Antimicrobial and antioxidant activities of Psydrax subcordata and Acioa dinklaglei

Psydrax subcordata (D. C. Bridson) (Family: Rubiaceae) and Acioa dinklagei (Engl.) (Family: Chrysobalanaceae) are plants widely distributed in the tropical region of West Africa. Leaves and stem bark of P. subcordata and the leaves of A. dinklagei are used to treat wound infections in West Africa. The aim of this study was to determine the antimicrobial and antioxidant activities of P. subcordata and A. dinklagei [1].

Preliminary phytochemical screening was carried out on the methanol leaf (PSLE) and stem bark (PSSE) extracts of P. subcordata and methanol leaf (ADLE) extract of A. dinklaglei to identify their phytochemical constituents [2]. The antimicrobial activity of PSLE, PSSE and ADLE were evaluated using the broth dilution method [3]. Antioxidant activities of the PSLE, PSSE and ADLE were determined using 1,1-diphenyl-2-picryl hyrdazyl [4].

MIC of PSLE was 12.5 mg/mL against test organisms. MIC of PSSE against test organisms was 25 mg/mL except P. aeruginosa (12.5 mg/mL). MICs of ADLE against B. subtilis, E. coli, S. pyogenes and P. aeruginosa were 2.5, 20, 10 and 5 mg/mL, respectively (Table 1). PSLE, PSSE and ADLE exhibited antioxidant activity with IC₅₀ of 7.0 ± 0.0016, 99.0 ± 0.0022 and 96.0 ± 0.017 µg/mL. Tannins, saponins, flavonoids and glycosides were identified in PSLE, PSSE and ADLE.

PSLE, PSSE and ADLE possess antimicrobial and antioxidant activities.

Tab. 1: MICs of PSLE, PSSE and ADLE against test organisms

Test organisms	MIC (mg/mL)
	PSLE	PSSE	ADLE
B. subtilis NTCC 10073	12.5	25.0	2.5
E. coli ATCC 25922	12.5	25.0	20.0
S. pyogenes (clinical strain)	12.5	25.0	10.0
P. aeruginosa ATCC 4833	12.5	12.5	5.0

[1] Agyare et al, J. Ethnopharmacol 2009; 125: 393 – 403

[2] Evans, WC. Trease and Evans Pharmacognosy 16th ed. Williams & Wilkins, Baltimore; 2009:1788

[3] Wiengand et al, Nat. Protoc 2008; 3:163 – 175

[4] Chizzola et al, J. Agric Food Chem 2008; 56:6897 – 6904