COMPARATIVE BIOCHEMICAL CHARACTERISTICS OF THE METHANOLIC LEAVES EXTRAC T OF LAPORTEA AESTUANS (LINN.) CHEW AND LAPORTEA OVALIFOLIA (SCHUMACH AND THONN) CHEW (URTICACEAE): ANTIOXIDANT, ANTIDIABETIC POTENTIAL AND CHEMOTAXONOMIC IMPLICATIONS

Laportea aestuans and Laportea ovalifolia (Urticaceae) are stinging herbs used in West and Central African ethnomedicine, yet they resemble each other so closely that they are easily confused in the field and in the preparation of herbal remedies. This study compared the biochemical profiles of their methanolic leaf extracts as a possible chemotaxonomic complement to morphological identification. Leaves were collected on the Obafemi Awolowo University campus, Ile-Ife, were extracted by cold maceration, and the extract were assessed for percentage yield, qualitative phytochemical composition, total phenolic content (TPC), total flavonoid content (TFC), total antioxidant capacity (TAC), ferric reducing antioxidant power (FRAP), hydroxyl radical scavenging activity (HRSA), DPPH radical scavenging, α-amylase and α-glucosidase inhibition. L. aestuans was the only species to test positive for steroids, it gave the higher yield (14.23%) than L. ovalifolia (6.81%), TPC (3.47 ± 0.01 mg GAE/g), TFC (5.15 ± 0.41 mg GAE/g), FRAP (30.08 ± 2.33 µmol Fe2+/g), and it was the better hydroxy radical scavenging (IC50 0.2 mg/mL) and DPPH radical scavenging (IC50 0.22 mg/mL while L. ovalifolia did not reach the 50% inhibition). L. ovalifolia on the other hand had the higher TAC (133.1 ± 2.1 mg AAE/g), and inhibited α-amylase more strongly (IC50 0.2 mg/mL) than acarbose (IC50 0.37 mg/mL). Both extracts inhibited α-glucosidase more strongly than acarbose. The two species therefore carry distinct but complementary biochemical profiles, which supports the use of biochemical profiling as a supporting chemotaxonomic tool in Laportea and give laboratory backing to the traditional antidiabetic reputation of L. ovalifolia.