The Plant Family Amaryllidaceae: Special Collection Celebrating the 80th Birthday of Professor Johannes van Staden

The Editor-in-Chief and publishers of Natural Product Communications are indeed gratified to facilitate this special collection on the Amaryllidaceae on the occasion of the 80th birthday of Prof. Johannes van Staden. A distinguished researcher, scientist and academic, Prof. van Staden is recognized the world over for his outstanding contributions to the plant sciences. He obtained his PhD in 1970 from the University of Natal (South Africa) after being appointed as Lecturer in the Department of Botany in 1967. He rose through the ranks to become Associate Professor (1976) and then Full Professor and Head of Department in 1987. Prof. van Staden has been a Research Fellow at University College of Wales, University of California Davis, National Australian University, the Hebrew University of Jerusalem, Broom’s Barn Experimental Station in the United Kingdom and University of West-Hungary (from where he also holds an Honorary DSc). He is presently Director of the Research Centre for Plant Growth and Development (RCPGD) at the University of KwaZulu-Natal, which is widely recognized for many of its groundbreaking endeavors in plant science research. Although Prof. van Staden would best describe himself as a plant physiologist, his interests cover several fields such as ethnobotany, phytochemistry, pharmacology, toxicology, biotechnology, molecular biology, and plant growth regulation. He has published prolifically, with over 1400 articles in ISI-rated journals which has seen him being ranked among the top 0.5% of most cited authors. Prof. van Staden is deeply indebted to the over 300 master’s, doctoral, and postdoctoral students whose arduous efforts at RCPGD have made this possible. He is the recipient of numerous awards both locally and internationally, most notably gold medals from the South African Association of Botanists (1994), South African Academy for Science and Arts (2007) and Southern Africa Association for the Advancement of Science (2010). He has played diverse roles over the years on several scientific journal boards, including that of an advisor to Natural Product Communications. His other notable editorial roles both past and present include Editor-in-Chief of South African Journal of Botany (2000-present), Editor-in-Chief of Plant Growth Regulation (2008-2013), Associate Editor of Acta Physiologia Plantarum (2011-present), Associate Editor of Frontiers in Ethnopharmacology (2015-present), Associate Editor of Journal of Ethnopharmacology (2003-2014), and Associate Editor of PCTOC: Journal of Biotechnology (2011-2015).

The geophytic plant family Amaryllidaceae J. St.-Hil. is conspicuous among bulbous plants. ¹ It has a pantropical distribution with centers of concentration in Andean South America, the Mediterranean and southern Africa. ¹ These plants are, however, recognizable all over the world for their appealing floral attributes which are epitomized in its members such as “daffodils” (Narcissus), “snowdrops” (Galanthus), and “snowflakes” (Leucojum). ¹ They also have a long and rich history in the traditional medicinal practices of indigenous populations around the globe. ^{2 -4} For example, the writings of Hippocrates refer to the usage of Narcissus plants during the classical Greek period. ² Apart from this, archeological findings suggest that Brunsvigia was being used by the first inhabitants of southern Africa around 3000 years ago. ³ Further back, there is evidence to show that Hymenocallis, Stenomesson and Zephyranthes were prevalent in Inca medicinal culture in South America. ⁴ The scope and expanse of the use of Amaryllidaceae plants in present day traditional medicine is quite broad. ³ For example, nearly 50 species from 25 different countries around the world have been indicated in treatments against infectious diseases alone. ⁵

Apart from these interesting floristic and cultural properties, the Amaryllidaceae is most recognizable for its isoquinoline alkaloid constituents which exhibit interesting chemical and biological properties. ⁶ The nearly 1000 species belonging to 80 genera of the family, the majority of which have yet to be studied, provide an excellent platform for phytochemical-based efforts. ⁶ The substances identified in such studies have been grouped according to their characteristic structural features, which include representatives such as lycorine (1), crinine (2), galanthamine (3), tazettine (4), homolycorine (5), montanine (6), pancratistatin (7), cherylline (8), belladine (9), augustamine (10), and cripowellin A (11) (Figure 1). ⁶ These fascinating and challenging molecular architectures have also provided the ideal backdrop for a plethora of target-orientated, multistep synthetic endeavors. ⁷ For example, over 60 formal syntheses have been published on structures related to the phenanthridone pancratistatin (7) alone. ⁷ Amaryllidaceae alkaloids exhibit a wide range of biological properties, such as antiviral, antibacterial, antifungal, antiparasitic, anti-oxidant, anti-inflammatory, and insect antifeedant effects, as well as ascorbic acid biosynthesis and DNA, RNA, and protein inhibitory activities. ⁶ However, they are best associated with their cytotoxicities and effects pertaining to the motor-neuron system. ⁶ In particular, galanthamine (3) has achieved widespread acclaim as a commercially successful Alzheimer’s drug due to its potent acetylcholinesterase inhibitory activity, which is known to be significant in the pathophysiology of this age-related disease. ⁶ Furthermore, pancratistatin (7) has evolved into a potential anticancer drug due to its potent and cell line selective antiproliferative properties. ⁶ As a consequence, interest in the Amaryllidaceae as a source of novel biologically active chemical entities has been rejuvenated in recent years.

Figure 1

Structurally diverse and biologically significant alkaloid representatives of the Amaryllidaceae.

Given this fascinating background of the Amaryllidaceae, as well as the accomplishments of Prof. van Staden in this field and elsewhere, Natural Product Communications is pleased to bring together via this special collection efforts from diverse fields of research. It should be noted that such an undertaking has never been attempted prior to the present effort. It aims to showcase the cutting-edge research being carried out on the chemical and biological aspects of the Amaryllidaceae in laboratories around the world. It consolidates and installs the Amaryllidaceae as truly unique among bulbous flowering plants, whose full potential is still to be realized.