African Journal of Traditional, Complementary and Alternative Medicines African Ethnomedicines Network ISSN: 0189-6016 Vol. 3, Num. 3, 2006, pp. 32-36

African Journal of Traditional, Complementary and Alternative Medicines Vol. 3, No. 3, 2006, pp. 32-36

Short Communication   

IN VITRO CYTOTOXIC ACTIVITY OF EXTRACTS OF MARCHANTIA CONVOLUTA ON HUMAN LIVER AND LUNG CANCER CELL LINES

Xiaoqing Chen and Jianbo Xiao 

College of Chemistry and Chemical Engineering, CentralSouthUniversity, Changsha 410083, PR China E-mail:jianbo_xiai@yahoo.com,newfourtharmy@163.com

Code Number: tc06034

Abstract

The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay was used to test cytotoxicity of the extracts from Marchantia convoluta against two human cancer cell lines (H1299 and HepG2). Low concentrations of theethyl acetate extract had toxic effects on HepG2 cells and inhibited H1299 cells at higher concentration. Inhibition of proliferation and induction of cell death were in a concentration-dependent. However, the petroleum ether and n-butanol extracts of Marchantia convoluta showed no cytotoxic activity.

Keywords: Cytotoxicity test; MTT assay; Marchantia convoluta

Marchantia plants (Chinese name, Di Qian) are well-known traditional Chinese medicinal herbs used extensively to treat tumefaction of skins (JIB, 1990), protect liver and treat hepatitis (Zhu et al., 2004) and as an antipyretic in countryside (Xiao et al., 2004). Marchantia convoluta is ample in Guangxi Zhuang Atuonomous District. According to our investigation, flavonoids and sesquiterpenes are the major constituents in Marchantia convoluta (Cao et al, 2005;Xiao et al, 2004;Xiao et al, 2005;Zhu et al, 2003;Zhu et al, 2005). There are few reports on the bioactivity of Marchantia convoluta. In this study, the effects of extracts of Marchantia convoluta as anti-cancer agents were investigated.

Hepatocellular carcinoma (HCC) is one of the most common malignancies worldwide. The high incidence of the liver cancer has been attributed to factors such as persistent infection with hepatitis virus and contact with hepatocarcinogens like nitrosamines and aflatoxins (Henry et al., 2002). Because of the mutlifocal nature of liver carcinoma, most cancer patients are considered nonresectable at the presentation of case. In these patients, chemotherapy is the only choice of treatment. Unfortunately, development of drug resistance in tumor after treatment is always a major obstacle to the successful management of liver cancer (Gottesman, 2002). Thus, developing new therapeutic agents that can overcome drug resistance becomes an urgent need for cancer patient.

The whole plants of Marchantia convoluta were collected in Shangling City of Guangxi Zhuang Autonomous District in August 2003. The specimen (No 20041364) was identified by Zhou Zi-jing at Biology Department of Guangxi Chinese Medical University. The leaves, after being washed with water and dried in the shade for several days, were powdered.

Preparation of plant extracts

The powdered plant material (500 g) was extracted three times with 50% ethanol (v/v) (3000 ml). The accumulated alcoholic extract was concentrated to dryness under reduced pressure and extracted with petroleum ether (3×100 ml). The residue was extracted three times with ethyl acetate (3 ×100 ml). Then the residue was extracted three times with n-butanol (100 ml). The filtrate was concentrated to dryness under reduced pressure. The residues were dissolved in ethanol to form stock solutions sterile filtered with filters (0.2 μm) before testing.

In vitro cytotoxic assay

Human cell lines

Human non-small cell lung carcinoma cell lines H1299 and human liver carcinoma HepG2 were used. Cells kindly provided by Dr. Xu of MSKCC, US were cultured in RPMI 1640 medium supplement with 10% heated foetal bovine serum, 1% of 2mM L-glutamine, 50 IU/ml penicillin and 50 μg/ml streptomycin and maintained at 37 ℃ in a 5% CO₂ atmosphere with 95% humidity.

