Phytochemical and nutritional compositions and antioxidants properties of wild edible flowers as sources of new tea formulations

Abstract

In this research, 4 wild flowers of Thailand were initially analysed for phytochemicals, nutritional compositions as well as their antioxidants properties. Bauhinia variegata L. (BV), Gmelina arborea Roxb. (GA), Shorea roxburghii G. Don (SR) and Viburnum inopinatum Craib (VI) were collected from Queen Sirikit Botanic Garden (QSBG) edible collection. VI contained the highest dietary fiber (25.26%), vitamin C (3.47 mg/100 g) as well other minerals including calcium (790 mg/100 g), potassium (2370 mg/100 g). SI, on the other hand had higher fat (32.30%) and iron (7.53 mg/100 g) to the others. Protein was maximum in BV (10.26 g/100 g), while GA contained the highest values carbohydrate (68.43%) and sodium (14.07 mg/100 g). Screening tests for bioactive compounds showed that flavonoids and saponins were mostly found in both water and ethanolic extracts of flowers. Tannin and polyphenols were detected in flowers of SR and VI. Moreover, terpenoids were detected only in ethanolic extracts of SR and VI. Thereafter, quantitative measurements of antioxidative compounds from the water and ethanolic extracts of these flowers were compared. Total phenolic contents were the highest in both extracts of BV and GG. GA gave the highest total flavonoid content and anti-oxidative properties by 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) assays. The phenolic compounds were also characterised using High Performance Thin Layer Chromatography (HPTLC) and Thin Layer Chromatography/ Compact Mass Spectrometer (TLC/ CMS). The QSBG tea products that incorporated these wild flowers were formulated. The total phenolic contents, total flavonoid contents and antioxidants of these formulations were also reported.