Instrumental Characterization of Black Soot of Glycyrrhiza glabra: A Colouring Pigment for Eye Cosmetics

Background: Añjanaṃ (collyrium) in Ayurveda is predominantly centered around its role in maintaining eye health rather than cosmetic use. This aligns with the traditional kohl/kajal application, prepared using herbs rich in anti-microbial properties, thus offering ocular benefits. Such kajals incorporate burnt black soot from plants to achieve the desired dark color. Analyzing this carbonized form is essential to confirm its therapeutic contribution among other ingredients. In this study, black soot particles obtained from Glycyrrhiza glabra (GG), a potent Ayurvedic herb known for promoting vision and addressing conditions such as dry eye disease, Cataract and conjunctivitis, were examined. Materials and Methods: The traditional method of preparing black soot was employed, involving scraping it from a copper plate after burning a wick dipped in GG's decoction seven times. Results: Physico-chemical analysis of the raw GG and its decoction met the API (Ayurvedic Pharmacopoeia of India) standards. The GG decoction pH, total solids and specific gravity were 5.3, 14.636% and 1.048 respectively. FT-IR analysis revealed four bands corresponding to GG's methylene and methane groups, while XRD indicated the presence of cupric and cuprous oxide. The SEM-EDX results showed that the black soot contained 68.29% carbon, 14.62% oxygen, and 17.09% copper. Conclusion: These findings suggest that even in its carbon form, black soot derived from GG using traditional methods retains active ingredients from the combustion of plant biomass. This underscores its potential therapeutic benefits in addition to its cosmetic purposes. The use of black soot from herbs in kajals can offer both cosmetic enhancement and ocular health advantages.