Study Of Antimicrobial, Phytochemical And Toxicological Properties Of Selected Plants Used In The Management Of Sexually Transmitted Infections In Samburu County, Kenya
According to World Health Organization (WHO), the traditional systems of medicine provide primary health care for over 80% of the world population. Antimicrobial resistance is now a major pitfall in the use of conventional antimicrobial drugs. Natural products used in Traditional Medicine (TM) may be used to combat multidrug resistant infectious diseases through careful elucidation and validation of their biological components that have novel mechanism of action. Use of medicinal plant remedies is of high importance in many African communities. The Samburu community in Kenya values traditional medicine administered by their traditional healers and this forms the most important means of treatment of diseases among the Samburu community. Ther are several reasons including Poor infrastructure and inadequate modern medical facilities that have made most pastoralist communities in Kenya to rely on herbal medicines. The traditional remedies used in Traditional African Medicine (TAM) lack proper documentation and data on safety and efficacy generated through scientific methods. The current study was carried out to document the use of medicinal plants in management of sexually transmitted infections among the Samburu community in Kenya and to study the pharmacological and toxicological profile of selected medicinal plant extracts. The first part of the study was an ethnobotanical survey on the use of herbal remedies used for the treatment of venereal diseases. This was followed by preliminary phytochemical screening, antimicrobial activity, cytotoxicity studies and in vivo toxicological studies of selected plant extracts. Data on use of plants for management of sexually transmitted infections was obtained through focused group discussions and administration of semi-structured questionnaires to the herbalists. The herbalists then identified the plants in situ; samples were collected and submitted to a herbarium for botanical identification and allocation of voucher specimen numbers. Data on identity of medicinal plants, herbal remedies preparation methods, herbalists views on effectiveness, safety, availability of plants, their use on sexually transmitted infections (STIs) and ethnodiagnostic skills was entered into a computer package for descriptive statistical analysis. Eight commonly used plant species in management of STIs as cited in the ethnobotanical survey were selected: Clerodendrum myricoides, (Hoecst) Vatke Carissa eduli (Forsk) vahl, Acassia tortilis (Fossk) Hayne, Myrsine Africana L., Rhamnus staddo A. Rich, Rhamnus prinoides L,herit, Psiadia arabica Jabb and Spach and Sansevierria enhribergii Bach. Preliminary phytochemical screening of aqueous and methanol/water plant extracts was done using standard phytochemical techniques for determination of the presence of alkaloids, steroids, triterpines, tannins, flavanoids, flavones, phenols, glycosides, anthraquinones, proteins and resins. The bioactivity (cytotoxicity) of methanol/water (70/30) v/v and chloroform extracts of the 8 plants was tested using the brine shrimp lethality test (BLT). Ten naupli were introduced in tubes containing various dilutions of the plant extracts and mortality after 24hrs recorded. Mortality data was entered into the Probit Method of Finney Computor Programme for determination of the lethal concentration (LC50) and its 95 % confidence interval. The calculations were based on the number of dose level, the number of brine shrimp that died per concentration and % mortality per concentration. The antimicrobial activities of the plant extracts against Neisseria gonorrhea, Staphylococcus aureus, Escherichia coli, Bacillus cereus Pseudomonas aeroginosa, and Streptococcus fecalis using broth dilution technique were determined. These were compared with those of benzyl penicillin, oxytetracycline and streptomycin as positive controls in the experiment. The toxicity of the aqueous extract of Clerodendrum myricoides (Hoechst) Vatke was determined in rats using the Organization of Economic Corporation and Development (OECD) protocols for toxicity testing, acute toxic class method for acute toxicity and 28-day repeated dose method for sub acute toxicity testing. Results of ethnobotanical survey showed that the ethnodiagnosis of sexually transmitted infections (STIs) by the Samburu traditional healers was mainly based on symptoms. The commonly used plants species in management of STIs were roots of Clerodendrum myricoides (Hoecst) Vatke, (93%), Carissa edulis (52%), Myrsine africana L., (31%), Rhamnus staddo A. Rich, (24%), Rhamnus prinoides L,herit 17%), Sansevieria enhribergii Bach, (10%) and Psiadia arabica Jabb and Spach (10%). Clerodendrum myricoides (Hoechst) Vatke was ranked first in STIs management and is used alone or in combination with other plants. The remedy was prepared as a decoction that was given orally. For treatment of chronic cases of STIs, Clerodendrum myricoides (Hoechst) Vatke is administered to the patient per rectum. The extract of C. myricoides was positive for tannins, triterpenoids, cardiac glycosides, phenolics compounds, saponins and resins. Alkaloids were present in the methanolic/water extract only. Results of BLT showed that all the aqueous extracts had an LC50 equal to or higher than 1000µg/ml. All medicinal plants tested for in vitro antimicrobial were inhibitory to the growth of bacteria as either aqueous or methanol/water extract. The aqueous extract of Clerodendrum myricoides (Hoechst) Vatke showed a broad spectrum of activity against various microorganisms tested except Streptococcus fecalis. The methanolic/water extract of Rhamnus prinoides L,herit had a broad spectrum of activity against all microorganisms tested except for Neisseria gonorrheae. In the Acute Toxic Class Method at dosage 2000mg/kg body weight mortality occurred within 24 hours. None of the rats died within 24 hrs after administration of C. myricoides aqueous extract at 300mg/kg body weight. Clinical signs of acute toxicity observed affected the respiratory, musculoskeletal and respiratory systems. The extract of C. myricoides was found to have an LD50 of 1000mg/kg and was therefore classified as slightly toxic. The signs of sub acute toxicity of Clerodendrum myricoides were characterized by behavioural changes, dyspnoea, piloerection, huddling together and scratching. The body weights of the treated animals increased significantly as compared to the control group (P<0.05). The weights of organs differed significantly from those in the control group. Administration of the extract of C. myricoides affected the biochemistry and the haematological parameters of the experimental animals. Gross and histopathology lesions were observed in the liver, lungs, kidney, heart muscle and spleen. Some biochemical changes observed were significant although they were not dose dependent. They included blood urea nitrogen and creatinine. Results of histopathological examination showed mild congestion in animals that received C. myricoides extract at the 300mg/kg dosage. Changes in Serum levels of Alanine aminotransferase (ALT) were observe but they were not dose dependent. The serum levels of Aspartate aminotransferase (AST) were within normal range. The histopathological changes observed within the liver were mild and included congestion. Results of haematological examination showed an increase in total white blood cells (WBC) and neutrophils. The lymphocytes counts significantly reduced in the experimental animals compared to the control group (P< 0.05). The survey showed that alone or in combination with other plants especially M. africana and C. edulis is considered as important medicinal remedy for STIs in the Samburu community. The plant contains several phytochemicals that are probably responsible for the medicinal value. This study also supports the medicinal use of the plants since the sensitivity tests revealed the plant extracts were active against most microorganisms. C. myricoides can be used as non cytotoxic drug although the toxicity results classified it as slightly toxic and probably the benefits of the plants outweigh the risk of toxicity. Further studies on formulation, dosage standardization, efficacy, clinical trials and value addition are needed for minimization of the observed side effects while maintaining the claimed medicinal values of the extract. The herbalist should be encouraged and facilitated to develop products that can be subjected to evaluation for registration by regulatory authorities. The pharmacological and toxicological data generated in this study may form part of the dossier for such products.