Antiviral screening and bioautographic assessment of radical scavenging, estrogenic and AchE-inhibitoric activity of Sideritis species

Sideritis L. (Lamiaceae) is a genus represented by more than 150 species [1] and is known in folk medicine to treat respiratory diseases [2], geriatric disorders [3], enhance memorizing skills [4],[5] and possess antioxidant properties [6].

In this work, the species S.clandestina (Bory&Chaub.)Hayek; S.endressii Willk.; S.glacialis Boiss.; S.hirsuta L.; S.italica (Mill.)Greuter&Burdet; S.dichotoma Huter; S.raeseri Boiss.&Heldr.; S.scardica Griseb.; S.syriaca L. and S.hyssopifolia L. were screened by planar DPPH, planar Acetylcholinesterase (AchE) & its microtiter format assay [7] and planar Yeast Estrogen Screen (YES) assay on the developed HPTLC plate (Silica 60-mobile phase: dichloromethane/methanol/water, for DPPH with acetic acid).

Selected extracts were tested against different infectious viruses: None of the extracts had an effect against the human corona virus (HCoV-229E). S.hirsuata showed a clear effect at concentration range 6-100 µg/ml on Influenza H3N2 virus.

All species except S.italica and S.clandestina exhibited AchE inhibition on HPTLC plate, some of them were elucidated as artefacts in a control assay. In microtiter plate, all extracts (10 mg/ml) demonstrate enzyme inhibition: S.scardica the strongest (70%) and S.italica the lowest (25%) effect. S.clandestina shows one spot with clear estrogenic activity. For S.dichotoma and S.glacialis only weak estrogenic zones were observed. In planar DPPH assay, all species show radical scavenging capacity at 75 µg/µl.

In conclusion, the screening indicates that not only the Sideritis species currently recognized by HMPC [8] might be of interest for health related treatments and further research is desirable, especially for antiviral activity, which is reported here the first time.

• References

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