Effect of gamma irradiation on the conversion of ginsenoside Rb1 to Rg3

Study on hypoglycemic effects of irradiated ginseng adventitious roots

We aimed to explore the effects of the 60Co-γ irradiated ginseng adventitious root (GAR) with different radiation doses on the hypoglycemic effects of its extract (GARSE) through in vivo and in vitro experiments. The total saponin of GARSE was increased by 4.50% after 5 kGy irradiation, and the 2,2-Diphenyl-1-picrylhydrazyl (DPPH) radical scavenging ability was enhanced by 5.10%. At 50 μg/mL, GARSE irradiated by 5 kGy displayed superior protective effects on human glomerular mesangial cells (HMCs) with high glucose damage. After feeding type 1 diabetes mellitus (T1DM) mice with GARSE irradiated by 5 kGy at 500 mg/kg·BW for 4 weeks, the glucose values was decreased by 16.0% compared with the unirradiated. The Keap1/Nrf2/HO-1 pathway was activated and the oxidative stress was attenuated, which further alleviated T1DM.

Gamma-irradiated black ginseng extract inhibits mast cell degranulation and suppresses atopic dermatitis-like skin lesions in mice

Gamma irradiation is able to affect various structural modification and an increase of the biological properties of biomaterials. This study was conducted to investigate the anti-allergenic effect of γ-irradiated black ginseng extract (BGE) using in vitro and in vivo experiments. IgEantigen complex-induced degranulation was measured in RBL-2H3 mast cells. In addition, an anti-atopic dermatitis (AD) test was carried out by spreading γ-irradiated BGE on the dorsal skin of 2,4-dinitrochlorobenzene (DNCB)-induced BALB/c mice. The content of arginylfructose (AF) of gamma-irradiated BGE was higher than that of BGE. In RBL-2H3 mast cells, γ-irradiated BGE treatments significantly reduced the IgE-antigen complex-induced release of β-hexosaminidase, histamine, intracellular ROS, and Ca2+ influx. A western blot analysis showed that γ-irradiated BGE had an inhibitory activity on the FcεRI-mediated signaling in mast cells. In the DNCB-induced AD model, γ-irradiated BGE significantly alleviated the ADlike skin symptoms and clinical signs. The suppression of AD by γ-irradiated BGE was accompanied by a decrease in the serum level of IgE and IL-4, as well as the number of leukocyte. Gamma-irradiated BGE also suppressed IL-4 and increased IFN-γ in splenocytes. Our data suggests that γ-irradiated BGE may be effective therapeutic agents for the treatment of AD.

Gamma irradiation of medicinally important plants and the enhancement of secondary metabolite production

PURPOSE

The profitable production of some important plant-based secondary metabolites (ginsenosides, saponins, camptothecin, shikonins etc.) in vitro by gamma irradiation is a current area of interest. We reviewed different types of secondary metabolites, their mode of synthesis and effect of γ-radiation on their yield for different plants, organs and in vitro cultures (callus, suspension, hairy root). Special effort has been made to review the biochemical mechanisms underlying the increase in secondary metabolites. A comparison of yield improvement with biotic and abiotic stresses was made.

RESULTS

Phenolic compounds increase with γ-irradiation in whole plants/plant parts; psoralen content in the common herb babchi (Psoralea corylifolia) was increased as high as 32-fold with γ-irradiation of seeds at 20 kGy. The capsaicinoids, a phenolic compound increased about 10% with 10 kGy in paprika (Capsicum annum L.). The in vitro studies show all the three types of secondary metabolites are reported to increase with γ-irradiation. Stevioside, total phenolic and flavonoids content were slightly increased in 15 Gy-treated callus cultures of stevia (Stevia rebaudiana Bert.). In terpenoids, total saponin and ginsenosides content were increased 1.4- and 1.8-fold, respectively, with 100 Gy for wild ginseng (Panax ginseng Meyer) hairy root cultures. In alkaloids, camptothecin yield increased as high as 20-fold with 20 Gy in callus cultures of ghanera (Nothapodytes foetida). Shikonins increased up to 4-fold with 16 Gy in suspension cultures of purple gromwell (Lithospermum erythrorhizon S.). The enzymes associated with secondary metabolite production were increased with γ-irradiation of 20 Gy; namely, phenylalanine ammonia-lyase (PAL) for phenolics, chalcone synthase (CHS) for flavonoids, squalene synthase (SS), squalene epoxidase (SE) and oxidosqualene cyclases (OSC) for ginsenosides and PHB (p-hydroxylbenzoic acid) geranyl transferase for shikonins.

CONCLUSIONS

An increase in secondary metabolites in response to various biotic and abiotic stresses is compared with ionizing radiation. A ∼5- to 20-fold increase is noted with ∼20 Gy irradiation dose. It increases the yield of secondary metabolites by enhancing the activity of certain key biosynthetic enzymes. Identification of the optimum dose is the important step in the large-scale production of secondary metabolites at industrial level.

Influence of organic acids and heat treatment on ginsenoside conversion

Background

Heat treatments are applied to ginseng products in order to improve physiological activities through the conversion of ginsenosides, which are key bioactive components. During heat treatment, organic acids can affect ginsenoside conversion. Therefore, the influence of organic acids during heat treatment should be considered.

Methods

Raw ginseng, crude saponin, and ginsenoside Rb₁ standard with different organic acids were treated at 130°C, and the chemical components, including ginsenosides and organic acids, were analyzed.

Results

The organic acid content in raw ginseng was 5.55%. Organic acids were not detected in crude saponin that was not subjected to heat treatment, whereas organic acids were found in crude saponin subjected to heat treatment. Major ginsenosides (Rb₁, Re, and Rg₁) in ginseng and crude saponin were converted to minor ginsenosides at 130°C; the ginsenoside Rb₁ standard was very stable in the absence of organic acids and was converted into minor ginsenosides in the presence of organic acids at high temperatures.

Conclusion

The major factor affecting ginsenoside conversion was organic acids in ginseng. Therefore, the organic acid content as well as ginsenoside content and processing conditions should be considered important factors affecting the quality of ginseng products.

20(s)-ginsenoside Rg3 promotes apoptosis in human ovarian cancer HO-8910 cells through PI3K/Akt and XIAP pathways

Ovarian cancer is a serious tumor which represents a great threat to women's health. Recently, researchers had found that 20(s)-ginsenoside Rg3 could inhibit growth of several cancer cell lines; however, the mechanism is not fully understood so far. In the present study, we found that 20(s)-ginsenoside Rg3 reduced cell viability and induced apoptosis in a dose- and time-dependent manner in the human ovarian cancer cells HO-8910. The induction of apoptosis was accompanied by downregulation of phosphatidylinositol 3-kinase (PI3K)/Akt family proteins and inhibitor of apoptosis protein (IAP) family proteins. 20(s)-ginsenoside Rg3 treatment resulted in activation of caspase-3 and -9, which may partly explain the anti-cancer activity of 20(s)-ginsenoside Rg3. Taken together, our study for the first time suggests that 20(s)-ginsenoside Rg3 is able to enhance apoptosis of HO-8910 cells, at least in part, through downregulation of PI3K/Akt and IAP family proteins. Moreover, the triggering of caspase-3 and -9 activation mediated apoptotic induction. Our data indicate that 20(s)-ginsenoside Rg3 is an effective apoptosis-inducing natural compound in ovarian cancer cells and may have a role in future therapies for ovarian cancer.