Ocimum Sanctum (Tulsi) Leaves and Herbal Syrup: A Review of Pharmacognostic And Phytochemical Evaluation and Formulation

Tulsi (Ocimum sanctum L., Lamiaceae) is a sacred and widely used medicinal herb of India, and its leaves are traditionally given for cough, bronchitis and fever. A syrup is a concentrated sugar solution containing the extract of the drug, and herbal syrups are popular for cough and respiratory complaints. The quality of a herbal syrup depends first of all on the quality of the leaf from which it is made, so the leaf must be authenticated and standardised. This review describes the pharmacognostic and phytochemical evaluation of tulsi leaves, which covers macroscopy, powder microscopy, loss on drying, ash and extractive values, phytochemical screening and thin layer chromatography, and the formulation of a herbal syrup by the decoction and sucrose method at three leaf strengths. It also describes the tests used for evaluating a syrup, namely organoleptic properties, pH, specific gravity, viscosity, sedimentation, total solids, microbial load and stability. Six published studies on tulsi standardisation, phytochemistry and tulsi-containing syrups are discussed. The reported syrups are mostly polyherbal, and the raw leaf and the finished syrup are seldom evaluated together; this gap is noted.