Multidrug-resistance modulators from Stephania japonica

Neuroprotective potential of traditionally used medicinal plants of Manipur against rotenone-induced neurotoxicity in SH-SY5Y neuroblastoma cells

ETHNOPHARMACOLOGICAL RELEVANCE

Alternanthera sessilis (L.) R. Br. ex DC., Eryngium foetidum L., and Stephania japonica (Thunb.) Miers plants are traditionally used to treat various central nervous system disorders like paralysis, epilepsy, seizure, convulsion, chronic pain, headache, sleep disturbances, sprain, and mental disorders. However, their possible neuroprotective effects have not been evaluated experimentally so far.

AIM OF THE STUDY

The study aims to examine the neuroprotective potential of the three plants against cytotoxicity induced by rotenone in SH-SY5Y neuroblastoma cells and assess its plausible mechanisms of neuroprotection.

MATERIALS AND METHODS

The antioxidant properties of the plant extracts were determined chemically by DPPH and ABTS assay methods. The cytotoxicity of rotenone and the cytoprotective activities of the extracts were evaluated using MTT assays. Microtubule-associated protein 2 (MAP2) expression studies in cells were performed to assess neuronal survival after rotenone and extract treatments. Mitochondrial membrane potential and intracellular levels of reactive oxygen species were evaluated using Rhodamine 123 and DCF-DA dye, respectively. Catalase, glutathione peroxidase, and superoxide dismutase activities were also measured. Apoptotic nuclei were examined using DAPI staining. Liquid chromatography-quadrupole time-of-flight tandem mass spectrometry (LC-QTOF-MS) analysis of the plant extracts was also performed.

RESULTS

The methanol extracts of A. sessilis, S. japonica, and E. foetidum showed excellent free radical scavenging activities. MAP2 expression studies show that A. sessilis and S. japonica have higher neuroprotective effects against rotenone-induced neurotoxicity in SH-SY5Y cells than E. foetidum. Pre-treating cells with the plant extracts reverses the rotenone-induced increase in intracellular ROS. The plant extracts could also restore the reduced mitochondrial membrane potential induced by rotenone treatment and reinstate rotenone-induced increases in catalase, glutathione peroxidase, and superoxide dismutase activities. All the extracts inhibited rotenone-induced changes in nuclear morphology and DNA condensation, an early event of cellular apoptosis. LC-QTOF-MS analysis of the plant extracts shows the presence of neuroprotective compounds.

CONCLUSIONS

The plant extracts showed neuroprotective activities against rotenone-treated SH-SY5Y cells through antioxidant and anti-apoptotic mechanisms. These findings support the ethnopharmacological uses of these plants in treating neurological disorders. They probably are a good source of neuroprotective compounds that could be further explored to develop treatment strategies for neurodegenerative diseases like Parkinson's disease.

The genus Stephania (Menispermaceae): chemical and pharmacological perspectives

The plants of the genus Stephania (Menispermaceae) are widely distributed, and have long been used in folk medicine for the treatment of various ailments such as asthma, tuberculosis, dysentery, hyperglycemia, malaria, cancer and fever. Over 150 alkaloids together with flavonoids, lignans, steroids, terpenoids and coumarins have been identified in the genus, and many of these have been evaluated for biological activity. This review presents comprehensive information on the chemistry and pharmacology of the genus together with the traditional uses of many of its plants. In addition, this review discusses the structure-activity relationship of different compounds as well as recent developments and the scope for future research in this aspect.

Reproductive effects of ethnomedicinal formulation of tape-vine leaves in female rats

Documented ethno-contraceptive use of Tape-vine or Stephania japonica (THUNB.) MIERS., Syn. Stephania hernandifolia (WILLD.) WALP. leaves is evaluated with regards to post-coital pregnancy interceptive activity of its aqueous extract (AE) and an ethnomedicinal formulation (EF) in Wistar rats. EF at 500 and 250 mg/kg doses induced 66.7% and 33.3% post-coital pregnancy interception respectively and the higher dose exhibited significant reduction in number of litters born and also anti-implantation property. In contrast, none of the dose levels of AE interfered in pregnancy but significant anti-implantation property was observed at doses of 2 and 1 g/kg, even as the higher dose produced significant reduction in number of litters born as well. EF at 500 mg/kg also exhibited significant uterotrophic activity and histological changes in uterus. Pair-wise comparison of sex hormone-levels exhibited significant increment in serum estradiol, LH and FSH but decrease in progesterone levels. Assessed blood lipid-carbohydrate profile exhibited substantial decrease in glucose, cholesterol, VLDL and triglyceride contents and significant increase in HDL. It is concluded that EF probably acts as better post-coital pregnancy interceptive agent through restriction of implantation by alteration of gonadal hormone levels and decline in blood-glucose levels that possibly disrupts oxidative energy metabolism in uterus during implantation. High surge in LH and FSH suggests negligible interference in ovulatory mechanism. This preparation also seems to be free of cardiovascular risk factors. HPTLC and HPLC analysis of both EF and AE exhibited marked chemical differences.

HPLC isolation of the anti-plasmodially active bisbenzylisoquinone alkaloids present in roots of Cissampelos mucronata

The methanolic extract of dried, powdered Cissampelos mucronata roots possesses significant in vitro activity against Plasmodium falciparum. In order to enable further pharmacological testing, the substances responsible for the observed activity were purified, mainly by HPLC, using various stationary and mobile phases. The active principles were determined to be a series of bisbenzylisoquinoline alkaloids, a group of natural products for which one of the first routine preparative HPLC separation methods is described.

The medicinal chemistry of multidrug resistance (MDR) reversing drugs

Multidrug resistance (MDR) is a kind of resistance of cancer cells to multiple classes of chemotherapic drugs that can be structurally and mechanistically unrelated. Classical MDR regards altered membrane transport that results in lower cell concentrations of cytotoxic drug and is related to the over expression of a variety of proteins that act as ATP-dependent extrusion pumps. P-glycoprotein (Pgp) and multidrug resistance protein (MRP1) are the most important and widely studied members of the family that belongs to the ABC superfamily of transporters. It is apparent that, besides their role in cancer cell resistance, these proteins have multiple physiological functions as well, since they are expressed also in many important non-tumoural tissues and are largely present in prokaryotic organisms. A number of drugs have been identified which are able to reverse the effects of Pgp, MRPI and sister proteins, on multidrug resistance. The first MDR modulators discovered and studied in clinical trials were endowed with definite pharmacological actions so that the doses required to overcome MDR were associated with unacceptably high side effects. As a consequence, much attention has been focused on developing more potent and selective modulators with proper potency, selectivity and pharmacokinetics that can be used at lower doses. Several novel MDR reversing agents (also known as chemosensitisers) are currently undergoing clinical evaluation for the treatment of resistant tumours. This review is concerned with the medicinal chemistry of MDR reversers, with particular attention to the drugs that are presently in development.