Not all Taua-tauas are Alike: A Morphological, Molecular Genetic, Phytochemical, and Anti-thrombocytopenic Profiling of Different Euphorbia hirta Linn. Plants from the Philippines

Abstract

Background and Objective: Despite the growing interest and the emergence of Euphorbia hirta-based commercial tea, drinks, and tablets as potential remedies for low-platelet count associated with dengue fever, no extensive characterization and toxicity testing were ever conducted on the different varieties found in the Philippines. The present study, therefore, investigated the morphological, molecular genetic, phytochemical, and antithrombocytopenic profile of the different varieties of Euphorbia hirta Linn, or snake weed, also known as taua-taua/tawa-tawa (Tag.).

Methodology:Ten plant samples of taua-taua were collected from different locations namely: Los Baños (LBG), Cebu (CG), Tagaytay (TGB), Dipolog (two varieties: DPG and DPR), Zamboanga City (ZCG), Quezon City (QCG) and Pagadian (three varieties: PGRB, PGRS and PGG). The plant samples were photodocumented and air-dried voucher specimens were preserved and submitted for taxonomic identification. A total of 14 character traits were scored and utilized in the construction of morphology-based tree. Morphometrics and DNA analysis of rbcL gene were done to provide support for the morphology-based analysis. Cut stems and leaves were soaked in 20 mL methanol overnight, filtered and prepared for phytochemical profiling by high performance liquid chromatography (HPLC). Anti-thrombocytopenia activity was determined using the cyclophosphamide-induced mouse model. The
morphological traits of some varieties of taua-taua found in different parts of the Philippines were defined.

Results: It was shown based on morphology, morphometrics and rbcL sequence analysis that there were two clades of putative taua-taua in a typical field collection area where these plants grow: the E. hirta clade and the E. lasiocarpa/E. prostrata clade. The HPLC analysis of the phytochemical signatures of these plants showed that taua-taua samples of the same species do not necessarily produce the same relevant compounds and this may be related to the environmental differences where these plants thrive.

Conclusion: The biological activities claimed by previous studies may not necessarily hold true for all taua-taua varieties. The anti-thrombocytopenic activity of taua-taua extracts could vary in terms of pattern where one elicits fluctuating pattern for its mean platelet count while the other exhibits stable mean platelet count followed by a late decline with corresponding effects on survival. Statistically significant anti-thrombocytopenic effect was demonstrated by the QCG extract. Further studies must be done to elucidate the cause of the mouse mortalities in the taua-taua fed mice and relate them with the components of the extract.

Key words: E. hirta, taua-taua, anti-thrombocytopenia, morphological analysis, molecular genetics, HPLC profiling