Influence of steeping time on biological activity of black mulberry leaves tea

Abstract

Black mulberry leaves teas (BMLTs) were prepared using boiled water and different steeping time (5 10, 20, 35 and 45 minutes). In order to establish the connection between steeping time and tea quality, total phenolics content (TPC), total flavonoids content TFC contents were measured, as well as two antioxidant assays (DPPH and reducing power assays), alone with antimicrobial and cytotoxic tests. The obtained results showed that TPC, TFC, IC 50 and EC 50 values increased with the increase in steeping time, while antimicrobial and cytotoxic activity exhibited different tendency. Based on the obtained results, the 10-minute steeping time was the optimum for tea preparation and this tea was used for the determination of polyphenolic profile using HPLC-MS technique. The results showed that the main compounds in BMLT were chlorogenic and caffeic acids with the contents of 7226.00 and 537.52 µg/g, respectively.

Optimization of ultrasound‐assisted water extraction conditions for the extraction of phenolic compounds from black mulberry leaves (Morus nigra L.)

“…The phenolic acids as chlorogenic acid, syringealdehyde, vanillic acid, m‐ coumaric acid, p‐ hydroxybenzoic acid, chlorogenic acid, syringic acid, p‐ coumaric acid, protocatechuic aldehyde were detected in M nigra leaves (Memon et al, ). In another study, Cestic et al () identified seven phenolic compounds (gallic acid, caffeic acid, sinapic acid, ferulic acid, vanillic acid, chlorogenic acid, and p ‐coumaric acid) in black mulberry leaves tea.…”

“…The mulberry plant, which belongs to the genus Morus of the Moraceae family, has been cultivated widely in India, China, Japan, Pakistan, Iran, Tunusia, Korea, Mexico, Brazil, Spain, including Turkey (Cestic, Radojkovic, Cvetanovic, Maskovic, & Durovic, ; Ercişli & Orhan, ; Thabti, Elfalleh, Hannachi, Ferchichi, & Campos, ). There are 24 species of Morus .…”

“…Generally, mulberry leaves are used for sericulture (Srivastava, Kapoor, Thathola, & Srivastava, ). In addition to being used for animal nutrition, it has been used as a traditional herbal medicine for the treatment of diabetes mellitus, hypertension, cough, and cancer for centuries (Abd El‐Mawla, Mohamed, & Mostafa, ; Cestic et al, ). The composition of phenolics and antioxidant properties of different Morus leaf species has been reported in some studies and mulberry leaf has been found to be a good source of antioxidant polyphenols (Memon et al, ; Thabti et al, ; Wang, Gong, & Chen, ).…”

“…The leaves of M nigra for herbal tea can be an alternative to black or green tea as a source of bioactive compounds which is beneficial to human health. Using black mulberry leaves as tea has been popular and an attractive subject for some researches (Cestic et al, ; Cestic et al, ; Sanchez‐Salcedo, Mena, Garcia‐Viguera, Hernandez, & Martinez, ). There are some studies on the health effects of black mulberry leaves, however, there are few studies on the effective extraction method.…”

“…Extraction can be thought as the main step in the preparation of tea. Ensuring the highest possible phenolic content in tea is important in the tea preparation process (Cestic et al, ). High extraction efficiency at low temperature is preferred to yield high quantities of phenolic compounds that are thermally unstable.…”