Plant Terpenoids as the Promising Source of Cholinesterase Inhibitors for Anti-AD Therapy

Simple Summary

Plant-derived terpenes have been a research interest in the recent years, as they are believed to possess the ability to function as a cholinesterase inhibitor. As the deficit of cholinergic activity is one of the factors that causes cognitive impairment in Alzheimer’s disease patients, it serves as a great therapeutic target. It has been found that various terpenoids, such as diterpenoids, triterpenoids and sesquiterpenoids, do have the ability to inhibit cholinesterase activity, and their chemical structures do play a role in this. As terpenoids possess anti-cholinesterase properties, it is encouraged to have future research on drug discovery and development in treating Alzheimer’s disease.

Abstract

Plant-derived terpenes are the prolific source of modern drugs such as taxol, chloroquine and artemisinin, which are widely used to treat cancer and malaria infections. There are research interests in recent years on terpene-derived metabolites (diterpenes, triterpenes and sesquiterpenes), which are believed to serve as excellent cholinesterase inhibitors. As cholinesterase inhibitors are the current treatment for Alzheimer’s disease, terpene-derived metabolites will have the potential to be involved in the future drug development for Alzheimer’s disease. Hence, a bibliographic search was conducted by using the keywords “terpene”, “cholinesterase” and “Alzheimer’s disease”, along with cross-referencing from 2011 to 2020, to provide an overview of natural terpenes with potential anticholinesterase properties. This review focuses on the extraction, chemical structures and anti-cholinesterase mechanisms of terpenes, which support and encourage future research on drug discovery and development in treating Alzheimer’s disease.

Rapid spheroid assays in a 3-dimensional cell culture chip

Objective

The spheroid model provides a physiological platform to study cancer cell biology and drug sensitivity. Usage of bovine collagen I for spheroid assays is costly especially when experiments are conducted in 24-well plates, as high volume of bovine collagen I is needed. The aim of the study was to downsize spheroid assays to a microfluidic 3D cell culture chip and compare the growth, invasion and response to drug/compound of spheroids embedded in the 3D chip to spheroids embedded in 24-well plates.

Results

Spheroids generated from nasopharyngeal carcinoma cell line HK-1 continuously grew and invaded into collagen matrix in a 24-well plate. Similar observations were noticed with spheroids embedded in the 3D chip. Large spheroids in both 24-well plate and the 3D chip disintegrated and invaded into the collagen matrix. Preliminary drug sensitivity assays showed that the growth and invasion of spheroids were inhibited when spheroids were treated with combination of cisplatin and paynantheine at high concentrations, in a 24-well plate. Comparable findings were obtained when spheroids were treated with the same drug combination in the 3D chip. Moving forward, spheroid assays could be performed in the 3D chip in a more high-throughput manner with minimal time and cost.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13104-021-05727-0.

Is kratom (Mitragyna speciosa Korth.) use associated with ECG abnormalities? Electrocardiogram comparisons between regular kratom users and controls

OBJECTIVES

Little is known about the cardiotoxic effects of kratom (Mitragyna speciosa Korth.), a medicinal plant. This analytical cross-sectional study investigated the prevalence of electrocardiogram (ECG) abnormalities and QTc intervals in regular kratom users compared with non-kratom-using control subjects.

METHODS

We enrolled regular kratom users and non-kratom-using control subjects from three communities. Demographic data, clinical data, kratom use characteristics, and ECG findings were recorded. The mitragynine content of kratom juice was quantified using a validated gas chromatography-mass spectrometry (GC-MS) method.

RESULTS

A total of 200 participants (100 kratom users and 100 control subjects) participated in this study. The prevalence of ECG abnormalities in kratom users (28%) did not differ from that of control subjects (32%). Kratom use was not associated with ECG abnormalities, except for significantly higher odds of sinus tachycardia (OR = 8.61, 95% CI = 1.06-70.17, p = 0.035) among kratom users compared with control subjects. The odds of observing borderline QTc intervals were significantly higher for kratom users compared with control subjects, regardless of the age of first use, the duration of use, the daily quantity consumed, and the length of time that had elapsed between last kratom use and ECG assessment. Nevertheless, there were no differences in the odds of having prolonged QTc intervals between kratom users and controls. The estimated average daily intake of mitragynine consumed by kratom users was 434.28 mg.

