Oral hygiene in Namibia: A case of chewing sticks.

ETHNOPHARMACOLOGICAL RELEVANCE: Chewing sticks have served as the primary form of dental care for rural communities in resource-poor settings for millennia. They are one of the most important under-researched, non-timber forest products in Namibia. This review provides an overview of plants that are used as chewing sticks in Namibia and highlights pharmacological as well as phytochemical studies conducted on them. AIM OF THE STUDY: This review aims to present a summary of studies that have been done on the ethnomedicinal uses, phytochemistry, biological activity as well as evidence on the scientific validation and geographical distribution of chewing sticks in Namibia. It also highlights research gaps and provides an impetus for the scientific investigations of these plant species. MATERIAL AND METHODS: Literature searches using keywords including oral hygiene, chewing sticks, ethnomedicinal uses, phytochemistry, antimicrobial, antioxidants, anti-inflammatory activities and toxicity studies, chewing sticks, and distribution in Namibia on various electronic search engines was conducted. RESULTS: Of the 41 plant species identified, Cordia sinensis Lam., Faidherbia albida (Delile) A.Chev. and Harpagophytum zeyheri Decne. are used for both gargling and as mouthwash. The plant families Fabacae, Ebenaceae, and Burseraceae account for 22.0%, 12.2%, and 7.30% of plant species recorded as chewing sticks in Namibia respectively. This study revealed a significant relationship between plant family and scientific validation. Species belonging to Burseraceae, Apocynaceae, Montiniaceae, and Cucurbitaceae families have only been partially validated. The Kunene region, home to the Ovahimba ethnic group, had the highest proportion (87.8%) of chewing sticks species compared to other regions. CONCLUSION: This review revealed that most of the plants used as chewing sticks in Namibia require an in-depth pharmacological and phytochemical investigation as deduced from the paucity of literature on the therapeutic methods, mechanisms of action, efficacy, toxicity, and clinical relevance of these species.

Tracking biological footprints of climate change using flowering phenology of the geophytes: Pancratium tenuifolium and Scadoxus multiflorus.

Drought-adapted geophytes are responding to the effects of climate change in arid and semi-arid environments. In this study, herbarium and historical rainfall data were used to examine the impact of rainfall changes on flowering trends of Pancratium tenuifolium Hochst. ex A.Rich and Scadoxus multiflorus (Martyn) Raf. subsp. multiflorus. Flowering was delayed by approximately 7 days per decade for P. tenuifolium during the period 1930 to 2018 and by approximately 14 days per decade for S. multiflorus subsp. multiflorus during the period 1924 to 2008. Scadoxus multiflorus subsp. multiflorus delayed the day of flowering by approximately 0.3 days per millimetre increase of rainfall, with Pancratium tenuifolium showing a non-significant response to summer rainfall during the same period. Overall, a linear mixed-effects model revealed that the day of flowering was delayed by approximately 8 days per degree rise in latitude and advanced by approximately 9 days per degree rise in longitude. Additionally, summer rainfall had significant effects on the day of flowering with a 1-mm increase in summer rainfall delaying the day of flowering by approximately 0.16 days. These changes in flowering times may ultimately alter the distribution of geophytes in Namibia.