1.       Introduction

Cancer is a major public health problem all over the world and constitutes the second leading cause of death after cardiovascular disease [1]. Because of serious side effects of both chemo-and radiation therapies, many patients seek alternative and complementary methods of treatment. Several anti-cancer agents derived from plant species (Taxol, Camptothecin, Topotecan, etc. and their derivatives) are in clinical use or in preclinical development (Flavopiridol, Silvestrol, Betulinic acid, etc.) [2].

Democratic Republic of the Congo (DRC) as one of the hotspots of plant biodiversity in the world could play a key role in the R & D of new anti-cancer agents from it flora [3]. The aims of this multidisciplinary research program were:(a)To validate scientifically the traditional use of selected plant species by investigating anti-cancer activity of their extracts as a possible source of anti-cancer hits using human prostate (PC-3) and breast (MCF-7) cancerous cell lines and non-cancerous rat skeletal muscle L6 cell lines as model systems (Scientific evidence based Traditional Medicine); (b)To evaluate the therapeutic index of the biologically active extracts; (c)To develop anti-cancer phytomedicines as a result of the transformation of indigenous/ethno-medical knowledge into large scale action by the mean of Science and Technology(Research for sustainable development).

2.       Materials and Methods

An ethno-botanical survey was conducted in DRC according to the principles laid out in the Declaration of Helsinki and the Nagoya protocol. Traditional Healers and/or medicinal plant vendors (50) were interviewed about medicinal plants used in Congolese folk medicine [4]. The powdered leaves of Gardenia ternifolia were extracted by maceration. Successive extractions were carried out with organic solvents of increasing polarity (Petroleum ether, Chloroform, Ethyl acetate, Methanol and Methanol 80%). Anti-cancer bioactivity of different extracts was assessed by MTT assay. Paclitaxel was used as positive control [5].

3.       Results and Discussion

Ethno-botanical survey revealed that the most cited plant species was Gardenia ternifolia (or Lembanzau in Kikongo) with a high value of informant consensus factor (0.361). Biological screening revealed that chloroform and ethyl acetate soluble fractions are biologically active against MCF-7 cell lines with a CC₅₀ (50% cytotoxic concentration) of 21.62±1.6μg/mL and 45.44±2.2μg/mL respectively. For PC-3 cell lines, the CC₅₀ were 9.66±2.6μg/ml and 24.47±1.1μg/ml, respectively for chloroform and ethyl acetate extracts. The petroleum ether, methanol and methanol 80% crude extracts were inactive against both MCF-7 and PC-3 cell lines (50 < CC₅₀<100 or CC₅₀> 100 μg/ml).The chloroform extract displayed interesting therapeutic index or safety ratio (CC₅₀ L6/CC₅₀ MCF-7 or PC-3 ≥3).This extract is 3 or 7 times selective in killing the cancerous cell lines (MCF-7 or PC-3) than the non-cancerous cell lines (L6) [5]. This could be due to the different secondary metabolites extracted with the chloroform solvent. (Figure 1)

4.       Conclusion

The chloroform extract of Gardenia ternifolia decreases the cancerous cell lines density in vitro. As potential candidate, G. ternifolia could be developed as therapeutic phytomedicine against human prostate and breast cancers. Further studies are therefore in progress to purify and elucidate the structure(s) of bioactive compounds.

5.       Acknowledgment

The authors are indebted to the Organization staff of Unesco-Merck Africa Research Summit 2017 on Cancer Research & Vaccines development held in Port Louis, Mauritius founded by Merck Foundation.

Figure 1: Gardenia ternifolia.

1.       Thibangu DST, Selvaraj D, Muthiah R, Govindarajan S, Ngbolua Rajandeep K, et al. (2011) Nat Prod Plant Res 1: 131-136.

2.       Ngbolua KN, Mudogo V, Tshilanda DD, Misengabu MN, Mpiana PT, et at. (2016) In Vitro Anticancer Assessment of Annickia chlorantha (Oliv.) Setten & Maas Stem (Annonaceae) Bark from Democratic Republic of Congo. Journal of Biosciences and Medicines 4: 23-29.

3.       Ngbolua KN, Rakotoarimanana H, Rafatro H, Ratsimamanga US, Mudogo V, et al. (2011) Comparative antimalarial and cytotoxic activities of two Vernonia species: V. amygdalina from the Democratic Republic of Congo and V. cinerea subsp vialis endemic to Madagascar. Int J Biol Chem Sci. 5: 345-353.

4.       Ngbolua KN, Shetonde OM, Mpiana PT, Inkoto LC, Masengo CA, et al. (2016) Ethno-pharmacological survey and Ecological studies of some plants used in traditional medicine in Kinshasa city (Democratic Republic of the Congo). Tropical Plant Research 3: 413-427.

5.       Tshibangu DS, Divakar S, Ramanathan M, Syamala G, Ngbolua KN, et al. (2016)  In vitro Screening of the leaf extracts from Gardenia ternifolia (Forest Gardenia) for their anticancer activity. Journal of Complementary and Alternative Medical Research1 2: 1-7.