Screening of indigenous plants from South Africa for affinity to the serotonin reuptake transport protein

Seventy five extracts from 34 indigenous plant species used in South African traditional medicine or taxonomically related to these were investigated for their affinity to the serotonin reuptake transport protein, making use of an in vitro serotonin reuptake transport protein binding assay. Aqueous and 70% ethanolic extracts of various plant parts were screened and 45 extracts derived from 15 plant species showed affinity. The affinity of 12 extracts from four plants was characterized as high (more than 50% inhibition at 5, 1, and 0.5 mg/ml). Plant species with high affinity to the serotonin reuptake transport protein included Agapanthus campanulatus, Boophane disticha, Datura ferox and Xysmalobium undulatum. Agapanthus campanulatus yielded high activity in aqueous extracts from leaves and flowers. Boophane disticha showed high activity both in aqueous and ethanolic extracts of leaves and bulbs. Datura ferox showed high activity in aqueous extracts from the seeds and Xysmalobium undulatum showed high activity in the ethanolic extract of the whole plant.