Light-emitting diodes and their potential in callus growth, plantlet development and saponin accumulation during somatic embryogenesis of Panax vietnamensis Ha et Grushv.

In recent years, LED (light-emitting diode) has been the subject of research within the field of plant growth and development. However, there has been little discussion about using LED in vitro cultures of Panax vietnamensis, one of the important medicinal plants belonging to the Panax genus. This study examines the influence of various LED lamps on callus growth and plant formation of P. vietnamensis. Results show significant differences in growth and development, as various light conditions were suitable for different stages. Callus of 70 mg in fresh weight cultured under yellow LEDs resulted in growth of 1197 mg in fresh weight and 91.7 mg of dry weight, within a period of three months. The most effective plant formation was obtained when embryogenic calli were cultured under the combination of 60% red LED and 40% blue LED with an average of 11.21 plantlets per explant; the shoot clump fresh weight and dry weight were of 1147 and 127 mg, respectively, and the average plant height was 3.1 cm. It was also shown that this light condition was the most efficient for P. vietnamensis in vitro plant growth and development. This study provided additional evidence regarding the influence of different LEDs on ginsenoside production applying high-performance liquid chromatography (HPLC) analysis with photo-diode array (PDA) detection at ultraviolet (UV) wavelength 203 nm. The highest MR2 content was recorded when plants maintained under 20% red LED combined with 80% blue LED. However, the highest Rg1 and Rb1 content was found under fluorescent light. The results presented might provide new strategies using LEDs for adequate micropropagation protocols of P. vietnamensis.

Anti-cholinesterase activity of lycopodium alkaloids from Vietnamese Huperzia squarrosa (Forst.) Trevis.

A series of Lycopodium alkaloids, namely lycosquarosine A (1), acetylaposerratinine (2), huperzine A (3), huperzine B (4), 8α-hydrophlemariurine B (5), and huperzinine (6), has been isolated from Vietnamese Huperzia squarrosa. Among them, lycosquarosine A (1) is the new metabolite of the natural source. Lycosquarosine A completely inhibited AChE activity in a dose dependent manner with an IC50 value of 54.3 µg/mL, while acetylaposerratinine (2) showed stronger inhibitory activity than 1 with an IC50 value of 15.2 µg/mL. This result indicates that these alkaloids may be a potent source of AChE inhibitors.

Labdane-type diterpenoids from Leonurus heterophyllus and their cholinesterase inhibitory activity.

In the course of screening plants used in natural medicines as memory enhancers, a 70% ethanol extract of the aerial parts of Leonurus heterophyllus showed significant AChE inhibitory activity. Bioassay-guided fractionation and repeated column chromatography led to the isolation of a new labdane-type diterpenoids (1), named leoheteronin F, and six known compounds (2-7). The chemical structures of isolated compounds were elucidated based on extensive 1D and 2D NMR spectroscopic data. The isolates 1-7 were investigated in vitro for their anticholinesterase activity using mouse cortex AChE enzyme. Leoheteronin A (5) and leopersin G (7), which possess a 15,16-epoxy group at the side chain, were found to be potent in the inhibition of AChE.

Anti-amnesic effect of alkaloid fraction from Lycopodiella cernua (L.) Pic. Serm. on scopolamine-induced memory impairment in mice.

Lycopodiella cernua (L.) Pic. Serm. (Licopodiaceae) has been used in Vietnamese folk medicine for treating central nervous system conditions. In this study, the alkaloid fraction from the methanol extract of this plant (VLC) was evaluated for in vitro acetylcholinesterase (AChE) inhibitory activity in cognition-relevant brain areas of mice. In in vivo study, the cognitive-enhancing effect of VLC on amnesic mice induced by scopolamine was investigated by assessing a passive avoidance and a Morris water maze test. VLC inhibited AChE activity in mouse frontal cortex, hippocampus and striatum with IC50 values of 26.7, 32.2 and 25.7µg/mL, respectively. Administration of VLC (10, 20, 50 and 100mg/kg, p.o.) significantly reversed cognitive impairments in mice by passive avoidance test. Treating with VLC (50mg/kg) reduced escape latencies in training trials and prolonged swimming times in the target quadrant during the probe trial in the water maze task (P<0.05). These results indicated that L. cernua originated from Vietnam has anti-cholinesterase activity and might be useful for the treatment of cognitive impairment.