In vivo tumour inhibitory and immunomodulatory effects of clinacanthus nutans ethanolic crude extract

Abstract

Clinacanthus nutans (belalai gajah) has been used extensively by Asian community to treat various diseases, including cancers. Despite of that, studies on its potential toxicity effect and tumour inhibitory efficacy have not been fully validated and supported by scientific evidence. Therefore, the present study aims at determining the sub-acute toxicity effect and tumour inhibitory potential of C. nutans crude ethanolic extract. In sub-acute toxicity, mice were orally administered with C. nutans leaves extracts for 28 days and were monitored for any physical and histological changes. Meanwhile, tumour inhibitory potential was determined by administering TC-1 tumour-bearing mice with C. nutans extract. Tumour growth was monitored and the influence on immune response was also evaluated. From the results, it was shown that all treatment groups (50, 300, 2000 and 5000 mg/kg) displayed no significant changes in body weight, relative organ weight and feeding pattern when compared to control. However, histolological analysis revealed slight structural changes in liver and kidney of mice administered with C. nutans at concentrations 300 to 5000 mg/kg, thus suggesting the lowest observed adverse effect level (LOAEL) is 300 mg/kg. In addition, the present study demonstrated that mice administered with C. nutans at 50 mg/kg significantly delayed tumor growth compared to untreated group. This result was supported by a significant increase of apoptotic cells, as well as significant reduction of proliferating cell nuclear antigen (PCNA)-positive cells, compared to untreated mice. Despite no substantial changes in all hematological parameters, the level of pro-inflammatory cytokines; IFN-? and IL-2, and anti-inflammatory cytokine, IL-10 in the treatment group was increased as compared to the control. In contrast, the level of chemokine MIP-2 was shown to decrease following treatment. The present findings also revealed the decreased level of CD4+ T lymphocytes and increased level of CD8+ T lymphocytes infiltrations following treatment as compared to control. In conclusion, results from this study highlight the therapeutic potential of C. nutans leaves extract in inhibiting tumour growth by mediating apoptosis, suppressing tumour cells proliferation and modulating immune response in tumour bearing mice.