No abstract

Bioassay-guided fractionation of the MeOH extract from the stem bark of Neonauclea purpurea used in traditional medicine, resulted in the isolation of 2 indole alkaloids, cadambine (1) and α-dihydrocadambine (2), as well as a quinolic compound, 2,6-dimethoxy-1,4-benzoquinone (3). Antimalarial activity evaluation showed that compounds 2 and 3 exhibited mild in vitro antimalarial activity against Plasmodium falciparum, the chloroquine-resistant strain K1 with IC 50 values of 6.6 and 11.3 µM, respectively. Compounds 1 and 2 showed no cytotoxicity to monkey (Vero) cells, but compound 3 showed weak cytotoxicity with an IC 50 value of 1.19 µM.

Plant materials and extraction Whole plants of A. donax L. during the flowering stage were collected in Thailand. The voucher specimen was prepared by Forest Herbarium (BKF) Department of National Parks, Wildlife and Plant Conservation, Ministry of Natural Resources and Environment to use as plant reference (Reference number: BKF NO. 19581). The voucher specimen compared with that in BKF database was identified as A. donax L. by Mr. Sukid Rueangruea, Forestier Professional Academician of BKF. A. donax L.

In this study, the interference of T-DNA insertion upon Agrobacterium-mediated transformation on the biochemical expression of the host genome is discussed. Plant extracts of transgenic Artemisia annua L. with or without an overexpressed farnesyl pyrophosphate synthase gene have been investigated for their bioactivity and metabolic profile in comparison with wild type A. annua. The highest antimicrobial activity against Staphylococcus aureus, Bacillus subtilis and Candida albicans was observed in the T253 transgenic lines. Moreover, the crude extract from T253 showed higher antimalarial activity against the Plasmodium faciparum K1 strain than those of the others. The terpenoid constituents and antimicrobial properties of the plant samples were grouped by hierarchical clustering analysis. The clustering showed that squalene is a putative compound that might be involved in increasing the bioactivity of the transgenic line. In addition, T253 had a triterpene content that was about twice as great as that of the T253-2 line, which had a higher content of sesquiterpenes. However, both lines were transformed by the same FPS gene. These results suggested that the different bioactive properties observed in each transgenic line may be caused by variations in their terpenoid composition, which is affected by T-DNA insertion at different positions in the host plant.

Cytokinins are phytohormones that play multiple roles to control plant growth and development. In this study, leaf biomass and the production of andrographolide compounds in a medicinal plant Andrographis paniculata were significantly increased after exogenously treating with the synthetic cytokinin cytokinin-1-(2-chloro-4-pyridyl)-3-phenylurea (CPPU) at 0 (water), 5, or 10 mg L and observed the results for 24 h, 48 h, and 7 days of treatment. It was found that CPPU could significantly enhance new axillary bud formation and further promote branching 4.6-5.6-fold higher, resulting in higher fresh weight (FW) and dry weight (DW) than the control. Application of CPPU at 5 mg L significantly promoted the highest contents of total reducing sugar at 2.5-fold in leaves and at 1.5-fold in roots. Although treatments of CPPU significantly affected the increasing contents of chlorophyll and carotenoid (1.2-1.6-fold), CPPU at 10 mg L slightly caused leaf stress and chlorophyll reduction. Interestingly, 5 mg L CPPU could enhance andrographolide content, an active anti-infectious compound in Andrographis paniculata (2.2-fold higher than the control) that reached the highest content at 24 h after treatment. This study suggested that CPPU should be suitable for field application to promote leaf yields and induce the production of useful pharmaceutical compounds in Andrographis paniculata.