(Vietnamese ginseng)

Panax vietnamensis (Vietnamese ginseng, Ngoc Linh ginseng) is an endemic Panax species of Vietnam. From the methanol extract of the leaves of Panax vietnamensis, five compounds (1-5) were isolated, including one new sesquiterpene lactone such as panaxolide (1) and four known compounds. The structures of the compounds (1-5) were elucidated by spectral techniques such as 1 D NMR (1H NMR, 13C NMR), 2 D NMR (COSY, HSQC, HMBC, NOESY) and mass spectrometry. The absolute configuration of 1 was determined based on the Cotton effects in the CD spectrum. All of the five compounds were screened for their in vitro growth inhibitory activities against cancerous cells (HepG2) and normal cells (fibroblast) using the SRB assay. Panaxolide (1) showed the highest potential for the growth inhibition of cancerous cells HepG2 with the IC50 values of 63.8 μM.

(Vietnamese ginseng)

Vietnamese ginseng (Panax vietnamensis Ha and Grushv., Araliaceae) is indigenous in the central highlands of Vietnam and the southernmost distribution in the Panax genus. Like other ginseng, Vietnamese ginseng is well known has been used as a tonic and for management of certain diseases in the traditional medicine. Nevertheless, it is noteworthy that in respect to the long history in use and systematic studied on Korean ginseng (P. ginseng), American ginseng (P. quinquefolius), Japanese ginseng (P. japonicus), and Chinese ginseng (P. notoginseng), the up-to-date published database on Vietnamese ginseng is relatively much less extensive. In our ongoing research on the promising Vietnamese medicinal plants, the present phytochemical investigation of the ethanol extract of the leaves of Panax vietnamensis led to the isolation of three compounds (1-3), including a new indole alkaloid N-glycoside (1) and two known compounds. Their structures were elucidated based on extensive physiochemical and chemical methods, especially the interpretation of NMR and MS spectra. The absolute configuration of 1 was determined based on the comparison of its experimental and theoretical ECD spectra along with NMR calculation. Compound 1 is naturally isolated N-glycoside, which is rarely found in natural products. The isolated compounds showed weak or no inhibitory activity against acetylcholinesterase enzyme (AChE).

Molecular Cloning and Functional Characterization of Oxidosqualene Cyclases from Panax vietnamensis

Panax vietnamensis is a valuable medicinal resource with promising preclinical applications. Ginsenosides, which are triterpenoids, are the primary active components in P. vietnamensis. Oxidosqualene cyclases (OSCs) catalyze the formation of the basic skeleton of triterpenes from 2,3-oxidosqualene, which is a crucial step in the biosynthesis of triterpenoids. The OSCs involved in triterpenoid biosynthesis in P. vietnamensis have not yet been characterized. Four OSC genes (PvOSC1-4) were cloned from P. vietnamensis and functionally characterized via heterologous expression in yeast. Transgenic yeast expressing PvOSC1, PvOSC3, and PvOSC4 produced the corresponding products β-amyrin, cycloartenol, and dammarenediol-II, respectively. PvOSC1, PvOSC3, and PvOSC4 are monofunctional OSCs. In this study, we characterized three PvOSC genes, providing a better understanding of the biosynthesis of triterpenoids in P. vietnamensis and the multiple choices of plant OSCs for metabolic engineering in yeast and other hosts.

Evaluation of the Saponin Content in Panax vietnamensis Acclimatized to Lam Dong Province by HPLC-UV/CAD

