Informant profiles
Table 1. Informant sociological profiles and average (± SD) number of reported species and diseases.
The majority of informants were male (57.4%). Most of them were traditional health practitioners (81.9%). The sector is dominated by adults (72.3%) followed by the elderly (23.4%). Lowest number of respondents were situated in Mbanza-Ngungu urban area (20.7%) compared to Kisantu (43.1%) and Mbanza-Ngungu rural area (36.2%) respondents. Majority of respondents had at least received primary (33%) and secondary (45.5%) school education. Most respondents were married (70.2%) and had more than 10 years of experience (78.7%) with phytomedicine. The highest average number of cited species and diseases, were recorded among elderly users (4.8±4.2 species and 2.1±1.9 diseases mentioned on average), practitioners with 5-10 years of experience (4.6±4.4 species and 1.9±1.9 diseases mentioned on average), male respondents (4.8±3.9 species and 1.9±1.9 diseases mentioned on average), curing healers (6.7±5.6 species and 3.1±2.6 diseases mentioned on average), married therapists (4.6±3.9 species and 1.8±1.9 diseases mentioned on average), respondents with at least secondary school education (4.7±4.1 species and 2.1±2.2 diseases mentioned on average) and therapists living in the Mbanza-Ngungu urban area (5.21±4.4 and 2.5±2.6) (Table 1).
Taxonomic diversity
From a total of 231 plants inventoried, 227 species could be identified and classified in 192 genera and 79 families. Families representing most species were Fabaceae (27 species, i.e. 11.9%), Euphorbiaceae (13 species, i.e. 5.7%), Rubiaceae (12 species, i.e. 5.3%), Asteraceae and Lamiaceae (each with 11 species, i.e. 4.8%) and Solanaceae (10 species, i.e. 4.4%). The other 73 families were represented by less than 10 species (Table 2).
Table 2. Taxonomic diversity of medicinal plant in the study area.
Medicinal plant use
A total of 337 plant medicine recipes have been identified, of which 203 are composed of at least two species, for the treatment of 103 diseases. Diseases most commonly treated by traditional medicine in the study area are haemorrhoids, hernias and sexual weakness or impotence. The leaf (39.4%) was the most commonly used organ, whereas decoction (41.7%) and oral intake (71.7%) were the most common preparation and administration methods, respectively, in all use reports (Fig. 2).
Fig. 2: Share (%) in use reports of organs harvested (a), preparation (b) and administration methods (c) of plant medicines.
Herbs (36.4%) are the most widespread biological form, whereas anthropized areas such as fields, roadsides, homegardens or in neighbourhoods (45.0%) are most frequent locations where inventoried medicinal plants are found (Fig.3).
Fig.3: Share (%) in medicinal plant use reports of biological forms (a) and plant locations (b).
Ethnobotanical data analysis
Relative importance of a given plant (UVS, IAR)
Medicinal plant use value ranged from 0.01 to 0.14. Elaeis guineensis Jacq., (0.14), Mondia whitei (Hook. f.) Skeels (0.10), Ocimum gratissimum L., (0.08) and Pentadiplandra brazzeana Baillon, (0.06) are the most important species in the traditional Kongo pharmacopoeia, with UVs >0.05 (Figure 4-a). The informant agreement on plant use ranged 0.1 to 1. Dioscorea smilacifolia De Wild. & T. Durand, Abelmoschus esculentus (L.).Moench, Corymbia citriodora(Hook.) K. D. Hill & L. A. S. Johnson, Garcinia kola Heckel, Musanga cecropioides R. Br., Steganotaenia araliacea Hochst, Strychnos pungens Soler. and Datura stramonium L. have the maximum IAR-value of 1 (Fig. 4-b). They represent the species with the highest level of consensus for their use as a remedy for diabetes, cough, epilepsy, laryngitis, hernia, elephantiasis, hair yellowing and tooth decay, respectively.
