Plant extracts from central Asia showing antiinflammatory activities in gene expression assays.

Plant natural products remain a good resource for the discovery of novel pharmaceuticals. A mouse macrophage-based quantitative, reverse transcription polymerase chain reaction (qRT-PCR) system was optimized to screen plant extracts for antiinflammatory activities using three well known genetic markers of inflammation. Plants used for extraction were taxonomically identified and vouchered species from two Central Asian countries, Uzbekistan and Kyrgyzstan, collected through the International Cooperative Biodiversity Groups (ICBG) program. The mRNA expression of cyclooxygenase-2, interleukin 1beta and inducible nitric oxide synthase genes in RAW macrophages was determined quantitatively in response to treatment with plant extracts applied at 100 microg/mL. The screening of 1000 extracts from 449 plant species belonging to 68 plant families resulted in 75 extracts (7.5%) showing strong (75% or higher inhibition) activity against at least one target gene. Many extracts showed qualitative and quantitative differences in the levels of activities against each target gene. Extracts identified from this screen were able to reduce inflammatory symptoms in vivo, thereby validating the screening approach.

Comparative phytochemical characterization of three Rhodiola species.

In comparison to the well-recognized adaptogenic herb Rhodiola rosea, phytochemical constituents of two other Rhodiola species (R. heterodonta and R. semenovii) were elucidated and characterized. Two major phytochemical groups; phenolic and/or cyanogenic glycosides and proanthocyanidins, were isolated and identified in the three species. Chemical similarities among the three species were observed; however, each species displayed differences in phytochemical constituents. R. heterodonta contained a newly detected phenylethanoid glycoside, heterodontoside, in addition to the known compounds tyrosol, viridoside, salidroside, and rhodiocyanoside A. Both R. heterodonta and R. rosea contained phenylethanoid/propanoid compounds that were not detected in R. semenovii. For R. semenovii, the cyanogenic glucosides rhodiocyanoside A and lotaustralin were detected. Although the three species have proanthocyanidins composed of (-)-epigallocatechin and its 3-O-gallate esters in common, the degree of polymerization greatly differed between them. In contrast to R. heterodonta and R. semenovii, R. rosea has higher molecular weight polymeric proanthocyanidins. This study resulted in the identification and isolation of phytochemical constituents for direct cross-comparison between three Rhodiola species of medicinal and pharmacological value.