Panax vietnamensis, or Vietnamese ginseng (VG), an endemic Panax species in Vietnam, possesses a unique saponin profile and interesting biological activities. This plant is presently in danger of extinction due to over-exploitation, resulting in many preservation efforts towards the geographical acclimatization of VG. Yet, no information on the saponin content of the acclimatized VG, an important quality indicator, is available. Here, we analyzed the saponin content in the underground parts of two- to five-year-old VG plants acclimatized to Lam Dong province. Nine characteristic saponins, including notoginsenoside-R1, ginsenoside-Rg1, -Rb1, -Rd, majonoside-R1, -R2 vina-ginsenoside-R2, -R11, and pseudoginsenoside-RT4, were simultaneously determined by HPLC coupled with UV and with a charged aerosol detector (CAD). Analyzing the results illustrated that the detection of characteristic ocotillol-type saponins in VG by CAD presented a superior capacity compared with that of UV, thus implying a preferential choice of CAD for the analysis of VG. The quantitative results indicating the saponin content in the underground parts of VG showed an increasing tendency from two to five years old, with the root and the rhizome exhibiting different saponin accumulation patterns. This is the first study that reveals the preliminary success of VG acclimatization and thereby encourages the continuing efforts to develop this valuable saponin-rich plant.

De novo assembly and Transcriptome characterization of an endemic species of Vietnam, Panax vietnamensis Ha et Grushv., including the development of EST-SSR markers for population genetics

BACKGROUND

Understanding the genetic diversity in endangered species that occur inforest remnants is necessary to establish efficient strategies for the species conservation, restoration and management. Panax vietnamensis Ha et Grushv. is medicinally important, endemic and endangered species of Vietnam. However, genetic diversity and structure of population are unknown due to lack of efficient molecular markers.

RESULTS

In this study, we employed Illumina HiSeq™ 4000 sequencing to analyze the transcriptomes of P. vietnamensis (roots, leaves and stems). Raw reads total of 23,741,783 was obtained and then assembled, from which the generated unigenes were 89,271 (average length = 598.3191 nt). The 31,686 unigenes were annotated in different databases i.e. Gene Ontology, Kyoto Encyclopedia of Genes and Genomes, Nucleotide Collection (NR/NT) and Swiss-Prot for functional annotation. Further, 11,343 EST-SSRs were detected. From 7774 primer pairs, 101 were selected for polymorphism validation, in which; 20 primer pairs were successfully amplified to DNA fragments and significant amounts of polymorphism was observed within population. The nine polymorphic microsatellite loci were used for population structure and diversity analyses. The obtained results revealed high levels of genetic diversity in populations, the average observed and expected heterozygosity were HO = 0.422 and HE = 0.479, respectively. During the Bottleneck analysis using TPM and SMM models (p < 0.01) shows that targeted population is significantly heterozygote deficient. This suggests sign of the bottleneck in all populations. Genetic differentiation between populations was moderate (FST = 0.133) and indicating slightly high level of gene flow (Nm = 1.63). Analysis of molecular variance (AMOVA) showed 63.17% of variation within individuals and 12.45% among populations. Our results shows two genetic clusters related to geographical distances.

CONCLUSION

Our study will assist conservators in future conservation management, breeding, production and habitats restoration of the species.

Accumulation of Saponins in Underground Parts of Panax vietnamensis at Different Ages Analyzed by HPLC-UV/ELSD

Panax vietnamensis (PV), a wild Panax species discovered in Vietnam in 1973, has been increasingly overexploited due to its economic value and therapeutic uses. This resulted in the development of PV cultivation to meet the market demand. There is little information on the accumulation of saponins in PV during cultivation, but this information could serve as an indication of the appropriate harvest time. In this study we developed an HPLC-UV/ELSD method to simultaneously determine the content of 10 characteristic saponins in PV from 2–7 years old, including G-Rb1, G-Rd, G-Rg1, G-Re, N-R1, M-R1, M-R2, V-R2, V-R11, and p-RT4. The result indicated that from 2 to 5 years, the content of saponins in PV rhizome and radix increase 3.02 and 4.2 times, respectively, whereas from 5 to 7 years, no significant changes were observed. Hence, our study suggests that after 5 years of growth could be considered as an appropriate time for PV to be harvested. Among the analyzed saponins, G-Rg1, G-Rb1, G-Rd, and especially M-R2 were the major saponins that contributed to the change of PV’s saponin content through the years. In addition, the developed and validated HPLC method was proven to be reliable and effective for quality control of PV.

