Articles
Targeted water stress treatments and the anti-tyrosinase activity of Greyia radlkoferi
Article number
1358_22
Pages
163 – 170
Language
English
Abstract
Greyia radlkoferi is a South African native tree.
The leaf extracts have the potential to treat skin hyperpigmentation in humans with an anti-tyrosinase IC50 value 17.86 µg mL‑1. However, there are differences in activity levels among plant populations.
It is critical to generate high-quality plant material with consistent activity for the long-term production of cosmeceutical products.
The impact of targeted water stress before harvesting on G. radlkoferi was examined on four different plant ages ranging from one year to four years old.
Four water stress treatments (water withheld before harvest) were applied: (1) severe stress (12 days without water), (2) moderate stress (8 days without water), (3) mild stress (4 days without water), and (4) control.
Treatments were replicated six times in an RCBD with five plants per experimental unit.
Data for gaseous exchange were taken after the onset of water stress.
The bottom and top leaves were harvested to measure the relative water content.
Anti-tyrosinase activity was evaluated using mushroom tyrosinase and kojic acid as a control.
Relative water content, photosynthesis, stomatal conductance, and water use efficiency all showed no significant differences.
Transpiration rate, internal carbon dioxide, and anti-tyrosinase showed significant variations.
Water use efficiency and transpiration significantly decreased after stress, while internal carbon dioxide showed an increase.
When compared to kojic acid (IC50 5.38 µg mL‑1), all treatments had significantly lower anti-tyrosinase activity.
Material collected from the bottom of 4-year-old, severely stressed plants had the best IC50 tyrosinase inhibition values (19.66 µg mL‑1) while the worst activity was observed from the bottom collected 4-year-old, mildly stressed (49.61 µg mL‑1) trees.
Water stress affected transpiration rate, water use efficiency, and internal carbon dioxide with the same trend over time.
The bioactivity of G. radlkoferi was not improved by using targeted water stress treatments, as the same variation in IC50 values of 19.66 to 49.61 µg mL‑1 was observed for treatments as compared to the control values of 20.12 to 37.46 µg mL‑1.
The leaf extracts have the potential to treat skin hyperpigmentation in humans with an anti-tyrosinase IC50 value 17.86 µg mL‑1. However, there are differences in activity levels among plant populations.
It is critical to generate high-quality plant material with consistent activity for the long-term production of cosmeceutical products.
The impact of targeted water stress before harvesting on G. radlkoferi was examined on four different plant ages ranging from one year to four years old.
Four water stress treatments (water withheld before harvest) were applied: (1) severe stress (12 days without water), (2) moderate stress (8 days without water), (3) mild stress (4 days without water), and (4) control.
Treatments were replicated six times in an RCBD with five plants per experimental unit.
Data for gaseous exchange were taken after the onset of water stress.
The bottom and top leaves were harvested to measure the relative water content.
Anti-tyrosinase activity was evaluated using mushroom tyrosinase and kojic acid as a control.
Relative water content, photosynthesis, stomatal conductance, and water use efficiency all showed no significant differences.
Transpiration rate, internal carbon dioxide, and anti-tyrosinase showed significant variations.
Water use efficiency and transpiration significantly decreased after stress, while internal carbon dioxide showed an increase.
When compared to kojic acid (IC50 5.38 µg mL‑1), all treatments had significantly lower anti-tyrosinase activity.
Material collected from the bottom of 4-year-old, severely stressed plants had the best IC50 tyrosinase inhibition values (19.66 µg mL‑1) while the worst activity was observed from the bottom collected 4-year-old, mildly stressed (49.61 µg mL‑1) trees.
Water stress affected transpiration rate, water use efficiency, and internal carbon dioxide with the same trend over time.
The bioactivity of G. radlkoferi was not improved by using targeted water stress treatments, as the same variation in IC50 values of 19.66 to 49.61 µg mL‑1 was observed for treatments as compared to the control values of 20.12 to 37.46 µg mL‑1.
Authors
J. Malele, R. Kleynhans, G. Prinsloo, B. Matsiliza-Mlathi
Keywords
relative water content, plant age, water use efficiency
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