Investigation of Sun Protective Factor (SPF) of Raspberry Seed Oil, Niacinamide and Zinc Oxide in combination for their possible use in a sunscreen formulation

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Investigation of Sun Protective Factor (SPF) of Raspberry Seed Oil, Niacinamide and Zinc Oxide in combination for their possible use in a sunscreen formulation

Debjit Ghosh¹, Maulik Manharlal Dhandha²

¹ MGL Group, Rajkot, Gujarat, India

² Woodland Clinic, Woodland, CA, USA

Investigation of Sun Protective Factor (SPF) of Raspberry Seed Oil, Niacinamide and Zinc Oxide in combination for their possible use in a sunscreen formulation

Abstract

The UV radiations emitted from the sun have several negative effects on the skin of humans. Some of the harmful effects of the UV rays are redness of skin (inflammation), rashes, sunburn, wrinkles, photoaging and skin cancer. Due to the rising cases of skin cancers secondary to UV rays, it is very important to find a perfect solution that could help reduce or prevent them by blocking or reflecting the UV rays. Sunscreens are presently one of the preferred and predominant modes of sun protection. To provide complete protection, sunscreens must be broad spectrum - be able to block both UVA and UVB. Due to the superior safety profile of herbal agents compared to synthetic agents, there is a lot of demand for herbal sunscreen formulations. The primary objective of our project is to assess the Sun Protection Factor (SPF) of a combination of three active ingredients: Zinc Oxide, Niacinamide, and Raspberry Seed Oil. Seven samples were prepared, each containing different combinations of these three active ingredients. These samples were then tested. The SPF of the seven samples was measured according to the standard procedure using an UV-Visible spectrophotometer. The SPF values were then calculated using the Mansur equation. The result revealed that the SPF of the formulation were below 30 which means they were not able to provide sufficient protection from the UV rays.

Keywords: Raspberry Seed Oil, Niacinamide, Zinc Oxide, SPF, UV radiation

Introduction

The skin is considered as the largest organ of our body. It also serves as a major protective organ of the body. It is well known that over exposure of skin to UV radiation results in oxidative stress, inflammation, immune suppression and DNA damage, which can lead to skin ageing and skin cancer. [1]. The UV rays that reach the earth are divided into Ultraviolet B (UVB) (280-315 nm), and Ultraviolet A (UVA) (315-400 nm). Thus, to prevent damage from both UVA and UVB irradiation and reduce the risk of skin cancers, broad spectrum sunscreens are used. 

Many oils which are extracted from the fruit and vegetable seeds possesses penetrating and carrying properties. Most of these oils contain natural tocopherols, carotenoids and essential fatty acids, which make them highly valuable [2].

Raspberry seed oil is gaining increasing attention by cosmetics industry. It is used as an ingredient in body and face moisturizers because it contains high concentrations of Vitamins A and E [3]. These vitamins are essential for the maintenance and repair of keratinocytes. Raspberry seed oil is also known to possess a Sun Protective Factor (SPF) value (29-50) [4,5] and thus can be used in sunscreen formulation.

Niacinamide or Vitamin B₃ can lock in moisture, help build proteins in the skin [6] and can also be used as an antioxidant and anti-inflammatory agent [7]. ZnO is considered as one of the best choices for ultraviolet (UV) protection as it offers a broad-spectrum coverage by blocking both UVA and UVB. Besides protecting against the UV radiation, it also possesses antimicrobial properties [8].

We are trying to formulate a sunscreen formulation containing Raspberry seed oil, Niacinamide and Zinc Oxide. Our objective is to assess the sun protection factor (SPF) of various formulations containing a combination of these three ingredients.

Materials Used

Ethanol, Distilled Water, Filter Paper, Raspberry Seed Oil (RSO), Zinc Oxide (ZnO), Niacinamide, Sodium hydroxide

Methods

Formulations

Sample 1: Low dose:  RSO (5%) + Niacinamide (2%) + Zinc Oxide (5%)

Sample 2: High dose: RSO (10%) + Niacinamide (5%) + Zinc Oxide (10%)

Sample 3: Low dose: RSO (5%) + Zinc Oxide (5%)

Sample 4: High dose: RSO (10%) + Zinc Oxide (10%)

Sample 5: Low dose: RSO (5%) + Niacinamide (2%)

Sample 6: High dose: RSO (10%) + Niacinamide (5%)

Sample 7: RSO (10%)

Protocol

Raspberry seed oil, Niacinamide and Zinc oxide were purchased from local pharmacies.  The experiments were performed according to Kaur and Saraf, 2010 [2] with a few modifications. The solubility of oils was determined in different ratios of ethanol and distilled. The maximum solubility was observed in 40% ethanol and 60% distilled water solution.  Initial stock solution of RSO (5%, 10%), Niacinamide (2%,5%) and ZnO (5%, 10%) was prepared in ethanol and water solution (40:60). Zinc oxide was first made soluble by addition of a base (NaOH) to form the stock solution. For making sample 1 – 6, the stock solutions were mixed in equal ratios per defined formulation. Next, a 0.1% solution was prepared from each of the sample. Then the prepared aliquots were scanned for measuring the absorbance using UV-Visible spectrophotometer.

Sun protection factor determination

The prepared aliquots were scanned between 290 and 320 nm at 5-nm intervals using a Shimadzu UV-Visible spectrophotometer, with a 40% ethanol and 60% distilled water solution serving as the blank.

SPF was calculated using Mansur equation described below: -

Where CF = correction factor (10), EE (λ) = erythmogenic effect of radiation with wavelength λ, Abs (λ) = spectrophotometric absorbance values at wavelength λ. The values of EE x I are constants.