CONCLUSION

We found no link between regular kratom use and electrocardiographic abnormalities with an estimated average daily intake of 434.28 mg of mitragynine.

Patterns and reasons for kratom (Mitragyna speciosa) use among current and former opioid poly-drug users

ETHNOPHARMACOLOGICAL RELEVANCE

Kratom (Mitragyna speciosa) is a native medicinal plant of Southeast Asia widely reported to be used to reduce opioid dependence and mitigate withdrawal symptoms. There is also evidence to suggest that opioid poly-drug users were using kratom to abstain from opioids.

AIM OF THE STUDY

To determine the patterns and reasons for kratom use among current and former opioid poly-drug users in Malaysia.

MATERIALS AND METHODS

A total of 204 opioid poly-drug users (142 current users vs. 62 former users) with current kratom use history were enrolled into this cross-sectional study. A validated UPLC-MS/MS method was used to evaluate the alkaloid content of a kratom street sample.

RESULTS

Results from Chi-square analysis showed that there were no significant differences in demographic characteristics between current and former opioid poly-drug users except with respect to marital status. Current users had higher odds of being single (OR: 2.2: 95%CI: 1.21-4.11; p < 0.009). Similarly, there were no significant differences in the duration (OR: 1.1: 0.62-2.03; p < 0.708), daily quantity (OR: 1.5: 0.85-2.82; p < 0.154) or frequency of kratom use between current and former opioid poly-drug users (OR: 1.1: 0.62-2.06; p < 0.680). While both current and former opioid users reported using kratom to ameliorate opioid withdrawal, current users had significantly higher likelihood of using kratom for that purpose (OR: 5.4: 95%CI: 2.81-10.18; p < 0.0001). In contrast, former opioid users were more likely to be using kratom for its euphoric (mood elevating) effects (OR: 1.9: 95%CI: 1.04-3.50; p < 0.035). Results from the UPLC-MS/MS analysis indicated the major alkaloids present in the representative kratom street sample (of approximately 300 mL of brewed kratom) were mitragynine, followed by paynantheine, speciociliatine and speciogynine, as well as low levels of 7-hydroxymitragynine.

CONCLUSIONS

Both current and former opioid poly-drug users regularly used kratom (three glasses or about 900 mL daily or the equivalent of 170.19 mg of mitragynine) to overcome opioid poly-drug use problems.

Self-reported prevalence and severity of opioid and kratom (Mitragyna speciosa korth.) side effects

ETHNOPHARMACOLOGICAL RELEVANCE

Mitragyna speciosa (Korth.) is a traditional medicinal plant widely used in Southeast Asia for its opioid-like effects. Although kratom produces analgesia through binding of mitragynine and other alkaloids at the mu-opioid receptor (MOR), the association of long-term kratom use with adverse opioid-like effects remains unknown.

AIM OF THE STUDY

To determine the self-reported prevalence and severity of opioid-related adverse effects after kratom initiation in a cohort of illicit opioid users.

MATERIALS AND METHODS

A total of 163 illicit opioid users with current kratom use history were recruited through convenience sampling from the northern states of Peninsular Malaysia. Face-to-face interviews were conducted using a semi-structured questionnaire.

RESULTS

Respondents were all males, majority Malays (94%, n = 154/163), with a mean age of 37.10 years (SD = 10.9). Most were single (65%, n = 106/163), had 11 years of education (52%, n = 85/163) and employed (88%, n = 144/163). Half reported using kratom for over >6 years (50%, n = 81/163), and 41% consumed >3 glasses of kratom daily (n = 67/163). Results from Chi-square analysis showed kratom initiation was associated with decreased prevalence of respiratory depression, constipation, physical pain, insomnia, depression, loss of appetite, craving, decreased sexual performance, weight loss and fatigue.

CONCLUSIONS

Our findings indicate that kratom initiation (approximately 214.29 mg of mitragynine) was associated with significant decreases in the prevalence and severity of opioid adverse effects.

