Taxonomic Notes on the 'Mahat' (Artocarpus lacucha and A. thailandicus, Moraceae) Species Complex in Thailand.

'Mahat' is a well-known medicinal plant utilized in Thailand. The Thai name 'Mahat' has been used in many scientific articles for years. However, it is, unpredictably, a homonym of two scientific names in Flora of Thailand, i.e., A. lacucha and A. thailandicus. Additionally, both species are complex due to their high morphological variation. This causes difficulties in species identification especially when this Thai name is referred to as the scientific name for research publication, quality control of pharmaceutical raw materials, and registration of pharmaceutical products. In this study, we scrutinized the taxonomy of 'Mahat' by detailed examination of its morphology and distribution, including molecular and qualitative phytochemical studies. Leaf surfaces were inspected using scanning electron microscopy. The phylogeny of both species was studied using DNA sequences of nuclear and plastid regions. Chromatographic fingerprints, focusing on the major active compound oxyresveratrol, were identified using high-performance liquid chromatography. According to our current study, phylogenetic evidence showed that some samples of both species were clustered together in the same clade and phytochemical fingerprints were almost identical. These results are valuable data for taxonomic revision in the near future and reveal the possible utilization of A. thailandicus as a new material source of oxyresveratrol in the pharmaceutical industry.