Identification of Orthosiphon stamineus from different phytogeographical zones in Indonesia by FTIR-fingerprinting and chemometrics

Abstract

Orthosiphon stamineus (OS) or cat’s whiskers (Lamiaceae) is one of the herbs broadly used as raw materials for functional food and traditional remedies, for it contains phenolic acids and flavonoids. OS grows well in tropical and subtropical regions of Asia and Africa. Phytogeographical characteristics are among many variables that greatly control plant growth and phytochemical content. This research was conducted to analyze and classify 14 samples of OS leaves from different regions in Indonesia according to phytogeographic profiles using a combination of Fourier-transform infrared (FTIR) fingerprinting and chemometrics, i.e., principal component analysis (PCA) and cluster analysis (CA). The first two PCs were used to show the grouping of 14 samples with a cumulative variance at 91%. Results showed that all samples had comparable FTIR spectra showing the stretching frequencies of O-H, C-H, and C=C bonds. Further discrimination with PCA and CA was able to classify them into four groups of different phytogeographical origins: group 1 comprised OS samples from Tawangmangu, Mojokerto, Batu, Sampang, Madiun, South Jakarta, Jombang, Surabaya, Kediri, and Ngawi, group 2 from Lampung and Gresik, group 3 from Badung, and group 4 from Kotabaru. Thus, it can be inferred that FTIR fingerprinting combined with chemometrics can distinguish between OS crude drugs from different locations. Introducing a wider variety of OS analytical methods is believed to positively influence the flexibility and ease of quality control of herbal ingredients, ultimately ensuring the safety and efficacy of herbal medicinal products.