Motives for using Kratom (Mitragyna speciosa Korth.) among regular users in Malaysia

ETHNOPHARMACOLOGICAL RELEVANCE

The leaves of Mitragyna speciosa (Korth.) or kratom have been traditionally used in Malaysia and Thailand mainly to enhance work productivity, as a folk remedy for treating common ailments, and as a mood enhancer.

AIM OF THE STUDY

This present study sought to investigate kratom use motives among regular kratom users in Malaysia.

MATERIALS AND METHODS

A total of 116 regular kratom users were recruited for this cross-sectional survey. The Drinking Motives Questionnaire (DMQ) was administered to measure kratom use motives.

RESULTS

Our results indicate that heavy (>3 glasses daily, each glass contains 48.24-50.4 mg of mitragynine) kratom use was associated with coping (t_87.09 =3.544, p < 0.001), and enhancement (t₁₁₄ =2.180, p = 003). Single subjects had higher mean scores on the coping domain, relative to married subject (t_113.89 =3.029, p < 0.003), while those earning more than RM1500 per month had higher mean scores on the enhancement domain, compare to those earning less than RM1500 per month (t₁₀₇ =2.151, p < 0.034). Higher scores on the coping domain was significantly associated with higher (>3 glasses daily) kratom consumption (p < 0.0045).

CONCLUSIONS

Coping was associated with high (>3 glasses daily) kratom consumption among regular kratom users in traditional, rural settings.

Assessment of gonadotropins and testosterone hormone levels in regular Mitragyna speciosa (Korth.) users

ETHNOPHARMACOLOGICAL RELEVANCE

Mitragyna speciosa (Korth.) also known as kratom, is a native medicinal plant of Southeast Asia with opioid-like effects. Kratom tea/juice have been traditionally used as a folk remedy and for controlling opiate withdrawal in Malaysia. Long-term opioid use is associated with depletion in testosterone levels.

AIM OF THE STUDY

Since kratom is reported to deform sperm morphology and reduce sperm motility, we aimed to clinically investigate the testosterone levels following long-term kratom tea/juice use in regular kratom users.

METHODS

A total of 19 regular kratom users were recruited for this cross-sectional study. A full-blood test was conducted including determination of testosterone level, follicle stimulating hormone (FSH) and luteinizing hormone (LH) profile, as well as hematological and biochemical parameters of participants.

RESULTS

We found long-term kratom tea/juice consumption with a daily mitragynine dose of 76.23-94.15 mg did not impair testosterone levels, or gonadotrophins, hematological and biochemical parameters in regular kratom users.

CONCLUSION

Regular kratom tea/juice consumption over prolonged periods (>2 years) was not associated with testosterone impairing effects in humans.

Evaluating the hematological and clinical-chemistry parameters of kratom (Mitragyna speciosa) users in Malaysia

ETHNOPHARMACOLOGICAL RELEVANCE

Kratom (Mitragyna speciosa Korth.) from the Rubiaceae family is an indigenous tropical medicinal tree of Southeast Asia. Kratom leaves have been used for decades in Malaysia and Thailand in traditional context for its perceived vast medicinal value, and as a mild stimulant among manual labourers. Kratom consumption has been reported to cause side-effects in kratom users.

AIM OF THE STUDY

To evaluate kratom's effects towards hematological and clinical-chemistry parameters among regular kratom users in Malaysia.

METHODS

A total of 77 subjects (n=58 regular kratom users, and n=19 healthy controls) participated in this cross-sectional study. All the surveys were conducted through face-to-face interview to elicit subject's socio-demographic characteristics and kratom use history. A full-blood test was also administered. Laboratory analysis was conducted using GC-MS to determine mitragynine content in the acquired kratom samples in order to relate mitragynine consumption with possible alterations in the blood parameters of kratom users.

RESULTS

Findings showed that there were no significant differences in the hematological and clinical-chemistry parameters of traditional kratom users and healthy controls, except for HDL and LDL cholesterol values; these were found to be above the normal reference range for the former. Similarly, long-term kratom consumption (>5 years), and quantity of daily kratom use (≥3 ½ glasses; mitragynine content 76.3-114.8mg) did not appear to alter the hematological and biochemical parameters of kratom users.

CONCLUSION

These data suggest that even long-term and heavy kratom consumption did not significantly alter the hematological and clinical-chemistry parameters of kratom users in a traditional setting.