Results

The UV absorbance was measured at different wavelengths for the prepared samples (Sample 1-7) using a UV spectrophotometer. The wavelengths included 290, 295, 300, 305, 310, 315, and 320 nm. Table 1 gives the normalized product function which was used in the calculation of SPF of the different samples and Table 2 mentions the SPF of all the samples in a tabulated format. The recorded absorbance and the calculation of SPF for the samples are given in Table 1S – 7S (Supplementary Material).

The SPF of a combination of Raspberry seed oil (5%), Niacinamide (2%), and Zinc Oxide (5%) was evaluated at low dose and the obtained results shows that the SPF of sample 1 has a value of 14.885. The SPF of the Raspberry seed oil (10%), Niacinamide (5%) and Zinc Oxide (10%) was measured in high dose as well in sample 2 which shows a value of 25.337. The results of the two samples revealed that the calculated SPF of sample 2 (high dose) is greater when compared to sample 1 (low dose). Therefore, we can say that the SPF is increasing with an increase in dose. 

The SPF value of sample 3 which contained RSO (5%) and Zinc Oxide (5%) in low doses was found to be 14.740. Whereas the calculated SPF value of sample 4 which contained RSO (10%) and Zinc Oxide (10%) in high doses was found to be 24.019. When comparing the results of sample 3 and sample 4, the SPF was more in sample 4 which was a high dose. Hereto, the SPF increased in a dose dependant manner.

The SPF value of sample 5 which contained Raspberry seed oil (5%) and Niacinamide (2%) combined in low doses came out to be 12.939, and the calculated SPF value of sample 6 which contained Raspberry seed oil (10%) and Niacinamide (5%) combined in high doses came out to be 23.559. The SPF of Raspberry seed oils (10%) was recorded at 20.191. 

Discussions

Many factors such as the combination and concentration of the sunscreens, the use of different solvents, interaction of vehicle components, type of emulsion, emulsifiers and pH used in the formulation affects the determination of SPF values [9]. Therefore, to develop sunscreens with better safety and high SPF, the formulator needs to take into consideration multiple physical and chemical properties of ingredients. 

Herbal ingredients can be considered in sunscreen for their photoprotective properties. Besides providing SPF, Raspberry Seed Oil is also considered a very gentle and lightweight moisturizing solution. RSO encourages natural water retention in the skin cells which helps prevent skin ageing. RSO will not clog any pores therefore it is non-comedogenic [3]. Niacinamide or Vitamin B₃ which can lock in moisture, act as an antioxidant and anti-inflammatory agent [7], can also be a valuable component in the formulation.

Zinc oxide is widely used to treat a variety of skin conditions, including itch, atopy/eczema, diaper rash etc. It is the broadest spectrum UVA and UVB absorber [10] that is approved for use as a sunscreen by the U.S. Food and Drug Administration (FDA) [10, 11]. Moreover, it is completely photostable [10]. It is a physical UV block that is deemed safe even in pediatric population. Therefore, addition of Zinc oxide may contribute to increase in the SPF of the formulation without compromising with the overall safety profile.

Our study shows that the SPF of raspberry seed oil is 20.191 at a high dose of 10%, whereas when used in combination with Niacinamide and Zinc oxide the SPF increases. This increase in SPF value might be due to the synergistic effect of the combination. The highest SPF was found to be of sample 2 which contains Raspberry seed oil (10%), Niacinamide (5%) and Zinc Oxide (10%) in high doses. It was previously mentioned that Raspberry seed oil contains an SPF of 29-50 [4,5] but our study showed an SPF activity of 20.191 at a dose of 10%. Our study showed that the SPF values of the combined samples (i.e. sample numbers 2, 4, and 6) in high doses were close to 30. The American academy of Dermatology suggests using sunscreens with at least 30 SPF [12]. Our formulations in combined form came close to the minimum SPF requirement for making sunscreens but were not completely there. One limitation we found is that addition of ZnO did not lead to high enough SPF as was expected. This may be because ZnO is insoluble in water/alcohol and to make it soluble NaOH was added. This may have resulted in formation of zincates as ZnO reacts with NaOH [13] thus degrading the ZnO. SPF determination is considered an important test for screening ingredients widely used in the cosmeceutical industry. The higher the SPF is, the more protection offered by phytoconstituents against UV light [14]. In fact, the seed oils mixed with other sunscreens like ZnO, if correctly mixed in cosmeceutical formulations, should absorb UV radiations (290–400 nm) to give enough SPF value for photoprotection. Once a formulation of SPF 30 and above is formulated it may provide the sufficient photoprotection without use of organic sunscreens like Avobenzone, Oxybenzone which have not been deemed completely safe by FDA [15]. 

Conclusion

The current study aimed to assess the sun protection factor (SPF) of a combination of three active ingredients. This combination has the potential to offer broad-spectrum UV protection while maintaining a favourable safety profile. Raspberry Seed Oil provided average UV protection by absorbing the harmful UV-rays and ensured the safety for the consumer without the addition of any harmful organic UV filters which could have produced serious toxic effects. When the raspberry seed oil was used in combination with Niacinamide and Zinc oxide the SPF values increased slightly which shows the synergistic activity of the active ingredients. However more research needs to be done to increase its SPF value without compromising its safety. 

References

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Supplementary Material

Investigation of Sun Protective Factor (SPF) of Raspberry Seed Oil, Niacinamide and Zinc Oxide in combination for their possible use in a sunscreen formulation