Effects of red ginseng extract on visual sensitivity and ERG b-wave of bullfrog's eye

Effect of red ginseng on visual function and vision-related quality of life in patients with glaucoma

Background

Red ginseng has been found to improve ocular perfusion and dry eye syndrome in glaucomatous eyes; however, its effects on visual function and vision-related quality of life have not been investigated. This study sought to evaluate the effects of red ginseng on visual function and vision-related quality of life in glaucoma patients using contrast sensitivity and a questionnaire.

Methods

Participants were randomly assigned to two groups in this prospective, randomized, double-blind study: in one group, red ginseng was taken first, followed by a placebo, and in the other, placebo was taken first, followed by red ginseng. We measured and compared changes in contrast sensitivity and vision-related quality of life between the two groups. Contrast sensitivity was measured using OPTEC® 6500P, and vision-related quality of life was evaluated using the 25-item National Eye Institute Visual Function Questionnaire. One-way and two-way repeated measure analyses of variance were used for the comparison. Relationships between respective changes in dry eye syndrome and contrast sensitivity were also analyzed.

Results

Daytime contrast sensitivity and ocular pain improved after the administration of red ginseng. Nighttime contrast sensitivity was improved in early or moderate glaucoma. Improved contrast sensitivity was not associated with improvement in dry eye syndrome.

Conclusion

Red ginseng could improve contrast sensitivity and ocular pain in patients with glaucoma. The mechanism underlying improvement in contrast sensitivity appears to be associated with enhanced retinal perfusion or retinal ganglion cell function, but not dry eye syndrome.

Red ginseng for atopic dermatitis

Red ginseng is known for its significant biological activities which include anti-inflammation. Red ginseng may be used for the management and prevention of atopic dermatitis based on its effect on an atopic dermatitis animal model. More therapeutic efficacies other than atopic dermatitis are also reviewed briefly.

Trends in ginseng research in 2010

A total of 470 papers directly related to research on the Panax species were retrieved by performing internet searches with the keywords Panax and ginseng as the search terms. The publications were categorized as follows: 399 research articles, 30 reviews, 30 meeting abstracts, 7 proceedings, and 4 letters. The majority of these publications were published by scientists from Korea (35.7%), China (32.3%), and the USA (11.3%). Scientists from a total of 29 nations were actively involved in conducting ginseng research. A total of 43.6% of the publications were categorized as pharmacodynamic studies. The effects of ginseng on cerebrovascular function and cancer were the two most common topics considered in the pharmacodynamic studies. More than half of the ginseng studies assessed the use of P. ginseng. A total of 23 countries participated in studies specifically related to P. ginseng, and more than 80% of these studies originated from Korea and China. A total of 50 topics within the pharmacodynamics category were examined in association with the use of P. ginseng.

Inhibitory Effects of Ginsenoside Metabolites, Compound K and Protopanaxatriol, on GABAC Receptor-Mediated Ion Currents

Ginsenosides, one of the active ingredients of Panax ginseng, show various pharmacological and physiological effects, and they are converted into compound K (CK) or protopanaxatriol (M4) by intestinal microorganisms. CK is a metabolite derived from protopanaxadiol (PD) ginsenosides, whereas M4 is a metabolite derived from protopanaxatriol (PT) ginsenosides. The γ-aminobutyric acid receptor_C (GABA_C) is primarily expressed in retinal bipolar cells and several regions of the brain. However, little is known of the effects of ginsenoside metabolites on GABA_C receptor channel activity. In the present study, we examined the effects of CK and M4 on the activity of human recombinant GABA_C receptor (ρ1) channels expressed in Xenopus oocytes by using a 2-electrode voltage clamp technique. In oocytes expressing GABA_C receptor cRNA, we found that CK or M4 alone had no effect in oocytes. However, co-application of either CK or M4 with GABA inhibited the GABA-induced inward peak current (I_GABA). Interestingly, pre-application of M4 inhibited I_GABA more potently than CK in a dose-dependent and reversible manner. The half-inhibitory concentration (IC₅₀) values of CK and M4 were 52.1±2.3 and 45.7±3.9 µM, respectively. Inhibition of I_GABA by CK and M4 was voltage-independent and non-competitive. This study implies that ginsenoside metabolites may regulate GABA_C receptor channel activity in the brain, including in the eyes.

Effects of Rubus coreanus extract on visual processes in bullfrog's eye

ETHNOPHARMACOLOGICAL RELEVANCE

The fruit of Rubus coreanus (Rosaceae) is traditionally used as an aphrodisiac, astringent, restorative and tonic in Asian countries. It is advised for treating diseases related to liver, kidney and urinary dysfunction, premature greying, blurred vision, infertility, impotence and premature ejaculation. Additionally, there is a long history of different parts of the plants being used in the treatment of ophthalmic diseases. However, no scientific studies have been undertaken to determine the effects of Rubus coreanus in visual processes of the vertebrate retina.

AIM OF STUDY

The purpose of the present study was to investigate the positive effects of Rubus coreanus extracts on visual processes in the vertebrate's eye.

MATERIALS AND METHODS

Electroretinogram (ERG) techniques were used to record the responses from a bullfrog's eye cup preparations. Active pharmacological agents were used to block specific receptors in the retina and to leave others unaffected. Lipid peroxidation in the retina was generated by adding FeSO(4)+Na-ascorbate.

RESULTS

It was observed that both dark- and light-adapted ERG b-wave peak amplitude significantly increases with Rubus coreanus treatment. It was found that Rubus coreanus acts as a retinal neural antagonist but not as GABA receptor antagonist. Rubus coreanus treatment lowered the duration of rhodopsin regeneration. The results obtained indicated that Rubus coreanus protects against lipid peroxidation drop off ERG amplitude in retina.

CONCLUSION

Based on results obtained, it is suggested that Rubus coreanus can potentially improve visual sensitivity and can be used to treat pathophysiological conditions of eye.