Salvadora persica L.: Toothbrush tree with health benefits and industrial applications - An updated evidence-based review

Salvadora persica L. is also known as Arak (in Arabic) and Peelu (in Urdu). Its frequent use as a toothbrush (miswak) is highly recommended by Prophet Muhammad. With a long history in folk medicine for centuries, S. persica was used in oral hygiene, food, cosmetics, fuel, and even as a medicine. Previous phytochemical investigation of its different parts afforded different classes of secondary metabolites such as flavonoids, glycosides, sterols, terpenes, carbohydrates and alkaloids. Organic sulfur-containing compounds and elemental sulfur are also present. In addition, there is a huge research on its biological potentials and industrial applications. Many pharmacological activities were reported experimentally, including antimicrobial, antioxidant, analgesic, anthelmintic, anti-inflammatory, antiulcer, sedative, anticonvulsant, anti-osteoporosis, antidiabetic, hypo-lipidemic, in addition to wound-healing, antidepressant and antitumor activities. Recently, a possible activity against COVID-19 protease was documented by molecular docking. This review tries to provide a recent detailed documentation of folk and modern uses of S. persica, focusing on the possible relations between its chemical constituents, pharmacological properties, and industrial applications. Moreover, a brief about recent analytical and validation methods for the major antimicrobial component is reported.

Optimization of the extraction condition for benzyl isothiocyanate contents in Salvadora persica roots "Siwak"

Benzyl isothocyanate is the major active antibacterial metabolite in Salvadora persica roots "Siwak" beside two minor isothiocyanate derivatives namely; 3-methoxy benzyl isothiocyanate and 3-hydroxy benzyl isothiocyanate. The extraction condition effect on the amount of benzyl isothiocyanate was explored in detailed study. Both cold and hot extraction with different solvents was applied. The amount of benzyl isothiocyanate was estimated using HPLC and HPTLC. The results indicated that cold extraction of the fresh samples with chloroform offers the maximum amount of benzyl isothiocyanate. Drying process leads to great loss of the active component of Siwak.

Effect of hydroxylated solvents on the active constituents of Salvadora persica root "Siwak"

Previously, the antimicrobial activity of Salvadora persica was traced to benzyl isothiocyanate. In the present study known inactive compounds were isolated from extracts obtained by different solvents including β-amyrin, β-sitosterol, stigmasterol glucoside, benzyl cyanide and sulphur. However, some inactive compounds were present only in the ethanol and methanol extracts. This observation indicated that these compounds most likely are artifacts resulted from interaction with the solvents used in extraction. Pure benzyl isothiocyanate was kept with different solvents for 72 h and after TLC study they were heated under reflux for 8 h to explore the possibility of interactions. Only solvents with OH groups reacted with benzyl isothiocyanate and gave products similar to those isolated from the alcohol extracts. In conclusion extraction of S. persica with hydroxylated solvents will alter the structure of the active compound benzyl isothiocyanate and leads to loss of antimicrobial activity.