Identification of possible reductants in the aqueous leaf extract of mangrove plant Rhizophora apiculata for the fabrication and cytotoxicity of silver nanoparticles against human osteosarcoma MG-63 cells.

Rhizophora apiculata is a less studied tannin-rich plant of the mangrove ecosystem with potent biomedical applications. Tannins have been known to reduce silver ions into silver nanoparticles which in particular are known to possess cytotoxic effects against a variety of cancer cells. The aqueous leaf extract was prepared and quantitatively analyzed for its phytochemical content. According to the quantitative phytochemical analysis, the extract was rich in tannins and other reducing sugars. The reducing sugar-rich extract was further used for the synthesis of silver nanoparticles. Taking these facts into consideration, in this study, an eco-friendly approach was followed to biosynthesize silver nanoparticles using a tannin-rich Rhizophora apiculata aqueous leaf extract. The synthesized nanoparticles were partially characterized by our previous reports. This report further characterizes the particles by determining its average size, polydispersity index and zeta potential using dynamic light scattering. After characterization, the nanoparticles were tested for cytotoxic effects against human osteosarcoma MG-63 cells. The effects were analyzed by microscopic observation and MTT assay. The results indicate that the tannin-rich extract reduced the precursor silver nitrate into silver nanoparticles of favorable size for tumor infiltration. The nanoparticles possessed significant cytotoxic effects against MG-63 cells which could be possibly attributed to the antioxidant activity of silver nanoparticles. Further studies at the molecular level can indicate its potential in nanomedicine for the treatment of bone cancer at the clinical level.

Pharmacokinetic synergy from the taxane extract of Taxus chinensis improves the bioavailability of paclitaxel.

BACKGROUND: Taxus chinensis (Pilger) Rehd is widely distributed in China and the northern hemisphere, and the most popular medicinal component isolated from Taxus chinensis is paclitaxel (PTX), which has now become the first-line chemotherapeutic drug for breast cancer and ovarian cancer. Oral administration of pure PTX as a potential anti-cancer agent is compromised by low bioavailability. HYPOTHESIS/PURPOSE: In the clinical practice of traditional Chinese medicine, drug co-administration in the form of mixtures or formula could achieve pharmacokinetic/pharmacodynamic synergies. In this study, we aimed to investigate whether there exist any 'inherent' phytochemical synergy from Taxus chinensis extract that could improve PTX bioavailability. STUDY DESIGN: Pharmacokinetic study of PTX after oral administration of Taxus chinensis extracts or single PTX was performed. In addition, comparative cytotoxic studies were carried out on the MCF-7 breast cancer cell lines. METHODS: The plasma concentrations of PTX were determined using a validated high performance chromatography tandem mass spectrometry method. The cytotoxicity was compared using the MTT assay. RESULTS: Oral administration of taxane fractions isolated from Taxus chinensis (containing 17.2% PTX) could achieve remarkably higher blood concentration and systemic exposure of PTX in rats, while the retention of PTX was significantly improved. Further tissue distribution analysis revealed that the penetration of PTX into major tissues was drastically increased compared with that of single PTX. In addition, in MCF-7 cells, the co-existing components in taxane mixtures could strengthen the inhibitory effects of PTX on tumor cell proliferation. CONCLUSION: Together, these results support that administration of PTX in the form of taxane mixtures may become a novel approach to improve the poor bioavailability of PTX. Moreover, the inherent synergy from Taxus chinensis taxane extracts promises a novel strategy to strengthen PTX efficacy.

23-Hydroxybetulinic acid from Pulsatilla chinensis (Bunge) Regel synergizes the antitumor activities of doxorubicin in vitro and in vivo.

UNLABELLED: ETHNOPHARMACOLOGICAL REVELANCE: Pulsatilla chinensis (Bunge)Regel has been used as adjuvant in chemotherapy in traditional Chinese medicine. 23-Hydroxybetulinic acid, an isolated pentacyclic triterpene, is the major active constituent of Pulsatilla chinensis (Bunge) Regel. AIM OF THIS STUDY: To evaluate the combinational anticancer effect of 23-hydroxybetulinic acid and doxorubicin in vitro and in vivo. MATERIALS AND METHODS: The effect of combination treatment with 23-hydroxybetulinic acid and doxorubicin was evaluated with a quantitative combination index method based on the median-effect analysis in various cancer cell lines. And in vivo efficacy of combination chemotherapy was also evaluated using ICR mice bearing sarcoma 180 carcinoma tumors. RESULTS: 23-Hydroxybetulinic acid showed a synergistic cytotoxic effect on multiple cancer cell lines by combined use with doxorubicin. In vivo studies further demonstrated that co-administration of 23-HBA significantly improved the sensitivity of the tumor to doxorubicin through increasing intra-tumor doxorubicin concentration and inhibiting doxorubicin-induced up-regulation of P-gp in tumor. CONCLUSION: These results suggest that the combined therapy with 23-hydroxybetulinic acid and doxorubicin may be a new promising strategy to promote the clinical chemotherapy, which needs further verification.