Background Aloe vera and Aloe ferox have over the years been among the most sought-after Aloe species in the treatment of ailments worldwide. This review provides categorized literature on the phytochemical and scientifically proven toxicological profiles of A. vera and A. ferox to facilitate their exploitation in therapy. Main body of the abstract Original full-text research articles were searched in PubMed, ScienceDirect, Research gate, Google Scholar, and Wiley Online Library using specific phrases. Phenolic acids, flavonoids, tannins, and anthraquinones were the main phytochemical classes present in all the two Aloe species. Most of the phytochemical investigations and toxicity studies have been done on the leaves. Aloe vera and Aloe ferox contain unique phytoconstituents including anthraquinones, flavonoids, tannins, sterols, alkaloids, and volatile oils. Aloe vera hydroalcoholic leaf extract showed a toxic effect on Kabir chicks at the highest doses. The methanolic, aqueous, and supercritical carbon dioxide extracts of A. vera leaf gel were associated with no toxic effects. The aqueous leaf extract of A. ferox is well tolerated for short-term management of ailments but long-term administration may be associated with organ toxicity. Long-term administration of the preparations from A. vera leaves and roots was associated with toxic effects. Short conclusion This review provides beneficial information about the phytochemistry and toxicity of A. vera and A. ferox and their potential in the treatment of COVID-19 which up to date has no definite cure. Clinical trials need to be carried out to clearly understand the toxic effects of these species.

Background Several local communities in Central, Western, Eastern, and Northern regions of Uganda have been using the whole leaf extracts of Aloe vera (L.) Burm. f. (Asphodelaceae) in the treatment of various ailments. Also, several commercial companies sell A. vera as soft drinks in Uganda. However, there are inadequate reports on the toxicities of such preparations. This paper reports the acute and sub-acute oral toxicity of aqueous extracts of whole leaf and green rind of A. vera in Wistar rats. Methods Acute oral toxicity test was carried out in female Wistar rats at doses of 175, 550, 1750, and 5000 mg/kg, p.o. The animals were observed for signs of toxicity for 14 days. Similarly, a sub-acute oral toxicity test was performed in both sexes of rats at doses of 200, 400, and 800 mg/kg, p.o. daily for 28 days. All the groups of animals were monitored for behavioral, morphological, biochemical, and physiological changes, including mortality and compared with respective controls. Body weights were measured weekly while the animals’ relative organ weights, hematological, biochemical, gross, and microscopic pathology were examined on day 29. Results There was no mortality or apparent behavioral changes at the doses tested in acute and sub-acute oral toxicity tests. Thus, the Median Lethal Dose (LD50) of green rind and whole leaf aqueous extracts was above 5000 mg/kg. Gross anatomy revealed that the rats’ relative spleen weight in green rind extract at 200 mg/kg significantly decreased compared to the control group. The creatinine levels in female rats that received green rind extract and the chloride ion levels in male rats administered whole leaf extract were significantly elevated. Conversely, Mean Corpuscular Hemoglobin Concentration (MCHC) levels significantly decreased at lower doses of the green rind extract compared to the control. Histopathology of the kidney revealed the renal interstitium’s inflammation at doses of 200 and 800 mg/kg of the whole leaf extract. Conclusion The findings demonstrated that A. vera green rind and whole leaf extracts are non-toxic at relatively high doses when used for a short duration. Prolonged use of the aqueous whole leaf extract might be associated with kidney toxicity.