Background Spondias mombin Linn. is a tropical climate plant with wide applications in ethnomedicinal practice. This study evaluates the phytotoxicity, cytotoxicity and chemical composition of the plant’s stem bark. Methods Dried stem bark sample of Spondias mombin Linn. was subjected to exhaustive extraction and partitioned into sub-fractions (hexane-ethylacetate, ethylacetate, ethylacetate-methanol and methanol) by graded polarity technique. The phytotoxicity and cytotoxicity indices of the crude hydro-ethanol extract and fractions were evaluated using Lemna minor and brine shrimp lethality assays, respectively, while chemical composition of the oily hexane:ethylacetate fraction was determined by gas chromatography-mass spectroscopy (GC-MS) technique. Results Phytotoxicity was dose-dependent which ranged from low (crude plant extract), moderate (hexane-ethylacetate and methanol fractions), high (ethylaacetate-methanol fraction) to significant toxicity (ethylacetate fraction) at the highest dose. However, for brine shrimp lethality assay only hexane-ethylacetate (LD50: 284.02 μg/mL) and ethylacetate (LD50: 210.24 μg/mL) fractions were cytotoxic at the highest dose. The GC-MS profile of the oily hexane:ethylacetate fraction identified sixty-eight compounds comprising hydrocarbons, fatty acids, alcohols, steroids, nitrogen and fluoride-containing compounds, terpenes and esters. Conclusion This study concludes that fractions of Spondias mombin Lin. could be potentially toxic. While its phytotoxic potential can be useful in the agrochemical industry for the production of natural herbicides, its cytotoxic property can be cautiously harnessed for ethnomedicinal purposes.

Background: Tetracarpidium conophorum (African walnut) is an African plant with ethnobotanical uses. Objectives: The purpose of this study was to evaluate the phytochemical screening and in vitro antioxidant activities of methanol extract and fractions (F) [n-hexane (HEX-F), dichloromethane (DCM-F) and, ethyl acetate (EA-F)] of T. conophorum seeds. Methods: Phytochemical screening and in vitro antioxidant activity study were carried out using DPPH, ABTs radical scavenging assays, nitric oxide inhibitory and reducing potential assays. Results: Methanol extract and its fractions contain phenols, flavonoids, saponins, tannins, terpenoids, and alkaloids. The concentrations of total phenols and flavonoids content were significantly higher in EA-F and crude methanol extract compared to other fractions. Crude methanol and EA-F contain higher concentrations of tannin while hexane fraction had the lowest tannin content but relatively higher proanthocyanidin content compared to other fractions. The antioxidant activity study showed that both methanol crude extract and fractions of T. conophorum seeds have significant activities for DPPH radical scavenging, reducing power, ferric reducing antioxidant potential, nitric oxide inhibitory activities, ABTS and hydroxyl radical scavenging for. DPPH radical scavenging activities of EA-F showed the lowest IC50 of 33.11 µg/mL, followed by Hex-F, DCM-F and crude methanol extract with IC50 of 33.43, 42.09 and 45.44 µg/mL, respectively, when compared to ascorbic acid with IC50 of 17.08 µg/mL. Conclusion: The study showed that T. conophorum seed is a rich source of secondary metabolites, which may be responsible for its antioxidant activities.

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