Multiple pharmacological targets, cytotoxicity, and phytochemical profile of Aphloia theiformis (Vahl.) Benn.

Aphloia theiformis (Vahl.) Benn. (AT) is traditionally used in Sub-Saharan African countries including Mauritius as a biomedicine for the management of several diseases. However, there is a dearth of experimental studies to validate these claims. We endeavoured to evaluate the inhibitory effects of crude aqueous extract as traditionally used together with the crude methanol extracts of AT leaves on urease, angiotensin (I) converting enzyme (ACE), acetylcholinesterase (AChE), cholesterol esterase (CEase), glycogen phosphorylase a (GPa), and glycation in vitro. The crude extract showing potent activity against the studied enzymes was further partitioned using different solvents of increasing polarity. The enzyme inhibitory and antiglycation activities of each fraction was assessed. Kinetic of inhibition of the active crude extract/fractions on the aforementioned enzymes was consequently determined using Lineweaver-Burk plots. An ultra-high performance liquid chromatography (UHPLC-UV/MS) system was used to establish the phytochemical profile of AT. The real time cell analysis system (iCELLigence™) was used to monitor any cellular cytotoxicity of AT. Crude methanolextract (CME) was a potent inhibitor of the studied enzymes, with IC50 ranging from 696.22 to 19.73µg/mL. CME (82.5%) significantly (p<0.05) inhibited glycation and was comparable to aminoguanidine (81.5%). Ethyl acetate and n-butanol fractions of CME showed non-competitive, competitive, and uncompetitive mode of inhibition against ACE, CEase, and AChE respectively. Mangiferin, a xanthone glucoside was present in CME, ethyl acetate, and n-butanol fractions. Active extract/fractions were found to be non-cytotoxic (IC50>20µg/mL) according to the U.S National Cancer Institute plant screening program. This study has established baseline data that tend to justify the traditional use of AT and open new avenues for future biomedicine development.

Effects of Aphloia theiformis on key enzymes related to diabetes mellitus.

CONTEXT: Aphloia theiformis (Vahl.) Benn. (Flacourtiaceae) (AT) is traditionally used for the management of diabetes mellitus (DM), but there is no scientific data regarding activity against enzymes linked to this condition. OBJECTIVE: To evaluate the kinetics of AT on key enzymes inhibition related to DM, and establish the antioxidant profile of AT. MATERIALS AND METHODS: Dried powdered AT leaves were used to prepare crude methanol extract (70% v/v) (CME). Kinetics of CME (5000 to 156.25 µg/mL) on α-amylase, α-glucosidase, and lipase inhibition were studied. CME was partitioned using solvents of increasing polarity and kinetics of enzyme inhibition of each fraction (1000-31.25 µg/mL) was evaluated. Potent fractions were combined to assess any synergistic effect. Total phenol, flavonoid, tannin, anthocyanin contents, and antioxidant capacity of AT was evaluated using standard spectrophotometric methods. RESULTS: CME, ethyl acetate, and n-butanol fractions showed potent inhibitory activities against the enzymes with IC50 ranging from 22.94-939.97 µg/mL. Significant (p < 0.05) reduction in IC50 (15.72 and 157.03 µg/mL against α-amylase and lipase, respectively) was observed when ethyl acetate and n-butanol fractions were combined; showing synergism. The extracts showed noncompetitive inhibition against α-amylase and α-glucosidase. Ethyl acetate, n-butanol fractions, and CME showed highest antioxidant capacities (0.44-1.41 µg GAE/mg sample), and phenol content (211.74-675.53 µg GAE/mg sample). CONCLUSION: This study supports the use of AT in the management of DM and provides the rationale for bioactivity guided isolation and characterization of compounds from the ethyl acetate and n-butanol fractions.