Cytotoxic effects of triterpenoid saponins from Androsace umbellata against multidrug resistance (MDR) and non-MDR cells

Anticancer activity of Nigerian medicinal plants: a review

Background

Cancer is currently the leading cause of death globally and the number of deaths from cancer is on the rise daily. Medicinal plants have been in continuous use over the years for the management of cancer, particularly, in most developing countries of the world including Nigeria. The use of synthetic drugs for the treatment of cancer is often accompanied by toxic side effects. Thus, the alternative use of readily available and inexpensive medicinal plants is the panacea to the toxic side effects associated with synthetic drugs.

Main body

The present review summarized the anticancer activity of 51 medicinal plants that are widespread in all regions of Nigeria. Furthermore, the proposed anticancer pharmacological actions as well as the anticancer bioactive compounds, the type of cancer cell inhibited, the plant parts responsible for the anticancer activity, and the nature of the extracts used for the studies were discussed in this review. The 51 Nigerian medicinal plants were reported to exhibit anticancer activities of the prostate, cervices, lung, skin, colon, esophagus, blood, ovary, central nervous system/brain, breast, stomach, pancreas, larynx, and kidney. The major classes of bioactive compounds indicated to be responsible for the anticancer activity include the polyphenols, flavonoids, alkaloids, saponins, triterpenes, tannins, and quinones. The major anticancer pharmacological actions of these bioactive compounds were antiproliferative, cytotoxic, cytostatic, antimetastatic, apoptotic, and antioxidative as well as provoked cell cycle arrest, inhibition of angiogenesis and reduction of cancer cell viability.

Conclusion

The Nigerian medicinal plants can be harnessed to provide for readily available and inexpensive anticancer drugs in the future because the plants reported in this review showed promising anticancer activity.

Phytochemicals in Anticancer Drug Development

BACKGROUND

In spite of major technological advances in conventional therapies, cancer continues to remain the leading cause of mortality worldwide. Phytochemicals are gradually emerging as a rich source of effective but safer agents against many life-threatening diseases.

METHODS

Various phytochemicals with reported anticancer activity have been simply categorized into major phytoconstituents- alkaloids, polyphenols, saponins, tannins and terpenoids.

RESULTS

The adverse effects associated with currently available anticancer medications may be overcome by using plant-derived compounds either alone or in combination. Exploration of plant kingdom may provide new leads for the accelerated development of new anticancer agents.

CONCLUSION

Although numerous potent synthetic drugs have been introduced for cancer chemotherapy, yet their serious toxicity concerns to normal cells apart from drug resistance have emerged as the major obstacles for their clinical utility over a prolonged duration of time. Current status and potential of phytochemicals and their derivatives in cancer therapy have been briefly reviewed in the present manuscript.

Saxifragifolin D attenuates phagosome maturation arrest in Mycobacterium tuberculosis-infected macrophages via an AMPK and VPS34-dependent pathway

Saxifragifolin D (SD), a traditional Chinese medicine, is a pentacyclic triterpenoid compound first isolated from Androsace umbellata. Various plant triterpenoids have been reported to exhibit antitubercular activity. In this study, THP-1-derived macrophages were infected with an attenuated M. tuberculosis (M.tb) strain, H₃₇Ra. Intracellular replication of M.tb was evaluated by counting the colonies after 4 weeks of incubation. The results indicated that SD treatment reduced the intracellular replication of M.tb in THP-1-derived macrophages but not in A549 cells. We performed a phagosome maturation test using confocal microscopy and found that SD treatment partially attenuated the phagosome arrest induced by M.tb infection. These effects were dependent on a VPS34-associated pathway. Immunoprecipitation assays showed that SD increased intracellular UVRAG-linked VPS34, the active VPS34 complex II. However, SD had no effect on the total VPS34 pool. Moreover, the results indicated that the SD-mediated increase in VPS34 complex II activity was mediated by an AMPK-dependent pathway. Collectively, these data indicate that SD may be a promising candidate for treatment of M.tb.

New triterpene saponins from the aerial parts of Androsace umbellata

Compound 8 bearing a 13β,28-epoxy group can induce apoptosis in HepG2/ADM cells.

