Radioprotective effects of diallyl disulphide and Carica papaya (L.) leaf extract in electron beam radiation induced hematopoietic suppression

Abstract

Numerous herbal and synthetic formulations have been used to determine the protective effects against radiation toxicity. In the present study, the radioprotective effects of aqueous leaf extract of Carica papaya (L.) and diallyl disulfide were studied in irradiated and non-irradiated groups. The optimum dose selection for papaya leaf extract and diallyl disulfide was done using Kaplan-Meier survival analysis. The mice were treated with papaya leaf extract at 5, 50, 100 and 200, 250, 500, 1,000 mg/kg body weight concentration and diallyl disulfide (DADS) at 0.5, 2, 5, 10, 20 mg/kg body weight for five consecutive days and on the 5th day one hour after dose administration they were irradiated with 10 Gy dose of lethal electron beam radiation. The mice were observed for maximum survival within 30 days post irradiation. The survival analysis from Kaplan-Meier curve indicated the optimum radioprotective dose for papaya leaf extract at 100 mg/kg body weight and for diallyl disulfide at 10 mg/kg body weight. The optimum dose was used for further studies with sublethal, lower sublethal, and adaptive split dose responses. The results indicate hematopoietic suppression in irradiated groups with sublethal, lower sublethal, and adaptive split dose groups. An increase in platelet levels and RBC levels were exhibited by papaya leaf extract pretreatment prior to irradiation with sublethal and lower sublethal doses. There was reduction in the antioxidant enzymes, total antioxidant capacity and increased lipid peroxidation seen in sublethal and lower sublethal radiation control groups. The pretreatment groups with papaya leaf extract and DADS prior irradiation have moderately enhanced the total antioxidant capacity, antioxidant enzyme levels, and reduced lipid peroxidation. There was a radio-adaptive response seen with the blood cell DNA damage in mice irradiated with an adaptive dose of 1 Gy 24 h prior to a dose of 5 Gy when compared to a single sublethal radiation dose group. The papaya leaf extract and DADS also contributed this effect and further enhanced the adaptive response.

Keywords:

• antioxidant
• radiation toxicity
• dose reduction factor
• radioadaptive response

Public Interest Statement

The study highlights the protective role of papaya leaf extract and diallyl disulfide against ionizing radiation induced tissue damages in Swiss albino mice. To understand the nature of protection offered by them we have studied at different levels like survival, antioxidant levels, changes in DNA integrity, and response at different doses. The results highlight these studies and their significance and relevance in offering the protection. The results indicate a protective role of papaya leaf extract and diallyl disulfide in improving the survival, enhancing the antioxidant levels, reducing the DNA damage, and also a radiation adaptive response in mice.

Competing Interest

The authors declare no competing interest.

Acknowledgements

The authors are grateful to the board of research in nuclear sciences (BRNS) sanction No. 2012/34/26/BRNS for funding the study and Nitte University for providing the laboratory facility. The authors acknowledge the support of Dr Ganesh Sanjeev, Professor, Microtron center, Mangalore University, Dr Damodhara Gowda, Department of Physiology and Dr Chandrika Rao, Department of Pathology, K.S. Hegde Medical Academy, Nitte University. The authors also thank Dr Sanal T.S., Associate professor, Department of Biostatistics, K.S. Hegde Medical Academy, Nitte University.

Additional information

Funding

This work was supported by Board of Research in Nuclear Sciences [grant number 2012/34/26/BRNS].

Notes on contributors

Suchetha Kumari N.

The authors of Central Research Laboratory, K S Hegde Medical Academy, Nitte University are majorly involved in studies related to radiation protectors, mitigators, and their mode of action in different systems of Invitro and Invivo. Most of the resources that are being studied are of plant origin as they are non-toxic and inexpensive. The present study is an attempt to understand the radioprotective role and radio-adaptive response of papaya leaf extract and diallyl disulfide using electron beam as a source of ionizing radiation.