Ginsenoside Rk1 bioactivity: a systematic review

Abstract

Ginsenoside Rk1 (G-Rk1) is a unique component created by processing the ginseng plant (mainly Sung Ginseng (SG)) at high temperatures. The aim of our study was to systematically review the pharmacological effects of G-Rk1. We utilized and manually searched eight databases to select in vivo and in vitro original studies that provided information about biological, pharmaceutical effects of G-Rk1 and were published up to July 2017 with no restriction on language or study design. Out of the 156 papers identified, we retrieved 28 eligible papers in the first skimming phase of research. Several articles largely described the G-Rk1 anti-cancer activity investigating "cell viability", "cell proliferation inhibition", "apoptotic activity", and "effects of G-Rk1 on G1 phase and autophagy in tumor cells" either alone or in combination with G-Rg5. Others proved that it has antiplatelet aggregation activities, anti-inflammatory effects, anti-insulin resistance, nephroprotective effect, antimicrobial effect, cognitive function enhancement, lipid accumulation reduction and prevents osteoporosis. In conclusion, G-Rk1 has a significant anti-tumor effect on liver cancer, melanoma, lung cancer, cervical cancer, colon cancer, pancreatic cancer, gastric cancer, and breast adenocarcinoma against in vitro cell lines. In vivo experiments are further warranted to confirm these effects.

Keywords: Clinical pharmacology; Ginsenoside; Rk1; Systematic review.

Figure 1. Chemical structure of the ginsenosides types.

(A) protopanaxadiol (PPD)-type ginsneosides including Rk1 represented in blue color, Rg5 represented in green color, and the rest of PPD-types are in violet; (B) protopanaxatriol (PPT)-type ginsneosides represented in brown color; (C) Ocotillol- type ginsneoside is represented in gray color; (D) Oleanic acid-type ginsneosides are represented in red color. glc, b-D-glucose; rha, a-L-rhamnose; arap, a-L-arabinose (pyranose); araf, a-L-arabinose (furanose).

Figure 2. Flowchart of our systematic review - summary of how the systematic search was conducted and eligible studies were identified (PRISMA flow diagram).

PRISMA, Preferred Reporting Items for Systematic reviews and Meta-Analyses.

Figure 3. Summary of G-Rk1 bioactivities and its mechanism of actions—ALP, alkaline phosphatase; Bax, BCL2-Associated X Protein; Bcl-2, B-cell lymphoma 2; BMP 2, bone morphogenetic protein-2; COX-2, Cyclooxygenase 2; CDK, cyclin-dependent kinase; erNSC, Epidermal growth factor-responsive neurosphere stem cells; GSH, Glutathione; GLUT-4, Glucose Transporter; IL, interleukin; iNOS, Inducible Nitric Oxide Synthase; IGF, insulin-like growth factor receptor; JNK, Jun N-terminal Kinase; MMP3, Matrix Metalloproteinase 3; NF-kB, Nuclear Factor Kappa B; PARP, Poly ADP (Adenosine Diphosphate)-Ribose Polymerase; TXB-2, Thromboxane B2; TNF-α, tumor necrosis factor.

*The number in the small circle indicates the number of studies that report this bioactivity.