An enquiry into antileishmanial activity and quantitative analysis of polyhydroxylated steroidal saponins from Solanum paniculatum L. leaves.

Solanum paniculatum L. is species whose fruits are widely consumed in Brazil as a tonic beverage with higher content of steroidal saponins. In this work, we developed an analytical method for the quantification of the eight saponins present in the 70 % ethanol extract from the leaves using ultra-high-performance liquid chromatography coupled to mass spectrometry (UHPLC-MS). Besides, the eight spirostanic saponins were screened for in vitro antileishmanial activity against promastigote and amastigote forms of Leishmania (L.) amazonensis. Substances 1, 2 and 3 were found to be the most active compounds, with inhibitory concentration (IC50) values of 8.51 ± 4.38, 10.75 ± 6.85 and 10.45 ± 4.21 µM, respectively, against promastigote forms and effective concentration (EC50) values of >25, 17.73 ± 0.99 and 19.57 ± 0.84 µM, respectively, against amastigote forms. The cytotoxic test with compounds 1-3 evidenced low toxicity in murine macrophage cells, with values above 50 µM at concentration lower than 25 µM. These findings show that saponins 1-3 should be evaluated in further studies for the treatment of cutaneous leishmaniasis.

New Polyhydroxylated Steroidal Saponins from Solanum paniculatum L. Leaf Alcohol Tincture with Antibacterial Activity against Oral Pathogens.

Solanum paniculatum L. is widely used in Brazilian folk medicine for the treatment of liver and gastrointestinal disorders as well as for culinary purposes and beverage production. Fractionation of hydroalcoholic [ethanol (EtOH) 70%] tincture from S. paniculatum leaves led to the isolation of six new spirostanic saponins which included 6- O-α-l-rhamnopyranosyl-(1''→3')-ß-d-quinovopyranosyl-(22 S,23 R,25 S)-3ß,6α,23-trihydroxy-5α-spirostane (1), 6- O-ß-d-xylopyranosyl-(1''→3')-ß-d-quinovopyranosyl-(22 S,23 R,25 R)-3ß,6α,23-trihydroxy-5α-spirostane (4), 3- O-α-l-rhamnopyranosyl-(1''→3')-ß-d-quinovopyranosyl-(22 S,23 S,25 R)-3ß,6α,23-trihydroxy-5α-spirostane (5), 3- O-ß-d-xylopyranosyl-(1''→3')-ß-d-quinovopyranosyl-(22 S,23 S,25 R)-3ß,6α,23-trihydroxy-5α-spirostane (6), 6- O-α-l-rhamnopyranosyl-(1''→3')-ß-d-quinovopyranosyl-(22 S,25 S)-1ß,3ß,6α-trihydroxy-5α-spirostane (7), and 6- O-ß-d-xylopyranosyl-(1''→3')-ß-d-quinovopyranosyl-(22 S,25 S)-3ß,4ß,6α-trihydroxy-5α-spirostane (8) together with two known spirostanic saponins (2, 3). The structures of these compounds were determined by one-dimensional (1D) and two-dimensional (2D) NMR experiments in addition to high-resolution electrospray ionization mass spectrometry (HRESIMS) analyses. The 70% alcohol tincture, used as phytomedicine, exhibited promising activities against oral pathogens, including, Steptococcus sanguinis, St. oralis, St. mutans, St. mitis, and Lactobacillus casei with minimal inhibitory concentration (MIC) values ranging from 6.25 to 50 µg/mL. The saponin fraction, nonetheless, showed lower activity against all the strains tested (from 100 to >400 µg/mL).