Fig.4: Ranking of most important medicinal plant species according to UV (a) and IAR (b).
Informant Consensus Factor (ICF) and Species Therapeutic Potential (STP)
ICF ranged 0.05 to 0.44 and a total of 31 diseases have been highlighted. Diseases with ICF-values ≥ 0.20 include haemorrhoids (0.44), amoebiasis (0.43), itchy rash (0.42), poliomyelitis (0.36), intestinal parasitosis (0.33), sexual weakness or impotence (0.32), splenomegaly (0.29), laryngitis (0.27), rheumatism (0.25), otitis, (0.25), hernia (0.2) and cough (0.2) (Table 3). For each reported disease, we identified the species with the highest STP. A total of 54 plant species has thus been identified and considered as having effective therapeutic potential (Table 3). Hernia is the pathology with the highest number of reported medicinal plant remedies. Elaeis guineensis Jacq. is said to be used to treat the highest number of diseases including amoebiasis, dental caries, migraine, sciatic neuralgia, splenomegaly and rheumatism (Table 3).
Table 3. Plant use consensus and species with high therapeutic potentiel.
Medicinal knowledge
Despite the large number of common species (105) and diseases (40) that are reported in both territories, a low ethnocultural similarity (RSI) was observed (16.7%) between respondents from Kisantu and Mbanza-Ngungu. Most similarity was observed in the use of common species for similar diseases between respondents from Kisantu and those of Mbanza-Ngungu rural areas (RSI = 15.6%), followed by similarity between respondents of Mbanza-Ngungu urban and rural areas, respectively (RSI= 8.1%). Ethnocultural similarity of medicinal plant knowledge was lowest (RSI = 5.7 %) between respondents from Kisantu and those from Mbanza-Ngungu urban areas (RSI = 5.7%).
Table 4. Ethnomedicinal cultural similarity between Kisantu and Mbanza-Ngungu territories.
Traditional Kongo medicinal knowledge (based on number of reported medicinal species and diseases) was found to be independent of age, education, experience and marital status (p>0.05), but was significantly (p<0.05) influenced by informant gender, quality and residence.
Mean number of species cited was found to be significantly (p<0.05) different between (1) curing healers, herbalists and traditional health practitioners; with curing healers citing 1.46 times more species (b=0.383; S.E=0.1056, p=0.00 than traditional health practitioners, and traditional practitioners citing 0.44 times more species than herbalists (b=-0.812; S.E=0.216; p=0.00); (2) informants from cities (in both Kisantu and Mbanza-Ngungu) and those from villages; with no significant differences (p>0.05) between Kisantu and Mbanza-Ngungu cities and with informants from Kisantu and Mbanza-Ngungu significantly citing 53 times (b=0.426; S.E=0.977; p=0.00) and 1.76 times (b=0.565; S.E=0.999; p=0.00) more species, respectively, than informants from villages near Mbanza-Ngungu; and (3) men and women, with men citing 0.75 times more species than women (b= 0.290; S.E= 0.764; p=0.00) (Table 5).
There were no significant differences between the mean number of diseases cited by curing herbalists and by traditional health practitioners. The number of diseases cited by curing healers was significantly (p<0.05) different from those cited by herbalists and traditional health practitioners. The number of diseases cited by traditional health practitioners was 0.63 times higher than that of herbalists, whereas curing healers significantly cited 1.77 times more diseases than traditional health practitioners. The mean number of cited diseases was significantly different between informant residence (p<0.05). Informants from Kisantu (b=0.520; S.E=0.1616; p=0.01) and Mbanza-Ngungu (b=0.874; S.E=0.1576; p=0.00) significantly cited respectively 1.68 and 2.40 times more diseases than informants from villages near Mbanza-Ngungu. To conclude, the mean number of cited diseases was also significantly different between men and women (p<0.05), with men citing 0.76 times more diseases than women.
Table 5. Average number of species and diseases cited by the different social groups.