Analysis of Health-Associated Phytochemical Compounds in Seven <i>Hypoxis</i>Species

Some species of the genus Hypoxis within the Hypoxidaceae family are known to contain phenolic glycosides that have different clinical functions. In the African continent Hypoxis species are regarded as valuable medicinal plants that have been used for decades by traditionalists and natives to treat numerous ailments. The corms and rhizomes of the geophytes contain hypoxoside, a norlignan diglucoside, which is one of the important phytochemicals with medicinal functions found in Hypoxis. In this study corm extracts of seven species: H. acuminata, H. argentea, H. filiformis, H. gerrardii, H. hemerocallidea, H. iridifolia and H. parvifolia were analyzed for the presence of ellagic acid, total phenolic content (TPC) and hypoxoside. Extracts of H. iridifolia and H. gerardii had the highest levels of total phenolic content of 369.6 μg/g and 318.2 μg/g, respectively, compared to the rest of the species. Hypoxoside was found to be present in corm extracts of all the species in varying proportions. H. gerrardii, H. argentea and H. filiformis had the highest relative hypoxoside content of 7.1%, 6.6% and 6.6%, respectively. It is interesting to note that Hypoxis hemerocallidea, the most commonly used species for medicinal extracts contained a much lower level of hypoxoside than most of the other species. Our study included species that have not been previously analyzed for either TPC or hypoxoside presence such as H. filiformis and H. gerrardii, thus providing novel information regarding the medicinal status and biochemical compounds of these Hypoxis species.

A Dual-radiolabel Marker Quantifies Decrease in HT29 Xenograft Hypoxia Induced by Mild Temperature Hyperthermia

Purpose: In this project, we developed novel methods to quantify changes in tumor hypoxia following a mild tempera-ture hyperthermia (MTH) treatment in rat HT29 human colon adenocarcinoma xenograft. Materials and Methods: An exogenous hypoxia marker (IAZGP) was labeled with two radioisotopes of iodine (131I and 123I, respectively) to form two distinct tracers. The two tracers were injected into HT29-bearing nude rats 4-hour before and immediately following 41.5℃, 45-minute mild hyperthermia treatment. The distributions of the two hypoxia tracers were obtained by performing digital autoradiography on tumor sections, and image processing resulted in quantitative information at 50 μm pixel size. Results: Following the hyperthermia treatment, there was a remarkable decrease in hypoxia tracer binding. The average whole tumor hypoxia tracer targeted fraction in five animals changed from 30.3% ± 9.7% to 13.0% ± 5.3% after the hyperthermia treatment (P = 0.001). Detailed pixelby-pixel analysis of the image data revealed a decline in hypoxia tracer uptake after hyperthermia in most regions. However, there was concomitant emergence of some new regions of hypoxia identified by increased tracer uptake. In the control group, the overall hypoxia tracer targeted fraction remained almost constant, with some hypoxic tracer redistribution (putative acute hypoxia) observed. Conclusion: Reoxygenation occurred in the rat HT29 xenograft following MTH treatment. This was evident with preponderance of decreased hypoxia specific tracer uptake on tumor sections. Our methodology might be a useful tool in hypoxia study.

Nitric oxide regulation of plant metabolism

Nitric oxide(NO)has emerged as an important signal molecule in plants,having myriad roles in plant devel-opment.In addition,NO also orchestrates both biotic and abiotic stress responses,during which intensive cellular metabolic reprogramming occurs.Integral to these responses is the location of NO biosynthetic and scavenging pathways in diverse cellular compartments,enabling plants to effectively organize signal transduction pathways.NO regulates plant metabolism and,in turn,metabolic pathways reciprocally regu-late NO accumulation and function.Thus,these diverse cellular processes are inextricably linked.This re-view addresses the numerous redox pathways,located in the various subcellular compartments that pro-duce NO,in addition to the mechanisms underpinning NO scavenging.We focus on how this molecular dance is integrated into the metabolic state of the cell.Within this context,a reciprocal relationship be-tween NO accumulation and metabolite production is often apparent.We also showcase cellular pathways,including those associated with nitrate reduction,that provide evidence for this integration of NO function and metabolism.Finally,we discuss the potential importance of the biochemical reactions governing NO levels in determining plant responses to a changing environment.