In vitro antimycobacterial and adjuvant properties of two traditional South African teas, Aspalathus linearis (Burm.f.) R. Dahlgren and Lippia scaberrima Sond

Abstract

Many plant extracts have been studied for their ability to treat tuberculosis and its associated symptoms. Both Lippia scaberrima Sond. and Aspalathus linearis (Burm.f.) R. Dahlgren, are popular forms of health teas in South Africa. This study focused on the ability of the ethanolic plant extracts of L. scaberrima and A. linearis, as well as the essential oil of L. scaberrima to act as adjuvants in host-directed therapy against tuberculosis. The ethanolic extract of L. scaberrima was found to have a minimum inhibitory concentration (MIC) of 125 µg/mL against Mycobacterium tuberculosis H37Rv, whereas the antiproliferative activity on HepG2 hepatocyte cells ranged between 109.20 ± 8.05 µg/mL and >400 µg/mL for all the samples tested. Due to the high antimycobacterial properties of the ethanolic extract from L. scaberrima, the sample was further tested for its cyclooxygenase (COX) II inhibitory potential and found to have an IC50 value of 36.39±1.62 µg/mL. The essential oil of L. scaberrima and the ethanolic extract of green A. linearis exhibited good hepatoprotective activity, with up to 34% and 40% protection against acetaminophen-induced toxicity, respectively. Additionally, the study investigated the composition of the essential oil of L. scaberrima through gas chromatography–mass spectrometry. Limonene was found to be the main component for the essential oil. The essential oil from L. scaberrima showed promising results with noteworthy hepatoprotective activity as well as moderate antimycobacterial activity. These herbal teas showed potential as an adjunct host-directed therapy in tuberculosis patients through the demonstration of its biological activities and should be considered for further investigation.