MTT assay

Cells were washed with phosphate buffered saline (PBS) free of Magnesium and Calcium. The PBS was decanted and cells detached with 0.025% trypsin-EDTA (Sigma) and PBS was added to a volume of 50 ml. The cell pellet, obtained by centrifugation was suspended in 10 ml of medium to make a single cell suspension, viable cells density being counted by trypan blue exclusion in a haemocytometer and then diluted with medium to give the previously-determined optimal plating densities for H1299 and HepG2 respectively. 100 μl/well of these cell suspensions were seeded in 96-well microtiter plates and incubated at 37 ^oC to allow for cell attachment. After 24 h the cells were treated with the extracts. Each extract (500 μg/ml) was tested initially against both cancer cell lines. The active extracts were considered to be those hich gave less than 50% survival at 72 h. The active extracts were further diluted in medium to produce 8 concentrations of 15, 30, 40, 50, 100, 200 μg/ml of each extract. 100 μl/well of each concentration was added to the plates in six replicates. At the end of exposure time, the medium was removed and then 3-(4,5-dimethylthiazol-2-yl)-2,5 -diphenyltetrazolium bromide (MTT) assays were performed by the cell titer kit^TM (Promega) following the standard procedure. 20ml of MTT (5 mg/ml) in PBS was incubated with cells in a 96-well plate for 2 h at 37 ^oC. Subsequently, the medium containing MTT was removed, and 100 ml of acidified isopropanol (0.04 N HCl) added. Spectrophotometric absorbance of each sample was measured at 470 nm using a microplate reader (Bio-Rad, model 3550). The datas were normalized (A570 nm). The mean absorbance was plotted against drug concentration. Three replicate plates were used to determine the cytotoxicity of each extract. The concentration of each extracts reduced cell survival by 50% (IC₅₀) was determined from cell survival curves.

Datas were expressed as the mean±SD. from at least three determinations. Statistical analysis was performed using Student’s t-test, with P < 0.001 as a criterion of significance.

The results are presented in Table 1 and Figure 1.

Table 1:Cellular sensitivity of H1299 and HepG2 cells to all extracts 

 IC₅₀, drug concentration causing a 50% decrease in a survival curve.

The effect of all extracts on different cell lines was studied by measuring cell numbers by MTT assay after treatment of the cultures with each extract for 72 h. The treatment of all cell lines with ethyl acetate extract decreased cell numbers (Figure 1). However, both petroleum ether and n-butanol extracts did not inhibit cell proliferation. As indicated in Table 1, treatment of H1299 and HepG2 cells with ethyl acetate extract resulted in loss of cell viability. However, H1299 and HepG2 cells more resistant to petroleum ether and n-butanol extracts, when compared to their corresponding IC₅₀ of H1299 and HepG2 cells.

Figure 1a showed that a high concentration of ethyl acetate extract (100 μg/ml) decreased the number of H1299 cells rapidly. At lower concentrations of ethyl acetate extract (15, 30 and 40 μg/ml), the HepG2 cells numbers started to decrease markedly (Figure 1b). For H1299 cells no inhibition was observed at 15 μg/ml of ethyl acetate extract. These results suggest that at low concentrations theethylacetate extract has toxic effect on HepG2 cells while the extract inhibited H1299 cells at higher concentrations. Inhibition of proliferation and induction of cell death were concentration - dependent.

The petroleum ether and n-butanol extracts of M. convoluta had no effect on the human non-small cell lung carcinoma cell lines H1299(IC₅₀> 500 and 200 μg/ml, respectively) and human liver carcinoma HepG2(IC₅₀> 500 and 200 μg/ml, respectively) in all cases.

The results obtained in this study indicated that one of the three extracts of M. convoluta was preferentially active against cancer cells. Theethylacetate extract of M. convoluta were the most cytotoxic against human non-small cell lung carcinoma cell lines H1299and human liver carcinoma HepG2 while petroleum ether and n-butanol extracts of M. convoluta showed no cytotoxic effect against cancer lines.

References

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