococcus aureus</em> whilst methanol extracts of micropropagated plantlets exerted activity on <em>Pseudomonas aeruginosa</em>. In antioxidant activity assays, the best antioxidant activity was up to IC₅₀ 9.41 mg/mL in DPPH and 1409.5 (mg/100 gm trolox equivalent) was found in FRAP. Extracts from natural plantlets showed higher cytotoxic activity micropropagated ones, with IC₅₀ of 0.099 µg/mL and IC₅₀of 0.211 µg/mL on HeLa cells, respectively. Total phenolics ranged from 87.47 to 605.12 in micropropagated samples while 771.46 (mg/100 gm gallic acid equivalent) in natural resources.