Lyophilised Aloe excelsa Fractions, Photo-protection and Actinic Damage Retardation Claims Substantiation
J Chifamba *
Department of Chemistry and Biochemistry, School of Physical Sciences, University of California, Los Angeles, Los Angeles, CA90095, USA and School of Pharmacy and Pharmaceutical Sciences, University of Zimbabwe, Harare, Zimbabwe.
A J Addae
Department of Chemistry and Biochemistry, School of Physical Sciences, University of California, Los Angeles, Los Angeles, CA90095, USA.
S Zengeni
School of Pharmacy and Pharmaceutical Sciences, University of Zimbabwe, Harare, Zimbabwe.
M Pomerai
Harare Institute of Technology, Belvedere, Harare, Zimbabwe.
N Kurebgaseka
KAZA Natural Oils, Harare, Zimbabwe.
*Author to whom correspondence should be addressed.
Abstract
Introduction: Ultraviolet radiation is potentially harmful to plants’ physiological structures and their photosynthetic apparatus through induction of photo-oxidative damage and photosynthetic inhibition. Aloe excelsa a resilient (sub) tropical plant has evolved various photo-protective mechanisms to proliferate in these harsh environments. With the current FDA, over-the-Counter Monograph M020 castigating 14 of the 16 approved sunscreens as “unsafe” to the ecology and human health, the hunt for safer sunscreens is on and phytoconstituents from photo-resilient plants may just be the next generation, safe and efficacious sunscreens.
Aims: This study investigated the photo-protective activity of lyophilized hydro-ethanolic Aloe excelsa extracts through phytoscreening and in-vitro estimations of their SPF, UVAPF, UVA/UVB ratio, critical wavelength, anti-oxidancy as well as anti-inflammatory potential.
Methods: The Aloe excelsa gel matrix was physically extracted from transversely cut fresh rossetes, macerated in 70% ethanol, lyophilized and then subjected to both quantitative and qualitative phytochemical screening techniques. The antioxidant activity was measured using the DPPH scavenging assay, the photoprotection investigation was performed in-vitro using directives from COLIPA 2011/FDA Final Rule 2011 as guidelines and the anti-inflammatory capacity was evaluated using the protein denaturing test.
Results: Qualitative phytochemical screening confirmed the presence of numerous primary and secondary metabolites of pharmacological interest, Quantitative phyto-analysis revealed that Aloe excelsa has higher levels of total phenols, tannins and flavonoids than Aloe vera. Anti-inflammatory capacity was closely related to the standard Diclofenac and the anti oxidancy was almost equivalent to ascorbic acid. A prepared 50% Aloe excelsa gel had an SPF of 7.6 and a UVAPF of 4 and a critical wavelength of 375. The calculated photostabilities: %SPFeff and %UVAPFeff were both above 97%.
Conclusion: The results confirm that Aloe excelsa is a multifunctional photoprotective material with confirmed anti-oxidancy, anti-inflammatory and UVR protection attributes. The 50% lyophilised Aloe excelsa gel can be technically classified as a low SPF sunscreen. The abundant primary and secondary metabolites correlate directly with the observed and calculated photoprotective parameters obtained in this study.
Keywords: Aloe excelsa, natural sunscreen, photoprotection, anti-inflamattory, anti-oxidant