Jacqueline J. Shan

Identification of kaempferol as a monoamine oxidase inhibitor and potential neuroprotectant in extracts of Ginkgo biloba leaves.

The effects of Ginkgo biloba leaf extract on rat brain or livermonoamine oxidase (MAO)‐A and ‐B activity, biogenic amine concentration in nervous tissue, N‐methyl‐d‐aspartate (NMDA)‐ and N‐(2‐chloroethyl)‐N‐ethyl‐2‐bromobenzylamine (DSP‐4)‐induced neurotoxicity and antioxidant activity was investigated to determine the effects of the extract on monoamine catabolism and neuroprotection.

Comparison of chemical components and antioxidant capacity of different Echinacea species

Alcoholic extracts of the roots and leaves of three Echinacea species (E. purpurea, E. angustifolia and E. pallida) were analysed for the presence of characteristic chemicals by HPLC directly coupled to ultraviolet absorbance and electrospray mass spectrometric detectors. The method permitted rapid characterization and tentative identification of a large number of caffeoyl conjugates and alkamides in all the samples investigated. The roots of the three species differed markedly in their contents of characteristic compounds. Cichoric acid and verbascoside predominated in extracts of E. purpurea root whereas cynarine and dodeca‐2E,4E,8Z,10Z/E‐tetraenoic acid isobutylamide were the major chemicals characteristic of E. angustifolia root extracts. Echinacoside and 6‐O‐caffeoylechinacoside predominated in extracts of E. pallida roots. Characteristic alkamides were also examined by electrospray tandem mass spectrometry (MS/MS) and these compounds provided characteristic fragmentation patterns. Extracts of the roots and leaves of all three species were found to have antioxidant properties in a free radical scavenging assay and in a lipid peroxidation assay.

Immunomodulating activity of CVT-E002, a proprietary extract from North American ginseng (Panax quinquefolium)

The activity of CVT‐E002, an aqueous extract containing mainly oligosaccharides and polysaccharides from North American ginseng (Panax quinquefolium), as an immunobooster on murine spleen cells and peritoneal macrophages, was studied in‐vitro. CVT‐E002 stimulated the proliferation of normal mouse spleen cells, of which the major responding subpopulation was identified as B lymphocytes. CVT‐E002 also activated peritoneal exudate macrophages leading to enhanced interleukin‐1 (IL‐1), interleukin‐6 (IL‐6), tumour necrosis factor‐α (TNF‐α) and nitric oxide (NO) production. In addition, CVT‐E002 stimulated in‐vivo immunoglobulin G (IgG) production in treated mice. These results identify some of the immunomodulating activities of CVT‐E002 and suggest its use clinically for the modulation of immune responses.

Enhanced survival and regeneration of axotomized retinal ganglion cells by a mixture of herbal extracts.

The aim of this study is to investigate the effects of Panax quinquefolius L. extract (PQE), Ginkgo biloba extract (GBE), and Hypericum perforatum extract (HPE), in combination or alone, on the survival and regeneration of axotomized retinal ganglion cells (RGCs) in an optic nerve transection model in adult hamsters. Unilateral transection of the optic nerve was performed to evaluate the effects of herbal extracts on the survival of axotomized RGCs. Effects of the herbal extracts on axonal regeneration of axotomized RGCs, on the other hand, were studied by attaching a peripheral nerve graft onto the transected ocular stump to induce regeneration. Operated animals received daily oral administration of vehicle or herbal extracts (PQE, GBE, and HPE), alone or in combination, for 7 and 21 days, respectively, in the survival and regeneration experiments. Surviving and regenerating RGCs were retrogradely labeled with Fluoro-Gold. The eyes were then enucleated and the retinas were flat-mounted for the counting of the labeled RGCs. Treatment with PQE, GBE and HPE alone failed to offer neuroprotection to injured RGCs. However, treatment with Menta-FX, a mixture of PQE, GBE, and HPE, significantly augmented RGC survival 7 days postaxotomy. Treatment with Menta-FX also induced a significant (87%) increase in the number of regenerating RGCs 21 days after optic nerve transection. This study demonstrates that herbs can act as a potential neuroprotective agent for damaged RGCs. It also suggests that the therapeutic value of herbal remedies can be maximized by the use of mixtures of appropriate herbs.

Synthesis of N-propargylphenelzine and analogues as neuroprotective agents.

A series of N(1)- and N(2)-propargylphenelzine derivatives and analogues (1-7) was synthesized. In addition to their activity as monoamine oxidase inhibitors, two of the compounds, N(1)- and N(2)-propargylphenelzines (3 and 6), were found to be potent at preventing DSP-4-induced noradrenaline (NA) depletion in mouse hippocampus, suggesting that they have neuroprotective properties.

Parathyroid hypertensive factor secretion from subcultured spontaneously hypertensive rat parathyroid cells.

Cells dissociated from spontaneously hypertensive rat (SHR) parathyroid glands were grown in culture. Media harvested from the cell cultures were analyzed for parathyroid hypertensive factor (PHF) using the blood pressure bioassay. Cells raised in DMEM containing normal (1.8 mmol/L) CaCl2 secreted a negligible amount of PHF, while cells cultured in Hams F-12 medium containing low (0.3 mmol/L) CaCl2 secreted higher amounts of PHF. The PHF secretion in Hams F-12 medium was highest in early passage cells, and was maintained for approximately 12 to 15 passages. PHF purified from the cell culture medium exhibited chromatographic properties identical to those previously described for PHF isolated from SHR plasma or SHR parathyroid gland organ culture medium. These results support the parathyroid gland as the organ of origin of PHF.

Quantitative determination of parathyroid hypertensive factor by enzyme-linked immunosorbent assay.

A new competitive enzyme immunoassay for the detection parathyroid hypertensive factor (PHF) in human plasma using a PHF-horseradish peroxidase conjugate and IgM antibody adsorbed on the microtiter plate was established. The antibodies raised against rat PHF could recognize human PHF. Cross-reactivity of anti-PHF antibodies with other serum haptens and proteins was negligible. Conjugation of PHF with horseradish peroxidase did not neutralize the antigen activity. The limit of detection of PHF was 0.02 U/mL in reference units and PHF levels between 0.02 and 1 U/mL could be detected. Within-run coefficient of variation (CV) was less than 10%, and between-run CV was less than 15% for over the dynamic range of the assay. Preliminary clinical studies were performed with plasma samples from hypertensive patients with confirmed diagnosis. Parathyroid hypertensive factor levels, as detected with this immunoassay, were positively correlated with PHF levels detected with the semiquantitative blood pressure (BP) bioassay previously used. Parathyroid hypertensive factor levels detected with the enzyme-linked immunosorbent assay (ELISA) were also correlated with BP in patients. The PHF ELISA provides a selective, simple, and rapid method that can be used for routine determination of PHF in human plasma, and provides useful clinical information.

Problems in the use of herbal and natural substances, with a specific example concerning the cardiovascular system.

1. There has been increasing awareness and use of natural preparations for health purposes by consumers.