In vitro anti-infective and antioxidant activities of Garcinia cola Heckel and Morinda lucida Benth

Abstract

Garcinia cola also known as “bitter cola” (Guttiferae) is a plant with a wide usage of its parts for various medicinal purposes. The seeds are chewed as aphrodisiac and for the treatment of coughs, dysentery and liver inflammation. Morinda lucida (Rubiaceae) commonly called “great morinda” has been shown to have antimalarial and anti-pyretic activities. This study aimed at evaluating the anti-infective and antioxidant properties of G. cola and M. lucida and to justify their folkloric uses. Ethanol extracts of the stem barks of G. cola (GCB) and M. lucida (MLB) were evaluated for their antimicrobial, anthelmintic and antioxidant activities. Antimicrobial activity was evaluated by determining the minimum inhibitory concentrations (MIC) using the micro broth dilution method against strains of Staphylococcus aureus, Streptococcus pyogenes, Escherichia coli, Pseudomonas aeruginosa, Salmonella typhi and Candida albicans. Anthelmintic activity was evaluated by determining the effects of the extracts on the paralytic and death times of Pheretima posthuma at concentrations of 50, 20 and 10 mg/mL using piperazine citrate (PZN) (15 mg/mL) and albendazole (ABZ) (20 mg/mL) as references. Antioxidant activity was determined by 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging activity using ascorbic acid (ASA) as reference standard. The results reveal that the extracts from both plants demonstrated antimicrobial activity with MIC values ranging from 50 to 80 mg/mL and 10 to 30 mg/mL for GCB and MLB, respectively. Both extracts also demonstrated a concentration dependent anthelmintic activity with decrease in paralytic and death times upon an increase in extract concentrations. GCB and MLB extract showed antioxidant activities with IC50 values, 6.830 and 342.1 µg/mL, respectively. Phytochemical screening of both extracts revealed the presence of tannins, glycosides, alkaloids and flavonoids. These findings may justify the folkloric uses of these plants.