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Bioassay-directed fractionation of the dried roots of Asparagus cochinchinensis led to the isolation of a new spirostanol saponin, asparacoside (1), two new C-27 spirosteroids, asparacosins A (2) and B (3), a new acetylenic derivative, 3' '-methoxyasparenydiol (4), and a new polyphenol, 3'-hydroxy-4'-methoxy-4'-dehydroxynyasol (6), as well as five known phenolic compounds, asparenydiol (5), nyasol (7), 3' '-methoxynyasol (8), 1,3-bis-di-p-hydroxyphenyl-4-penten-1-one (9), and trans-coniferyl alcohol (10). Compounds 1, 6, and 8 demonstrated moderate cytotoxicities in a panel comprised of KB, Col-2, LNCaP, Lu-1, and HUVEC cells, with IC(50) values ranging from 4 to 12 microg/mL. The structures were determined by spectroscopic and chemical methods.

Context An ethnobotany-based approach in the selection of raw plant materials to study was implemented. Objective To acquire raw plant materials using ethnobotanical field interviews as starting point to discover new bioactive compounds from medicinal plants of the Lao People’s Democratic Republic. Methods Using semi-structured field interviews with healers in the Lao PDR, plant samples were collected, extracted, and bio-assayed to detect bioactivity against cancer, HIV/AIDS, TB, malaria. Plant species demonstrating activity were recollected and the extracts subjected to a bioassay-guided isolation protocol to isolate and identify the active compounds. Results Field interviews with 118 healers in 15 of 17 provinces of Lao PDR yielded 753 collections (573 species) with 955 plant samples. Of these 955, 50 extracts demonstrated activity in the anticancer, 10 in the anti-HIV, 30 in the anti-TB, and 52 in the antimalarial assay. Recollection of actives followed by bioassay-guided isolation processes yielded a series of new and known in vitro-active anticancer and antimalarial compounds from 5 species. Discussion Laos has a rich biodiversity, harboring an estimated 8000–11,000 species of plants. In a country highly dependent on traditional medicine for its primary health care, this rich plant diversity serves as a major source of their medication. Conclusions Ethnobotanical survey has demonstrated the richness of plant-based traditional medicine of Lao PDR, taxonomically and therapeutically. Biological assays of extracts of half of the 955 samples followed by in-depth studies of a number of actives have yielded a series of new bioactive compounds against the diseases of cancer and malaria.

Bioassay-directed fractionation led to the isolation of seven compounds from a sample of the dried leaves, twigs, and branches of Diospyros quaesita Thw. (Ebenaceae). One of the isolates, betulinic acid 3-caffeate (1), showed in vitro antimalarial activity against Plasmodium falciparum clones D(6) (chloroquine-sensitive) and W(2) (chloroquine-resistant) with IC(50) values of 1.40 and 0.98 microM, respectively. Evaluation of compound 1 in the human oral epidermoid (KB) cancer cell line revealed cytotoxicity at ED(50) of 4.0 microM. In an attempt to reduce the cytotoxicity of 1, the acetylated derivative 1a and betulinic acid (1b) were prepared. Of the seven isolates, diospyrosin (2) was determined to be a new neolignan. In addition to 1, other known compounds isolated in this study were pinoresinol, lariciresinol, N-benzoyl-L-phenylalaninol, scopoletin, and poriferast-5-en-3beta,7alpha-diol. The structure of 2 was elucidated based on spectroscopic data analysis including 1D- and 2D-NMR, and HR-ESI-MS.

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