In vitro antimicrobial effects of Hypoxis hemerocallidea against six pathogens with dermatological relevance and its phytochemical characterization and cytotoxicity evaluation.

Hypoxis hemerocallidea (commonly known as African Potato) is popular in African traditional medicine. It is used in the management of diverse ailments including burns, wounds and skin-related diseases.The current study investigated antimicrobial effects of Hypoxis hemerocallidea against six microorganisms associated with skin diseases. In addition, the antioxidant activity, phytochemical profiles and cytotoxicity evaluation of the bulb extracts were evaluated.The antimicrobial activity of 50% methanol (MeOH) and petroleum ether (PE) extracts of Hypoxis hemerocallidea bulbs was tested against two bacterial and four fungal strains implicated in causing opportunistic skin-related diseases. Antioxidant potential of the extract was investigated via the 2,2-diphenyl-1-picryhydrazyl (DPPH) free radical scavenging and β-carotene linoleic acid models. Phytochemical profiling of the 50% methanol extract of Hypoxis hemerocallidea was done using spectrophotometric and Gas Chromatography-Mass Spectrometry (GC-MS) methods. The extracts were also evaluated for cytotoxicity against African green monkey Vero kidney cell lines based on the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) colorimetric assay.Both 50% MeOH and PE extracts showed considerable activities against all six microorganisms. The extracts were potent against Shigella flexneri and Trichophyton tonsurans with minimum inhibitory concentration (MIC) values less than 1 mg/ml. However, there was relatively poor antifungal activity against the other fungal strains. In the DPPH assay, the Hypoxis hemerocallidea bulb MeOH extract had an EC of 29.8 μg/ml while 76.91% antioxidant activity was observed in the β-carotene-linoleic acid model assay. The extract contained total phenolics (41 mg GAE/g) and flavonoids (10 mg CE/g). The GC-MS analysis of Hypoxis hemerocallidea bulb revealed 29 and 160 bioactive compounds for 50% MeOH and PE extracts, respectively. Based on the cytotoxicity test, Hypoxis hemerocallidea had LC value of 210.9 ± 18.4 and 95.5 ± 13.3 μg/ml for PE and MeOH extracts, respectively.The bulb extracts of Hypoxis hemerocallidea exhibited good antimicrobial and antioxidant activities, which could be attributed to the presence of phenolics, flavonoids and the other bioactive compounds identified through GC-MS, making it a potentially effective cosmetic plant. These findings also account for the multi-pharmacological use of Hypoxis hemerocallidea in traditional medicine, especially related to skin diseases. The plant extracts can be considered as safe based on LC values (<20 μg/ml). However, more cytotoxicity studies need to be carried out on Hypoxis hemerocallidea, as well as in vivo tests, to confirm its safety and efficacy as a treatment for skin-related diseases.