Isolation and characterization of linoleic-linolenic acid mixture, spinasterol and lupeol from Strobilanthes dyeriana leaf extract using HPTLC, HPLC, LC-MS/MS, IR and NMR techniques.

<title>Abstract</title> <p> Background Plants act as vast and renewable reservoir of critical organic compounds which are basically present as secondary metabolites commonly referred to as phytochemicals. Most of these compounds have been found vital for human health and in diverse applications. This study sought to investigate into the constituent organic compounds in the leaves of <italic>Strobilanthes dyeriana</italic> which is locally used in the African traditional medicine. Hot extraction approach was deployed. Extract was screened to identify constituent phytochemicals and partitioned <italic>via</italic> column chromatography. Isolation, purification and characterization of the isolates were done using chromatographic and spectroscopic techniques. Results Alkaloids, glycosides, flavonoids, steroids and terpenoids were identified. First isolate revealed a mixture of linoleic and linolenic acids with <italic>m/z</italic> 278 and <italic>m/z</italic> 276, a broad –OH stretch at 2400–3600 cm ^–1 , a very strong –C = O band of carboxylic acid at 1700–1750 cm ^–1 and the bis-allylic protons at δ2.82 ppm and δ2.78 ppm that distinguish linoleic and linolenic acids. Second isolate, <italic>m/z</italic> 451, produced a broad –OH absorption at 3000–3600 cm ^− 1 , proton NMR signals at δ5.160 ppm and δ5.110 ppm suggesting the C22 and C7 olefinic protons of spinasterol and ¹³ C-NMR signals at δ139.532, 138.175, 129.394 and 117.442 ppm associated with the double bonds at C8, C22, C23 and C7 positions respectively. Isolate 3, <italic>m/z</italic> 427, produced a very weak –OH band at 3000–3400 cm ^− 1 , and seven singlet methyl protons at δ0.751, 0.780, 0.876, 0.960, 0.964, 1.005 and 1.66 ppm associated with the C24, C28, C25, C27, C23, C26, and C30 carbon atoms in lupeol. The ¹³ C-NMR signals at δ151. 011 and δ109.332 indicate the C20–C29 doubly bonded carbon atoms. Conclusion Findings confirm that <italic>Strobilanthes dyeriana</italic> leaves contain spinasterol, lupeol, linoleic and linolenic acids. </p>