A new species and three taxonomic changes in Piper (Piperaceae) from Thailand

A new species, Piper chiangdaoense from Doi Chiangdao Wildlife Sanctuary, Chiang Mai province, Thailand, is described and illustrated. Piper trichostigma is raised to specific status and an epitype is selected. Piper maculaphyllum and P. rubroglandulosum are reduced to the synonymy of P. argyrites and P. betle, respectively. A lectotype for P. argyrites is selected

Thunbergia impatienoides (Acanthaceae), a new species from Thailand

A new species, Thunbergia impatienoides, was discovered from Thailand and is here described. Detailed descriptions including pollen and seed morphologies, distribution, ecology and illustration are provided

In vitro antioxidant, antityrosinase, antibacterial and cytotoxicity activities of the leaf and stem essential oil from piper magnibaccum c. Dc.

The chemical composition of essential oils obtained from two parts of Piper magnibaccum C.DC. were analyzed by gas chromatography with a flame ionization detector (GC-FID) and gas chromatography-mass spectrometry (GC-MS). 25 components representing 93.5% of the essential oil were characterized from the leaf of P. magnibaccum. The essential oil was dominated by germacrene D (40.8%), β-caryophyllene (8.5%) and α-cadinol (6.1%). A total of 33 components, representing 87.6% of the total oil were identified from the stem of P. magnibaccum. The major constituents were β-caryophyllene (19.7%), germacrene D (10.7%), and α- cadinol (8.2%). The antioxidant potential of the leaf and stem essential oils of P. magnibaccum were determined on the basis of phenolic content and scavenging activity of the stable 1,1-diphenyl-2-picrylhydrazyl (DPPH) (IC 50 20.5, 17.5 μg/mL) and 2,2′-azino-bis-3-ethylbenzothiazoline-6-sulphonic acid (ABTS) (IC 50 11.7, 12.9 μg/ mL) free radicals. Antityrosinase activity of the leaf and stem were also screened using mushroom tyrosinase assay (I %= 49.50±0.6, 57.01±0.8). The essential oil of P. magnibaccum leaf showed a moderate antibacterial activity with MIC value of 250 μg/mL against P. aeruginosa. None of the essential oils exhibited acute cytotoxicity against MCF-7 and A-549 cells proliferation