Antimelanogenic Activity of Ocotillol-Type Saponins from Panax vietnamensis

The ocotillol (OCT)-type saponins have been known as a tetracyclic triterpenoid, possessing five- or six-membered epoxy ring in the side chain. Interestingly, this type saponin was mostly found in Panax vietnamensis Ha et Grushv., Araliaceae (VG), hence making VG unique from the other Panax spp. Five OCT-type saponins, majonoside R2, vina-ginsenoside R2, majonoside R1, pseudoginsenoside RT4, vina-ginsenoside R11, together with three protopanaxadiol (PPD)-type saponins and four protopanaxatriol (PPT)-type saponins from VG were evaluated for their antimelanogenic activity. All of isolates were found to be active. More importantly, the five OCT-type saponins inhibited melanin production in B16-F10 mouse melanoma cells, without showing any cytotoxicity. Besides ginsenoside Rd and ginsenoside Rg3 in PPD and notoginsenoside R1 in PPT-type saponins, majonoside R2 was the most potent melanogenesis inhibitory activity in OCT-type saponins. In this article, we highlighted antimelanogenic activity of OCT-type saponins and potential structure-activity relationship (SAR) of ginsenosides. Our results suggested that OCT-type saponins could be used as a depigmentation agent.

Increase in Protective Effect of Panax vietnamensis by Heat Processing on Cisplatin-Induced Kidney Cell Toxicity

Cisplatin is a platinum-based anticancer agent used for treating a wide range of solid cancers. One of the side effects of this drug is its severe nephrotoxicity, limiting the safe dose of cisplatin. Therefore, many natural products have been studied and applied to attenuate the toxicity of this compound. In this study, we found that steamed Vietnamese ginseng (Panax vietnamensis) could significantly reduce the kidney damage of cisplatin in an in vitro model using porcine proximal tubular LLC-PK1 kidney cells. From processed ginseng under optimized conditions (120 °C, 12 h), we isolated seven compounds (20(R,S)-ginsenoside Rh2, 20(R,S)-ginsenoside Rg3, ginsenoside Rk1, ginsenoside-Rg5, and ocotillol genin) that showed kidney-protective potential against cisplatin toxicity. By comparing the 50% recovery concentration (RC₅₀), the R form of ginsenoside, Rh2 and Rg3, had RC₅₀ values of 6.67 ± 0.42 µM and 8.39 ± 0.3 µM, respectively, while the S forms of ginsenoside, Rh2 and Rg3, and Rk1, had weaker protective effects, with RC₅₀ ranging from 46.15 to 88.4 µM. G-Rg5 and ocotillol, the typical saponin of Vietnamese ginseng, had the highest RC₅₀ (180.83 ± 33.27; 226.19 ± 66.16, respectively). Our results suggest that processed Vietnamese gingseng (PVG), as well as those compounds, has the potential to improve kidney damage due to cisplatin toxicity.

Protective Effect of Panaxynol Isolated from Panax vietnamensis against Cisplatin-Induced Renal Damage: In Vitro and In Vivo Studies

Polyacetylenic compounds isolated from Panax species are comprised of non-polar C17 compounds, exhibiting anti-inflammatory, antitumor, and antifungal activities. Panaxynol represents the major component of the essential oils of ginseng. We investigated whether panaxynol isolated from Panax vietnamensis (Vietnamese ginseng, VG) could prevent cisplatin-induced renal damage induced in vitro and in vivo. Cisplatin-induced apoptotic cell death was observed by staining with annexin V conjugated with Alexa Fluor 488, and western blotting evaluated the molecular mechanism. Panaxynol at concentrations above 0.25 μM prevented cisplatin-induced LLC-PK1 porcine renal proximal tubular cell death. LLC-PK1 cells treated with cisplatin demonstrated an increase in apoptotic cell death, whereas pretreatment with 2 and 4 μM panaxynol decreased this effect. Cisplatin demonstrated a marked increase in the phosphorylation of c-Jun N-terminal kinase (JNK), P38, and cleaved caspase-3. However, pretreatment with 2 and 4 μM panaxynol reversed the upregulated phosphorylation of JNK, P38, and the expression of cleaved caspase-3. We confirmed that the protective effect of panaxynol isolated from P. vietnamensis in LLC-PK1 cells was at least partially mediated by reducing the cisplatin-induced apoptotic damage. In the animal study, panaxynol treatment ameliorated body weight loss and blood renal function markers and downregulated the mRNA expression of inflammatory mediators.

