Doctoral defence: Khan Nguyen Viet “Chemical composition and bioactivity of extracts and constituents isolated from the medicinal plants in Vietnam and their nanotechnology-based delivery systems”

On 14 February at 15:00 Khan Nguyen Viet will defend his doctoral thesis “Chemical composition and bioactivity of extracts and constituents isolated from the medicinal plants in Vietnam and their nanotechnology-based delivery systems”.

Supervisors:
Professor Ain Raal, University of Tartu
Professor Jyrki Tapio Heinämäki, University of Tartu

Opponent:
Associate Professor Yvonne Holm, University of Helsinki (Finland)

Summary
Medicinal plants and traditional medicines have been proved to be the highly successful source for the discovery of new drugs. Plant-origin drugs, however, could have limitations such as poor solubility or poor absorption in the body, thus leading to low bioavailability, consequently restricting their utility in clinical practice. Nanotechnology-based drug delivery systems for plant-origin actives have been demonstrated to increase several to hundred times oral bioavailability compared to drug alone. A combination of herbal medicines with pharmaceutical nanotechnology can be expectedly a key tool for the advancement of medicinal plant research and therapy.

The aim of the study was to gain knowledge on the chemical composition and bioactivity of herbal extracts and compounds isolated from Chisocheton paniculatus, Alphonsea tonkinensis A.DC. and Zephyranthes ajax Hort. used in the traditional medicine of Vietnam, and to develop novel nanotechnology-based drug delivery systems for the present herbal extract(s) and constituent(s).

The present study provided scientific databases of phytochemical constituents and bioactivities of the selected medicinal plants. Seven new compounds and fifteen known compounds were isolated and characterized. Many of them isolated from their genus for the first time. Some compounds and/or extracts showed promising potential agents for anti-cancer, anti-inflammatory and/or Alzheimer's disease therapeutics.

Haemanthamine isolated from Zephyranthes ajax Hort., exhibiting a potent anti-cancer substance, were first successfully prepared nanofibers intended for a solid template for self-assembled liposomes. The results showed the present nanofiber-based strategy for delivering self-assembled liposomes is applicable for such plant-origin alkaloids. The nanofibers loaded with haemanthamine were verified to be an alternative approach for the formulation of a liposomal drug delivery system and stabilization of the liposomes of the present alkaloid.