Studies on Phytochemicals and Bioactivities of Methanolic Extract of Leucaena leucocephala (Lam.) de Wit Fruit Pods

Objectives: The study was designed to screen for the phytochemical constituents, and investigate the antioxidant, antibacterial, and anti-inflammatory activities of Leucaena leucocephala fruit pods methanolic extract (LLFPME).

Materials and Methods: Matured and dried fruit pods were pulverized and extracted with methanol using maceration method. The filtrate was concentrated in a rotary evaporator under reduced pressure to obtain powdery form termed LLFPME. The LLFPME was tested for the presence of phytochemicals using TLC and GC-MS technique. The phenolic and flavonoid contents of the extract were quantified; the antioxidant potential of the extract was examined using DPPH and H2O2 radical scavenging, metal chelating, FRAP and TAC assays. The anti-inflammatory potential was evaluated using the membrane stabilizing and lipoxygenase inhibitory activities while the antibacterial activity was investigated by determining the zone of inhibition, minimum inhibition concentration (MIC) and minimum bactericidal concentration (MBC) of extract against the test bacterial isolates.

Results: TLC revealed the presence of flavonoids, saponins, alkaloids, tannins, and others while the GC-MS analysis also showed the presence of 27 compounds. It was shown that the LLFPME displayed measurable antioxidant activity by exhibiting DPPH and H2O2 free radical scavenging potential and dose dependent metal chelating ability. FRAP and TAC were estimated to be 14.88 ± 0.04 and 25.53 ± 0.21 mgAAE/g of extract, respectively. The extract protected the RBC membrane integrity of RBC subjected to heat and hypotonic stress; and inhibited the activity of lipoxygenase. The extract inhibited the growth of some bacterial strains but had no visible effect on Pseudomonas aeuroginosa growth. The zone of inhibition, MIC and MBC exhibited by the extract against susceptible test bacteria ranges between 13 - 17 mm, 2.5 - 20 and 20 mg/ml, respectively..

Conclusion: It was concluded that LLFPME exhibited antioxidant potential through various mechanisms that possibly aided its ability to stabilize stressed cell membrane and similarly inhibited the growth of some bacterial strain.