Microscopic Characterization as a Tool for Separation of Stemona Groups

Abstract

Introduction: Stemona plants have been traditionally used as an insecticide, scabicide and pediculocide, and for the treatment of skin and respiratory diseases. Stemona can be separated into two groups according to their morphological characters and bioactive components i.e. stichoneurine and protostemonine groups. Protostemonine group contains alkaloids that possess potent insecticidal activity while stichoneurine group accumulates alkaloids with antitussive activity. In Thailand, a vernacular name "Non Tai Yak" refers to the roots of different species of Stemona, making it confusing to discern different species. The purposes of this study are to investigate the microscopic characteristics of the roots of seven species of Stemona growing in Thailand and to distinguish and identify these groups of Stemona. Methods: Cross-sectional histology of fresh root samples and powdered drug characteristics of 7 species of Stemona were studied under a microscope. Results: The roots of Stemona in the stichoneurine group (S. tuberosa and S. phyllantha) contained a non-lignified large pith while the roots of protostemonine group (S. burkillii, S. cochinchinensis, S. collinsiae, S. curtisii and S. kerrii) had a small lignified one. The powder of stichoneurine group contained numerous thin-walled parenchyma, but only few thick-walled parenchyma and lignified fibers and vessels were present. In contrast, thick-walled parenchyma and lignified fibers and vessels were frequently found in the powdered roots of protostemonine Stemona. These characteristics could be used to discern between Stemona in the stichoneurine and protostemonine groups. Conclusions: The microscopic characterizations can be used as a primary tool to categorize and separate 2 main Stemona groups.

The Diversity of Stemona Stilbenoids As a Result of Storage and Fungal Infection

“…Following up on the present survey, Stemona species can be separated into two different groups due to the presence or absence of phenylbenzofurans (Figure , Table ). This separation is also supported by morphological characters and DNA sequencing . Infection of living roots leads to an increasing formation of the stilbenes 1 and 2 and dihydrostilbenes 3 and 4 in almost all species, suggesting that they play an ecological role as phytoalexins. ,, In this case, the phenylbenzofuran-producing species were characterized additionally by the structurally corresponding stemofurans A and C ( 38 , 39 ) (Table ), confirming the supposed biosynthetic connection between stilbenes and phenylbenzofurans shown in Figure .…”

“…11 Following up on the present survey, Stemona species can be separated into two different groups due to the presence or absence of phenylbenzofurans (Figure 4, Table 1). This separation is also supported by morphological characters 41 and DNA sequencing. 42 Infection of living roots leads to an increasing formation of the stilbenes 1 and 2 and dihydrostilbenes 3 and 4 in almost all species, suggesting that they play an ecological role as phytoalexins.…”

Structural Relationships of Stemona Alkaloids: Assessment of Species-Specific Accumulation Trends for Exploiting Their Biological Activities

“…Basically, most effects can be attributed to either tuberostemonine ( 3 ) or stemofoline ( 10 ) derivatives, representing two different skeletal types . As shown in a previous overview, this chemical divergence also suggests a clear taxonomic segregation within the genus Stemona , later confirmed by morphological characters , and microsatellite markers . Further progress in exploiting the various biological activities is greatly hampered by using not properly identified and documented plant material or, even more, by purchasing mixtures of underground parts from local markets or medical plant suppliers originating from different localities or species .…”

“…In the course of identifying the genetic diversity of 68 Stemona samples, collected from different geographical localities in Thailand, corresponding plant material was cultivated under field conditions in the Maize and Sorghum Research Centre “Rai Suwan” of Kasetsart University near Nakhon Ratchasima in east Thailand . Besides morphological and anatomical studies, this comprehensive collection also served for a broad-based phytochemical comparison to establish species-specific accumulation trends. Additional collections from natural habitats are included to complete this survey.…”