Effects of Saponins on Lipid Metabolism: A Review of Potential Health Benefits in the Treatment of Obesity

Obesity is one of the greatest public health problems. This complex condition has reached epidemic proportions in many parts of the world, and it constitutes a risk factor for several chronic disorders, such as hypertension, cardiovascular diseases and type 2 diabetes. In the last few decades, several studies dealt with the potential effects of natural products as new safe and effective tools for body weight control. Saponins are naturally-occurring surface-active glycosides, mainly produced by plants, whose structure consists of a sugar moiety linked to a hydrophobic aglycone (a steroid or a triterpene). Many pharmacological properties have been reported for these compounds, such as anti-inflammatory, immunostimulant, hypocholesterolemic, hypoglycemic, antifungal and cytotoxic activities. The aim of this review is to provide an overview of recent studies about the anti-obesity therapeutic potential of saponins isolated from medicinal plants. Results on the in vitro and in vivo activity of this class of phytochemicals are here presented and discussed. The most interesting findings about their possible mechanism of action and their potential health benefits in the treatment of obesity are reported, as well.

In vitro cytotoxic and anticlastogenic activities of saxifragifolin B and cyclamin isolated from Cyclamen persicum and Cyclamen libanoticum

CONTEXT

The genus Cyclamen L. (Primulaceae) is rich in saponins known to have interesting biological activities.

OBJECTIVE

To isolate saxifragifolin B and cyclamin, two triterpene saponins, from Cyclamen libanoticum Hildebr and Cyclamen persicum Mill, and to assess their cytotoxic, clastogenic/aneugenic, and anticlastogenic effects, as well as antioxidant potential.

MATERIALS AND METHODS

Saxifragifolin B and cyclamin were tested for their cytotoxicity against SK-BR-3, HT-29, HepG2/3A, NCI-H1299, BXPC-3, 22RV1, and normal DMEM cell lines using WST-1 assay. Their clastogenic/aneugenic activities and anticlastogenic effects against the anticancer drug mitomycin C were assessed by the in vitro micronucleus assay in CHO cells. Their antioxidant capacities were determined using Fe(2+)-chelating and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging assays.

RESULTS

Both saponins were described for the first time in Cyclamen libanoticum. They showed strong cytotoxic activities against the tested cancer cell lines. Saxifragifolin B was found to be 56- and 37-times more active than mitomycin C against breast adenocarcinoma (SK-BR-3) and lung carcinoma (NCI-H1299), respectively. Also, saxifragifolin B did not induce micronuclei formation and prevented cells from mitomycin C clastogenic effect. Cyclamin induced a significant increase of micronucleated cells after metabolic activation with S9 mix, and did not possess any anticlastogenic activity. Both molecules exhibited low antioxidant activities as compared to reference compounds.

DISCUSSION AND CONCLUSIONS

This study showed the remarkable cytotoxic activity of saxifragifolin B, especially against breast adenocarcinoma and lung carcinoma and its chemoprotective activity against mitomycin C. Thus, saxifragifolin B could be suggested as a potential cytotoxic drug with a preventive effect against possible exposures to genotoxic agents.

Saxifragifolin D induces the interplay between apoptosis and autophagy in breast cancer cells through ROS-dependent endoplasmic reticulum stress

Breast cancer is the leading cause of cancer death among females, and novel chemotherapeutic drugs for treating breast cancer are needed urgently. Saxifragifolin D (SD) was isolated by our group from Androsace umbellata which is commonly used to treat solid tumor. In this study, we evaluated its growth inhibitory effect on breast cancer cells and explored the underlying molecular mechanisms. Our results showed that SD inhibited the growth of both MCF-7 and MDA-MB-231 cells significantly. Mechanistic studies demonstrated that SD induced apoptosis through mitochondrial apoptotic pathway. Evidence of SD-induced autophagy included the occurrence of autophagic vacuoles, up-regulation of LC3-II, Beclin1 and Vps34. Inhibition of autophagy by bafilomycin A1 or Beclin1 siRNA pretreatment decreased the ratio of apoptosis, indicating that autophagy induction contributes to apoptosis and is required for the latter. SD was also found to induce endoplasmic reticulum stress, accompanied by ROS production, increase of intracellular calcium and up-regulation of Bip, IRE1α and XBP-1s. Inhibition of endoplasmic reticulum stress by N-acetyl-l-cysteine, tauroursodeoxycholic acid or IRE1α siRNA pretreatment could suppress both apoptosis and autophagy. Besides, increases in CHOP, calnexin, calpain, p-JNK and p-Bcl-2 were followed by subsequent dissociation of Beclin1 from Bcl-2, further suggesting endoplasmic reticulum stress to be the common signaling pathway shared by SD-induced apoptosis and autophagy. In conclusion, SD inhibits breast cancer cell growth and induces interplay between apoptosis and autophagy through ROS-mediated endoplasmic reticulum stress. It will provide molecular bases for developing SD into a drug candidate for the treatment of breast cancer.