Developing antibacterials and sunscreens from medicinal plants in Uganda

Jane Namukobe is a Ugandan chemist and AESA-RISE Postdoctoral Fellow based at Makerere University in Uganda. The AESA- Regional Initiative in Science and Education (RISE), postdoctoral fellowship is a scheme to support the training of postdoctoral researchers in Africa. It supports globally competitive research in universities and research institutes in Africa and to contribute to the creation of knowledge-based economies on the continent. AESA-RISE is implemented through the AESA Platform. AESA (Alliance for Accelerating Excellence in Science in Africa) is a funding, agenda-setting, programme management initiative of the African Academy of Sciences (AAS), African Union Development Agency (AUDA-NEPAD), founding and funding global partners, and through a resolution of the summit of African Union Heads of Governments. AESA-RISE is supported by the Carnegie Corporation of New York, African Institute for Mathematical Sciences, University of Cambridge, Oxford University, African Research Universities Alliance (ARUA), Uppsala University and University of Basel.

Summary

With the emerging bacterial resistance to antimicrobials in skin infections and reported skin cancer cases, especially in neglected minority groups like albinos, there is need for cheap, readily available and effective therapeutic agents that can combat resistant skin bacterial strains and also prevent skin conditions that develop due to the Ultra Violet (UV) exposure. The project has advanced knowledge by revealing bioactive compounds from plants that can be used as chemical markers in herbal skin care formulations and leads in the discovery of drugs that can be used in the treatment of skin infections.  

 Background

Though skin infections and disorders are not life-threatening, they are globally reported as the fourth leading cause of nonfatal disability. They therefore have a serious impact on quality of life, causing lost productivity at work and school, and discrimination that may result in psycho-social consequences. Skin changes may also indicate the presence of more serious diseases that may require treatment. Many people develop skin conditions due to UV exposure leading to sunburns, lower immunity against skin infections (wounds, sores and boils), premature skin aging and skin cancer. With the prevalence of albinos estimated at 1 in 2000-5000 inhabitants in sub-Saharan Africa and 1 in 3000 in Uganda, this group of people is at an increased risk of 1000 fold of developing skin cancer as compared to the general population.

With the emerging bacterial resistance to antimicrobials in skin infections, there is need to search for novel therapeutic agents to combat resistant bacterial strains. Moreover, artificial sunscreens are expensive, been suspected of causing cancer and can break down, compromising effectiveness. Plants have been used in cosmetics for centuries; they are now sought as new sources of agents for use in the discovery of drugs. Besides their sunscreen potential, plants have also been investigated for their antioxidant properties. Though plants have been documented in Uganda as effective for treating different skin diseases, they have not been exploited widely in terms of formulations and drug discovery. Thus, there is little scientific information on their efficacy, safety and bioactive constituents.

Description of the study

Uganda has an increasing population of albinos known to suffer from skin problems. Our work seeks out locally used herbs for their potential as next-generation treatment for skin diseases. With such knowledge, cultivation, commercialization and use can be promoted by and for the local community. Such an effort must rest solidly on scientific knowledge of the efficacy, safety of active ingredients to formulate standardized herbal skin cosmetics and drug discovery.

We have focused on plants with potential efficacy against Staphylococcus aureus and Pseudomonas aeruginosa, bacteria that are common in causing bacterial skin infections. We have also looked at the potential of these plants to be used as sunscreens. Since the skin is exposed to many free radicals from UV radiation, the potential of these plants for use as antioxidants was also explored.

In order to ensure safety, we examined toxicity profiles of selected plants in mice and rat animal models to determine acute (causing death) and subacute (causing vital organ toxicity) toxicity.

 We investigated the bioactive compounds from some of these plants since these are crucial to their formulations.

Study outcomes

We discovered that several plants -- Psorospermum febrifugum (Kanzironziro), Plectranthus caespitosus (Kashenda), Erlangea tomentosa (Ekitokotoko) and Spermacoce princeace (Kisakimu) -- are active against the two bacteria. This not only validates traditional practices of using plants for treatment of skin infections, but also suggests that these plants could contain bioactive molecules that can be used in drug development.

These plants also show potential as sunscreens, indicating the possibility of their use in the cosmetic industry for herbal soaps, jellies and creams. Early results indicate that some plants have yielded active ingredients that can be used as markers in the formulation of herbal drugs.

We determined that these plants are not toxic and can be taken orally or applied dermally without serious adverse effects. Our immediate goal is to incorporate these plants into a validated and standardized herbal medicine or herbal soap, jelly and/or cream for use by the local community.

Lessons learned

Drug discovery from herbal formulations is a major research undertaking that requires broad collaboration. Networks and teams must consist of both professionals and non-professionals, especially from the local community. We learned that effective collaboration can go a long way towards mitigating the disadvantages of lack of resources and expertise, enabling the advancement of powerful research.

The community can be impacted positively even before the completion of the lengthy drug discovery process, using knowledge of formulations that can help the local population immediately. 

Impact

The capacity of the plants studied as sunscreens and antibacterials has promoted their acceptance by the local community and their use in cosmetic formulation, especially for the stigmatized minority of citizens who have albinism. Since there is no cure for this condition, it requires life-long management: cheap, effective and available sunscreens derived from plants can be a life saver for this kind of marginalized population.

My own skills in graduate supervision have been strengthened by the opportunity to mentor others in this work, primarily two graduate students who are in advanced stages of their research and who through this work are building capacity of others in natural products and medicinal plants research.

The project has also strengthened and increased collaboration both at the local and international levels.