Tephrosia is widely distributed throughout tropical, subtropical, and arid regions. This genus is known for several biological activities, including its anti-Candida activity, which is mainly attributed to prenylated flavonoids. The biological activities of most Tephrosia species have been studied, except T. apollinea. This study was conducted to investigate the underlying anti-Candida activity of T. apollinea, wildly grown in the United Arab Emirates (UAE). The T. apollinea plant was collected, dried, and the leaves were separated. The leaves were ground and extracted. The dried extract was subjected to successive chromatography to identify unique phytochemicals with a special pharmacological activity. The activity of the compound was validated by homology modeling and molecular docking studies. A novel steroidal compound (ergosta-6, 8(14), 22, 24(28)-tetraen-3-one) was isolated and named TNS. In silico target identification of TNS revealed a high structural similarity with the Candida 14-α-demethylase enzyme substrate. The compound exhibited a significant anti-Candida activity, specifically against the multi-drug-resistant Candida auris at MIC50, 16 times less than the previously reported prenylated flavonoids and 5 times less than the methanol extract of the plant. These findings were supported by homology modeling and molecular docking studies. TNS may represent a new class of Candida 14-α-demethylase inhibitors.
Keywords: Tephrosia apollinea; anti-Candida; hot arid desert; natural optimization; novel steroid.