METHODS: In this work, the biochemical potential of M. buxifolia (Falc.) A. DC was explored and linked with its biological activities. Methanol and chloroform extracts from leaves and stems were investigated for total phenolic and flavonoid contents. Ultrahigh-performance liquid chromatography coupled with mass spectrometry (UHPLC-MS) was used to determine secondary-metabolite composition, while high-performance liquid chromatography coupled with photodiode array detection (HPLC-PDA) was used for polyphenolic quantification. In addition, we carried out in vitro assays to determine antioxidant potential and the enzyme-inhibitory response of M. buxifolia extracts.
RESULTS: Phenolics (91 mg gallic-acid equivalent (GAE)/g) and flavonoids (48.86 mg quercetin equivalent (QE)/g) exhibited their highest concentration in the methanol extract of stems and the chloroform extract of leaves, respectively. UHPLC-MS analysis identified a number of important phytochemicals, belonging to the flavonoid, phenolic, alkaloid, and terpenoid classes of secondary metabolites. The methanol extract of leaves contained a diosgenin derivative and polygalacin D, while kaempferol and robinin were most abundant in the chloroform extract. The methanol extract of stems contained a greater peak area for diosgenin and kaempferol, whereas this was true for lucidumol A and 3-O-cis-coumaroyl maslinic acid in the chloroform extract. Rutin, epicatechin, and catechin were the main phenolics identified by HPLC-PDA analysis. The methanol extract of stems exhibited significant 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid (ABTS) radical-scavenging activities (145.18 and 279.04 mmol Trolox equivalent (TE)/g, respectively). The maximum cupric reducing antioxidant capacity (CUPRAC) (361.4 mg TE/g), ferric-reducing antioxidant power (FRAP) (247.19 mg TE/g), and total antioxidant potential (2.75 mmol TE/g) were depicted by the methanol extract of stems. The methanol extract of leaves exhibited stronger inhibition against acetylcholinesterase (AChE) and glucosidase, while the chloroform extract of stems was most active against butyrylcholinesterase (BChE) (4.27 mg galantamine equivalent (GALAE)/g). Similarly, the highest tyrosinase (140 mg kojic-acid equivalent (KAE)/g) and amylase (0.67 mmol acarbose equivalent (ACAE)/g) inhibition was observed for the methanol extract of stems.
CONCLUSIONS: UHPLC-MS analysis and HPLC-PDA quantification identified a number of bioactive secondary metabolites of M. buxifolia, which may be responsible for its antioxidant potential and enzyme-inhibitory response. M. buxifolia can be further explored for the isolation of its active components to be used as a drug.
RESULTS: Higher calcium concentrations (1.5 and 2% w/v) increased calcium concentration in the peel and pulp tissues, maintained firmness, and reduced anthracnose incidence and severity. While leakage of calcium-treated fruit was lower for 1.5 and 2% calcium treatments compared to the control, microscopic results confirmed that pulp cell wall thickness was higher after 6 days in storage, for the 2% calcium treatment compared to the control. Calcium-treated fruit also had higher total antioxidant activity and total phenolic compounds during storage.
CONCLUSION: Calcium chloride, especially at higher concentrations, is effective in maintaining papaya fruit quality during ambient storage. © 2015 Society of Chemical Industry.