Yunbao Liu

An efficient and economical MTT assay for determining the antioxidant activity of plant natural product extracts and pure compounds.

Antioxidants scavenge free radicals, singlet oxygen, and electrons in cellular redox reactions. The yellow MTT [3-(4,5-dimethylthiazole-2-yl)-2,5-diphenyltetrazolium bromide] is reduced to a purple formazan by mitochondrial enzymes. NADPH is the basis of established in vitro cell viability assays. An antioxidant assay has been developed utilizing the redox reaction between MTT and selected natural product extracts and purified compounds. This simple, fast, and inexpensive MTT antioxidant assay is comparable with the lipid peroxidation inhibitory assay and can be mechanized to achieve high throughput.

Curcuma longa and Curcuma mangga leaves exhibit functional food property

Although leaves of Curcuma mangga and Curcuma longa are used in food preparations, the bioactive components in it are not known. In this study, antioxidant, antiinflammatory and anticancer activities of leave extracts and its isolates were investigated using established bioassay procedures in our laboratory. The leaf extracts of both plants gave similar bioassay and chromatographic profiles. The methanolic and water extracts of C. mangga (CMM and CMW) and C. longa (CLM and CLW), at 100 μg/mL, inhibited lipid peroxidation (LPO) by 78%, 63%, 81% and 43%, cyclooxygenase enzymes COX-1 by 55%, 33%, 43% and 24% and COX-2 by 65%, 55%, 77% and 69%, respectively. At same concentration, CMM, CMW, CLM and CLW showed growth inhibition of human tumour cell lines by 0-46%. Therefore, a bioassay-guided isolation of water and methanolic extracts of C. longa was carried out and afforded nine isolates. At 25 μg/mL, these compounds inhibited LPO by 11-87%, COX-1 and -2 enzymes by 0-35% and 0-82% and growth of human tumour cells by 0-36%, respectively.

Bioactive acylphloroglucinols from Hypericum densiflorum.

Three acylphloroglucinol derivatives have been isolated from the hexane and acetone extracts of the aerial parts of Hypericum densiflorum Pursch. The compounds were characterized by NMR spectroscopy and mass spectrometry and identified as 4‐geranyloxy‐2,6‐dihydroxybenzophenone (1), 4‐geranyloxy‐1‐(2‐methylpropanoyl)‐ phloroglucinol (2) and 4‐geranyloxy‐1‐(2‐methylbutanoyl)‐phloroglucinol (3). Compounds 1–3 were evaluated for in vitro cell proliferation inhibitory activity against human breast (MCF‐7), lung (NCI H460), CNS (SF‐268), stomach (AGS) and colon (HCT‐116) tumor cell lines; antibacterial activity against methicillin‐resistant Staphylococcus aureus (MRSA); inhibition of cyclooxygenase (COX‐1 and ‐2) enzymes; and antioxidant activity in the lipid peroxidation (LPO) assay. All three compounds showed moderate to strong antitumor, antibacterial, antioxidant and inhibition of COX‐2 activities. Also, this is the first reported occurrence of compound 3 in the Hypericum genus. Copyright

Blood–Brain Barrier Permeability of Bioactive Withanamides Present in Withania somnifera Fruit Extract

The neuroprotective effect of Withania somnifera L. Dunal fruit extract, in rodent models, is known. Withanamides, the primary active constituents in W. somnifera fruit extract exhibited neuroprotective effects against β‐amyloid‐induced cytotoxicity in neuronal cell culture studies. Therefore, we investigated the blood–brain barrier permeability of withanamides in W. somnifera fruit extract in mice using HPLC coupled with high resolution quadrupole time of flight mass spectrometer (Q‐TOF/MS) detection. Mice were administered with 250 mg/kg of W. somnifera extract by intraperitoneal injection, and the blood and brain samples analyzed by Q‐TOF/MS detection. Four major withanamides were detected in brain and blood of mice administered with W. somnifera extract. The results suggested that the withanamides crossed the blood–brain barrier. These results may help to develop W. somnifera fruit extract as a preventive or therapeutic botanical drug for stress‐induced neurological disorders. Copyright

Leaf constituents of Curcuma spp. suppress Meloidogyne hapla and increase bacterial-feeding nematodes

Bioactive compounds extracted from agronomical plants have the potential to be ecologically safe and efficient alternatives to restricted broad-spectrum nematicides for managing root pests like Meloidogyne hapla. This study determined the effects of Curcuma longa and C. mangga leaf extracts and constituents on M. hapla infection, beneficial nematodes found in soil, and plant growth under glasshouse conditions over 350-420 degree-days (base 10°C). Incorporation of 60 and 120 g fresh leaves (kg soil)−1 of both Curcuma spp. suppressed the numbers of M. hapla infecting roots of tomato cv. Rutgers but increased beneficial nematodes in soil with minimal negative effect on plant health and growth. Curcuma mangga appears to be more favourable to beneficial nematodes than C. longa. Rhabditis, Acrobeloides and Eucephalobus were the dominant beneficial nematodes isolated from soils amended with Curcuma spp. The safe and selective activities of Curcuma spp. suggest potential for developing biologically integrated M. hapla management strategies.