Abstract:
The marine sponge Neopetrosia exigua is known as a goldmine of novel compounds, yet its
pharmacological activities remain poorly characterised. Herein, this study investigates the bioactivities
of N. exigua collected from Mauritius waters. The crude extract (dichloromethane:
methanol), hexane, ethyl acetate and aqueous fractions obtained from N. exigua were subjected to
in vitro antioxidant assays. Their antibacterial activities were evaluated using the broth microdilution
method to determine the minimum inhibitory concentration (MIC). The cytotoxic and
epigenetic activities were further screened using the MTT assay and a cell-based image system
that measures de-repression of a silenced Green Fluorescent Protein (GFP) reporter gene,
respectively. Higher antioxidant activity was recorded for the ethyl acetate fraction as demonstrated
by its significant ferric reducing antioxidant power, radical scavenging, and metal
chelating activities relative to control (p < 0.05). The best antibacterial profile was presented by
the ethyl acetate fraction against Cutibacterium acnes (MIC: 0.039 mg/ml), Streptococcus mutans
(MIC: 0.078 mg/ml) and Mycobacterium smegmatis (MIC: 0.313 mg/ml). Similarly, the fraction
displayed significant cytotoxicity against the human liposarcoma SW872 cells with IC50 value of
44.34 ± 2.64 μg/ml and GFP re-activation capacity of 43.79 ± 3.19% (p < 0.05). This work
conveys interesting data on the antioxidant, antimicrobial, and anticancer properties of N. exigua.
In particular, this study indicates the promising potential of N. exigua as a reservoir of epigenetically
active agents that can modulate transcription of silenced genes involved in carcinogenesis.
Hence, further investigations to isolate the active constituents is actively warranted.
