*3.1. General Experimental Procedures*

NMR spectra were recorded in DMSO-*d*<sup>6</sup> and acetone-d6 on a Bruker DPX-500 and DRX-700 (Bruker BioSpin GmbH, Rheinstetten, Germany) spectrometers, using TMS as an internal standard. HRESIMS spectra were measured on a Maxis impact mass spectrometer (Bruker Daltonics GmbH, Rheinstetten, Germany).

Low-pressure liquid column chromatography was performed using silica gel (50/100 μm, Imid Ltd., Krasnodar, Russia). Plates (4.5 cm × 6.0 cm) precoated with silica gel (5–17 μm, Imid Ltd., Krasnodar, Russia) were used for thin-layer chromatography. Preparative HPLC was carried out on a Shimadzu LC-20 chromatograph (Shimadzu USA Manufacturing, Canby, OR, USA) with a Shimadzu RID-20A refractometer (Shimadzu Corporation, Kyoto, Japan) using a YMC ODS-AM (YMC Co., Ishikawa, Japan) (5 μm, 10 mm × 250 mm) and YMC SIL (YMC Co., Ishikawa, Japan) (5 μm, 10 mm × 250 mm) columns.

Melatonin (**1a**) was purchased from «JSC «PE «Obolenskoe» (Obolensk, Russia).
