Rosea1 (Ros1) and Delila (Del) co-expression controls anthocyanin accumulation in snapdragon flowers, while their overexpression in tomato strongly induces anthocyanin accumulation. However, little data exist on how Del expression alone influences anthocyanin accumulation. In tobacco (Nicotiana tabacum ‘Xanthi’), Del expression enhanced leaf and flower anthocyanin production through regulating NtCHS, NtCHI, NtF3H, NtDFR, and NtANS transcript levels. Transgenic lines displayed different anthocyanin colors (e.g., pale red: T0-P, red: T0-R, and strong red: T0-S), resulting from varying levels of biosynthetic gene transcripts. Under salt stress, the T2 generation had higher total polyphenol content, radical (DPPH, ABTS) scavenging activities, antioxidant-related gene expression, as well as overall greater salt and drought tolerance than wild type (WT). We propose that Del overexpression elevates transcript levels of anthocyanin biosynthetic and antioxidant-related genes, leading to enhanced anthocyanin production and antioxidant activity. The resultant increase of anthocyanin and antioxidant activity improves abiotic stress tolerance.

Agrimonia pilosa L. (AP) showed potent α-glucosidase inhibitory (AGI) activity, but it is uncertain what phytochemicals play a key factor. The phytochemical study of AP based on AGI activity led to the isolation of four isocoumarins; agrimonolide (1), agrimonolide-6-O-β-d-glucopyranoside (2), desmethylagrimonolide (3), desmethylagrimonolide-6-O-β-d-glucopyranoside (4), and four flavonoids; luteolin (5), quercetin (6), vitexin (7), and isovitexin (8). The four isocoumarins were isolated as α-glucosidase inhibitors for the first time. Isocoumarins, compound 1 (agrimonolide) and 3 (desmethylagrimonolide) showed strong α-glucosidase inhibitory activities with IC₅₀ values of 24.2 and 37.4 µM, respectively. Meanwhile, isocoumarin and flavonoid glycosides showed weak AGI activity. In the kinetic analysis, isocoumarins, compounds 1 and 3 showed non-competitive inhibition, whereas flavonoid, compound 6 showed competitive inhibition.

Extracts from the pericarp, placenta and stalk of red pepper (Capsicum annuum L) were investigated to determine their antioxidant and in vitro inhibitory potential against key enzymes relevant for hyperglycemia and hypertension. We examined the total phenolic and capsaicin content in red pepper extract. Anti-hyperglycemia relevant in vitro α-glucosidase inhibitory activity correlated strongly to the antioxidant activity measured by the 1, 1-diphenyl-2-picrylhydrazyl method. The high phenolic and capsaicin content-containing red pepper stalk was found to have strong α-amylase and strong α-glucosidase inhibitory effects. The pericarp and placenta had high angiotensin I-converting enzyme (ACE) inhibitory activity and also had good α-glucosidase inhibitory profiles. Inhibition of these enzymes provides a strong biochemical basis for the management of type 2 diabetes by controlling glucose absorption and reducing associated hypertension, respectively. Practical Applications The inhibitory effect on key enzymes relevant for hyperglycemia (α-glucosidase and α-amylase) and hypertension (ACE) of the red pepper pericarp, placenta and stalk was investigated in this study. The in vitro inhibitory activities of α-amylase, α-glucosidase and ACE provide a strong biochemical rationale for further in vivo studies for type 2 diabetes through the control of glucose absorption and for the reduction of the associated hypertension. Furthermore, red pepper stalk, which has always been considered as an agricultural waste product, was an effective inhibitor of α-glucosidase and α-amylase. This study shows the potential of this agricultural waste product as a food additive and therapeutic agent for clinical applications.