Benzoin is an incomplete lithified resin secreted from the trunk of the Styrax Linn. that is known as "semipetrified amber" and has been widely used in medicine due to its blood circulation-promoting and pain-relieving properties. However, the lack of an effective species identification method due to the numerous sources of benzoin resin and the difficulty of DNA extraction has led to the uncertainty of species of benzoin in the trade process. Here, we report the successful extraction of DNA from benzoin resin containing bark-like residues and the evaluation of commercially available benzoin species using molecular diagnostic techniques. By performing a BLAST alignment of ITS2 primary sequences and homology prediction analysis of ITS2 secondary structures, we found that commercially available benzoin species were derived from Styrax tonkinensis (Pierre) Craib ex Hart. and Styrax japonicus Sieb. et Zucc. of the genus Styrax Linn. In addition, some of the benzoin samples were mixed with plant tissues from other genera, accounting for 29.6%. Therefore, this study provides a new method to solve the problem of species identification of semipetrified amber benzoin using information from bark residues.

Benzoin, also known as semipetrified amber, is the resin secreted from the trunk of the benzoin plant. This medicinal material has blood circulation-promoting and pain-relieving properties. There are approximately 130 species of benzoin plants in the world, and the resin of many plants in the benzoin genus is used, so there is confounding of the species of origin. In this study, DNA was successfully extracted from the semipetrified amber medicinal material benzoin, and the species of benzoin in the medicinal herb market were evaluated by DNA barcoding. BLAST comparison of ITS2 primary sequences and homology prediction analysis of ITS2 secondary structures showed that the commercially available benzoin base originated from Styrax tonkinensis (Pierre) Craib ex Hart. and Styrax japonicus Sieb. et Zucc. of the genus Styrax Linn., and tissue from other genera was also detected to be mixed in with some samples, accounting for 29.6% of the samples. There is a risk that benzoin resin medical materials will be mixed with tissues from other plants. This is the first report on the subject, and the approach taken provides technical feasibility for the identification of the basis of the benzoin resin medical materials.