Insight on structural modification, biological activity, structure-activity relationship of PPD-type ginsenoside derivatives

Ginsenosides, characterized by triterpenoid, are one of the active components of ginseng. Among them, PPD-type ginsenosides have potent and diverse pharmacological activities, while the effective applications and clinical studies are limited by the poor stability, water solubility and oral bioavailability. In this review, we have attempted to demonstrate the structural-activity relationship of chemical modifications on the dammarane-type skeleton and the C-17 side chain, noting that certain structurally modified derivatives exhibit satisfactory pharmacological activity. This review will provide ideas for the design and synthesis of novel PPD derivatives, and valuable help for the further study of PPD derivatives to make it realize clinical application.

Application of Amino Acids in the Structural Modification of Natural Products: A Review

Natural products and their derivatives are important sources for drug discovery; however, they usually have poor solubility and low activity and require structural modification. Amino acids are highly soluble in water and have a wide range of activities. The introduction of amino acids into natural products is expected to improve the performance of these products and minimize their adverse effects. Therefore, this review summarizes the application of amino acids in the structural modification of natural products and provides a theoretical basis for the structural modification of natural products in the future. The articles were divided into six types based on the backbone structures of the natural products, and the related applications of amino acids in the structural modification of natural products were discussed in detail.

Novel ginsenoside derivatives have shown their effects on PC-3 cells by inducing G1-phase arrest and reactive oxygen species-mediate cell apoptosis

In this study, piperazine groups were introduced into ginsenoside to enhance its ability to induce Reactive Oxygen Species (ROS) production and apoptosis in cancer cells. In total, 27 ginsenoside piperazine derivatives were synthesized and tested for their anti-proliferative activity in cancer cell lines by MTT assay. The results showed that compounds 4a, 4g, 4f, 4i, 5g, 5i, 6a, 6g, 6f and 6i had significant inhibitory effects on cancer cell growth. Compound 6g showed the strongest anti-proliferative effect on PC-3 cells with an IC₅₀ of 1.98 ± 0.34 μM. Compound 6g could also induce G1-phase arrest and apoptosis in PC-3 cells, with apoptosis rates of 8.1%, 41% and 56.1% observed at 5, 10 and 20 μM, respectively. Compound 6g also significantly enhanced the intracellular fluorescence of ROS sensitive substrates, with a fluorescence intensity ratio of 23.1% observed in treated cells, indicative of ROS production. Following N-acetylcysteine treatment, apoptotic rates of the cancer cell lines decreased from 38.9% to 7.3%, and the expression of Cl-PARP, Cl-Caspase-3 and Cl-Caspase-9 also decreased, confirming that compound 6g induced apoptosis through ROS induction. Compound 6g also stimulated the translocation of Bax from the cytoplasm to the mitochondria, which enhanced Cytochrome C (Cyt C) release, and increased the expression of the apoptotic markers Cl-PARP, Cl-Caspase-3, and Cl-Caspase-9 in PC-3 cells. Taken together, these data reveal the anti-cancer effects of compound 6g that enhance ROS production, and then induce apoptosis through mitochondrial pathway.

Highly regioselective biotransformation of ginsenoside Rg1 to 25-OH derivatives of 20(S/R)-Rh1 by Cordyceps Sinensis

25-OH ginsenosides are potent and rare prodrugs in natural sources. However current strategies for such modification always end up in undesirable side products and unsatisfied yield that hinders them from further applications. Herein, ginsenoside Rg1 was thoroughly converted into 20(S/R)-Rh1 and 25-OH-20(S/R)-Rh1 by Cordyceps Sinensis in an optimum medium. The chemical correctness of either 25-OH-20(S/R)-Rh1 epimers was validated by LC-IT-TOF-MSn and ¹³C NMR spectrometry. The biocatalytic pathway was established as Rg1 → 20(S/R)-Rh1 → 25-OH-20(S/R)-Rh1. The molar bioconversion rate for total 25-OH-20(S/R)-Rh1 was calculated to be 82.5%, of which S-configuration accounted for 43.2% while R-configuration 39.3%. These two 25-OH derivatives are direct hydration products from 20(S/R)-Rh1 without other side metabolites, suggesting this is a highly regioselective process. In conclusion, this biocatalytic system could be harnessed to facilitate the preparation of diversified 25-OH ginsenosides with high yields of the target compound and simple chemical background in the reaction mixture.

Highly regioselective bioconversion of ginsenoside Re into 20(S/R)-Rf2 by an optimized culture of Cordyceps sinensis

Highly regioselective hydration of the C24–C25 double bond is discovered during the bioconversion of ginsenoside Re by Cordyceps sinensis.

Synthesis and Anticancer Activity Evaluation of Hydrolyzed Derivatives of Panaxnotoginseng Saponins

To increase the antitumor activity of ginsenosides and acetylsalicylic acid, acid hydrolysis products of Panaxnotoginseng saponin were used as raw materials to be combined with salicylic acid to obtain ginsenoside salicylic acid derivatives. All derivatives were assessed for anti-cancer activity. A total of 20 target compounds were designed and synthesized. The cytotoxic activity on five cancer cell lines, including human colon cancer (HT-29), gastric cancer (BGC-823), cervical cancer (Hela), human breast cancer (MCF-7), human lung cancer cells (A549), and two normal cancer cell lines (human gastric epithelial cells (GES-1), and human ovarian epithelial cells (IOSE144)) was evaluated following treatment with the compounds. The results showed that all compounds inhibited the growth of cancer cells. Compounds 1a, 3a, 7a, 1b, 2b, 3b and 8b showed strong anticancer activity. For MCF-7 cells, compound 3b showed the strongest inhibitory activity, IC₅₀ = 2.56 ± 0.09 μM. In the cytotoxicity test, all compounds showed low toxicity or no toxicity (IC₅₀ > 100 μM). In addition, a cell cycle distribution assay and wound healing assay demonstrated that compound 3b specifically inhibited MCF-7 proliferation and migration ability. Our results indicate that compound 3b represents a promising compound for further cancer studies.

Non-protein amino acid derivatives of 25-methoxylprotopanaxadiol/25-hydroxyprotopanaxadioland their anti-tumour activity evaluation

As active components of ginseng, 25-methoxylprotopanaxadiol and 25-hydroxyprotopanaxadiol exhibited an ability to inhibit the growth and proliferation or to induce the differentiation and apoptosis of tumour cells. We modified 25-OCH₃-PPD and 25-OH-PPD with non-protein amino acids and a series of derivatives was obtained by chromatographic separation, purification and spectroscopy analysis. Thirteen derivatives of 25-OCH₃-PPD (compounds 1-13) and 12 derivatives of 25-OH-PPD (compounds 14-25) were synthesised. The anti-cancer activities of the derivatives were evaluated on HCT-116 and BGC-823 cell lines by MTT assay. Compound 9 and compound 14 exhibited considerable anti-tumour activity for HCT-116 and BGC-823 cell lines, exhibited higher cytotoxic activity than 25-OCH₃-PPD and 25-OH-PPD. Therefore, these ginsenoside derivatives could be used as potential lead for the development of a new type of anticancer agent.