Enoch Chan

A review of the pharmacological effects of Arctium lappa (burdock).

Arctium lappa, commonly known as burdock, is being promoted/recommended as a healthy and nutritive food in Chinese societies. Burdock has been used therapeutically in Europe, North America and Asia for hundreds of years. The roots, seeds and leaves of burdock have been investigated in view of its popular uses in traditional Chinese medicine (TCM). In this review, the reported therapeutic effects of the active compounds present in the different botanical parts of burdock are summarized. In the root, the active ingredients have been found to “detoxify” blood in terms of TCM and promote blood circulation to the skin surface, improving the skin quality/texture and curing skin diseases like eczema. Antioxidants and antidiabetic compounds have also been found in the root. In the seeds, some active compounds possess anti-inflammatory effects and potent inhibitory effects on the growth of tumors such as pancreatic carcinoma. In the leaf extract, the active compounds isolated can inhibit the growth of micro-organisms in the oral cavity. The medicinal uses of burdock in treating chronic diseases such as cancers, diabetes and AIDS have been reported. However, it is also essential to be aware of the side effects of burdock including contact dermatitis and other allergic/inflammatory responses that might be evoked by burdock.

A review of the anticancer and immunomodulatory effects of Lycium barbarum fruit

The anticancer effects of traditional Chinese medicine (TCM) have attracted the attention of the public vis-à-vis existing cancer therapies with various side effects. Lycium barbarum fruit, commonly known as Gou Qi Zi in China, is a potential anticancer agent/adjuvant. Its major active ingredients, L. barbarum polysaccharides (LBP), scopoletin and 2-O-β-d-glucopyranosyl-l-ascorbic acid (AA-2βG), are found to have apoptotic and antiproliferative effects on cancer cell lines. Moreover, LBP also contributes to body’s immunomodulatory effects and enhances effects of other cancer therapies. It is not known whether there are any undesirable effects. Further studies on its pharmacological mechanisms and toxicology could facilitate a safe usage of this TCM herb.

Extract of scutellaria baicalensis georgi root exerts protection against myocardial ischemia-reperfusion injury in rats

Ischemic heart disease is a major cause of death in the world. Common therapies, such as primary coronary angioplasty and thrombolysis, are applied to restore blood supply to the heart, limit infarct size and reduce mortality. However, the restoration of blood supply would generate reactive oxygen species in damaged sites of the myocardium, intensifying the damage to the cardiac tissues. Radix Scutellariae baicalensis (Huangqin) is a well-known herb in traditional Chinese medicine with high antioxidant power. In this study, extract of the dry root of Scutellaria baicalensis Georgi (Sb) was confirmed to have a high content of flavonoids and phenolic compounds. The cardioprotective effects of the Sb extracts (3, 30 and 300 mg/kg) were evaluated in myocardial ischemia-reperfusion injuried rats. The results showed that animals that had received five-day pretreatment of the Sb extract (30 mg/kg) had a significant reduction in myocardial infarct size and a marked increase in the activity of catalase in the liver. The Sb extract could additionally enhance acetylcholine-induced vasorelaxation. It was proposed that the Sb extract exerted its cardioprotection by stimulating the catalase activity and improving vascular elasticity.

Enhancement of in vitro and in vivo anticancer activities of polysaccharide peptide from Grifola frondosa by chemical modifications

Context: Grifola frondosa (Polyporaceae), maitake, is a widely consumed edible mushroom in some Asian countries. The fruit bodies and mycelia of maitake have shown different bioactive compounds with anticancer and other therapeutic properties. Objective: This study evaluated three chemically modified maitake polysaccharide-peptides’ (MPSP) adjuvant effect (in vivo) and anticancer activity (in vitro growth inhibitory effect) compared with crude MPSP from G. frondosa. Materials and methods: We investigated the possibility of enhancing the adjuvant effect and anticancer effect of crude MPSP by using simple chemical modification methods to convert crude MPSP to phosphorylated, acetylated or esterified MPSPs. The adjuvant effect and growth inhibitory effect were evaluated by C6 cell inoculated rat model with cyclophosphamide (CPA) treatment and in vitro cell viability assay, respectively. Results: All four tested MPSPs showed significant adjuvant effect to CPA treatment on rats inoculated with C6 cancer cells. In addition, an obvious growth inhibitory effect was observed in C6 cancer cells but not in normal brain cells treated with various forms of MPSPs. Only phosphorylation could significantly (p < 0.05) improve the adjuvant effect (in vivo) and growth inhibitory effect. A same rank order (phosphorylated MPSP > esterified MPSP ≥ acetylated MPSP ≥ crude MPSP) of efficacy was observed in both the in vivo and in vitro assays. Discussion and conclusion: This study showed chemical phosphorylation could markedly enhance both adjuvant effects and growth inhibitory effects. This study demonstrated the feasibility of enhancing the efficacy of MPSP by using a simple chemical modification method, and this provides a foundation for future study in this area.

Structure of the hepatitis A virion: identification of potential surface-exposed regions

SummaryIodination of highly purified hepatitis A (HAV) virus results in the selective labeling of two viral polypeptides, which are identified as the the VP 1 and VP 2 capsid polypeptides. Based upon the kinetics of labeling, the exposed region of VP 1 appears to be more accessible to iodination, although the ultimate proportion of label present within VP 1 and VP 2 is approximately equal. By utilizing iodinated whole virions, isolated VP 1, VP 2, and the tryptic digest derived from VP 1 and VP 2, binding by heterologous anti-160 S antibody indicated that a significant portion of the antibodies was directed against an epitope on VP 2 that was not affected by denaturation. Identification of the regions exposed for iodination on these two polypeptides was accomplished by tryptic digestion of the isolated polypeptides followed by characterization of the iodinated tryptic peptide by gel filtration and reverse-phase chromatography. The results indicate that tyrosine 100 on VP 2 and a large tryptic peptide composed of amino acids 222 through 260 on VP 1 which contains four tyrosine residues are two regions that are surface-exposed on these molecules.

Serum nitric oxide synthase activity is a novel predictor of impaired vasorelaxation in rats

It is well documented that both acetylcholine (ACh)‐evoked arterial relaxation and brachial artery flow‐mediated vasodilatation are blunted in hypercholesterolaemic patients. However, there are no simple diagnostic methods to detect the pathology of blood vessels of patients. To establish the use of serum nitric oxide synthase (NOS) activity as a diagnostic parameter for impaired vasorelaxation, animals with different levels of vascular healthiness were made by feeding Sprague–Dawley rats a normal diet, a high‐cholesterol diet (HCD) or an HCD supplemented with 10 mg/kg per day, p.o., simvastatin, a cholesterol‐lowering drug, for 30 days. Serum total cholesterol levels, serum NOS activity and ACh‐induced vasorelaxation of the isolated aorta were determined at the end of the experiment. Consumption of HCD for 30 days resulted in an increase in serum total cholesterol, attenuated ACh‐induced nitric oxide/endothelium‐dependent aortic relaxation and decreased NOS activity. Concomitant administration of simvastatin lowered the elevated blood cholesterol levels with complete reversal of the attenuated ACh‐induced aortic relaxation and serum NOS activity. An attempt was made to correlate serum NOS activity and the magnitude of ACh‐elicited vascular relaxation among the different groups. A positive correlation (r = 0.8329; P < 0.001; n = 30) was found between serum NOS activity and vascular relaxation. This finding is a good foundation for the development of a simple and low‐cost alternative for diagnosing vascular diseases and evaluating the effectiveness of drugs on the vascular system in patients.