Piceain 1

Picrorhiza kurroa is a well-known herb in Ayurvedic medicine. Although it shows antioxidant, antiinflammatory and immunomodulatory activities, it is most valued for its hepatoprotective effect. The rhizomes are widely used against indigestion problems since ancient times due to improper digestive secretions. Aim of this study was to explore antioxidant study of P. kurroa leaves for a new source of naturally occurring antioxidants. Two pure compounds, luteolin-5-O-glucopyranoside (1) and picein (2) were isolated from butanol extract through column chromatography. Different extracts of P. kurroa leaves (ethanol, ethyl acetate, butanol) were quantified for isolated compound (2) by high-performance liquid chromatography. All the extracts and isolated compounds were evaluated for its antioxidant activity using two assays, 2,2-diphenyl-1-picrylhydrazyl radical and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) assay. The linear detection range was 1.56-200 μg/ml for picein. The limit of detection and limit of quantification for picein were 2.34 and 7.81 μg/ml, respectively. Butanol and ethyl acetate extract showed greater antioxidant activity as compare to ethanol extract. Compound 1 and ascorbic acid showed nearly similar antioxidant activity where as 2 showed no activity at standard concentration. The IC50 values for 2,2-diphenyl-1-picrylhydrazyl radical and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) assay for ascorbic acid, compound 1, ethanol extract and its different fractions (ethyl acetate and butanol) were found to be 0.81, 1.04, 67.48, 39.58, 37.12 and 2.59, 4.02, 48.36, 33.24, 29.48 μg, respectively.

Eastern spruce budworm (Choristoneura fumiferiana Clemens) (ESBW) is a major forest pest which feeds on young shoots of white spruce (Picea glauca) and can cause landscape level economic and ecological losses. Release of acetophenone metabolites, piceol and pungenol, from their corresponding glycosides, picein and pungenin, can confer natural resistance of spruce to ESBW. A beta-glucosidase gene, Pgβglu-1, was recently discovered and the encoded enzyme was characterized in vitro to function in the release of the defensive acetophenone aglycons. Here we describe overexpression of Pgβglu-1 in a white spruce genotype whose metabolome contains the glucosylated acetophenones, but no detectable amounts of the aglycons. Transgenic overexpression of Pgβglu-1 resulted in release of the acetophenone aglycons in planta. This work provides in vivo evidence for the function of Pgβglu-1.

Several bioactive compounds are in use for the treatment of neurodegenerative disorders, such as Alzheimer's and Parkinson's disease. Historically, willow (salix sp.) bark has been an important source of salisylic acid and other natural compounds with anti-inflammatory, antipyretic and analgesic properties. Among these, picein isolated from hot water extract of willow bark, has been found to act as a natural secondary metabolite antioxidant. The aim of this study was to investigate the unrevealed pharmacological action of picein. In silico studies were utilized to direct the investigation towards the neuroprotection abilities of picein. Our in vitro studies demonstrate the neuroprotective properties of picein by blocking the oxidative stress effects, induced by free radical generator 2-methyl-1,4-naphthoquinone (menadione, MQ), in neuroblastoma SH-SY5Y cells. Several oxidative stress-related parameters were evaluated to measure the protection for mitochondrial integrity, such as mitochondrial superoxide production, mitochondrial activity (MTT), reactive oxygen species (ROS) and live-cell imaging. A significant increase in the ROS level and mitochondrial superoxide production were measured after MQ treatment, however, a subsequent treatment with picein was able to mitigate this effect by decreasing their levels. Additionally, the mitochondrial activity was significantly decreased by MQ exposure, but a follow-up treatment with picein recovered the normal metabolic activity. In conclusion, the presented results demonstrate that picein can significantly reduce the level of MQ-induced oxidative stress on mitochondria, and thereby plays a role as a potent neuroprotectant.