POSTER 549 - Protective Effects Of Naupaka Juice (Scaevola taccada) Against UV Radiation : An Alternative To Commercial Sunscreen Chemicals ?
Keanu Rochette Yu-Tsuen，Mike Ross, M.Sc., John Berestecky, Ph.D Kapi‘olani Community College, Honolulu, HI
Introduction
- Scaevola taccada, or Naupaka Kahakai (Figure 1), is a coastal shrub indigenous to the Hawaiian Islands.
- Indigenous knowledge suggests that the fruits of this plant have UV absorbing properties.
- Studies have shown that sunscreens can negatively affect coral growth and recruitment.
- If the juice of the fruits do offer protection against UVB, it could potentially serve as an alternative to the dangerous chemicals present in commercial sunscreens and mineral sunblocks.
- Saccharomyces cerevisiae cultures share similar characteristics with human cells that allow us to visualize the effects of UV damage in vitro.
- Our hypothesis is that the juice of the S. taccada fruits will absorb UV radiation and prevent S. cerevisiae from cellular damages associated with UV rays.
Introduction
- Scaevola taccada, or Naupaka Kahakai (Figure 1), is a coastal shrub indigenous to the Hawaiian Islands.
- Indigenous knowledge suggests that the fruits of this plant have UV absorbing properties.
- Studies have shown that sunscreens can negatively affect coral growth and recruitment.
- If the juice of the fruits do offer protection against UVB, it could potentially serve as an alternative to the dangerous chemicals present in commercial sunscreens and mineral sunblocks.
- Saccharomyces cerevisiae cultures share similar characteristics with human cells that allow us to visualize the effects of UV damage in vitro.
- Our hypothesis is that the juice of the S. taccada fruits will absorb UV radiation and prevent S. cerevisiae from cellular damages associated with UV rays.
Materials & Methods: UV Absorption
- The fruits of S. taccada were collected in Honolulu, HI (Figure 1).
- The juice of the three fruits were extracted by squeezing the fruits in a sterile muslin cloth and centrifuged to pellet the debris.
- The supernatant was separated for the pellet in 5 mL centrifuge tubes.
- The fruit juice was extracted from ripe, semi-ripe, and unripe fruits. The extracts were tested for UV absorbing properties using a NanoDrop™.
- A Sun Protection Factor (SPF) has been calculated from the absorption spectrum of each fruit (Table 1).
Materials & Methods: UV Absorption
- The fruits of S. taccada were collected in Honolulu, HI (Figure 1).
- The juice of the three fruits were extracted by squeezing the fruits in a sterile muslin cloth and centrifuged to pellet the debris.
- The supernatant was separated for the pellet in 5 mL centrifuge tubes.
- The fruit juice was extracted from ripe, semi-ripe, and unripe fruits. The extracts were tested for UV absorbing properties using a NanoDrop™.
- A Sun Protection Factor (SPF) has been calculated from the absorption spectrum of each fruit (Table 1).
Results: UV Absorption
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- The absorption spectrum shows a very high absorption peak in the UVC.
- We have a very strong absorption in the UVB that continues and drops as we reach the UVA.
- UVB is the cause of sunburns and alter the DNA structure causing pyrimidine dimers that can potentially evolve in skin cancer.
- An SPF has been calculated using the formula in Figure 3.
Results: UV Absorption
- The absorption spectrum shows a very high absorption peak in the UVC.
- We have a very strong absorption in the UVB that continues and drops as we reach the UVA.
- UVB is the cause of sunburns and alter the DNA structure causing pyrimidine dimers that can potentially evolve in skin cancer.
- An SPF has been calculated using the formula in Figure 3.
Results: Viability of Yeast Cultures
- We tested the effects of the fruit juice on yeast cultures.
- S. taccada juice does not inhibit the growth of S. cerevisiae when added to the suspensions.
- The control plates showed that the cultures exposed to UV rays had no viability while the unexposed plates presented uninhibited growth.
- Plates containing the S.taccada extract showed no viability when exposed to UV radiation of 253 nm and uninhibited growth when unexposed.
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Results: Viability of Yeast Cultures
- We tested the effects of the fruit juice on yeast cultures.
- S. taccada juice does not inhibit the growth of S. cerevisiae when added to the suspensions.
- The control plates showed that the cultures exposed to UV rays had no viability while the unexposed plates presented uninhibited growth.
- Plates containing the S.taccada extract showed no viability when exposed to UV radiation of 253 nm and uninhibited growth when unexposed.
Materials & Methods: Viability of Yeast Cultures
- We collected about 8.5 mL of juice from 20 ripe fruits.
- 0.5 mL of sterile S. taccada juice was added to S. cerevisiae suspensions diluted to 1/2, 1/10 and 1/100.
- The plated suspensions were exposed to UV radiations (253 nm) at a distance of 5 cm for 0 min, 0.5 min, 2 min and 5 min.
- For the control plates, the S. taccada juice was substituted for a PBS solution.
Materials & Methods: Viability of Yeast Cultures
- We collected about 8.5 mL of juice from 20 ripe fruits.
- 0.5 mL of sterile S. taccada juice was added to S. cerevisiae suspensions diluted to 1/2, 1/10 and 1/100.
- The plated suspensions were exposed to UV radiations (253 nm) at a distance of 5 cm for 0 min, 0.5 min, 2 min and 5 min.
- For the control plates, the S. taccada juice was substituted for a PBS solution.
Conclusion
- The absorption spectrum from the Nanodrop™ spectrophotometer indicated that the Naupaka (S. taccada) juice does contain UV absorbing properties that can be exploited, with a calculated SPF of 20.
- The plates exposed to UV radiation (253 nm) showed no signs of viability with the conditions given by the experiments. Therefore, the results do not support the original hypothesis.
- These results suggest that we need to critically review our protocols and methods before we repeat the experiment.
- In future experiments, S. cerevisiae will be exposed to UVB and UVA rather than UVC (germicidal). The distance from the UV source will be subject to variations.
- The toxicity of Naupaka Kahakai extracts will also be tested on coral colonies in lab conditions in hopes of making a reef safe sunblock.
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Conclusion
- The absorption spectrum from the Nanodrop™ spectrophotometer indicated that the Naupaka (S. taccada) juice does contain UV absorbing properties that can be exploited, with a calculated SPF of 20.
- The plates exposed to UV radiation (253 nm) showed no signs of viability with the conditions given by the experiments. Therefore, the results do not support the original hypothesis.
- These results suggest that we need to critically review our protocols and methods before we repeat the experiment.
- In future experiments, S. cerevisiae will be exposed to UVB and UVA rather than UVC (germicidal). The distance from the UV source will be subject to variations.
- The toxicity of Naupaka Kahakai extracts will also be tested on coral colonies in lab conditions in hopes of making a reef safe sunblock.
