4,8-Dihydroxy-5-methoxy-2-naphthaldehyde (Compound I) was isolated from blackened heartwood of Diospyros kaki and was methylated with diazomethane. Antioxidant and cytotoxic activities of Compound I and two methylated derivatives [4-hydroxy-5,8-dimethoxy-2-(2oxopropyl)-naphthalene (D-1) and 2-glycidyl-4-hydroxy-5,8-dimethoxy naphthalene (D-2)] were evaluated. Compound I showed higher 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity and reducing power than D-1 and D-2. However, D-1 and D-2 exhibited slightly stronger 2,2-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) + (ABTS + ) radical scavenging activity than Compound I. Compound I also exhibited stronger cytotoxic activity than D-1 and D-2 against the growth of HT-29 colon cancer cells. The results supported the hypothesis that methylation of naphthalene derivatives slightly increased ABTS + radical scavenging activity, but signifi cantly decreased DPPH radical scavenging activity, reducing power, and cytotoxic activity.

No abstract

This study was performed to investigate the physiological activities of stings of Gleditsia sinensis extracts. Antioxidant activity was evaluated by measuring total phenolic contents (TPC), comet assay, and 2.2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity (RSA). Anti-diabetic activity was measured by inhibition activities on α-glucosidase. Stings of Gleditsia sinensis extracts were prepared by extracting them with methanol and ethanol. The methanolic extracts showed the highest phenol content (1.12 g/100 g gallic acid equivalents). The α-glucosidase inhibitory activity of methanol extracts were 17.9% higher, and that of ethanol extracts were 10.3% higher at a concentration of 1 mg/ml. These results indicate that stings of Gleditsia sinensis might be potential candidates as antioxidant and anti-diabetic agents.

No abstract

Ola leaf manuscripts from Sri Lanka date back to several centuries. While they have been well preserved over the last century, their condition has worsened in recent years when black dots caused by microorganisms started occurring on their surface. In this study, the current state of preservation and the factors causing deterioration are examined using microscopy techniques. Microscopic images clearly show that the manuscripts are contaminated by microorganisms which penetrated deeply into the carrier material, destroying the internal structure. A Penicillium griseofulvum strain was recognized as the most active microorganism in xylan degradation. Sri Lanka’s climate provides favorable conditions for the growth of these fungi. Therefore, it is suggested that temperature and humidity of the archival space should be better controlled in order to ensure the Ola leaf manuscripts’ long-term preservation.