Biomass accumulation of Panax vietnamensis in cell suspension cultures varies with addition of plant growth regulators and organic additives

OBJECTIVE

To evaluate the impact of plant growth regulators including kinetin (KN), benzyl adenine and naphthalene acetic acid, yeast extract and casein hydrolyzate on biomass accumulation of Vietnamese ginseng Panax vietnamensis (P. vietnamensis) in cell suspension culture.

METHODS

Cell suspension cultures were established from friable calluses derived from leaves and petioles of 3-year-old in-vitro P. vietnamensis plants. The cell suspension cultures were grown in Murashige and Skoog basal media supplemented with various concentrations of KN, benzyl adenine, naphthalene acetic acid, and yeast extract and casein hydrolyzate.

RESULTS

All tested factors generated an increase in the cell biomass of P. vietnamensis in suspension culture, but the impact of each varies depended on the factor type, concentration, and incubation period. Addition of 2.0 mg/L KN resulted in the largest biomass increase after 24 d, (57.0 ± 0.9) and (3.1 ± 0.1) mg/mL fresh and dry weight, respectively, whereas addition of benzyl adenine or naphthalene acetic acid produced optimum levels of Panax cell biomass at 1.0 and 1.5 mg/L, respectively. Addition of the elicitor yeast extract led to a 1.4-2.4 fold increase in biomass of P. vietnamensis, while addition of casein hydrolyzate enhanced biomass accumulation 1.8-2.6 fold.

CONCLUSIONS

The addition of each factor causes significant changes in biomass accumulation of P. vietnamensis. The largest biomass accumulation is from cultures grown in MS media containing 2.0 mg/L KN for 24 d. The outcome of the present study provides new insights into the optimal suspension culture conditions for studies on the in vitro cell biomass production of P. vietnamensis.

The psychopharmacological activities of Vietnamese ginseng in mice: characterization of its psychomotor, sedative-hypnotic, antistress, anxiolytic, and cognitive effects

Background

Panax vietnamensis Ha et Grushv. or Vietnamese ginseng (VG) is a recently discovered ginseng species. Studies on its chemical constituents have shown that VG is remarkably rich in ginseng saponins, particularly ocotillol saponins. However, the psychopharmacological effects of VG have not been characterized. Thus, in the present study we screened the psychopharmacological activities of VG in mice.

Methods

VG extract (VGE) was orally administered to mice at various dosages to evaluate its psychomotor (open-field and rota-rod tests), sedative–hypnotic (pentobarbital-induced sleeping test), antistress (cold swimming test), anxiolytic (elevated plus-maze test), and cognitive (Y-maze and passive-avoidance tests) effects.

Results

VGE treatment increased the spontaneous locomotor activity, enhanced the endurance to stress, reduced the anxiety-like behavior, and ameliorated the scopolamine-induced memory impairments in mice. In addition, VGE treatment did not alter the motor balance and coordination of mice and did not potentiate pentobarbital-induced sleep, indicating that VGE has no sedative-hypnotic effects. The effects of VGE were comparable to those of the Korean Red Ginseng extract.

Conclusion

VG, like other ginseng products, has significant and potentially useful psychopharmacological effects. This includes, but is not limited to, psychomotor stimulation, anxiolytic, antistress, and memory enhancing effects.

The complete chloroplast genome sequence of Panax vietnamensis Ha et Grushv (Araliaceae)

The complete chloroplast genome sequence of Panax vietnamensis, a medicinal herb belonging to Araliaceae family, was generated by de novo assembly using whole genome next-generation sequences. The chloroplast genome was a circular form of 155 992 bp long and showed typical chloroplast genome structure consisting of a large single-copy region of 86 177 bp, a small single copy region of 17 935 bp and a pair of inverted repeats of 25 940 bp. The chloroplast genome had 79 protein-coding genes, 29 tRNA genes and 4 rRNA genes. The phylogenetic analysis with the reported chloroplast genomes revealed that four Panax species were grouped in the same clade and P. vietnamensis is more closely related to P. notoginseng than P. ginseng and P. quinquefolius.

Anti-inflammatory effects of vina-ginsenoside R2 and majonoside R2 isolated from Panax vietnamensis and their metabolites in lipopolysaccharide-stimulated macrophages

Panax vietnamensis Ha et Grushv., with its main constituents vina-ginsenoside R2 (VR2) and majonoside R2 (MR2), is used in traditional folk medicine in the hill tribes of Vietnam for anti-fatigue, anti-inflammatory, and life-saving purposes. In a preliminary study, VR2 and MR2 were shown to be metabolized to pseudoginsenoside RT4 (PRT4) and ocotillol by human gut microbiota. Therefore, we measured the anti-inflammatory effects of VR2, MR2, and their metabolites in lipopolysaccharide (LPS)-stimulated mouse peritoneal macrophages. Among these ginsenosides, only VR2 exhibited cytotoxicity against peritoneal macrophages. MR2, PRT4, and ocotillol inhibited LPS-stimulated transcription factor (NF)-κB activation, and expression of the proinflammatory cytokines tumor necrosis factor-α and interleukin (IL)-1. However, these ginsenosides did not inhibit peptidoglycan-induced NF-κB activation in the macrophages. These three ginsenosides also inhibited LPS-stimulated cyclooxygenase-2 and inducible NO synthase expression, and phosphorylation of NF-κB signal molecules IL-1 receptor-associated kinase 1 and tumor growth factor-β-activated kinase 1 in peritoneal macrophages. Treatment with either PRT4 or ocotillol inhibited the Alexa Fluor 488-conjugated LPS-mediated shift of macrophages, as observed by flow cytometry. They also potently inhibited the binding of LPS to TLR4 on peritoneal macrophages, both with and without transfected MyD88 siRNA. Among the tested ginsenosides, ocotillol exhibited the strongest inhibitory effect on inflammation in LPS-stimulated macrophages via the NF-κB signaling pathway. Based on these findings, orally administered VR2 and MR2 of P. vietnamensis may be metabolized to ocotillol via PRT4, and the metabolites, particularly ocotillol, may inhibit inflammation by inhibiting the binding of LPS to TLR4 on macrophages.

Processed Vietnamese ginseng: Preliminary results in chemistry and biological activity

Background

This study was carried out to investigate the effect of the steaming process on chemical constituents, free radical scavenging activity, and antiproliferative effect of Vietnamese ginseng.

Methods

Samples of powdered Vietnamese ginseng were steamed at 120°C for various times and their extracts were subjected to chemical and biological studies.

Results

Upon steaming, contents of polar ginsenosides, such as Rb1, Rc, Rd, Re, and Rg1, were rapidly decreased, whereas less polar ginsenosides such as Rg3, Rg5, Rk1, Rk3, and Rh4 were increased as reported previously. However, ocotillol type saponins, which have no glycosyl moiety at the C-20 position, were relatively stable on steaming. The radical scavenging activity was increased continuously up to 20 h of steaming. Similarly, the antiproliferative activity against A549 lung cancer cells was also increased.

Conclusion

It seems that the antiproliferative activity is closely related to the contents of ginsenoside Rg3, Rg5, and Rk1.